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Vanderzwalmen M, Sánchez Lacalle D, Tamilselvan P, McNeill J, Delieuvin D, Behlouli K, Hursthouse A, McLellan I, Alexander ME, Henriquez FL, Snellgrove D, Sloman KA. The Effect of Substrate on Water Quality in Ornamental Fish Tanks. Animals (Basel) 2022; 12:ani12192679. [PMID: 36230419 PMCID: PMC9558538 DOI: 10.3390/ani12192679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 09/23/2022] [Accepted: 09/23/2022] [Indexed: 11/05/2022] Open
Abstract
Simple Summary Fish kept as pets are almost always held in tanks with substrate such as gravel or sand on the bottom of the tank. This may be added as a form of enrichment to encourage natural fish behaviours, or for aesthetic reasons. However, substrate can also harbour elevated levels of waste products and unwanted bacteria; therefore, whether the use of substrate in home aquaria is advantageous or disadvantageous has not been fully considered. Here, we investigated whether there was a difference in water quality in home aquaria that contained either no substrate (bare tanks), plastic plants as enrichment but no substrate, sand or gravel substrate. Water quality (e.g., temperature, oxygen, pH and ammonia) and the presence of bacteria were measured over a 7-week period. As water quality can also vary with the season, the study was repeated at different times of the year. Addition of both gravel and sand substrate resulted in increased pH and the waste products ammonia and nitrate. Substrate was also associated with a greater presence of bacteria. In conclusion, the use of substrate affected water quality, with further research needed on the use of substrate in home aquaria. Abstract Almost all home aquaria contain substrate, either as intentional enrichment or for aesthetic purposes. For fishes, benefits of structural enrichment have been well considered, particularly in research and aquaculture settings. However, our understanding of the impacts of tank substrate as enrichment is limited. While substrate can induce foraging in some species, a major drawback is the potential of substrate to harbour elevated levels of waste and pathogenic bacteria. Here, we considered whether substrate as a form of environmental enrichment significantly altered water quality and bacterial presence in home aquaria. Water quality (temperature, oxygen, pH, TAN, unionised ammonia, nitrate, Ca2+, Na+, Mg2+ and K+) and bacterial presence (Pseudomonas spp.) were measured over two seven-week periods in stand-alone, tropical, freshwater tanks that simulated home aquaria. The following four enrichment conditions were considered: bare tanks, plastic plants, gravel substrate or sand substrate. The addition of both gravel and sand resulted in increased pH, concentrations of total ammonia nitrogen and nitrate. Substrate was also associated with a greater Pseudomonas presence. Decreased pH alongside an increased concentration of ions were also observed depending on the time of year. In conclusion, enrichment type affected the water quality of home aquaria, with further research needed on the role of the tank biome in fish welfare.
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Affiliation(s)
- Myriam Vanderzwalmen
- Institute of Biomedical and Environmental Health Research, University of the West of Scotland, Paisley Campus, Paisley PA1 2BE, UK
| | - Daniel Sánchez Lacalle
- Institute of Biomedical and Environmental Health Research, University of the West of Scotland, Paisley Campus, Paisley PA1 2BE, UK
| | - Priyadarshini Tamilselvan
- Institute of Biomedical and Environmental Health Research, University of the West of Scotland, Paisley Campus, Paisley PA1 2BE, UK
| | - Jason McNeill
- Institute of Biomedical and Environmental Health Research, University of the West of Scotland, Paisley Campus, Paisley PA1 2BE, UK
| | - Dorine Delieuvin
- Institute of Biomedical and Environmental Health Research, University of the West of Scotland, Paisley Campus, Paisley PA1 2BE, UK
| | - Khadidja Behlouli
- Institute of Biomedical and Environmental Health Research, University of the West of Scotland, Paisley Campus, Paisley PA1 2BE, UK
| | - Andrew Hursthouse
- Institute of Biomedical and Environmental Health Research, University of the West of Scotland, Paisley Campus, Paisley PA1 2BE, UK
| | - Iain McLellan
- Institute of Biomedical and Environmental Health Research, University of the West of Scotland, Paisley Campus, Paisley PA1 2BE, UK
| | - Mhairi E. Alexander
- Institute of Biomedical and Environmental Health Research, University of the West of Scotland, Lanarkshire Campus, Glasgow G72 0LH, UK
| | - Fiona L. Henriquez
- Institute of Biomedical and Environmental Health Research, University of the West of Scotland, Lanarkshire Campus, Glasgow G72 0LH, UK
| | - Donna Snellgrove
- WALTHAM Petcare Science Institute, Freeby Lane, Waltham-on-the-Wolds, Leicestershire LE14 4RT, UK
| | - Katherine A. Sloman
- Institute of Biomedical and Environmental Health Research, University of the West of Scotland, Lanarkshire Campus, Glasgow G72 0LH, UK
- Correspondence:
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Alexander ME, Skein L, Robinson TB. Rapid learning in a native predator shifts diet preferences towards invasive prey. Biol Lett 2022; 18:20210655. [PMID: 35259942 PMCID: PMC8905153 DOI: 10.1098/rsbl.2021.0655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Biological invasions often exert negative impacts on native communities and can disrupt a range of biotic interactions such as those between predators and prey. For example, when invasive species alter the foraging landscape, native predators can fail to recognize them as profitable prey because of unfamiliarity. This study therefore investigated whether a native predator (rock lobster Jasus lalandii) can develop a new preference for an invasive prey (mussel Semimytilus patagonicus) following conditioning through a short-term exposure. Conditioned lobsters, exposed to only S. patagonicus for a month, demonstrated a significant change in preference for the novel invasive prey, which was found to contrast with non-conditioned lobsters that continued to show predator preferences toward a native mussel (Choromytilus meridionalis). There is therefore potential for native predators such as J. lalandii to adapt and switch towards feeding on an abundant invasive prey, even if they avoid it at first. This indicates that rapid learning can occur in a species exposed to novel food resources and demonstrates that native species can adapt to biological invasions.
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Affiliation(s)
- M E Alexander
- School of Health and Life Sciences, Institute of Biomedical and Environmental Health Research (IBEHR), University of the West of Scotland, High Street, Paisley PA1 2BE, UK
| | - L Skein
- Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Stellenbosch, South Africa
| | - T B Robinson
- Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Stellenbosch, South Africa
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DeRoy EM, Crookes S, Matheson K, Scott R, McKenzie CH, Alexander ME, Dick JTA, MacIsaac HJ. Predatory ability and abundance forecast the ecological impacts of two aquatic invasive species. NB 2022. [DOI: 10.3897/neobiota.71.75711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Characterising interspecific interaction strengths, combined with population abundances of prey and their novel predators, is critical to develop predictive invasion ecology. This is especially true of aquatic invasive species, which can pose a significant threat to the structure and stability of the ecosystems to which they are introduced. Here, we investigated consumer-resource dynamics of two globally-established aquatic invasive species, European green crab (Carcinus maenas) and brown trout (Salmo trutta). We explored the mediating effect of prey density on predatory impact in these invaders relative to functionally analogous native rock crab (Cancer irroratus) and Atlantic salmon (Salmo salar), respectively, feeding on shared prey (Mytilus sp. and Tenebrio molitor, respectively). We subsequently combined feeding rates with each predator’s regional abundance to forecast relative ecological impacts. All predators demonstrated potentially destabilising Type II functional responses towards prey, with native rock crab and invasive brown trout exhibiting greater per capita impacts relative to their trophic analogues. Functional Response Ratios (attack rates divided by handling times) were higher for both invasive species, reflecting greater overall per capita effects compared to natives. Impact projections that incorporated predator abundances with per capita effects predicted severe impacts by European green crabs. However, brown trout, despite possessing higher per capita effects than Atlantic salmon, are projected to have low impact owing to currently low abundances in the sampled watershed. Should brown trout density increase sixfold, we predict it would exert higher impact than Atlantic salmon. Such impact-forecasting metrics and methods are thus vital tools to assist in the determination of current and future adverse impacts associated with aquatic invasive species.
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Moore EM, Alexander ME, Sloman KA, Pereira MG, Thacker SA, Orton F. Laboratory-Based Comparison for the Effects of Environmental Stressors Supports Field Evidence for the Relative Importance of Pollution on Life History and Behavior of the Pond Snail, Lymnaea stagnalis. Environ Sci Technol 2021; 55:8806-8816. [PMID: 34167293 DOI: 10.1021/acs.est.1c01640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Biodiversity is declining at an alarming rate globally, with freshwater ecosystems particularly threatened. Field-based correlational studies have "ranked" stressors according to their relative effects on freshwater biota, however, supporting cause-effect data from laboratory exposures are lacking. Here, we designed exposures to elicit chronic effects over equivalent exposure ranges for three ubiquitous stressors (temperature: 22-28 °C; pollution [14 component mixture]: 0.05-50 μg/L; invasive predator cue [signal crayfish, Pacifasticus leniusculus]: 25-100% cue) and investigated effects on physiological end points in the pond snail (Lymnaeastagnalis). All stressors reduced posthatch survival at their highest exposure levels, however, highly divergent effects were observed at lower test levels. Temperature stimulated hatching, growth, and reproduction, whereas pollution delayed hatching, decreased growth, reduced egg number/embryo viability, and induced avoidance behavior. The invasive predator cue stimulated growth and reduced embryo viability. In agreement with field-based ranking of stressors, pollution was identified as having the most severe effects in our test system. We demonstrate here the utility of laboratory studies to effectively determine hierarchy of stressors according to their likelihood of causing harm in the field, which has importance for conservation. Finally, we report negative impacts on life-history traits central to population stability (survival/reproduction) at the lowest pollution level tested (0.05 μg/L).
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Affiliation(s)
- Emily M Moore
- School of Health and Life Sciences, University of the West of Scotland, Paisley, PA1 2BE Scotland
| | - Mhairi E Alexander
- School of Health and Life Sciences, University of the West of Scotland, Paisley, PA1 2BE Scotland
| | - Katherine A Sloman
- School of Health and Life Sciences, University of the West of Scotland, Paisley, PA1 2BE Scotland
| | - M Glória Pereira
- UK Centre for Ecology and Hydrology, Lancaster Environment Centre, Bailrigg, Lancaster LA1 4AP, United Kingdom
| | - Sarah A Thacker
- UK Centre for Ecology and Hydrology, Lancaster Environment Centre, Bailrigg, Lancaster LA1 4AP, United Kingdom
| | - Frances Orton
- School of Health and Life Sciences, University of the West of Scotland, Paisley, PA1 2BE Scotland
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Seraphim MJ, Sloman KA, Alexander ME, Janetski N, Jompa J, Ambo-Rappe R, Snellgrove D, Mars F, Harborne AR. Interactions between coral restoration and fish assemblages: implications for reef management. J Fish Biol 2020; 97:633-655. [PMID: 32564370 DOI: 10.1111/jfb.14440] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 06/01/2020] [Accepted: 06/18/2020] [Indexed: 06/11/2023]
Abstract
Corals create complex reef structures that provide both habitat and food for many fish species. Because of numerous natural and anthropogenic threats, many coral reefs are currently being degraded, endangering the fish assemblages they support. Coral reef restoration, an active ecological management tool, may help reverse some of the current trends in reef degradation through the transplantation of stony corals. Although restoration techniques have been extensively reviewed in relation to coral survival, our understanding of the effects of adding live coral cover and complexity on fishes is in its infancy with a lack of scientifically validated research. This study reviews the limited data on reef restoration and fish assemblages, and complements this with the more extensive understanding of complex interactions between natural reefs and fishes and how this might inform restoration efforts. It also discusses which key fish species or functional groups may promote, facilitate or inhibit restoration efforts and, in turn, how restoration efforts can be optimised to enhance coral fish assemblages. By highlighting critical knowledge gaps in relation to fishes and restoration interactions, the study aims to stimulate research into the role of reef fishes in restoration projects. A greater understanding of the functional roles of reef fishes would also help inform whether restoration projects can return fish assemblages to their natural compositions or whether alternative species compositions develop, and over what timeframe. Although alleviation of local and global reef stressors remains a priority, reef restoration is an important tool; an increased understanding of the interactions between replanted corals and the fishes they support is critical for ensuring its success for people and nature.
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Affiliation(s)
- Marie J Seraphim
- School of Health and Life Sciences, University of the West of Scotland, Paisley, UK
| | - Katherine A Sloman
- School of Health and Life Sciences, University of the West of Scotland, Paisley, UK
| | - Mhairi E Alexander
- School of Health and Life Sciences, University of the West of Scotland, Paisley, UK
| | | | - Jamaluddin Jompa
- Faculty of Marine Science and Fisheries, Hasanuddin University, Makassar, Indonesia
| | - Rohani Ambo-Rappe
- Faculty of Marine Science and Fisheries, Hasanuddin University, Makassar, Indonesia
| | - Donna Snellgrove
- Waltham Petcare Science Institute, Melton Mowbray, Leicestershire, UK
| | | | - Alastair R Harborne
- Institute of Environment and Department of Biological Sciences, Florida International University, North Miami, Florida, USA
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Cuthbert RN, Wasserman RJ, Dalu T, Kaiser H, Weyl OLF, Dick JTA, Sentis A, McCoy MW, Alexander ME. Influence of intra- and interspecific variation in predator-prey body size ratios on trophic interaction strengths. Ecol Evol 2020; 10:5946-5962. [PMID: 32607203 PMCID: PMC7319243 DOI: 10.1002/ece3.6332] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 04/07/2020] [Accepted: 04/14/2020] [Indexed: 01/18/2023] Open
Abstract
Predation is a pervasive force that structures food webs and directly influences ecosystem functioning. The relative body sizes of predators and prey may be an important determinant of interaction strengths. However, studies quantifying the combined influence of intra- and interspecific variation in predator-prey body size ratios are lacking.We use a comparative functional response approach to examine interaction strengths between three size classes of invasive bluegill and largemouth bass toward three scaled size classes of their tilapia prey. We then quantify the influence of intra- and interspecific predator-prey body mass ratios on the scaling of attack rates and handling times.Type II functional responses were displayed by both predators across all predator and prey size classes. Largemouth bass consumed more than bluegill at small and intermediate predator size classes, while large predators of both species were more similar. Small prey were most vulnerable overall; however, differential attack rates among prey were emergent across predator sizes. For both bluegill and largemouth bass, small predators exhibited higher attack rates toward small and intermediate prey sizes, while larger predators exhibited greater attack rates toward large prey. Conversely, handling times increased with prey size, with small bluegill exhibiting particularly low feeding rates toward medium-large prey types. Attack rates for both predators peaked unimodally at intermediate predator-prey body mass ratios, while handling times generally shortened across increasing body mass ratios.We thus demonstrate effects of body size ratios on predator-prey interaction strengths between key fish species, with attack rates and handling times dependent on the relative sizes of predator-prey participants.Considerations for intra- and interspecific body size ratio effects are critical for predicting the strengths of interactions within ecosystems and may drive differential ecological impacts among invasive species as size ratios shift.
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Affiliation(s)
- Ross N. Cuthbert
- GEOMARHelmholtz‐Zentrum für Ozeanforschung KielKielGermany
- Institute for Global Food SecuritySchool of Biological SciencesQueen's University BelfastBelfastUK
- South African Institute for Aquatic BiodiversityMakhandaSouth Africa
| | - Ryan J. Wasserman
- South African Institute for Aquatic BiodiversityMakhandaSouth Africa
- Department of Zoology and EntomologyRhodes UniversityMakhandaSouth Africa
| | - Tatenda Dalu
- South African Institute for Aquatic BiodiversityMakhandaSouth Africa
- Department of Ecology and Resource ManagementUniversity of VendaThohoyandouSouth Africa
| | - Horst Kaiser
- Department of Ichthyology and Fisheries ScienceRhodes UniversityMakhandaSouth Africa
| | - Olaf L. F. Weyl
- Department of Ichthyology and Fisheries ScienceRhodes UniversityMakhandaSouth Africa
- DSI/NRF Research Chair in Inland Fisheries and Freshwater EcologySouth African Institute for Aquatic BiodiversityMakhandaSouth Africa
| | - Jaimie T. A. Dick
- Institute for Global Food SecuritySchool of Biological SciencesQueen's University BelfastBelfastUK
| | - Arnaud Sentis
- INRAEAix Marseille UniversityUMR RECOVERAix‐en‐ProvenceFrance
| | | | - Mhairi E. Alexander
- South African Institute for Aquatic BiodiversityMakhandaSouth Africa
- Institute for Biomedical and Environmental Health ResearchSchool of Health and Life SciencesUniversity of the West of ScotlandPaisleyUK
- Department of Botany and ZoologyCentre for Invasion BiologyStellenbosch UniversityMatielandSouth Africa
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7
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Skein L, Alexander ME, Robinson TB. Co-occurring predators increase biotic resistance against an invasive prey. Mar Environ Res 2020; 157:104929. [PMID: 32275511 DOI: 10.1016/j.marenvres.2020.104929] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 02/21/2020] [Accepted: 02/23/2020] [Indexed: 06/11/2023]
Abstract
The presence of multiple predators can lead to variation in predator behavior and ultimately altered risk for shared prey. This concept has seldom been accounted for in studies that consider predator-driven biotic resistance from native marine predators against invasive prey. This study compared the prey selection of whelks and rock lobsters when co-occurring and when foraging in isolation. When in isolation, both predators preferred the native mussel Choromytilus meridionalis, regardless of the abundance of alternative prey. However, when co-occurring, predation risk for all prey species, including the invasive mussel Semimytilus algosus, increased. This was largely driven by greater variation in prey selection by rock lobsters in the presence of whelks. This indicates that predatory efforts from co-occurring predators can result in stronger predation pressure on invasive prey than would be recognized if predators were assessed in isolation.
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Affiliation(s)
- Lisa Skein
- Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Natural Sciences Building, Merriman Avenue, Stellenbosch, Matieland, 7602, South Africa
| | - Mhairi E Alexander
- Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Natural Sciences Building, Merriman Avenue, Stellenbosch, Matieland, 7602, South Africa; Institute of Biomedical and Environmental Health Research (IBEHR), School of Health and Life Sciences, University of the West of Scotland, High Street, Paisley, PA1 2BE, UK
| | - Tamara B Robinson
- Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Natural Sciences Building, Merriman Avenue, Stellenbosch, Matieland, 7602, South Africa.
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Bardera G, Owen MA, Façanha FN, Sloman KA, Alexander ME. The influence of sex on feeding behaviour in Pacific white shrimp (Litopenaeus vannamei). Appl Anim Behav Sci 2020. [DOI: 10.1016/j.applanim.2020.104946] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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9
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Thorp CJ, Alexander ME, Vonesh JR, Measey J. Size-dependent functional response of Xenopus laevis feeding on mosquito larvae. PeerJ 2018; 6:e5813. [PMID: 30386704 PMCID: PMC6204824 DOI: 10.7717/peerj.5813] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 09/21/2018] [Indexed: 11/29/2022] Open
Abstract
Predators can play an important role in regulating prey abundance and diversity, determining food web structure and function, and contributing to important ecosystem services, including the regulation of agricultural pests and disease vectors. Thus, the ability to predict predator impact on prey is an important goal in ecology. Often, predators of the same species are assumed to be functionally equivalent, despite considerable individual variation in predator traits known to be important for shaping predator–prey interactions, like body size. This assumption may greatly oversimplify our understanding of within-species functional diversity and undermine our ability to predict predator effects on prey. Here, we examine the degree to which predator–prey interactions are functionally homogenous across a natural range of predator body sizes. Specifically, we quantify the size-dependence of the functional response of African clawed frogs (Xenopus laevis) preying on mosquito larvae (Culex pipiens). Three size classes of predators, small (15–30 mm snout-vent length), medium (50–60 mm) and large (105–120 mm), were presented with five densities of prey to determine functional response type and to estimate search efficiency and handling time parameters generated from the models. The results of mesocosm experiments showed that type of functional response of X. laevis changed with size: small predators exhibited a Type II response, while medium and large predators exhibited Type III responses. Functional response data showed an inversely proportional relationship between predator attack rate and predator size. Small and medium predators had highest and lowest handling time, respectively. The change in functional response with the size of predator suggests that predators with overlapping cohorts may have a dynamic impact on prey populations. Therefore, predicting the functional response of a single size-matched predator in an experiment may misrepresent the predator’s potential impact on a prey population.
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Affiliation(s)
- Corey J Thorp
- Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Stellenbosch, South Africa
| | - Mhairi E Alexander
- Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Stellenbosch, South Africa.,Institute for Biomedical and Environmental Health Research (IBEHR), School of Health and Life Sciences, University of the West of Scotland, Paisley, UK
| | - James R Vonesh
- Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Stellenbosch, South Africa.,Department of Biology, Virginia Commonwealth University, Richmond, VA, USA.,Center for Environmental Studies, Virginia Commonwealth University, Richmond, VA, USA
| | - John Measey
- Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Stellenbosch, South Africa
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10
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Dalu T, Wasserman RJ, Tonkin JD, Alexander ME, Dalu MTB, Motitsoe SN, Manungo KI, Bepe O, Dube T. Corrigendum to "Assessing drivers of benthic macroinvertebrate community structure in African highlands: an exploration using multivariate analysis" [Sci. Total Environ. 601-602 (2017) 1340-1348]. Sci Total Environ 2018; 637-638:934. [PMID: 29763874 DOI: 10.1016/j.scitotenv.2018.05.086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Accepted: 05/06/2018] [Indexed: 06/08/2023]
Affiliation(s)
- Tatenda Dalu
- Zoology and Entomology, Rhodes University, Grahamstown, Eastern Cape, South Africa.
| | - Ryan J Wasserman
- School of Science, Monash University, Jalan Lagoon Selatan, Bandar Sunway, Selangor 47500, Malaysia; South African Institute for Aquatic Biodiversity, Grahamstown, South Africa
| | | | - Mhairi E Alexander
- Institute of Biomedical and Environmental Health Research, School of Science and Sport, University of the West of Scotland, Paisley, Scotland, United Kingdom
| | - Mwazvita T B Dalu
- Environmental Science, Rhodes University, Grahamstown, Eastern Cape, South Africa
| | - Samuel N Motitsoe
- Zoology and Entomology, Rhodes University, Grahamstown, Eastern Cape, South Africa
| | | | - Onias Bepe
- Nyanga National Park, Nyanga, Manicaland, Zimbabwe
| | - Timothy Dube
- Geography and Environmental Science, University of Limpopo, Sovenga 0727, Polokwane, South Africa
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11
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Howard BR, Barrios-O’Neill D, Alexander ME, Dick JT, Therriault TW, Robinson TB, Côté IM. Functional responses of a cosmopolitan invader demonstrate intraspecific variability in consumer-resource dynamics. PeerJ 2018; 6:e5634. [PMID: 30280022 PMCID: PMC6166631 DOI: 10.7717/peerj.5634] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Accepted: 08/24/2018] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Variability in the ecological impacts of invasive species across their geographical ranges may decrease the accuracy of risk assessments. Comparative functional response analysis can be used to estimate invasive consumer-resource dynamics, explain impact variability, and thus potentially inform impact predictions. The European green crab (Carcinus maenas) has been introduced on multiple continents beyond its native range, although its ecological impacts appear to vary among populations and regions. Our aim was to test whether consumer-resource dynamics under standardized conditions are similarly variable across the current geographic distribution of green crab, and to identify correlated morphological features. METHODS Crabs were collected from multiple populations within both native (Northern Ireland) and invasive regions (South Africa and Canada). Their functional responses to local mussels (Mytilus spp.) were tested. Attack rates and handling times were compared among green crab populations within each region, and among regions (Pacific Canada, Atlantic Canada, South Africa, and Northern Ireland). The effect of predator and prey morphology on prey consumption was investigated. RESULTS Across regions, green crabs consumed prey according to a Type II (hyperbolic) functional response curve. Attack rates (i.e., the rate at which a predator finds and attacks prey), handling times and maximum feeding rates differed among regions. There was a trend toward higher attack rates in invasive than in native populations. Green crabs from Canada had lower handling times and thus higher maximum feeding rates than those from South Africa and Northern Ireland. Canadian and Northern Ireland crabs had significantly larger claws than South African crabs. Claw size was a more important predictor of the proportion of mussels killed than prey shell strength. DISCUSSION The differences in functional response between regions reflect observed impacts of green crabs in the wild. This suggests that an understanding of consumer-resource dynamics (e.g., the per capita measure of predation), derived from simple, standardized experiments, might yield useful predictions of invader impacts across geographical ranges.
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Affiliation(s)
- Brett R. Howard
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Daniel Barrios-O’Neill
- Institute for Global Food Security, School of Biological Sciences, The Queen’s University Belfast, Belfast, Northern Ireland, United Kingdom
| | - Mhairi E. Alexander
- Institute of Biomedical and Environmental Health Research (IBEHR), School of Science and Sport, University of the West of Scotland, Paisley, United Kingdom
| | - Jaimie T.A. Dick
- Institute for Global Food Security, School of Biological Sciences, The Queen’s University Belfast, Belfast, Northern Ireland, United Kingdom
| | - Thomas W. Therriault
- Pacific Biological Station, Fisheries & Oceans Canada, Nanaimo, British Columbia, Canada
| | - Tamara B. Robinson
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, Maiteland, South Africa
| | - Isabelle M. Côté
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
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12
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Wasserman RJ, Cuthbert RN, Alexander ME, Dalu T. Shifting interaction strength between estuarine mysid species across a temperature gradient. Mar Environ Res 2018; 140:390-393. [PMID: 30054133 DOI: 10.1016/j.marenvres.2018.07.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 06/26/2018] [Accepted: 07/20/2018] [Indexed: 06/08/2023]
Abstract
In many coastal regions, mean coastal atmospheric and water temperatures are projected to shift as climate change ensues. Interaction strengths between organisms are likely to change along with environmental changes, given interspecific heterogeneity in responses to physico-chemical variables. Biological interaction outcomes have the potential to alter food web production and trophic level biomass distribution. This is particularly pertinent for key species that are either abundant or play disproportionately large roles in ecosystem processes. Using a functional response approach, we quantified the effects of shifting temperatures on interactions between key mysid species-sympatric in their distribution across a biogeographic transition zone along the east coast of South Africa. The Rhopalophthalmus terranatalis functional response type toward Mesopodopsis wooldridgei prey was independent of temperature, with all treatments producing Type II functional responses. Temperature effects on predator-prey dynamics were, however, evident as interaction strength was greatest at 21 °C, as measured by maximum feeding rates. Unlike maximum feeding rate, attack rates increased linearly with increasing temperature across the experimental treatments. Our findings suggest that interaction strength between the mysid shrimp species is likely to vary spatially along the current length of their sympatric distribution and temporally in certain regions where temperatures are projected to change. Such experimental interaction investigations are becoming increasingly important given our relatively poor understanding of the consequences of environmental change for effects on interactions among species and their wider ecosystem implications.
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Affiliation(s)
- Ryan J Wasserman
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, P. Bag 16, Palapye, Botswana; South African Institute for Aquatic Biodiversity (SAIAB), P. Bag 1015, Grahamstown, 6140, South Africa.
| | - Ross N Cuthbert
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast, BT9 7BL, Northern Ireland, United Kingdom
| | - Mhairi E Alexander
- Institute for Biomedical and Environmental Health Research, School of Science and Sport, University of the West of Scotland, Paisley, Scotland, United Kingdom
| | - Tatenda Dalu
- Department of Ecology and Resource Management, University of Venda, Thohoyandou, 0950, South Africa
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Ellender BR, Weyl OLF, Alexander ME, Luger AM, Nagelkerke LAJ, Woodford DJ. Out of the pot and into the fire: Explaining the vulnerability of an endangered small headwater stream fish to black-bass Micropterus spp. invasion. J Fish Biol 2018; 92:1035-1050. [PMID: 29479690 DOI: 10.1111/jfb.13562] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Accepted: 01/14/2018] [Indexed: 06/08/2023]
Abstract
Introduced predatory fishes have had consistently severe consequences for native fishes in stream environments around the world, although the drivers of these effects are often unclear. In the Swartkops River headwaters in South Africa, native Eastern Cape redfin Pseudobarbus afer were always absent from sites occupied by non-native black basses Micropterus salmoides and Micropterus dolomieu, but generally co-occurred with the native predators Anguilla marmorata and Anguilla mossambica. A natural experiment provided by flood-mediated recolonization of black-bass occupied sites by P. afer demonstrated depletion in black-bass invaded sites. Field behavioural observations of P. afer indicated that they foraged among benthic cover during the day, but suspended in open water at night. As the nocturnal A. marmorata and A. mossambica foraged actively within structural cover at night and M. dolomieu and M. salmoides are diurnal or crepuscular predators, P .afer is thus optimized to avoid predation by native anguillid predators and not the functionally unique predatory black basses. The integration of distributional, temporal population dynamics and behavioural data suggests that the severe effects of Micropterus spp. are probably a consequence of prey naïveté and behaviour evolved to evade native predators.
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Affiliation(s)
- B R Ellender
- Department of Ichthyology and Fisheries Science, P.O. Box 96, Grahamstown, 6140, South Africa
- Centre for Invasion Biology, South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown, 6140, South Africa
| | - O L F Weyl
- Department of Ichthyology and Fisheries Science, P.O. Box 96, Grahamstown, 6140, South Africa
- Centre for Invasion Biology, South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown, 6140, South Africa
- DST/NRF Research Chair in Inland Fisheries and Freshwater Ecology, South African Institute for Aquatic Biodiversity, Grahamstown, South Africa
| | - M E Alexander
- Centre for Invasion Biology, South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown, 6140, South Africa
- Institute of Biomedical and Environmental Health Research (IBEHR), School of Science and Sport, University of West Scotland, High Street, Paisley, PA1 2BE
| | - A M Luger
- Centre for Invasion Biology, South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown, 6140, South Africa
- Aquaculture and Fisheries Group, Wageningen University, Wageningen, The Netherlands
| | - L A J Nagelkerke
- Aquaculture and Fisheries Group, Wageningen University, Wageningen, The Netherlands
| | - D J Woodford
- Centre for Invasion Biology, South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown, 6140, South Africa
- Centre for Invasion Biology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, Wits, 2050, South Africa
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Affiliation(s)
- Lisa Skein
- Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Stellenbosch, Matieland, South Africa
| | - Tamara B Robinson
- Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Stellenbosch, Matieland, South Africa
| | - Mhairi E Alexander
- Institute of Biomedical and Environmental Health Research (IBEHR), School of Science and Sport, University of the West of Scotland, Paisley, UK
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Dalu T, Wasserman RJ, Tonkin JD, Alexander ME, Dalu MTB, Motitsoe SN, Manungo KI, Bepe O, Dube T. Assessing drivers of benthic macroinvertebrate community structure in African highland streams: An exploration using multivariate analysis. Sci Total Environ 2017; 601-602:1340-1348. [PMID: 28605853 DOI: 10.1016/j.scitotenv.2017.06.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 05/20/2017] [Accepted: 06/03/2017] [Indexed: 06/07/2023]
Abstract
Understanding the drivers of community structure is fundamental for adequately managing ecosystems under global change. Here we used a large dataset of eighty-four headwater stream sites in three catchments in the Eastern Highlands of Zimbabwe, which represent a variety of abiotic conditions and levels of impairment, to examine the drivers of benthic macroinvertebrate community structure. We focused our assessment on macroinvertebrate family level community composition and functional feeding group classifications. Taxonomic richness was weakly positively correlated with ammonium, phosphates and pH, and weakly negatively correlated with detrital cover and dissolved oxygen. Measured abiotic variables, however, had limited influence on both macroinvertebrate diversity and functional feeding group structure, with the exception of ammonium, channel width and phosphates. This reflected the fact that many macroinvertebrate families and functional feeding guilds were well represented across a broad range of habitats. Predatory macroinvertebrates were relatively abundant, with collector-filterers having the lowest relative abundances. The findings of the study suggest that for certain ecological questions, a more detailed taxonomic resolution may be required to adequately understand the ecology of aquatic macroinvertebrates within river systems. We further recommend management and conservation initiatives on the Save River system, which showed significant impact from catchment developmental pressures, such as urbanisation, agriculture and illegal mining.
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Affiliation(s)
- Tatenda Dalu
- Zoology and Entomology, Rhodes University, Grahamstown, Eastern Cape, South Africa.
| | - Ryan J Wasserman
- School of Science, Monash University, Jalan Lagoon Selatan, Bandar Sunway, Selangor 47500, Malaysia; South Africa Institute for Aquatic Biodiversity, Grahamstown, South Africa
| | | | - Mhairi E Alexander
- Institute of Biomedical and Environmental Health Research, School of Science and Sport, University of the West of Scotland, Paisley, Scotland
| | - Mwazvita T B Dalu
- Environmental Science, Rhodes University, Grahamstown, Eastern Cape, South Africa
| | - Samuel N Motitsoe
- Zoology and Entomology, Rhodes University, Grahamstown, Eastern Cape, South Africa
| | | | - Onias Bepe
- Nyanga National Park, Nyanga, Manicaland, Zimbabwe
| | - Timothy Dube
- Geography and Environmental Science, University of Limpopo, Sovenga, 0727 Polokwane, South Africa
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Penk M, Saul W, Dick JT, Donohue I, Alexander ME, Linzmaier S, Jeschke JM. A trophic interaction framework for identifying the invasive capacity of novel organisms. Methods Ecol Evol 2017. [DOI: 10.1111/2041-210x.12817] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marcin Penk
- School of Natural SciencesTrinity College Dublin Dublin Ireland
- Department of Biology, Chemistry, PharmacyInstitute of BiologyFreie Universität Berlin Berlin Germany
| | - Wolf‐Christian Saul
- Department of Biology, Chemistry, PharmacyInstitute of BiologyFreie Universität Berlin Berlin Germany
- Leibniz‐Institute of Freshwater Ecology and Inland Fisheries (IGB) Berlin Germany
- Berlin‐Brandenburg Institute of Advanced Biodiversity Research (BBIB) Berlin Germany
- Centre for Invasion Biology (CIB)Department of Botany and Zoology & Department of Mathematical SciencesStellenbosch University Matieland South Africa
| | - Jaimie T.A. Dick
- Institute for Global Food SecuritySchool of Biological SciencesQueen's University Belfast Belfast UK
| | - Ian Donohue
- School of Natural SciencesTrinity College Dublin Dublin Ireland
| | - Mhairi E. Alexander
- Institute for Biomedical and Environmental Health Research (IBEHR)School of Science and SportUniversity of the West of Scotland Paisley UK
| | - Stefan Linzmaier
- Department of Biology, Chemistry, PharmacyInstitute of BiologyFreie Universität Berlin Berlin Germany
- Leibniz‐Institute of Freshwater Ecology and Inland Fisheries (IGB) Berlin Germany
- Berlin‐Brandenburg Institute of Advanced Biodiversity Research (BBIB) Berlin Germany
| | - Jonathan M. Jeschke
- Department of Biology, Chemistry, PharmacyInstitute of BiologyFreie Universität Berlin Berlin Germany
- Leibniz‐Institute of Freshwater Ecology and Inland Fisheries (IGB) Berlin Germany
- Berlin‐Brandenburg Institute of Advanced Biodiversity Research (BBIB) Berlin Germany
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Dick JTA, Alexander ME, Ricciardi A, Laverty C, Downey PO, Xu M, Jeschke JM, Saul WC, Hill MP, Wasserman R, Barrios-O’Neill D, Weyl OLF, Shaw RH. Fictional responses from Vonesh et al. Biol Invasions 2017. [DOI: 10.1007/s10530-016-1360-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Dick JT, Laverty C, Lennon JJ, Barrios-O'Neill D, Mensink PJ, Robert Britton J, Médoc V, Boets P, Alexander ME, Taylor NG, Dunn AM, Hatcher MJ, Rosewarne PJ, Crookes S, MacIsaac HJ, Xu M, Ricciardi A, Wasserman RJ, Ellender BR, Weyl OL, Lucy FE, Banks PB, Dodd JA, MacNeil C, Penk MR, Aldridge DC, Caffrey JM. Invader Relative Impact Potential: a new metric to understand and predict the ecological impacts of existing, emerging and future invasive alien species. J Appl Ecol 2017. [DOI: 10.1111/1365-2664.12849] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Jaimie T.A. Dick
- Institute for Global Food Security; School of Biological Sciences; Queen's University Belfast; MBC, 97 Lisburn Road Belfast BT9 7BL UK
| | - Ciaran Laverty
- Institute for Global Food Security; School of Biological Sciences; Queen's University Belfast; MBC, 97 Lisburn Road Belfast BT9 7BL UK
| | - Jack J. Lennon
- Institute for Global Food Security; School of Biological Sciences; Queen's University Belfast; MBC, 97 Lisburn Road Belfast BT9 7BL UK
| | - Daniel Barrios-O'Neill
- Institute for Global Food Security; School of Biological Sciences; Queen's University Belfast; MBC, 97 Lisburn Road Belfast BT9 7BL UK
| | - Paul J. Mensink
- Institute for Global Food Security; School of Biological Sciences; Queen's University Belfast; MBC, 97 Lisburn Road Belfast BT9 7BL UK
| | - J. Robert Britton
- Department of Life and Environmental Sciences; Faculty of Science and Technology; Bournemouth University; Fern Barrow, Poole Dorset BH12 5BB UK
| | - Vincent Médoc
- Institute of Ecology and Environmental Sciences; Université Pierre et Marie Curie (Paris 6); 75005 Paris France
| | - Pieter Boets
- Provinciaal Centrum voor Milieuonderzoek; Godshuizenlaan 95 9000 Ghent Belgium
| | - Mhairi E. Alexander
- Institute for Biomedical and Environmental Health Research (IBEHR); School of Science and Sport; University of the West of Scotland; Paisley PA1 2BE UK
| | - Nigel G. Taylor
- School of Biology; Faculty of Biological Sciences; University of Leeds; Leeds LS2 9JT UK
| | - Alison M. Dunn
- School of Biology; Faculty of Biological Sciences; University of Leeds; Leeds LS2 9JT UK
| | - Melanie J. Hatcher
- School of Biology; Faculty of Biological Sciences; University of Leeds; Leeds LS2 9JT UK
| | - Paula J. Rosewarne
- School of Biology; Faculty of Biological Sciences; University of Leeds; Leeds LS2 9JT UK
| | - Steven Crookes
- Great Lakes Institute for Environmental Research; University of Windsor; Windsor ON N9B 3P4 Canada
| | - Hugh J. MacIsaac
- Great Lakes Institute for Environmental Research; University of Windsor; Windsor ON N9B 3P4 Canada
| | - Meng Xu
- Pearl River Fisheries Research Institute; Chinese Academy of Fishery Sciences; Key Laboratory of Tropical and Subtropical Fishery Resource Application and Cultivation; Ministry of Agriculture; Guangzhou 510380 China
| | - Anthony Ricciardi
- Redpath Museum; McGill University; 859 Sherbrooke Street West Montreal QC H3A 0C4 Canada
| | - Ryan J. Wasserman
- South African Institute for Aquatic Biodiversity (SAIAB); P. Bag 1015 Grahamstown 6140 South Africa
- Centre for Invasion Biology; South African Institute for Aquatic Biodiversity (SAIAB); P. Bag 1015 Grahamstown 6140 South Africa
| | - Bruce R. Ellender
- South African Institute for Aquatic Biodiversity (SAIAB); P. Bag 1015 Grahamstown 6140 South Africa
- Centre for Invasion Biology; South African Institute for Aquatic Biodiversity (SAIAB); P. Bag 1015 Grahamstown 6140 South Africa
| | - Olaf L.F. Weyl
- South African Institute for Aquatic Biodiversity (SAIAB); P. Bag 1015 Grahamstown 6140 South Africa
- Centre for Invasion Biology; South African Institute for Aquatic Biodiversity (SAIAB); P. Bag 1015 Grahamstown 6140 South Africa
| | - Frances E. Lucy
- Department of Life and Environmental Sciences; Faculty of Science and Technology; Bournemouth University; Fern Barrow, Poole Dorset BH12 5BB UK
- Centre for Environmental Research, Innovation & Sustainability; Institute of Technology Sligo; Ash Lane, Co. Sligo Ireland
| | - Peter B. Banks
- School of Life and Environmental Sciences; The University of Sydney; Science Road Cottage A10 Camperdown NSW 2006 Australia
| | - Jennifer A. Dodd
- Scottish Centre for Ecology & the Natural Environment; IBAHCM; University of Glasgow; Rowardennan Glasgow G63 0AW UK
| | - Calum MacNeil
- Department of Environment, Food and Agriculture; This Slieau Whallian; Foxdale Road St. Johns IM4 3AS Isle of Man
| | - Marcin R. Penk
- Department of Zoology; School of Natural Sciences; Trinity College Dublin; Dublin 2 Ireland
| | - David C. Aldridge
- Department of Zoology; University of Cambridge; David Attenborough Building, Downing Street Cambridge CB2 3EJ UK
| | - Joseph M. Caffrey
- Department of Life and Environmental Sciences; Faculty of Science and Technology; Bournemouth University; Fern Barrow, Poole Dorset BH12 5BB UK
- INVAS Biosecurity; 6 Lower Ballymount Road, Walkinstown Dublin 12 Ireland
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Wasserman RJ, Alexander ME, Dalu T, Ellender BR, Kaiser H, Weyl OLF. Using functional responses to quantify interaction effects among predators. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12682] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ryan J. Wasserman
- South African Institute for Aquatic Biodiversity (SAIAB) P. Bag 1015 Grahamstown 6140 South Africa
- Centre for Invasion Biology South African Institute for Aquatic Biodiversity (SAIAB) P. Bag 1015 Grahamstown 6140 South Africa
| | - Mhairi E. Alexander
- Centre for Invasion Biology South African Institute for Aquatic Biodiversity (SAIAB) P. Bag 1015 Grahamstown 6140 South Africa
- Institute for Biomedical and Environmental Health Research (IBEHR) School of Science and Sport University of the West of Scotland Paisley PA1 2BE ScotlandUK
- Department of Botany and Zoology Centre for Invasion Biology Stellenbosch University Matieland 7602 South Africa
| | - Tatenda Dalu
- Department of Zoology and Entomology Rhodes University P.O. Box 94 Grahamstown 6140 South Africa
| | - Bruce R. Ellender
- South African Institute for Aquatic Biodiversity (SAIAB) P. Bag 1015 Grahamstown 6140 South Africa
- Centre for Invasion Biology South African Institute for Aquatic Biodiversity (SAIAB) P. Bag 1015 Grahamstown 6140 South Africa
| | - Horst Kaiser
- Department of Ichthyology and Fisheries Science Rhodes University P.O. Box 94 Grahamstown 6140 South Africa
| | - Olaf L. F. Weyl
- South African Institute for Aquatic Biodiversity (SAIAB) P. Bag 1015 Grahamstown 6140 South Africa
- Centre for Invasion Biology South African Institute for Aquatic Biodiversity (SAIAB) P. Bag 1015 Grahamstown 6140 South Africa
- Department of Ichthyology and Fisheries Science Rhodes University P.O. Box 94 Grahamstown 6140 South Africa
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Wasserman RJ, Alexander ME, Weyl OLF, Barrios-O'Neill D, Froneman PW, Dalu T. Emergent effects of structural complexity and temperature on predator-prey interactions. Ecosphere 2016. [DOI: 10.1002/ecs2.1239] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Ryan J. Wasserman
- South African Institute for Aquatic Biodiversity (SAIAB); Private Bag 1015 Grahamstown 6140 South Africa
- Centre for Invasion Biology; South African Institute for Aquatic Biodiversity (SAIAB); Private Bag 1015 Grahamstown 6140 South Africa
| | - Mhairi E. Alexander
- Department of Botany and Zoology; Centre for Invasion Biology; Stellenbosch University; Matieland 7602 South Africa
| | - Olaf L. F. Weyl
- South African Institute for Aquatic Biodiversity (SAIAB); Private Bag 1015 Grahamstown 6140 South Africa
- Centre for Invasion Biology; South African Institute for Aquatic Biodiversity (SAIAB); Private Bag 1015 Grahamstown 6140 South Africa
| | - Daniel Barrios-O'Neill
- Institute for Global Food Security; School of Biological Sciences; Queens University Belfast; 97 Lisburn Road Belfast BT9 7BL UK
| | - P. William Froneman
- Department of Zoology and Entomology; Rhodes University; P.O. Box 94 Grahamstown 6140 South Africa
| | - Tatenda Dalu
- Department of Zoology and Entomology; Rhodes University; P.O. Box 94 Grahamstown 6140 South Africa
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Dalu T, Sachikonye MTB, Alexander ME, Dube T, Froneman WP, Manungo KI, Bepe O, Wasserman RJ. Ecological Assessment of Two Species of Potamonautid Freshwater Crabs from the Eastern Highlands of Zimbabwe, with Implications for Their Conservation. PLoS One 2016; 11:e0145923. [PMID: 26751064 PMCID: PMC4713832 DOI: 10.1371/journal.pone.0145923] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 12/10/2015] [Indexed: 11/22/2022] Open
Abstract
The spatial ecology of freshwater crabs and their conservation status is largely understudied in Africa. An ecological assessment was conducted at 104 localities in 51 rivers and/or streams in the Eastern Highlands of Zimbabwe whereby the distribution and abundances of freshwater crab species were mapped and the possible drivers of the observed trends in population structure explored. In addition, information on crab utilisation as a food resource by local communities was assessed via face to face interviews across the region. Finally, the conservation status of each species was assessed using the IUCN Red List criteria. Only two crab species Potamonautes mutareensis and Potamonautes unispinus were recorded within the region of study. Potamonautes mutareensis was largely restricted to less impacted environments in the high mountainous river system, whereas P. unispinus was found in low laying areas. In stretches of river where both species were found to co-occur, the species were never sampled from the same site, with P. mutareensis occurring in shallower, faster flowing environments and P. unispinus in deeper, slow flowing sites. Interview results revealed that the local communities, particularly in the southern part of the Eastern Highlands around the Chipinge area, had a considerable level of utilisation (55% of households) on the harvesting of crabs for household consumption during the non-agricultural season (May to September). Results from the IUCN Red List assessment indicate that both species should be considered as "Least Concern". Threats to freshwater crabs in the Eastern Highlands, however, include widespread anthropogenic impacts such as habitat destruction associated with gold and diamond mining, inorganic and organic pollution and possibly exploitation for human consumption. The current study provides important information and insight towards the possible development of a freshwater crab conservation action plan within the region.
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Affiliation(s)
- Tatenda Dalu
- Zoology and Entomology, Rhodes University, Grahamstown, Eastern Cape, South Africa
| | | | - Mhairi E. Alexander
- Institute of Biomedical and Environmental Health Research, School of Science and Sport, University of the West of Scotland, Paisley, Scotland
| | - Timothy Dube
- School of Agriculture, Earth and Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg, KwaZulu Natal, South Africa
| | - William P. Froneman
- Zoology and Entomology, Rhodes University, Grahamstown, Eastern Cape, South Africa
| | | | - Onias Bepe
- Nyanga National Park, Nyanga, Manicaland, Zimbabwe
| | - Ryan J. Wasserman
- South Africa Institute for Aquatic Biodiversity, Grahamstown, Eastern Cape, South Africa
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Bunke M, Alexander ME, Dick JTA, Hatcher MJ, Paterson R, Dunn AM. Eaten alive: cannibalism is enhanced by parasites. R Soc Open Sci 2015; 2:140369. [PMID: 26064614 PMCID: PMC4448826 DOI: 10.1098/rsos.140369] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 02/16/2015] [Indexed: 06/01/2023]
Abstract
Cannibalism is ubiquitous in nature and especially pervasive in consumers with stage-specific resource utilization in resource-limited environments. Cannibalism is thus influential in the structure and functioning of biological communities. Parasites are also pervasive in nature and, we hypothesize, might affect cannibalism since infection can alter host foraging behaviour. We investigated the effects of a common parasite, the microsporidian Pleistophora mulleri, on the cannibalism rate of its host, the freshwater amphipod Gammarus duebeni celticus. Parasitic infection increased the rate of cannibalism by adults towards uninfected juvenile conspecifics, as measured by adult functional responses, that is, the rate of resource uptake as a function of resource density. This may reflect the increased metabolic requirements of the host as driven by the parasite. Furthermore, when presented with a choice, uninfected adults preferred to cannibalize uninfected rather than infected juvenile conspecifics, probably reflecting selection pressure to avoid the risk of parasite acquisition. By contrast, infected adults were indiscriminate with respect to infection status of their victims, probably owing to metabolic costs of infection and the lack of risk as the cannibals were already infected. Thus parasitism, by enhancing cannibalism rates, may have previously unrecognized effects on stage structure and population dynamics for cannibalistic species and may also act as a selective pressure leading to changes in resource use.
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Affiliation(s)
- Mandy Bunke
- School of Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Mhairi E. Alexander
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Matieland 7602, South Africa
| | - Jaimie T. A. Dick
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast BT9 7BL, , UK
| | | | - Rachel Paterson
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast BT9 7BL, , UK
| | - Alison M. Dunn
- School of Biology, University of Leeds, Leeds LS2 9JT, UK
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Hatcher MJ, Dick JTA, Paterson RA, Alexander ME, Bunke M, Dunn AM. Trait-Mediated Effects of Parasites on Invader-Native Interactions. Host Manipulations by Parasites and Viruses 2015. [PMCID: PMC7120441 DOI: 10.1007/978-3-319-22936-2_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Parasites have a variety of behavioural effects on their hosts, which can in turn affect species with which the host interacts. Here we review how these trait-mediated indirect effects of parasites can alter the outcomes of invader-native interactions, illustrating with examples from the literature and with particular regard to the invader-native crustacean systems studied in our laboratories. Parasites may potentially inhibit or exacerbate invasions via their effects on host behaviour, in addition to their direct virulence effects on hosts. In several crustacean systems, we have found that parasites influence both host predation rates on intra- and inter-guild prey and host vulnerability to being preyed upon. These trait effects can theoretically alter invasion impact and patterns of coexistence, as they indirectly affect interactions between predators and prey with the potential for further ramifications to other species in the food web. The fitness consequences of parasite-induced trait-mediated effects are rarely considered in traditional parasitological contexts, but demand attention in the context of ecological communities. We can regard these trait effects as a form of cryptic virulence that only becomes apparent when hosts are examined in the context of the other species with which they interact.
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Laverty C, Dick JTA, Alexander ME, Lucy FE. Differential ecological impacts of invader and native predatory freshwater amphipods under environmental change are revealed by comparative functional responses. Biol Invasions 2014. [DOI: 10.1007/s10530-014-0832-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Alexander ME, Dick JTA, Weyl OLF, Robinson TB, Richardson DM. Existing and emerging high impact invasive species are characterized by higher functional responses than natives. Biol Lett 2014; 10:20130946. [PMID: 24522629 DOI: 10.1098/rsbl.2013.0946] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Predicting ecological impacts of invasive species and identifying potentially damaging future invaders are research priorities. Since damage by invaders is characterized by their depletion of resources, comparisons of the 'functional response' (FR; resource uptake rate as a function of resource density) of invaders and natives might predict invader impact. We tested this by comparing FRs of the ecologically damaging 'world's worst' invasive fish, the largemouth bass (Micropterus salmoides), with a native equivalent, the Cape kurper (Sandelia capensis), and an emerging invader, the sharptooth catfish (Clarias gariepinus), with the native river goby (Glossogobius callidus), in South Africa, a global invasion hotspot. Using tadpoles (Hyperolius marmoratus) as prey, we found that the invaders consumed significantly more than natives. Attack rates at low prey densities within invader/native comparisons reflected similarities in predatory strategies; however, both invasive species displayed significantly higher Type II FRs than the native comparators. This was driven by significantly lower prey handling times by invaders, resulting in significantly higher maximum feeding rates. The higher FRs of these invaders are thus congruent with, and can predict, their impacts on native communities. Comparative FRs may be a rapid and reliable method for predicting ecological impacts of emerging and future invasive species.
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Affiliation(s)
- Mhairi E Alexander
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, , Matieland 7602, South Africa
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Barrios-O'Neill D, Dick JTA, Emmerson MC, Ricciardi A, MacIsaac HJ, Alexander ME, Bovy HC. Fortune favours the bold: a higher predator reduces the impact of a native but not an invasive intermediate predator. J Anim Ecol 2013; 83:693-701. [PMID: 24117414 DOI: 10.1111/1365-2656.12155] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 09/24/2013] [Indexed: 11/30/2022]
Abstract
Emergent multiple predator effects (MPEs) might radically alter predictions of predatory impact that are based solely on the impact of individuals. In the context of biological invasions, determining if and how the individual-level impacts of invasive predators relates to their impacts in multiple-individual situations will inform understanding of how such impacts might propagate through recipient communities. Here, we use functional responses (the relationship between prey consumption rate and prey density) to compare the impacts of the invasive freshwater mysid crustacean Hemimysis anomala with a native counterpart Mysis salemaai when feeding on basal cladoceran prey (i) as individuals, (ii) in conspecific groups and (iii) in conspecific groups in the presence of a higher fish predator, Gasterosteus aculeatus. In the absence of the higher predator, the invader consumed significantly more basal prey than the native, and consumption was additive for both mysid species - that is, group consumption was predictable from individual-level consumption. Invaders and natives were themselves equally susceptible to predation when feeding with the higher fish predator, but an MPE occurred only between the natives and higher predator, where consumption of basal prey was significantly reduced. In contrast, consumption by the invaders and higher predator remained additive. The presence of a higher predator serves to exacerbate the existing difference in individual-level consumption between invasive and native mysids. We attribute the mechanism responsible for the MPE associated with the native to a trait-mediated indirect interaction, and further suggest that the relative indifference to predator threat on the part of the invader contributes to its success and impacts within invaded communities.
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Affiliation(s)
- Daniel Barrios-O'Neill
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Jaimie T A Dick
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Mark C Emmerson
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Anthony Ricciardi
- Redpath Museum, McGill University, 859 Sherbrooke Street West, Montreal, QC, H3A OC4, Canada
| | - Hugh J MacIsaac
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, N9B 3P4, Canada
| | - Mhairi E Alexander
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Helene C Bovy
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK
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Dick JTA, Alexander ME, Jeschke JM, Ricciardi A, MacIsaac HJ, Robinson TB, Kumschick S, Weyl OLF, Dunn AM, Hatcher MJ, Paterson RA, Farnsworth KD, Richardson DM. Advancing impact prediction and hypothesis testing in invasion ecology using a comparative functional response approach. Biol Invasions 2013. [DOI: 10.1007/s10530-013-0550-8] [Citation(s) in RCA: 184] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Abstract
Invasion ecology urgently requires predictive methodologies that can forecast the ecological impacts of existing, emerging and potential invasive species. We argue that many ecologically damaging invaders are characterised by their more efficient use of resources. Consequently, comparison of the classical ‘functional response’ (relationship between resource use and availability) between invasive and trophically analogous native species may allow prediction of invader ecological impact. We review the utility of species trait comparisons and the history and context of the use of functional responses in invasion ecology, then present our framework for the use of comparative functional responses. We show that functional response analyses, by describing the resource use of species over a range of resource availabilities, avoids many pitfalls of ‘snapshot’ assessments of resource use. Our framework demonstrates how comparisons of invader and native functional responses, within and between Type II and III functional responses, allow testing of the likely population-level outcomes of invasions for affected species. Furthermore, we describe how recent studies support the predictive capacity of this method; for example, the invasive ‘bloody red shrimp’ Hemimysis anomala shows higher Type II functional responses than native mysids and this corroborates, and could have predicted, actual invader impacts in the field. The comparative functional response method can also be used to examine differences in the impact of two or more invaders, two or more populations of the same invader, and the abiotic (e.g. temperature) and biotic (e.g. parasitism) context-dependencies of invader impacts. Our framework may also address the previous lack of rigour in testing major hypotheses in invasion ecology, such as the ‘enemy release’ and ‘biotic resistance’ hypotheses, as our approach explicitly considers demographic consequences for impacted resources, such as native and invasive prey species. We also identify potential challenges in the application of comparative functional responses in invasion ecology. These include incorporation of numerical responses, multiple predator effects and trait-mediated indirect interactions, replacement versus non-replacement study designs and the inclusion of functional responses in risk assessment frameworks. In future, the generation of sufficient case studies for a meta-analysis could test the overall hypothesis that comparative functional responses can indeed predict invasive species impacts.
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Dick JTA, Gallagher K, Avlijas S, Clarke HC, Lewis SE, Leung S, Minchin D, Caffrey J, Alexander ME, Maguire C, Harrod C, Reid N, Haddaway NR, Farnsworth KD, Penk M, Ricciardi A. Ecological impacts of an invasive predator explained and predicted by comparative functional responses. Biol Invasions 2012. [DOI: 10.1007/s10530-012-0332-8] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Alexander ME, Moghadas SM, Rohani P, Summers AR. Modelling the effect of a booster vaccination on disease epidemiology. J Math Biol 2005; 52:290-306. [PMID: 16283412 DOI: 10.1007/s00285-005-0356-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 07/29/2005] [Indexed: 10/25/2022]
Abstract
Despite the effectiveness of vaccines in dramatically decreasing the number of new infectious cases and severity of illnesses, imperfect vaccines may not completely prevent infection. This is because the immunity afforded by these vaccines is not complete and may wane with time, leading to resurgence and epidemic outbreaks notwithstanding high levels of primary vaccination. To prevent an endemic spread of disease, and achieve eradication, several countries have introduced booster vaccination programs. The question of whether this strategy could eventually provide the conditions for global eradication is addressed here by developing a seasonally-forced mathematical model. The analysis of the model provides the threshold condition for disease control in terms of four major parameters: coverage of the primary vaccine; efficacy of the vaccine; waning rate; and the rate of booster administration. The results show that if the vaccine provides only temporary immunity, then the infection typically cannot be eradicated by a single vaccination episode. Furthermore, having a booster program does not necessarily guarantee the control of a disease, though the level of epidemicity may be reduced. In addition, these findings strongly suggest that the high coverage of primary vaccination remains crucial to the success of a booster strategy. Simulations using estimated parameters for measles illustrate model predictions.
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Affiliation(s)
- M E Alexander
- Institute for Biodiagnostics, National Research Council Canada, R3B 1Y6, Winnipeg, Manitoba, Canada.
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Alexander ME, Moghadas SM. Periodicity in an epidemic model with a generalized non-linear incidence. Math Biosci 2004; 189:75-96. [PMID: 15051415 DOI: 10.1016/j.mbs.2004.01.003] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2003] [Revised: 01/13/2004] [Accepted: 01/16/2004] [Indexed: 11/22/2022]
Abstract
We develop and analyze a simple SIV epidemic model including susceptible, infected and perfectly vaccinated classes, with a generalized non-linear incidence rate subject only to a few general conditions. These conditions are satisfied by many models appearing in the literature. The detailed dynamics analysis of the model, using the Poincaré index theory, shows that non-linearity of the incidence rate leads to vital dynamics, such as bistability and periodicity, without seasonal forcing or being cyclic. Furthermore, it is shown that the basic reproductive number is independent of the functional form of the non-linear incidence rate. Under certain, well-defined conditions, the model undergoes a Hopf bifurcation. Using the normal form of the model, the first Lyapunov coefficient is computed to determine the various types of Hopf bifurcation the model undergoes. These general results are applied to two examples: unbounded and saturated contact rates; in both cases, forward or backward Hopf bifurcations occur for two distinct values of the contact parameter. It is also shown that the model may undergo a subcritical Hopf bifurcation leading to the appearance of two concentric limit cycles. The results are illustrated by numerical simulations with realistic model parameters estimated for some infectious diseases of childhood.
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Affiliation(s)
- M E Alexander
- Institute for Biodiagnostics, National Research Council Canada, 435 Ellice Avenue, Winnipeg, Man., Canada R3B 1Y6.
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Berul CI, Triedman JK, Forbess J, Bevilacqua LM, Alexander ME, Dahlby D, Gilkerson JO, Walsh EP. Minimally invasive cardioverter defibrillator implantation for children: an animal model and pediatric case report. Pacing Clin Electrophysiol 2001; 24:1789-94. [PMID: 11817814 DOI: 10.1046/j.1460-9592.2001.01789.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The smaller venous capacitance in infants and small children may hamper transvenous ICD lead implantation, and epicardial approaches require thoracotomy and have associated complications. The study evaluated the feasibility and performance of subcutaneous arrays and active can ICDs without transvenous shocking coils or epicardial patches. An immature and mature pig were anesthetized and ventilated. A pacing lead was inserted in the right ventricle for fibrillation induction and rate sensing. Subcutaneous arrays were positioned in the right and left chest walls. An ICD emulator was placed in abdominal and prepectoral pockets. Fluoroscopic images were acquired for each electrical vector configuration (array --> can, can --> array, array --> array, array + array --> can). Ventricular fibrillation was induced and DFT testing performed. Defibrillation was achieved in all ten trials in the immature piglet, with DFT < or = 9 J, regardless of vector configuration. Using a single subcutaneous array and active can, the shock impedance ranged from 28-36 ohms. With two arrays, shocking impedance fell to 15-22 ohms. In the adult pig, defibrillation was not accomplished with maximum energy of 40 J, using all vector configurations. Using data garnered from these experiments, this technique was then successfully performed in a 2-year-old child with VT and repaired congenital heart disease, needing an ICD. This study demonstrates the feasibility of leadless ICD implantation in an immature animal and successful implementation in a small child. A single subcutaneous array and active can resulted in excellent implant characteristics and DFTs with a minimally invasive approach. Defibrillation was not possible in a larger animal, possibly due to maximal available energy. This may be of value for small children requiring ICD implantation.
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Affiliation(s)
- C I Berul
- Department of Cardiology, Children's Hospital Boston, Harvard Medical School, Massachusetts 02115, USA.
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Love BA, Barrett KS, Alexander ME, Bevilacqua LM, Epstein MR, Triedman JK, Walsh EP, Berul CI. Supraventricular arrhythmias in children and young adults with implantable cardioverter defibrillators. J Cardiovasc Electrophysiol 2001; 12:1097-101. [PMID: 11699514 DOI: 10.1046/j.1540-8167.2001.01097.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Rapidly conducted supraventricular tachycardias (SVTs) can lead to inappropriate device therapy in implantable cardioverter defibrillator (ICD) patients. We sought to determine the incidence of SVTs and the occurrence of inappropriate ICD therapy due to SVT in a pediatric and young adult population. METHODS AND RESULTS We undertook a retrospective review of clinical course, Holter monitoring, and ICD interrogations of patients receiving ICD follow-up at our institution between March 1992 and December 1999. Of 81 new ICD implantations, 54 eligible patients (median age 16.5 years, range 1 to 48) were identified. Implantation indications included syncope and/or spontaneous/inducible ventricular arrhythmia with congenital heart disease (30), long QT syndrome (9), structurally normal heart (ventricular tachycardia/ventricular fibrillation [VT/VF]) (7), and cardiomyopathies (7). Sixteen patients (30%) received a dual-chamber ICD. SVT was recognized in 16 patients, with 12 of 16 having inducible or spontaneous atrial tachycardias. Eighteen patients (33%) received > or =1 appropriate shock(s) for VT/VF; 8 patients (15%) received inappropriate therapy for SVT. Therapies were altered after an inappropriate shock by increasing the detection time or rate and/or increasing beta-blocker dosage. No single-chamber ICD was initially programmed with detection enhancements, such as sudden onset, rate stability, or QRS discriminators. Only one dual-chamber defibrillator was programmed with an atrial discrimination algorithm. Appropriate ICD therapy was not withheld due to detection parameters or SVT discrimination programming. CONCLUSION SVT in children and young adults with ICDs is common. Inappropriate shocks due to SVT can be curtailed even without dual-chamber devices or specific SVT discrimination algorithms.
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Affiliation(s)
- B A Love
- Department of Cardiology, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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Affiliation(s)
- R E Walker
- Department of Cardiology, Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
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Triedman JK, Alexander ME, Berul CI, Bevilacqua LM, Walsh EP. Electroanatomic mapping of entrained and exit zones in patients with repaired congenital heart disease and intra-atrial reentrant tachycardia. Circulation 2001; 103:2060-5. [PMID: 11319195 DOI: 10.1161/01.cir.103.16.2060] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Characterization of reentrant circuits and targeting ablation sites remains difficult for intra-atrial reentrant tachycardias (IART) in congenital heart disease (CHD). METHODS AND RESULTS Electroanatomic mapping and entrainment pacing were performed before successful ablation of 18 IART circuits in 15 patients with CHD. Principal features of IART circuits were atrial septal defect (4 patients), atriotomy (3 patients), other atrial scar (3 patients), crista terminalis (3 patients), and right atrioventricular valve (5 patients). A median of 176 sites (range, 96 to 317 sites) was mapped for activation and 13 sites (range, 9 to 28 sites) for entrainment response. Postpacing intervals within 20 ms of tachycardia cycle length and stimulus-to-P-wave intervals of 0 to 90 ms (exit zones) were mapped to atrial surfaces generated by electroanatomic mapping. Criteria for entrainment were met over a median of 21 cm2 of atrial surface (range, 2 to 75 cm2), 19% (range, 1% to 81%) of total area tested. Using integrated data, relations between activation sequence and protected corridor of conduction could be inferred for 16 of 17 LARTs. Successful ablation was achieved at a site distant from the putative protected corridor in 9 of 18 (50%) circuits. CONCLUSIONS The right atrium in CHD supports a variety of IART mechanisms. Fusion of activation and entrainment data provided insight into specific IART mechanisms relevant to ablation.
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Affiliation(s)
- J K Triedman
- Department of Cardiology, Children's Hospital, Boston, MA 02115, USA.
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Triedman JK, Alexander ME, Berul CI, Bevilacqua LM, Walsh EP. Estimation of atrial response to entrainment pacing using electrograms recorded from remote sites. J Cardiovasc Electrophysiol 2000; 11:1215-22. [PMID: 11083242 DOI: 10.1046/j.1540-8167.2000.01215.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Assessing the entrainment response by measuring postpacing intervals (PPIs) at the pacing site facilitates localization of reentrant circuits, but may be technically difficult. METHODS AND RESULTS There were 269 right atrial sites entrained in 21 circuits in congenital heart patients left atrial (LA) electrograms were recorded. Entrainment response was measured by two methods: (1) PPI-tachycardia cycle length, and (2) the difference in latencies between the stimulus artifact and the pacing site electrogram, referenced to the LA electrogram. PPI also was measured from the LA as an index of antidromic activation. Among 43 pacing sites with antidromic LA activation, half showed a discrepancy 225 msec between methods 1 and 2. At the other 226 sites, agreement between the two methods was high (mean discrepancy -3+/-8 msec, r = 0.975, 0 sites with discrepancy 225 msec). Correcting all sites by LA antidromicity reduced the mean discrepancy to +1+/-6 msec and improved correlation (r = 0.988). CONCLUSION LA electrograms can be used to estimate right atrial entrainment response, if antidromic activation of the LA is recognized and taken into account.
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Affiliation(s)
- J K Triedman
- Department of Cardiology, Children's Hospital, Boston, Massachusetts 02115, USA.
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Abstract
Although isolated premature ventricular contractions may be seen in as many as 15% of normal newborns, one third of normal adolescents, and two thirds of adolescents and adults with repaired heart disease, sustained ventricular arrhythmias are relatively rare in young normal hearts. Sudden cardiac health is rare in young normal hearts, although there is an increased incidence in dilated cardiomyopathies and following repair of particular congenital heart lesions. Noninvasive and invasive techniques imperfectly stratify these patients. Patients with cardiomyopathy often have ventricular arrhythmias, although the risk of mortality is more closely linked to ventricular function. There are many infants and pediatric patients with apparently normal hearts who have combinations of asymptomatic nonsustained ventricular tachycardia and potentially serious symptoms. The clinical concern is to identify diagnoses such as long QT syndrome associated with recurrent cardiac syncope and premature mortality so that appropriate choices can be made regarding drug and device therapy. Although this broad range of disease places a premium on careful evaluation, selective therapy, and continued research, serious symptoms, even in the absence of ectopy, are concerning in any patient.
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Affiliation(s)
- M E Alexander
- Arrhythmia Service, Department of Cardiology, Children's Hospital-Boston, 300 Longwood Avenue, Boston, MA 02115, USA
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Abstract
This note describes the implementation of a three-dimensional (3D) registration algorithm, generalizing a previous 2D version [Alexander, Int J Imaging Systems and Technology 1999;10:242-57]. The algorithm solves an integrated form of linearized image matching equation over a set of 3D rectangular sub-volumes ('patches') in the image domain. This integrated form avoids numerical instabilities due to differentiation of a noisy image over a lattice, and in addition renders the algorithm robustness to noise. Registration is implemented by first convolving the unregistered images with a set of computationally fast [O(N)] filters, providing four bandpass images for each input image, and integrating the image matching equation over the given patch. Each filter and each patch together provide an independent set of constraints on the displacement field derived by solving a set of linear regression equations. Furthermore, the filters are implemented at a variety of spatial scales, enabling registration parameters at one scale to be used as an input approximation for deriving refined values of those parameters at a finer scale of resolution. This hierarchical procedure is necessary to avoid false matches occurring. Both downsampled and oversampled (undecimating) filtering is implemented. Although the former is computationally fast, it lacks the translation invariance of the latter. Oversampling is required for accurate interpolation that is used in intermediate stages of the algorithm to reconstruct the partially registered from the unregistered image. However, downsampling is useful, and computationally efficient, for preliminary stages of registration when large mismatches are present. The 3D registration algorithm was implemented using a 12-parameter affine model for the displacement: u(x) = Ax + b. Linear interpolation was used throughout. Accuracy and timing results for registering various multislice images, obtained by scanning a melon and human volunteers in various stationary positions, is described. The algorithm may be generalized to more general models of the displacement field, and is also well suited to parallel processing.
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Affiliation(s)
- P Zhilkin
- National Research Council Canada, Institute for Biodiagnostics, 435 Ellice Avenue, R3B 1Y6, Winnipeg, Manitoba, Canada.
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Alexander ME, Baumgartner R, Summers AR, Windischberger C, Klarhoefer M, Moser E, Somorjai RL. A wavelet-based method for improving signal-to-noise ratio and contrast in MR images. Magn Reson Imaging 2000; 18:169-80. [PMID: 10722977 DOI: 10.1016/s0730-725x(99)00128-9] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Magnetic resonance (MR) images acquired with fast measurement often display poor signal-to-noise ratio (SNR) and contrast. With the advent of high temporal resolution imaging, there is a growing need to remove these noise artifacts. The noise in magnitude MR images is signal-dependent (Rician), whereas most de-noising algorithms assume additive Gaussian (white) noise. However, the Rician distribution only looks Gaussian at high SNR. Some recent work by Nowak employs a wavelet-based method for de-noising the square magnitude images, and explicitly takes into account the Rician nature of the noise distribution. In this article, we apply a wavelet de-noising algorithm directly to the complex image obtained as the Fourier transform of the raw k-space two-channel (real and imaginary) data. By retaining the complex image, we are able to de-noise not only magnitude images but also phase images. A multiscale (complex) wavelet-domain Wiener-type filter is derived. The algorithm preserves edges better when the Haar wavelet rather than smoother wavelets, such as those of Daubechies, are used. The algorithm was tested on a simulated image to which various levels of noise were added, on several EPI image sequences, each of different SNR, and on a pair of low SNR MR micro-images acquired using gradient echo and spin echo sequences. For the simulated data, the original image could be well recovered even for high values of noise (SNR approximately 0 dB), suggesting that the present algorithm may provide better recovery of the contrast than Nowak's method. The mean-square error, bias, and variance are computed for the simulated images. Over a range of amounts of added noise, the present method is shown to give smaller bias than when using a soft threshold, and smaller variance than a hard threshold; in general, it provides a better bias-variance balance than either hard or soft threshold methods. For the EPI (MR) images, contrast improvements of up to 8% (for SNR = 33 dB) were found. In general, the improvement in contrast was greater the lower the original SNR, for example, up to 50% contrast improvement for SNR of about 20 dB in micro-imaging. Applications of the algorithm to the segmentation of medical images, to micro-imaging and angiography (where the correct preservation of phase is important for flow encoding to be possible), as well as to de-noising time series of functional MR images, are discussed.
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Affiliation(s)
- M E Alexander
- Institute for Biodiagnostics, National Research Council Canada, Winnipeg, Manitoba, Canada.
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Abstract
Sudden arrhythmic death in patients with repaired tetralogy of Fallot or its variants has a variety of causes. Consequently, it can serve as a paradigm for management of potentially malignant arrhythmias in all pediatric patients, particularly with regard to the use of nonpharmacologic therapy for management. Five cases are presented as touchpoints for discussion and demonstrate a number of important issues concerning the assessment and reduction of sudden cardiac death risk in these patients. First, there are no clinical parameters that can be used to accurately assess risk. Second, pharmacologic agents alone rarely are adequate therapy. Third, catheter ablation and antitachycardia devices continue to play an ever increasing role in management of these patients, and, finally, additional data are necessary to establish clear management guidelines in patients with congenital heart disease at risk for arrhythmic death.
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Affiliation(s)
- J P Saul
- The Children's Heart Center of South Carolina, Department of Pediatrics, Medical University of South Carolina, Charleston 29425, USA.
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Abstract
INTRODUCTION The role of programmed ventricular stimulation (VSTIM) for risk stratification in congenital heart disease is unclear. We analyzed the results of VSTIM in selected congenital heart disease survivors at a single center to determine whether it improved the ability to predict a serious outcome. METHODS AND RESULTS Between July 1985 and September 1996, 140 primary VSTIM studies were performed on 130 patients (median age 18.1 years, range 0 to 51). Tetralogy of Fallot (33 %), d-transposition of the great arteries (25 %), and left ventricular outflow tract obstruction (12%) accounted for the majority of patients. Indications included spontaneous ventricular tachycardia (VT) of > or = 3 beats (72%) and/or symptoms (68%). Sustained VT was induced in 25% of the studies, and nonsustained VT in 12%. Atrial flutter or other supraventricular tachycardia was documented in 32% and bradyarrhythmias in 26%. By univariate analysis, mortality was increased in patients with positive VSTIM versus negative VSTIM (18% vs 7%, P = 0.04). Using multivariate analysis, positive VSTIM was associated with a sixfold increased risk of decreased survival and a threefold increased risk of serious arrhythmic events, allowing up to 87% sensitivity in predicting mortality. However, 7 (33%) of 21 patients with documented clinical VT had false-negative studies. CONCLUSION VSTIM in a large, selected group of congenital heart disease patients identified a subgroup with significantly increased mortality and sudden arrhythmic events. Failure to induce VT was a favorable prognostic sign, but the frequency of false-negative studies was high. Frequent supraventricular tachycardia further complicated risk stratification. Although VSTIM appears to be a reasonable tool for evaluation of this population, a larger, multicenter trial is recommended to clarify its utility.
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MESH Headings
- Adolescent
- Adult
- Child
- Child, Preschool
- Death, Sudden, Cardiac/prevention & control
- Electric Stimulation
- Electrocardiography, Ambulatory
- Female
- Heart Block/diagnosis
- Heart Block/etiology
- Heart Block/mortality
- Heart Defects, Congenital/complications
- Heart Defects, Congenital/mortality
- Heart Defects, Congenital/physiopathology
- Heart Ventricles/physiopathology
- Humans
- Infant
- Infant, Newborn
- Male
- Middle Aged
- Predictive Value of Tests
- Retrospective Studies
- Risk Factors
- Survival Rate
- Tachycardia, Supraventricular/diagnosis
- Tachycardia, Supraventricular/etiology
- Tachycardia, Supraventricular/mortality
- Tachycardia, Ventricular/diagnosis
- Tachycardia, Ventricular/etiology
- Tachycardia, Ventricular/mortality
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Affiliation(s)
- M E Alexander
- Department of Cardiology, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
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Affiliation(s)
- J P Saul
- Department of Cardiology, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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Abstract
This note describes an improvement to an accurate, robust, and fast registration algorithm (Alexander, M.E. and Somorjai, R.L., Mag. Reson. Imaging, 14:453-468, 1996). A computationally inexpensive preregistration method is proposed, consisting of simply aligning the image centroids, from which estimates of the translation shifts are derived. The method has low sensitivity to noise, and provides starting values of sufficient accuracy for the iterative registration algorithm to allow accurate registration of images that have significant levels of noise and/or large misalignments. Also, it requires a smaller computational effort than the Fourier Phase Matching (FPM) preregistration method used previously. The FPM method provides accurate preregistration for low-noise images, but fails when significant noise is present. For testing the various methods, a 256 x 256 pixel T2*-weighted image was translated, rotated, and scaled to produce large misalignments and occlusion at the image boundaries. The two situations of no noise being present in the images and in which Gaussian noise is added, were tested. After preregistration, the images were registered by applying one or several passes of the iterative algorithm at different levels of preblurring of the input images. Results of using the old and new preregistration methods, as well as no preregistration, are compared for the final accuracy of recovery of registration parameters. In addition, the performances of three robust estimators: Least Median of Squares, Least Trimmed Squares, and Least Winsorized Mean, are compared with those of the nonrobust Least Squares and Woods' methods, and found to converge to correct solutions in cases where the nonrobust methods do not.
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Affiliation(s)
- M E Alexander
- National Research Council Canada, Institute for Biodiagnostics, Winnipeg, Canada
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45
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Abstract
Acquisition of MR images involves their registration against some prechosen reference image. Motion artifacts and misregistration can seriously flaw their interpretation and analysis. This article provides a global registration method that is robust in the presence of noise and local distortions between pairs of images. It uses a two-stage approach, comprising an optional Fourier phase-matching method to carry out preregistration, followed by an iterative procedure. The iterative stage uses a prescribed set of registration points, defined on the reference image, at which a robust nonlinear regression is computed from the squared residuals at these points. The method can readily accommodate general linear or even nonlinear, registration transformations on the images. The algorithm was tested by recovering the registration transformation parameters when a 256 x 256 pixel T2*-weighted human brain image was scaled, rotated, and translated by prescribed amounts, and to which different amounts of Gaussian noise had been added. The results show subpixel accuracy of recovery when no noise is present, and graceful degradation of accuracy as noise is added. When 40% noise is added to images undergoing small shifts, the recovery errors are less than 3 pixels. The same tests applied to the Woods algorithm gave slightly inferior accuracy for these images, but failed to converge to the correct parameters in some cases of large-scale-shifted images with 10% added noise.
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Affiliation(s)
- M E Alexander
- National Research Council Canada, Institute for Biodiagnostics, Winnipeg, Canada.
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Abstract
Neuronal population activity was investigated by computer simulation of a network model based on the neostriatum. Three network topologies were studied, based on different assumptions about the synaptic connectivity among medium spiny neurons. In all networks neurons were interconnected by inhibitory synapses. The connectivity was either symmetric, in which case all connections between cells were reciprocal and equal in strength; or asymmetric. Simulations showed that networks with symmetric connectivity receiving randomly distributed afferent excitation produced stationary spatial activity patterns. In contrast, asymmetric connectivity in homogeneous networks produced slow travelling-wave activity across the network. We suggest that the shape of the medium spiny neurons is an important determinant of synaptic connectivity and that changes in the shape of these neurons caused by Huntington's disease would result in asymmetric connectivity. Slow travelling-wave activity produced by asymmetric connectivity in the neostriatum could explain some aspects of the choreic movement and some electromyographic features seen in Huntington's patients.
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Affiliation(s)
- J R Wickens
- Department of Anatomy & Structural Biology, University of Otago, Dunedin, New Zealand
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47
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Abstract
The qualitative dynamical behaviour of a neural model based on the mammalian neostriatum was analyzed. The neostriatum was modelled as a mutually inhibitory network of physiological neurones, which was driven by excitatory afferents from the cerebral cortex. The analysis defined the conditions under which the system would enter into one of two dynamic modes, competition or co-activation, in terms of the parameters defining receptor-operated and voltage-sensitive channels in the neuronal membrane. We have previously argued that the mode of co-activation in the neostriatum may correspond to the state of muscular rigidity which occurs as a symptom of Parkinson's disease. The present work extends a preliminary analysis of a two-neurone system to a system of arbitrary size. An explicit prediction is made of the conditions under which a transition from co-activation to competition will occur, which is testable experimentally. The wavelength of a non-uniform activity pattern produced by small departures from uniform afferent drive is determined for one- and two-dimensional arrays of neurones. Two mild assumptions about the connectivity of the network were used to simplify the analysis, namely that the network was symmetric and homogeneous. The implications of departures from these assumptions for understanding the disordered movement seen in Huntington's disease are also considered.
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Affiliation(s)
- M E Alexander
- Department of Computer Science, University of Otago, Dunedin, New Zealand
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Rivers EP, Rady MY, Martin GB, Fenn NM, Smithline HA, Alexander ME, Nowak RM. Venous hyperoxia after cardiac arrest. Characterization of a defect in systemic oxygen utilization. Chest 1992; 102:1787-93. [PMID: 1446489 DOI: 10.1378/chest.102.6.1787] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Supranormal mixed venous oxygen saturation (mixed venous hyperoxia), although reported, has never been characterized in humans resuscitated from cardiac arrest (postarrest cardiogenic shock). By contrast, cardiogenic shock without cardiopulmonary arrest (primary cardiogenic shock) is accompanied by mixed venous hypoxia under similar conditions of low oxygen delivery (DO2). The appearance of mixed venous hyperoxia indicates an excessive supply relative to demand in perfused tissue or cellular impairment of oxygen utilization, ie, low systemic oxygen consumption (VO2). Failure to improve VO2 has been associated with a poor outcome in other shock states. STUDY OBJECTIVE This study evaluates the clinical significance of mixed venous hyperoxia and its implications for impaired systemic oxygen utilization. The oxygen transport patterns in surviving and nonsurviving cardiac arrest patients are compared for their prognostic and therapeutic implications. STUDY DESIGN Consecutive, nonrandomized series. SETTING Large urban emergency department (ED). PARTICIPANTS Adult normothermic, nontraumatic out-of-hospital cardiac arrest patients presenting to the ED who develop a return of spontaneous circulation (ROSC). INTERVENTIONS On arrival to the ED, a fiberoptic catheter was placed in the central venous position for continuous central venous oxygen saturation monitoring (ScvO2). A proximal aortic catheter was placed via the femoral artery for blood pressure monitoring. Upon ROSC, the fiberoptic catheter was advanced to the pulmonary artery. Mean arterial pressure (MAP), cardiac index (CI), VO2, DO2, systemic oxygen extraction ratio (OER), and systemic vascular resistance index (SVRI-dynes.s/cm5.m2) were measured immediately and every 30 min. The duration of cardiac arrest (DCA) in minutes and amount of epinephrine (milligrams) administered during ACLS was recorded. MEASUREMENTS AND RESULTS Twenty-three patients were entered into the study. Survivors (living more than 24 h) and nonsurvivors (living less than 24 h) were compared. CONCLUSIONS These findings indicate an impairment of systemic oxygen utilization in postarrest cardiogenic shock patients. In spite of a lower DO2 than survivors, the OER in nonsurvivors remained lower than expected. Venous hyperoxia is a clinical manifestation of this derangement. Epinephrine dose may have a causal relationship. The inability to attain a VO2 of greater than 90 ml/min.m2 after the first 6 h of aggressive therapy was associated with a 100 percent mortality in 24 h.
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Affiliation(s)
- E P Rivers
- Department of Emergency Medicine, Henry Ford Health Systems, Detroit, MI 48202
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Reo NV, Alexander ME, Goel R. A nuclear magnetic resonance investigation of the upper airways in ferrets. II. Contrast-enhanced imaging to distinguish vascular from other nasal fluids. Magn Reson Med 1992; 27:34-43. [PMID: 1435208 DOI: 10.1002/mrm.1910270105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Proton magnetic resonance imaging (MRI), used in conjunction with the intravascular contrast agent albumin-(Gd-DTPA), provides a means to distinguish vascular fluids from other nasal fluids in the upper airways. Ferrets were given an intravenous dose of albumin-(Gd-DTPA) followed by an intranasal challenge with either histamine (HS) or methacholine (MC). An observed increase in image intensity indicates that HS and MC both cause an accumulation of fluids in the nasal turbinate region. The MRI data are also influenced by the presence of blood, which contains the contrast agent, and a clear distinction can be made between vascular fluids and other nasal fluids (i.e., cellular and glandular secretions). The results show that HS causes an increase in vascular fluids in the nasal turbinates while MC does not. This methodology represents a new means to investigate airway pharmacology and the pathophysiology associated with various pharmacological agents, allergens, or viral infections.
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Affiliation(s)
- N V Reo
- Department of Biochemistry, Kettering-Scott Magnetic Resonance Laboratory, Wright State University, Dayton, Ohio
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Reo NV, Barnett JK, Neubecker TA, Alexander ME, Goecke CM. A nuclear magnetic resonance investigation of the upper airways in ferrets. I. Effects of histamine and methacholine. Magn Reson Med 1992; 27:21-33. [PMID: 1435207 DOI: 10.1002/mrm.1910270104] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Alterations induced in the upper airways of ferrets by intranasal provocation with methacholine (MC) and histamine (HS) were monitored using proton magnetic resonance imaging (MRI) and spin-spin relaxation rate (R2) measurements. Both MC and HS cause a significant increase in the MRI signal intensity and a decrease in R2 in the nasal turbinates. A dose-dependent response is observed for 20 to 315 nmol of HS, with a maximum increase in intensity of ca. 50% occurring above 80 nmol. A single unilateral challenge with MC yields a 62 +/- 3% increase in intensity. Control animals (saline-treated) show little change in image intensity. MC and HS cause decreases in the proton R2 by -27.0 +/- 5.5% and -17.2 +/- 4.3%, respectively. These data are indicative of an accumulation of fluid in the nasal airways. MRI provides an effective means to monitor changes in the nasal airways which occur as a result of pharmacological treatment.
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Affiliation(s)
- N V Reo
- Department of Biochemistry, Kettering-Scott Magnetic Resonance Laboratory, Wright State University, Dayton, Ohio
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