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Calvo-Monge J, Arroyo-Esquivel J, Gehman A, Sanchez F. Source-Sink Dynamics in a Two-Patch SI Epidemic Model with Life Stages and No Recovery from Infection. Bull Math Biol 2024; 86:102. [PMID: 38976154 DOI: 10.1007/s11538-024-01328-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 06/10/2024] [Indexed: 07/09/2024]
Abstract
This study presents a comprehensive analysis of a two-patch, two-life stage SI model without recovery from infection, focusing on the dynamics of disease spread and host population viability in natural populations. The model, inspired by real-world ecological crises like the decline of amphibian populations due to chytridiomycosis and sea star populations due to Sea Star Wasting Disease, aims to understand the conditions under which a sink host population can present ecological rescue from a healthier, source population. Mathematical and numerical analyses reveal the critical roles of the basic reproductive numbers of the source and sink populations, the maturation rate, and the dispersal rate of juveniles in determining population outcomes. The study identifies basic reproduction numbers R 0 for each of the patches, and conditions for the basic reproduction numbers to produce a receiving patch under which its population. These findings provide insights into managing natural populations affected by disease, with implications for conservation strategies, such as the importance of maintaining reproductively viable refuge populations and considering the effects of dispersal and maturation rates on population recovery. The research underscores the complexity of host-pathogen dynamics in spatially structured environments and highlights the need for multi-faceted approaches to biodiversity conservation in the face of emerging diseases.
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Affiliation(s)
- Jimmy Calvo-Monge
- Escuela de Matemática, Universidad de Costa Rica, San Pedro, San José, 11501, Costa Rica
| | - Jorge Arroyo-Esquivel
- Department of Global Ecology, Carnegie Institution for Science, Washington, DC, 20015, USA.
| | | | - Fabio Sanchez
- Escuela de Matemática, Universidad de Costa Rica, San Pedro, San José, 11501, Costa Rica
- Centro de Investigación en Matemática Pura y Aplicada, Universidad de Costa Rica, San Pedro, San José, 11501, Costa Rica
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2
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Maganhe BL, Andrade LS, Camilo LDO, Neto HG, Sanches EG. Food-related substrate preference in juveniles seastar Echinaster (Othilia) brasiliensis (Müller & Troschel,1842) in captivity. Zoo Biol 2023; 42:675-682. [PMID: 37171149 DOI: 10.1002/zoo.21777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 04/20/2023] [Accepted: 04/27/2023] [Indexed: 05/13/2023]
Abstract
There are only a few studies that describe the larval development of Echinaster or aspects on culture systems for the genus. For starfishes, the choice of suitable substrates has received special attention since it could influence the acid-base balance of the water, movement capacity and predation rate. The objective of this study was to evaluate the ideal food-related substrate for the rearing of juvenile Echinaster brasiliensis. A batch of fertilized eggs released in spontaneous spawning was collected and kept in a plankton-kreisel until metamorphosis. Data on preference of food-related substrate was recorded for 10 weeks from day 58 post-release. From release to 132 days old, arm length increased from 0.81 mm to 1.31 ± 0.03 mm. Considering the sudden increase in arm length (AL), it was estimated that feeding started around 40 days of age. Regarding food-related substrate preferences, biofilm grown on "rocks" showed a significant difference among other treatments, adding up to 50% of preference (p < .05). For sponge and biofilm from bio media, there was no statistical difference for the whole period. In this study, sponges showed to be the least preferred food-related substrate for post-settlement juveniles. Considering that Echinaster and other starfish are commonly maintained on a diet of collected or cultured sponges, difficulties in sourcing a ready supply throughout the year represent limitations to their sole use within commercial or laboratory-scale production. In this sense, the use of biofilm from biological media for the feeding of juvenile starfish is not yet reported in the literature and showed to be an easy and promising option.
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Affiliation(s)
- Bruna L Maganhe
- Postgraduate Program in Aquaculture and Fisheries, Fisheries Institute, Secretariat of Agriculture and Supply, São Paulo, São Paulo, Brazil
- Ubatuba Aquarium, Ubatuba, São Paulo, Brazil
| | | | - Laura de O Camilo
- Postgraduate Program in Aquaculture and Fisheries, Fisheries Institute, Secretariat of Agriculture and Supply, São Paulo, São Paulo, Brazil
- Ubatuba Aquarium, Ubatuba, São Paulo, Brazil
| | - Hugo G Neto
- Ubatuba Aquarium, Ubatuba, São Paulo, Brazil
| | - Eduardo G Sanches
- Marine Fish Laboratory, Fisheries Institute, Ubatuba, São Paulo, Brazil
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Moran AL, McLachlan RH, Thurber AR. Sea star wasting syndrome reaches the high Antarctic: Two recent outbreaks in McMurdo Sound. PLoS One 2023; 18:e0282550. [PMID: 37498849 PMCID: PMC10374074 DOI: 10.1371/journal.pone.0282550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 07/03/2023] [Indexed: 07/29/2023] Open
Abstract
Sea star wasting syndrome (SSWS) can cause widespread mortality in starfish populations as well as long-lasting changes to benthic community structure and dynamics. SSWS symptoms have been documented in numerous species and locations around the world, but to date there is only one record of SSWS from the Antarctic and this outbreak was associated with volcanically-driven high temperature anomalies. Here we report outbreaks of SSWS-like symptoms that affected ~30% of individuals of Odontaster validus at two different sites in McMurdo Sound, Antarctica in 2019 and 2022. Unlike many SSWS events in other parts of the world, these outbreaks were not associated with anomalously warm temperatures. Instead, we suggest they may have been triggered by high nutrient input events on a local scale. Although the exact cause of these outbreaks is not known, these findings are of great concern because of the keystone role of O. validus and the slow recovery rate of Antarctic benthic ecosystems to environmental stressors.
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Affiliation(s)
- Amy L Moran
- School of Life Sciences, University of Hawai'i at Mānoa, Mānoa, Hawaii, United States of America
| | - Rowan H McLachlan
- Department of Microbiology, College of Science, Oregon State University, Corvallis, Oregon, United States of America
| | - Andrew R Thurber
- Department of Microbiology, College of Science, Oregon State University, Corvallis, Oregon, United States of America
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, United States of America
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Loudon AH, Park J, Parfrey LW. Identifying the core microbiome of the sea star Pisaster ochraceus in the context of sea star wasting disease. FEMS Microbiol Ecol 2023; 99:6998556. [PMID: 36690340 DOI: 10.1093/femsec/fiad005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 11/08/2022] [Accepted: 01/21/2023] [Indexed: 01/25/2023] Open
Abstract
Sea stars are keystone species and their mass die-offs due to sea star wasting disease (SSWD) impact marine communities and have fueled recent interest in the microbiome of sea stars. We assessed the host specificity of the microbiome associated with three body regions of the sea star Pisaster ochraceus using 16S rRNA gene amplicon surveys of the bacterial communities living on and in Pisaster, their environment, and sympatric marine hosts across three populations in British Columbia, Canada. Overall, the bacterial communities on Pisaster are distinct from their environment and differ by both body region and geography. We identified core bacteria specifically associated with Pisaster across populations and nearly absent in other hosts and the environment. We then investigated the distribution of these core bacteria on SSWD-affected Pisaster from one BC site and by reanalyzing a study of SSWD on Pisaster from California. We find no differences in the distribution of core bacteria in early disease at either site and two core taxa differ in relative abundance in advanced disease in California. Using phylogenetic analyses, we find that most core bacteria have close relatives on other sea stars and marine animals, suggesting these clades have evolutionary adaptions to an animal-associated lifestyle.
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Affiliation(s)
- Andrew H Loudon
- Biodiversity Research Centre, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Jungsoo Park
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Laura Wegener Parfrey
- Biodiversity Research Centre, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Hakai Institute, PO Box 25039, Campbell River, BC V9W 0B7, Canada
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Oulhen N, Byrne M, Duffin P, Gomez-Chiarri M, Hewson I, Hodin J, Konar B, Lipp EK, Miner BG, Newton AL, Schiebelhut LM, Smolowitz R, Wahltinez SJ, Wessel GM, Work TM, Zaki HA, Wares JP. A Review of Asteroid Biology in the Context of Sea Star Wasting: Possible Causes and Consequences. THE BIOLOGICAL BULLETIN 2022; 243:50-75. [PMID: 36108034 PMCID: PMC10642522 DOI: 10.1086/719928] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
AbstractSea star wasting-marked in a variety of sea star species as varying degrees of skin lesions followed by disintegration-recently caused one of the largest marine die-offs ever recorded on the west coast of North America, killing billions of sea stars. Despite the important ramifications this mortality had for coastal benthic ecosystems, such as increased abundance of prey, little is known about the causes of the disease or the mechanisms of its progression. Although there have been studies indicating a range of causal mechanisms, including viruses and environmental effects, the broad spatial and depth range of affected populations leaves many questions remaining about either infectious or non-infectious mechanisms. Wasting appears to start with degradation of mutable connective tissue in the body wall, leading to disintegration of the epidermis. Here, we briefly review basic sea star biology in the context of sea star wasting and present our current knowledge and hypotheses related to the symptoms, the microbiome, the viruses, and the associated environmental stressors. We also highlight throughout the article knowledge gaps and the data needed to better understand sea star wasting mechanistically, its causes, and potential management.
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Affiliation(s)
- Nathalie Oulhen
- Department of Molecular and Cell Biology and Biochemistry, Brown University, Providence, Rhode Island
| | - Maria Byrne
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Paige Duffin
- Department of Genetics, University of Georgia, Athens, Georgia
| | - Marta Gomez-Chiarri
- Department of Fisheries, Animal, and Veterinary Science, University of Rhode Island, Kingston, Rhode Island
| | - Ian Hewson
- Department of Microbiology, Cornell University, Ithaca, New York
| | - Jason Hodin
- Friday Harbor Labs, University of Washington, Friday Harbor, Washington
| | - Brenda Konar
- College of Fisheries and Ocean Sciences, University of Alaska, Fairbanks, Alaska
| | - Erin K. Lipp
- Department of Environmental Health Science, University of Georgia, Athens, Georgia
| | - Benjamin G. Miner
- Department of Biology, Western Washington University, Bellingham, Washington
| | | | - Lauren M. Schiebelhut
- Department of Life and Environmental Sciences, University of California, Merced, California
| | - Roxanna Smolowitz
- Department of Biology and Marine Biology, Roger Williams University, Bristol, Rhode Island
| | - Sarah J. Wahltinez
- Department of Comparative, Diagnostic, and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, Florida
| | - Gary M. Wessel
- Department of Molecular and Cell Biology and Biochemistry, Brown University, Providence, Rhode Island
| | - Thierry M. Work
- US Geological Survey, National Wildlife Health Center, Honolulu Field Station, Honolulu, Hawaii
| | - Hossam A. Zaki
- Department of Molecular and Cell Biology and Biochemistry, Brown University, Providence, Rhode Island
| | - John P. Wares
- Department of Genetics, University of Georgia, Athens, Georgia
- Odum School of Ecology, University of Georgia, Athens, Georgia
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Hart MW, Guerra VI, Allen JD, Byrne M. Cloning and Selfing Affect Population Genetic Variation in Simulations of Outcrossing, Sexual Sea Stars. THE BIOLOGICAL BULLETIN 2021; 241:286-302. [PMID: 35015625 DOI: 10.1086/717293] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
AbstractMany sea stars are well known for facultative or obligate asexual reproduction in both the adult and larval life-cycle stages. Some species and lineages are also capable of facultative or obligate hermaphroditic reproduction with self-fertilization. However, models of population genetic variation and empirical analyses of genetic data typically assume only sexual reproduction and outcrossing. A recent reanalysis of previously published empirical data (microsatellite genotypes) from two studies of one of the most well-known sea star species (the crown-of-thorns sea star; Acanthaster sp.) concluded that cloning and self-fertilization in that species are rare and contribute little to patterns of population genetic variation. Here we reconsider that conclusion by simulating the contribution of cloning and selfing to genetic variation in a series of models of sea star demography. Simulated variation in two simple models (analogous to previous analyses of empirical data) was consistent with high rates of cloning or selfing or both. More realistic scenarios that characterize population flux in sea stars of ecological significance, including outbreaks of crown-of-thorns sea stars that devastate coral reefs, invasions by Asterias amurensis, and epizootics of sea star wasting disease that kill Pisaster ochraceus, also showed significant but smaller effects of cloning and selfing on variation within subpopulations and differentiation between subpopulations. Future models or analyses of genetic variation in similar study systems might benefit from simulation modeling to characterize possible contributions of cloning or selfing to genetic variation in population samples or to understand the limits on inferring the effects of cloning or selfing in nature.
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Work TM, Weatherby TM, DeRito CM, Besemer RM, Hewson I. Sea star wasting disease pathology in Pisaster ochraceus shows a basal-to-surface process affecting color phenotypes differently. DISEASES OF AQUATIC ORGANISMS 2021; 145:21-33. [PMID: 34080580 DOI: 10.3354/dao03598] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Sea star wasting disease (SSWD) refers to a suite of poorly described non-specific clinical signs including abnormal posture, epidermal ulceration, and limb autotomy (sloughing) causing mortalities of over 20 species of sea stars and subsequent ecological shifts throughout the northeastern Pacific. While SSWD is widely assumed to be infectious, with environmental conditions facilitating disease progression, few data exist on cellular changes associated with the disease. This is unfortunate, because such observations could inform mechanisms of disease pathogenesis and host susceptibility. Here, we replicated SSWD by exposing captive Pisaster ochraceus to a suite of non-infectious organic substances and show that development of gross lesions is a basal-to-surface process involving inflammation (e.g. infiltration of coelomocytes) of ossicles and mutable collagenous tissue, leading to epidermal ulceration. Affected sea stars also manifest increases in a heretofore undocumented coelomocyte type, spindle cells, that might be a useful marker of inflammation in this species. Finally, compared to purple morphs, orange P. ochraceus developed more severe lesions but survived longer. Longer-lived, and presumably more visible, severely-lesioned orange sea stars could have important demographic implications in terms of detectability of lesioned animals in the wild and measures of apparent prevalence of disease.
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Affiliation(s)
- Thierry M Work
- US Geological Survey, National Wildlife Health Center, Honolulu Field Station, Honolulu, HI 96850, USA
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Aquino CA, Besemer RM, DeRito CM, Kocian J, Porter IR, Raimondi PT, Rede JE, Schiebelhut LM, Sparks JP, Wares JP, Hewson I. Evidence That Microorganisms at the Animal-Water Interface Drive Sea Star Wasting Disease. Front Microbiol 2021; 11:610009. [PMID: 33488550 PMCID: PMC7815596 DOI: 10.3389/fmicb.2020.610009] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 11/30/2020] [Indexed: 12/19/2022] Open
Abstract
Sea star wasting (SSW) disease describes a condition affecting asteroids that resulted in significant Northeastern Pacific population decline following a mass mortality event in 2013. The etiology of SSW is unresolved. We hypothesized that SSW is a sequela of microbial organic matter remineralization near respiratory surfaces, one consequence of which may be limited O2 availability at the animal-water interface. Microbial assemblages inhabiting tissues and at the asteroid-water interface bore signatures of copiotroph proliferation before SSW onset, followed by the appearance of putatively facultative and strictly anaerobic taxa at the time of lesion genesis and as animals died. SSW lesions were induced in Pisaster ochraceus by enrichment with a variety of organic matter (OM) sources. These results together illustrate that depleted O2 conditions at the animal-water interface may be established by heterotrophic microbial activity in response to organic matter loading. SSW was also induced by modestly (∼39%) depleted O2 conditions in aquaria, suggesting that small perturbations in dissolved O2 may exacerbate the condition. SSW susceptibility between species was significantly and positively correlated with surface rugosity, a key determinant of diffusive boundary layer thickness. Tissues of SSW-affected individuals collected in 2013–2014 bore δ15N signatures reflecting anaerobic processes, which suggests that this phenomenon may have affected asteroids during mass mortality at the time. The impacts of enhanced microbial activity and subsequent O2 diffusion limitation may be more pronounced under higher temperatures due to lower O2 solubility, in more rugose asteroid species due to restricted hydrodynamic flow, and in larger specimens due to their lower surface area to volume ratios which affects diffusive respiratory potential.
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Affiliation(s)
- Citlalli A Aquino
- Department of Biology, Estuary and Ocean Science Center, San Francisco State University, Tiburon, CA, United States
| | - Ryan M Besemer
- Center for Marine Science, University of North Carolina Wilmington, Wilmington, NC, United States
| | | | - Jan Kocian
- Unaffiliated Researcher, Freeland, WA, United States
| | - Ian R Porter
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
| | - Peter T Raimondi
- Institute of Marine Sciences, Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Jordan E Rede
- Department of Microbiology, Cornell University, Ithaca, NY, United States
| | - Lauren M Schiebelhut
- Life and Environmental Sciences, University of California, Merced, Merced, CA, United States
| | - Jed P Sparks
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, United States
| | - John P Wares
- Department of Genetics, University of Georgia, Athens, GA, United States
| | - Ian Hewson
- Department of Microbiology, Cornell University, Ithaca, NY, United States
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Gehman AM, Satterfield DA, Keogh CL, McKay AF, Budischak SA. To improve ecological understanding, collect infection data. Ecosphere 2019. [DOI: 10.1002/ecs2.2770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Alyssa‐Lois M. Gehman
- Odum School of Ecology University of Georgia Athens Georgia USA
- Hakai Institute End of Kwakshua Channel, Calvert Island British Columbia Canada
- Department of Zoology University of British Columbia Vancouver British Columbia Canada
| | - Dara A. Satterfield
- Odum School of Ecology University of Georgia Athens Georgia USA
- Smithsonian Migratory Bird Center Smithsonian Conservation Biology Institute Washington D.C. USA
| | - Carolyn L. Keogh
- Odum School of Ecology University of Georgia Athens Georgia USA
- Department of Environmental Sciences Emory University Atlanta Georgia USA
| | | | - Sarah A. Budischak
- Odum School of Ecology University of Georgia Athens Georgia USA
- W. M. Keck Science Department of Claremont McKenna College Claremont California USA
- W. M. Keck Science Department of Pitzer College Claremont California USA
- W. M. Keck Science Department of Scripps College Claremont California USA
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Kay SWC, Gehman ALM, Harley CDG. Reciprocal abundance shifts of the intertidal sea stars, Evasterias troschelii and Pisaster ochraceus, following sea star wasting disease. Proc Biol Sci 2019; 286:20182766. [PMID: 31014216 PMCID: PMC6501928 DOI: 10.1098/rspb.2018.2766] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 03/30/2019] [Indexed: 12/18/2022] Open
Abstract
Disease emergence occurs within the context of ecological communities, and disease driven declines in host populations can lead to complex direct and indirect ecological effects. Varying effects of a single disease among multiple susceptible hosts could benefit relatively resistant species. Beginning in 2013, an outbreak of sea star wasting disease (SSWD) led to population declines of many sea star species along the west coast of North America. Through field surveys and laboratory experiments, we investigated how and why the relative abundances of two co-occurring sea star species, Evasterias troschelii and Pisaster ochraceus, shifted during the ongoing wasting epidemic in Burrard Inlet, British Columbia, Canada. We hypothesized that Evasterias is competitively inferior to Pisaster but more resistant to SSWD. Thus, we predicted that SSWD-induced declines of Pisaster could mitigate the negative effects of SSWD on Evasterias, as the latter would experience competitive release. We document shifts in sea star abundance from 2008-2017: Pisaster abundance and mean size declined during the outbreak, while Evasterias abundance increased from relatively rare to numerically dominant within the intertidal. When exposed to symptomatic sea stars, Pisaster and Evasterias both showed signs of SSWD, but transmission and susceptibility was lower in Evasterias. Despite diet overlap documented in our field surveys, Evasterias was not outcompeted by Pisaster in laboratory trails conducted with the relatively small Pisaster available after the outbreak. Interference competition with larger Pisaster, or prey exploitation by Pisaster during the summer when Evasterias is primarily subtidal, may explain the rarity of Evasterias prior to Pisaster declines. Our results suggest that indirect effects mediated by competition can mask some of the direct effects of disease outbreaks, and the combination of direct and indirect effects will determine the restructuring of a community after disturbance.
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Affiliation(s)
- Sharon W. C. Kay
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Alyssa-Lois M. Gehman
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
- Hakai Institute, End of Kwakshua Channel, Calvert Island, British Columbia, Canada
| | - Christopher D. G. Harley
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
- Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, British Columbia, Canada
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