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Kingston ACN, Woodin SA, Wethey DS, Speiser DI. Snapping shrimp have helmets that protect their brains by dampening shock waves. Curr Biol 2022; 32:3576-3583.e3. [PMID: 35793681 DOI: 10.1016/j.cub.2022.06.042] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [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: 12/29/2021] [Revised: 04/28/2022] [Accepted: 06/14/2022] [Indexed: 11/28/2022]
Abstract
Shock waves are supersonic high-amplitude pressure waves that cause barotrauma when they transfer kinetic energy to the tissues of animals.1-4 Snapping shrimp (Alpheidae) produce shock waves and are exposed to them frequently, so we asked if these animals have evolved mechanisms of physical protection against them. Snapping shrimp generate shock waves by closing their snapping claws rapidly enough to form cavitation bubbles that release energy as an audible "snap" and a shock wave when they collapse.5-8 We tested if snapping shrimp are protected from shock waves by a helmet-like extension of their exoskeleton termed the orbital hood. Using behavioral trials, we found shock wave exposure slowed shelter-seeking and caused a loss of motor control in Alpheus heterochaelis from which we had removed orbital hoods but did not significantly affect behavior in shrimp with unaltered orbital hoods. Shock waves thus have the potential to harm snapping shrimp but may not do so under natural conditions because of protection provided to shrimp by their orbital hoods. Using pressure recordings, we discovered the orbital hoods of A. heterochaelis dampen shock waves. Sealing the anterior openings of orbital hoods diminished how much they altered the magnitudes of shock waves, which suggests these helmet-like structures dampen shock waves by trapping and expelling water so that kinetic energy is redirected and released away from the heads of shrimp. Our results indicate orbital hoods mitigate blast-induced neurotrauma in snapping shrimp by dampening shock waves, making them the first biological armor system known to have such a function.
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Affiliation(s)
- Alexandra C N Kingston
- Department of Biological Science, The University of Tulsa, 800 South Tucker Drive, Tulsa, OK 74104 USA; Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208 USA.
| | - Sarah A Woodin
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208 USA
| | - David S Wethey
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208 USA
| | - Daniel I Speiser
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208 USA
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2
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Domínguez R, Vázquez E, Smallegange IM, Woodin SA, Wethey DS, Peteiro LG, Olabarria C. Predation risk increases in estuarine bivalves stressed by low salinity. Mar Biol 2021; 168:132. [PMID: 34720192 PMCID: PMC8550793 DOI: 10.1007/s00227-021-03942-8] [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] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/07/2021] [Indexed: 06/13/2023]
Abstract
UNLABELLED Salinity drops in estuaries after heavy rains are expected to increase in frequency and intensity over the next decades, with physiological and ecological consequences for the inhabitant organisms. It was investigated whether low salinity stress increases predation risk on three relevant commercial bivalves in Europe. In laboratory, juveniles of Venerupis corrugata, Cerastoderma edule, and the introduced Ruditapes philippinarum were subjected to low salinities (5, 10 and control 35) during two consecutive days and, afterwards, exposed to one of two common predators in the shellfish beds: the shore crab Carcinus maenas and the gastropod Bolinus brandaris, a non-indigenous species present in some Galician shellfish beds. Two types of choice experiment were done: one offering each predator one prey species previously exposed to one of the three salinities, and the other offering each predator the three prey species at the same time, previously exposed to one of the three salinities. Consumption of both predators and predatory behaviour of C. maenas (handling time, rejections, consumption rate) were measured. Predation rates and foraging behaviour differed, with B. brandaris being more generalist than C. maenas. Still, both predators consumed significantly more stressed (salinity 5 and 10) than non-stressed prey. The overall consumption of the native species C. edule and V. corrugata was greater than that of R. philippinarum, likely due to their vulnerability to low salinity and physical traits (e.g., thinner shell, valve gape). Increasing precipitations can alter salinity gradients in shellfish beds, and thus affect the population dynamics of harvested bivalves via predator-prey interactions. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s00227-021-03942-8.
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Affiliation(s)
- Rula Domínguez
- Centro de Investigación Mariña, Universidade de Vigo, Departamento de Ecoloxía e Bioloxía Animal, Facultade de Ciencias do Mar, 36331 Vigo, Spain
| | - Elsa Vázquez
- Centro de Investigación Mariña, Universidade de Vigo, Departamento de Ecoloxía e Bioloxía Animal, Facultade de Ciencias do Mar, 36331 Vigo, Spain
| | - Isabel M. Smallegange
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, the Netherlands
| | - Sarah A. Woodin
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208 USA
| | - David S. Wethey
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208 USA
| | - Laura G. Peteiro
- Centro de Investigación Mariña, Universidade de Vigo, Departamento de Ecoloxía e Bioloxía Animal, Facultade de Ciencias do Mar, 36331 Vigo, Spain
- Instituto de Investigacións Mariñas Consejo Superior de Investigaciones Científicas, C/Eduardo Cabello, 6, 36208 Vigo, Spain
| | - Celia Olabarria
- Centro de Investigación Mariña, Universidade de Vigo, Departamento de Ecoloxía e Bioloxía Animal, Facultade de Ciencias do Mar, 36331 Vigo, Spain
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Galaska MP, Wethey DS, Arias A, Dubois SF, Halanych KM, Woodin SA. The impact of aquaculture on the genetics and distribution of the onuphid annelid Diopatra biscayensis. Ecol Evol 2021; 11:6184-6194. [PMID: 34141211 PMCID: PMC8207402 DOI: 10.1002/ece3.7447] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 02/15/2021] [Accepted: 02/22/2021] [Indexed: 01/30/2023] Open
Abstract
AIM Evolutionary history of natural populations can be confounded by human intervention such as the case of decorator worm species Diopatra (Onuphidae), which have a history of being transported through anthropogenic activities. Because they build tubes and act as ecosystem engineers, they can have a large impact on the overall ecosystem in which they occur. One conspicuous member, Diopatra biscayensis, which was only described in 2012, has a fragmented distribution that includes the Bay of Biscay and the Normanno-Breton Gulf in the English Channel. This study explores the origin of these worms in the Normanno-Breton region, which has been debated to either be the result of a historic range contraction from a relic continuous population or a more recent introduction. LOCATION Northeastern Atlantic, the Bay of Biscay, and the Normanno-Breton Gulf. METHODS We utilized a RAD-tag-based SNP approach to create a reduced genomic data set to recover fine-scale population structure and infer which hypothesis best describes the D. biscayensis biogeographic distribution. The reduced genomic data set was used to calculate standard genetic diversities and genetic differentiation statistics, and utilized various clustering analyses, including PCAs, DAPC, and admixture. RESULTS Clustering analyses were consistent with D. biscayensis as a single population spanning the Bay of Biscay to the Normanno-Breton Gulf in the English Channel, although unexpected genetic substructure was recovered from Arcachon Bay, in the middle of its geographic range. Consistent with a hypothesized introduction, the isolated Sainte-Anne locality in the Normanno-Breton Gulf was recovered to be a subset of the diversity found in the rest of the Bay of Biscay. MAIN CONCLUSIONS These results are congruent with previous simulations that did not support connectivity from the Bay of Biscay to the Normanno-Breton Gulf by natural dispersal. These genomic findings, with support from previous climatic studies, further support the hypothesis that D. biscayensis phylogeographic connectivity is the result of introductions, likely through the regions' rich shellfish aquaculture, and not of a historically held range contraction.
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Affiliation(s)
- Matthew P. Galaska
- Cooperative Institute for Climate, Ocean, & Ecosystem StudiesNOAA Pacific Marine Environmental LabUniversity of WashingtonSeattleWashingtonUSA
- Department of Biological SciencesAuburn UniversityAuburnAlabamaUSA
| | - David S. Wethey
- Department of Biological SciencesUniversity of South CarolinaColumbiaSouth CarolinaUSA
| | - Andrés Arias
- Departamento de Biología de Organismos y Sistemas (Zoología)Universidad de OviedoOviedoSpain
| | | | | | - Sarah A. Woodin
- Department of Biological SciencesUniversity of South CarolinaColumbiaSouth CarolinaUSA
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Domínguez R, Olabarria C, Woodin SA, Wethey DS, Peteiro LG, Macho G, Vázquez E. Contrasting responsiveness of four ecologically and economically important bivalves to simulated heat waves. Mar Environ Res 2021; 164:105229. [PMID: 33316606 DOI: 10.1016/j.marenvres.2020.105229] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 11/25/2020] [Accepted: 11/30/2020] [Indexed: 06/12/2023]
Abstract
Heat waves are expected to increase in duration and frequency, impacting coastal ecosystems, especially intertidal organisms living near their thermal tolerance limits. Sedentary infaunal species are limited to some extent in escapes from sudden temperature changes, rather modifications to their physiology and behaviour are expected. This may lead to strong ecological and economic impacts on commercial bivalve species, such as Venerupis corrugata, Ruditapes decussatus, the introduced Ruditapes philippinarum and Cerastoderma edule, the most relevant in NW Spain. We investigated lethal and sublethal effects of heat during low tide on these species in the laboratory. Summer temperatures experienced within field, shallow sediments at approximately 2 cm depth i.e. 20 °C (control), 27 °C, 32 °C, and 37 °C, were replicated during four consecutive days and the diffusion of heat at the burrowing depth of each species was estimated; temperature exposure was expressed as degree hours above 22 °C. After two days of tidal exposure, C. edule and V. corrugata suffered significant mortalities, and also the most dramatic decrease in scope for growth (SFG) as well as reduction in burrowing activity. After four days under stress, all species had negative SFG. On recovery, species showed compensation at longer exposures, particularly C. edule. These effects of temperature on mortality, growth potential and burrowing ability may increase the time to achieve commercial size and exposure to predation. Particularly, V. corrugata, with a center of distribution lower in the intertidal and subtidal, and C. edule, shallower in the sediment, may be the most affected. Clearly the intensity and frequency of heat waves will affect these key species in the intertidal sediment flats changing ecosystem functioning and fisheries management strategies.
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Affiliation(s)
- Rula Domínguez
- Departamento de Ecoloxía e Bioloxía Animal, Facultade de Ciencias Do Mar, Campus As Lagoas-Marcosende s/n and Centro de Investigación Mariña, Universidade de Vigo, Illa de Toralla s/n, 36331, Vigo, Spain.
| | - Celia Olabarria
- Departamento de Ecoloxía e Bioloxía Animal, Facultade de Ciencias Do Mar, Campus As Lagoas-Marcosende s/n and Centro de Investigación Mariña, Universidade de Vigo, Illa de Toralla s/n, 36331, Vigo, Spain
| | - Sarah A Woodin
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC, 29208, USA
| | - David S Wethey
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC, 29208, USA
| | - Laura G Peteiro
- Departamento de Ecoloxía e Bioloxía Animal, Facultade de Ciencias Do Mar, Campus As Lagoas-Marcosende s/n and Centro de Investigación Mariña, Universidade de Vigo, Illa de Toralla s/n, 36331, Vigo, Spain; Instituto de Investigacións Mariñas - Consejo Superior de Investigaciones Científicas, C/ Eduardo Cabello, 6, 36208, Vigo, Spain
| | - Gonzalo Macho
- Departamento de Ecoloxía e Bioloxía Animal, Facultade de Ciencias Do Mar, Campus As Lagoas-Marcosende s/n and Centro de Investigación Mariña, Universidade de Vigo, Illa de Toralla s/n, 36331, Vigo, Spain
| | - Elsa Vázquez
- Departamento de Ecoloxía e Bioloxía Animal, Facultade de Ciencias Do Mar, Campus As Lagoas-Marcosende s/n and Centro de Investigación Mariña, Universidade de Vigo, Illa de Toralla s/n, 36331, Vigo, Spain
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5
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Crickenberger S, Wethey DS. Annual temperature variation as a time machine to understand the effects of long-term climate change on a poleward range shift. Glob Chang Biol 2018; 24:3804-3819. [PMID: 29748990 DOI: 10.1111/gcb.14300] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [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: 04/10/2018] [Revised: 04/10/2018] [Accepted: 04/17/2018] [Indexed: 06/08/2023]
Abstract
Range shifts due to annual variation in temperature are more tractable than range shifts linked to decadal to century long temperature changes due to climate change, providing natural experiments to determine the mechanisms responsible for driving long-term distributional shifts. In this study we couple physiologically grounded mechanistic models with biogeographic surveys in 2 years with high levels of annual temperature variation to disentangle the drivers of a historical range shift driven by climate change. The distribution of the barnacle Semibalanus balanoides has shifted 350 km poleward in the past half century along the east coast of the United States. Recruits were present throughout the historical range following the 2015 reproductive season, when temperatures were similar to those in the past century, and absent following the 2016 reproductive season when temperatures were warmer than they have been since 1870, the earliest date for temperature records. Our dispersal dependent mechanistic models of reproductive success were highly accurate and predicted patterns of reproduction success documented in field surveys throughout the historical range in 2015 and 2016. Our mechanistic models of reproductive success not only predicted recruitment dynamics near the range edge but also predicted interior range fragmentation in a number of years between 1870 and 2016. All recruits monitored within the historical range following the 2015 colonization died before 2016 suggesting juvenile survival was likely the primary driver of the historical range retraction. However, if 2016 is indicative of future temperatures mechanisms of range limitation will shift and reproductive failure will lead to further range retraction in the future. Mechanistic models are necessary for accurately predicting the effects of climate change on ranges of species.
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Affiliation(s)
- Sam Crickenberger
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina
| | - David S Wethey
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina
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6
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Peteiro LG, Woodin SA, Wethey DS, Costas-Costas D, Martínez-Casal A, Olabarria C, Vázquez E. Responses to salinity stress in bivalves: Evidence of ontogenetic changes in energetic physiology on Cerastoderma edule. Sci Rep 2018; 8:8329. [PMID: 29844535 PMCID: PMC5974369 DOI: 10.1038/s41598-018-26706-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 05/17/2018] [Indexed: 11/19/2022] Open
Abstract
Estuarine bivalves are especially susceptible to salinity fluctuations. Stage-specific sensibilities may influence the structure and spatial distribution of the populations. Here we investigate differences on the energetic strategy of thread drifters (3–4 mm) and sedentary settlers (9–10 mm) of Cerastoderma edule over a wide range of salinities. Several physiological indicators (clearance, respiration and excretion rates, O:N) were measured during acute (2 days) and acclimated responses (7 days of exposure) for both size classes. Our results revealed a common lethal limit for both developmental stages (Salinity 15) but a larger physiological plasticity of thread drifters than sedentary settlers. Acclimation processes in drifters were initiated after 2 days of exposure and they achieved complete acclimation by day 7. Sedentary settlers delay acclimation and at day 7 feeding activity had not resumed and energetic losses through respiration and excretion were higher at the lowest salinity treatment. Different responses facing salinity stress might be related to differences in habitat of each stage. For sedentary settlers which occupy relatively stable niches, energy optimisation include delaying the initiation of the energetically expensive acclimation processes while drifters which occupy less stable environments require a more flexible process which allow them to optimize energy acquisition as fast as possible.
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Affiliation(s)
- Laura G Peteiro
- Departament of Ecology and Marine Biology, University of Vigo, 36200, Vigo, Spain. .,Toralla Marine Station (ECIMAT), University of Vigo, 36311, Vigo, Spain.
| | - Sarah A Woodin
- Department of Biological Sciences, University of South Carolina, Columbia, 29208, USA
| | - David S Wethey
- Department of Biological Sciences, University of South Carolina, Columbia, 29208, USA
| | | | | | - Celia Olabarria
- Departament of Ecology and Marine Biology, University of Vigo, 36200, Vigo, Spain.,Toralla Marine Station (ECIMAT), University of Vigo, 36311, Vigo, Spain
| | - Elsa Vázquez
- Departament of Ecology and Marine Biology, University of Vigo, 36200, Vigo, Spain.,Toralla Marine Station (ECIMAT), University of Vigo, 36311, Vigo, Spain
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7
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Affiliation(s)
- Cristián J. Monaco
- Department of Biological Sciences University of South Carolina Columbia South Carolina 29208 USA
| | - David S. Wethey
- Department of Biological Sciences University of South Carolina Columbia South Carolina 29208 USA
| | - Brian Helmuth
- Marine Science Center Northeastern University Nahant Massachusetts 01908 USA
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8
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Kish NE, Helmuth B, Wethey DS. Physiologically grounded metrics of model skill: a case study estimating heat stress in intertidal populations. Conserv Physiol 2016; 4:cow038. [PMID: 27729979 PMCID: PMC5055285 DOI: 10.1093/conphys/cow038] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 08/16/2016] [Accepted: 08/18/2016] [Indexed: 05/25/2023]
Abstract
Models of ecological responses to climate change fundamentally assume that predictor variables, which are often measured at large scales, are to some degree diagnostic of the smaller-scale biological processes that ultimately drive patterns of abundance and distribution. Given that organisms respond physiologically to stressors, such as temperature, in highly non-linear ways, small modelling errors in predictor variables can potentially result in failures to predict mortality or severe stress, especially if an organism exists near its physiological limits. As a result, a central challenge facing ecologists, particularly those attempting to forecast future responses to environmental change, is how to develop metrics of forecast model skill (the ability of a model to predict defined events) that are biologically meaningful and reflective of underlying processes. We quantified the skill of four simple models of body temperature (a primary determinant of physiological stress) of an intertidal mussel, Mytilus californianus, using common metrics of model performance, such as root mean square error, as well as forecast verification skill scores developed by the meteorological community. We used a physiologically grounded framework to assess each model's ability to predict optimal, sub-optimal, sub-lethal and lethal physiological responses. Models diverged in their ability to predict different levels of physiological stress when evaluated using skill scores, even though common metrics, such as root mean square error, indicated similar accuracy overall. Results from this study emphasize the importance of grounding assessments of model skill in the context of an organism's physiology and, especially, of considering the implications of false-positive and false-negative errors when forecasting the ecological effects of environmental change.
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Affiliation(s)
- Nicole E. Kish
- Marine Science Program, University of South Carolina, Columbia, SC 29208, USA
| | - Brian Helmuth
- Marine Science Program, University of South Carolina, Columbia, SC 29208, USA
- Marine Science Center, Northeastern University, Nahant, MA 01908, USA
| | - David S. Wethey
- Marine Science Program, University of South Carolina, Columbia, SC 29208, USA
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9
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Seabra R, Wethey DS, Santos AM, Gomes F, Lima FP. Equatorial range limits of an intertidal ectotherm are more linked to water than air temperature. Glob Chang Biol 2016; 22:3320-3331. [PMID: 27109165 DOI: 10.1111/gcb.13321] [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] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 03/29/2016] [Accepted: 04/11/2016] [Indexed: 06/05/2023]
Abstract
As climate change is expected to impose increasing thermal stress on intertidal organisms, understanding the mechanisms by which body temperatures translate into major biogeographic patterns is of paramount importance. We exposed individuals of the limpet Patella vulgata Linnaeus, 1758, to realistic experimental treatments aimed at disentangling the contribution of water and air temperature for the buildup of thermal stress. Treatments were designed based on temperature data collected at the microhabitat level, from 15 shores along the Atlantic European coast spanning nearly 20° of latitude. Cardiac activity data indicated that thermal stress levels in P. vulgata are directly linked to elevated water temperature, while high air temperature is only stressful if water temperature is also high. In addition, the analysis of the link between population densities and thermal regimes at the studied locations suggests that the occurrence of elevated water temperature may represent a threshold P. vulgata is unable to tolerate. By combining projected temperatures with the temperature threshold identified, we show that climate change will likely result in the westward expansion of the historical distribution gap in the Bay of Biscay (southwest France), and northward contraction of the southern range limit in south Portugal. These findings suggest that even a minor relaxing of the upwelling off northwest Iberia could lead to a dramatic increase in thermal stress, with major consequences for the structure and functioning of the intertidal communities along Iberian rocky shores.
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Affiliation(s)
- Rui Seabra
- CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal
- Departamento de Biologia, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre, s/n, 4169-007, Porto, Portugal
| | - David S Wethey
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA
| | - António M Santos
- Departamento de Biologia, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre, s/n, 4169-007, Porto, Portugal
| | - Filipa Gomes
- CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal
| | - Fernando P Lima
- CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal
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10
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Woodin SA, Volkenborn N, Pilditch CA, Lohrer AM, Wethey DS, Hewitt JE, Thrush SF. Same pattern, different mechanism: Locking onto the role of key species in seafloor ecosystem process. Sci Rep 2016; 6:26678. [PMID: 27230562 PMCID: PMC4882525 DOI: 10.1038/srep26678] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 05/04/2016] [Indexed: 11/16/2022] Open
Abstract
Seafloor biodiversity is a key mediator of ecosystem functioning, but its role is often excluded from global budgets or simplified to black boxes in models. New techniques allow quantification of the behavior of animals living below the sediment surface and assessment of the ecosystem consequences of complex interactions, yielding a better understanding of the role of seafloor animals in affecting key processes like primary productivity. Combining predictions based on natural history, behavior of key benthic species and environmental context allow assessment of differences in functioning and process, even when the measured ecosystem property in different systems is similar. Data from three sedimentary systems in New Zealand illustrate this. Analysis of the behaviors of the infaunal ecosystem engineers in each system revealed three very different mechanisms driving ecosystem function: density and excretion, sediment turnover and surface rugosity, and hydraulic activities and porewater bioadvection. Integrative metrics of ecosystem function in some cases differentiate among the systems (gross primary production) and in others do not (photosynthetic efficiency). Analyses based on behaviors and activities revealed important ecosystem functional differences and can dramatically improve our ability to model the impact of stressors on ecosystem and global processes.
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Affiliation(s)
- Sarah Ann Woodin
- Department of Biological Sciences, University of South Carolina, 701 Sumter Street, Columbia, South Carolina 29208, USA
| | - Nils Volkenborn
- Department of Biological Sciences, University of South Carolina, 701 Sumter Street, Columbia, South Carolina 29208, USA.,School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York 11794-5000, USA
| | - Conrad A Pilditch
- School of Science, Faculty of Science and Engineering, University of Waikato, Hamilton 3240, New Zealand
| | - Andrew M Lohrer
- National Institute of Water and Atmospheric Research, PO Box 11-115, Hamilton 3251, New Zealand
| | - David S Wethey
- Department of Biological Sciences, University of South Carolina, 701 Sumter Street, Columbia, South Carolina 29208, USA
| | - Judi E Hewitt
- National Institute of Water and Atmospheric Research, PO Box 11-115, Hamilton 3251, New Zealand
| | - Simon F Thrush
- National Institute of Water and Atmospheric Research, PO Box 11-115, Hamilton 3251, New Zealand.,Institute of Marine Science, University of Auckland, Private Bag 92091, Auckland, 1142, New Zealand
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11
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Lima FP, Gomes F, Seabra R, Wethey DS, Seabra MI, Cruz T, Santos AM, Hilbish TJ. Loss of thermal refugia near equatorial range limits. Glob Chang Biol 2016; 22:254-263. [PMID: 26426985 DOI: 10.1111/gcb.13115] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [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: 08/13/2015] [Revised: 09/21/2015] [Accepted: 09/21/2015] [Indexed: 06/05/2023]
Abstract
This study examines the importance of thermal refugia along the majority of the geographical range of a key intertidal species (Patella vulgata Linnaeus, 1758) on the Atlantic coast of Europe. We asked whether differences between sun-exposed and shaded microhabitats were responsible for differences in physiological stress and ecological performance and examined the availability of refugia near equatorial range limits. Thermal differences between sun-exposed and shaded microhabitats are consistently associated with differences in physiological performance, and the frequency of occurrence of high temperatures is most probably limiting the maximum population densities supported at any given place. Topographical complexity provides thermal refugia throughout most of the distribution range, although towards the equatorial edges the magnitude of the amelioration provided by shaded microhabitats is largely reduced. Importantly, the limiting effects of temperature, rather than being related to latitude, seem to be tightly associated with microsite variability, which therefore is likely to have profound effects on the way local populations (and consequently species) respond to climatic changes.
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Affiliation(s)
- Fernando P Lima
- CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Universidade do Porto, Vairão, 4485-661, Portugal
| | - Filipa Gomes
- CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Universidade do Porto, Vairão, 4485-661, Portugal
| | - Rui Seabra
- CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Universidade do Porto, Vairão, 4485-661, Portugal
- Departamento de Biologia, Faculdade de Ciências da, Universidade do Porto, R. Campo Alegre, s/n, Porto, 4169-007, Portugal
| | - David S Wethey
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA
| | - Maria I Seabra
- MARE - Marine and Environmental Sciences Centre, Laboratório de Ciências do Mar (CIEMAR), Universidade de Évora, Avenida Vasco da Gama, Apartado 190, Sines, 7520-903, Portugal
| | - Teresa Cruz
- MARE - Marine and Environmental Sciences Centre, Laboratório de Ciências do Mar (CIEMAR), Universidade de Évora, Avenida Vasco da Gama, Apartado 190, Sines, 7520-903, Portugal
- Departamento de Biologia, Universidade de Évora, Évora, 7002-554, Portugal
| | - António M Santos
- Departamento de Biologia, Faculdade de Ciências da, Universidade do Porto, R. Campo Alegre, s/n, Porto, 4169-007, Portugal
| | - Thomas J Hilbish
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA
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12
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Abstract
Extreme heat events cause patchy mortality in many habitats. We examine biophysical mechanisms responsible for patchy mortality in beds of the competitively dominant ecosystem engineer, the marine mussel Mytilus californianus, on the west coast of the United States. We used a biophysical model to predict daily fluctuations in body temperature at sites from southern California to Washington and used results of laboratory experiments on thermal tolerance to determine mortality rates from body temperature. In our model, we varied the rate of thermal conduction within mussel beds and found that this factor can account for large differences in body temperature and consequent mortality during heat waves. Mussel beds provide structural habitat for other species and increase local biodiversity, but, as sessile organisms, they are particularly vulnerable to extreme weather conditions. Identifying critical biophysical mechanisms related to mortality and ecological performance will improve our ability to predict the effects of climate change on these vulnerable ecosystems.
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13
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Chennu A, Volkenborn N, de Beer D, Wethey DS, Woodin SA, Polerecky L. Effects of Bioadvection by Arenicola marina on Microphytobenthos in Permeable Sediments. PLoS One 2015; 10:e0134236. [PMID: 26230398 PMCID: PMC4521690 DOI: 10.1371/journal.pone.0134236] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [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: 02/08/2015] [Accepted: 07/07/2015] [Indexed: 11/18/2022] Open
Abstract
We used hyperspectral imaging to study short-term effects of bioturbation by lugworms (Arenicola marina) on the surficial biomass of microphytobenthos (MPB) in permeable marine sediments. Within days to weeks after the addition of a lugworm to a homogenized and recomposed sediment, the average surficial MPB biomass and its spatial heterogeneity were, respectively, 150-250% and 280% higher than in sediments without lugworms. The surficial sediment area impacted by a single medium-sized lugworm (~4 g wet weight) over this time-scale was at least 340 cm2. While sediment reworking was the primary cause of the increased spatial heterogeneity, experiments with lugworm-mimics together with modeling showed that bioadvective porewater transport from depth to the sediment surface, as induced by the lugworm ventilating its burrow, was the main cause of the increased surficial MPB biomass. Although direct measurements of nutrient fluxes are lacking, our present data show that enhanced advective supply of nutrients from deeper sediment layers induced by faunal ventilation is an important mechanism that fuels high primary productivity at the surface of permeable sediments even though these systems are generally characterized by low standing stocks of nutrients and organic material.
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Affiliation(s)
- Arjun Chennu
- Max Planck Institute for Marine Microbiology, Bremen, Germany
- * E-mail:
| | - Nils Volkenborn
- Department of Biological Sciences, University of South Carolina, Columbia, United States of America
| | - Dirk de Beer
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - David S. Wethey
- Department of Biological Sciences, University of South Carolina, Columbia, United States of America
| | - Sarah A. Woodin
- Department of Biological Sciences, University of South Carolina, Columbia, United States of America
| | - Lubos Polerecky
- Max Planck Institute for Marine Microbiology, Bremen, Germany
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14
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Woodin SA, Wethey DS, Dubois SF. Population structure and spread of the polychaete Diopatra biscayensis along the French Atlantic coast: human-assisted transport by-passes larval dispersal. Mar Environ Res 2014; 102:110-121. [PMID: 24933436 DOI: 10.1016/j.marenvres.2014.05.006] [Citation(s) in RCA: 7] [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: 11/02/2013] [Revised: 04/18/2014] [Accepted: 05/08/2014] [Indexed: 06/03/2023]
Abstract
Intertidal populations of the ecosystem engineering polychaete, Diopatra biscayensis, were analyzed on the French Atlantic coast for three years with individual size estimated from tube-cap aperture. All but the northernmost population along the Bay of Biscay have yearly recruitment. Individuals live 3-5 years and are likely reproductive as one year olds. Simulations indicate dispersal distances are <50 km; yet, populations also exist within the Normano-Breton Gulf in the western English Channel, more than 450 km from the northernmost Bay of Biscay population at La Trinité-sur-Mer. Three of the four populations in the Normano-Breton Gulf have no young of the year, but are near to active mussel culture where mussel seed is transported on ropes from dense D. biscayensis areas in the Vendée-Charente region in the Bay of Biscay. The majority of D. biscayensis were adjacent to the likely source, mussel seed ropes. Transport assisted by aquaculture is the likely explanation for the populations in the Normano-Breton Gulf.
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Affiliation(s)
- Sarah Ann Woodin
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208, USA.
| | - David S Wethey
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208, USA.
| | - Stanislas F Dubois
- IFREMER, DYNECO Laboratoire d'Ecologie Benthique, F-29280 Plouzané, France.
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15
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Abstract
We present a Dynamic Energy Budget (DEB) model for the quintessential keystone predator, the rocky-intertidal sea star Pisaster ochraceus. Based on first principles, DEB theory is used to illuminate underlying physiological processes (maintenance, growth, development, and reproduction), thus providing a framework to predict individual-level responses to environmental change. We parameterized the model for P. ochraceus using both data from the literature and experiments conducted specifically for the DEB framework. We devoted special attention to the model’s capacity to (1) describe growth trajectories at different life-stages, including pelagic larval and post-metamorphic phases, (2) simulate shrinkage when prey availability is insufficient to meet maintenance requirements, and (3) deal with the combined effects of changing body temperature and food supply. We further validated the model using an independent growth data set. Using standard statistics to compare model outputs with real data (e.g. Mean Absolute Percent Error, MAPE) we demonstrated that the model is capable of tracking P. ochraceus’ growth in length at different life-stages (larvae: MAPE = 12.27%; post-metamorphic, MAPE = 9.22%), as well as quantifying reproductive output index. However, the model’s skill dropped when trying to predict changes in body mass (MAPE = 24.59%), potentially because of the challenge of precisely anticipating spawning events. Interestingly, the model revealed that P. ochraceus reserves contribute little to total biomass, suggesting that animals draw energy from structure when food is limited. The latter appears to drive indeterminate growth dynamics in P. ochraceus. Individual-based mechanistic models, which can illuminate underlying physiological responses, offer a viable framework for forecasting population dynamics in the keystone predator Pisaster ochraceus. The DEB model herein represents a critical step in that direction, especially in a period of increased anthropogenic pressure on natural systems and an observed recent decline in populations of this keystone species.
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Affiliation(s)
- Cristián J. Monaco
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, United States of America
- * E-mail:
| | - David S. Wethey
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, United States of America
| | - Brian Helmuth
- Marine Science Center, Northeastern University, Nahant, Massachusetts, United States of America
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16
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Thrush SF, Hewitt JE, Parkes S, Lohrer AM, Pilditch C, Woodin SA, Wethey DS, Chiantore M, Asnaghi V, De Juan S, Kraan C, Rodil I, Savage C, Van Colen C. Experimenting with ecosystem interaction networks in search of threshold potentials in real-world marine ecosystems. Ecology 2014; 95:1451-7. [PMID: 25039209 DOI: 10.1890/13-1879.1] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Thresholds profoundly affect our understanding and management of ecosystem dynamics, but we have yet to develop practical techniques to assess the risk that thresholds will be crossed. Combining ecological knowledge of critical system interdependencies with a large-scale experiment, we tested for breaks in the ecosystem interaction network to identify threshold potential in real-world ecosystem dynamics. Our experiment with the bivalves Macomona liliana and Austrovenus stutchburyi on marine sandflats in New Zealand demonstrated that reductions in incident sunlight changed the interaction network between sediment biogeochemical fluxes, productivity, and macrofauna. By demonstrating loss of positive feedbacks and changes in the architecture of the network, we provide mechanistic evidence that stressors lead to break points in dynamics, which theory predicts predispose a system to a critical transition.
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17
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Woodin SA, Hilbish TJ, Helmuth B, Jones SJ, Wethey DS. Climate change, species distribution models, and physiological performance metrics: predicting when biogeographic models are likely to fail. Ecol Evol 2013; 3:3334-46. [PMID: 24223272 PMCID: PMC3797481 DOI: 10.1002/ece3.680] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [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: 03/27/2013] [Revised: 05/14/2013] [Accepted: 06/06/2013] [Indexed: 11/12/2022] Open
Abstract
Modeling the biogeographic consequences of climate change requires confidence in model predictions under novel conditions. However, models often fail when extended to new locales, and such instances have been used as evidence of a change in physiological tolerance, that is, a fundamental niche shift. We explore an alternative explanation and propose a method for predicting the likelihood of failure based on physiological performance curves and environmental variance in the original and new environments. We define the transient event margin (TEM) as the gap between energetic performance failure, defined as CTmax, and the upper lethal limit, defined as LTmax. If TEM is large relative to environmental fluctuations, models will likely fail in new locales. If TEM is small relative to environmental fluctuations, models are likely to be robust for new locales, even when mechanism is unknown. Using temperature, we predict when biogeographic models are likely to fail and illustrate this with a case study. We suggest that failure is predictable from an understanding of how climate drives nonlethal physiological responses, but for many species such data have not been collected. Successful biogeographic forecasting thus depends on understanding when the mechanisms limiting distribution of a species will differ among geographic regions, or at different times, resulting in realized niche shifts. TEM allows prediction of the likelihood of such model failure.
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Affiliation(s)
- Sarah A Woodin
- Department of Biological Sciences, University of South Carolina Columbia, South Carolina
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18
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19
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Abstract
Gridded weather data were evaluated as sources of forcing variables for biophysical models of intertidal animal body temperature with model results obtained using local weather station data serving as the baseline of comparison. The objective of the study was to determine which gridded data are sufficient to capture observed patterns of thermal stress. Three coastal sites in western North America were included in this analysis: Boiler Bay, Oregon; Bodega Bay, California; and Pacific Grove, California. The gridded data with the highest spatial resolution, the 32-km North American Regional Reanalysis (NARR) and the 38-km Climate Forecasting System Reanalysis (CFSR), predicted daily maximum intertidal animal temperature most similarly to the local weather Station data. Time step size was important for variables that change rapidly throughout the day, such as solar radiation. There were site-based differences in the ability of the model to predict daily maximum intertidal animal temperature, with the gridded data predictions being the closest to local weather station predictions in Boiler Bay, Oregon. In a review of gridded data used as part of ecological studies, there was broad use of the data across subject areas and ecosystems so the recent improvements in the spatial (from 2 degrees to 32 km) and temporal scales (from 6 hours to 1 hour) of gridded data will further add to the applicability within the ecological community particularly for mechanistic studies.
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Affiliation(s)
- K A S Mislan
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, South Carolina 29208, USA.
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20
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Jones SJ, Mieszkowska N, Wethey DS. Linking thermal tolerances and biogeography: Mytilus edulis (L.) at its southern limit on the east coast of the United States. Biol Bull 2009; 217:73-85. [PMID: 19679724 DOI: 10.1086/bblv217n1p73] [Citation(s) in RCA: 47] [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] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Temperature is a major factor contributing to the latitudinal distribution of species. In the Northern Hemisphere, a species is likely to be living very close to its upper thermal tolerance limits at the southern limit of its biogeographic range. With global warming, this southern limit is expected to shift poleward. Moreover, intertidal ecosystems are expected to be especially strongly affected, mostly due to their large daily and seasonal variations in temperature and exposure. Hence, these are model systems in which to conduct experiments examining the ecological effects of climate change. In this study we determined the upper lethal thermal limits, for both air and water, of the blue mussel Mytilus edulis via laboratory experiments. Tolerances vary seasonally, with a difference between media of 0.7 degrees C in June and 4.8 degrees C in November, as well as a decrease with multiple exposures. Measured lethal limits were then compared to field measurements of environmental temperature and concurrent measurements of mortality rates. Field results indicate that mortality in the intertidal occurs at rates expected from laboratory responses to elevated temperature. Hindcasts, retrospective analyses of historical data, indicate that high rates of mortality have shifted 51 and 42 days earlier in Beaufort, North Carolina, and Oregon Inlet, North Carolina, respectively, between 1956 and 2007. The combined data suggest that the historical southern limit of M. edulis near Cape Hatteras, North Carolina, is indeed the result of intolerance to high temperature, and that this range edge is shifting poleward in a manner indicative of global warming.
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Affiliation(s)
- Sierra J Jones
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208, USA.
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21
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Schmidt PS, Serrão EA, Pearson GA, Riginos C, Rawson PD, Hilbish TJ, Brawley SH, Trussell GC, Carrington E, Wethey DS, Grahame JW, Bonhomme F, Rand DM. Ecological genetics in the North Atlantic: environmental gradients and adaptation at specific loci. Ecology 2009; 89:S91-107. [PMID: 19097487 DOI: 10.1890/07-1162.1] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The North Atlantic intertidal community provides a rich set of organismal and environmental material for the study of ecological genetics. Clearly defined environmental gradients exist at multiple spatial scales: there are broad latitudinal trends in temperature, meso-scale changes in salinity along estuaries, and smaller scale gradients in desiccation and temperature spanning the intertidal range. The geology and geography of the American and European coasts provide natural replication of these gradients, allowing for population genetic analyses of parallel adaptation to environmental stress and heterogeneity. Statistical methods have been developed that provide genomic neutrality tests of population differentiation and aid in the process of candidate gene identification. In this paper, we review studies of marine organisms that illustrate associations between an environmental gradient and specific genetic markers. Such highly differentiated markers become candidate genes for adaptation to the environmental factors in question, but the functional significance of genetic variants must be comprehensively evaluated. We present a set of predictions about locus-specific selection across latitudinal, estuarine, and intertidal gradients that are likely to exist in the North Atlantic. We further present new data and analyses that support and contradict these simple selection models. Some taxa show pronounced clinal variation at certain loci against a background of mild clinal variation at many loci. These cases illustrate the procedures necessary for distinguishing selection driven by internal genomic vs. external environmental factors. We suggest that the North Atlantic intertidal community provides a model system for identifying genes that matter in ecology due to the clarity of the environmental stresses and an extensive experimental literature on ecological function. While these organisms are typically poor genetic and genomic models, advances in comparative genomics have provided access to molecular tools that can now be applied to taxa with well-defined ecologies. As many of the organisms we discuss have tight physiological limits driven by climatic factors, this synthesis of molecular population genetics with marine ecology could provide a sensitive means of assessing evolutionary responses to climate change.
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Affiliation(s)
- Paul S Schmidt
- Department of Biology, 433 South University Avenue, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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22
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Jenkins SR, Moore P, Burrows MT, Garbary DJ, Hawkins SJ, Ingólfsson A, Sebens KP, Snelgrove PVR, Wethey DS, Woodin SA. COMPARATIVE ECOLOGY OF NORTH ATLANTIC SHORES: DO DIFFERENCES IN PLAYERS MATTER FOR PROCESS? Ecology 2008; 89:S3-23. [PMID: 19097481 DOI: 10.1890/07-1155.1] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Stuart R Jenkins
- School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey LL595AB, United Kingdom.
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23
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Richmond CE, Wethey DS, Woodin SA. Climate change and increased environmental variability: Demographic responses in an estuarine harpacticoid copepod. Ecol Modell 2007. [DOI: 10.1016/j.ecolmodel.2007.06.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Gilman SE, Wethey DS, Helmuth B. Variation in the sensitivity of organismal body temperature to climate change over local and geographic scales. Proc Natl Acad Sci U S A 2006; 103:9560-5. [PMID: 16763050 PMCID: PMC1480446 DOI: 10.1073/pnas.0510992103] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [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: 11/18/2022] Open
Abstract
Global climate change is expected to have broad ecological consequences for species and communities. Attempts to forecast these consequences usually assume that changes in air or water temperature will translate into equivalent changes in a species' organismal body temperature. This simple change is unlikely because an organism's body temperature is determined by a complex series of interactions between the organism and its environment. Using a biophysical model, validated with 5 years of field observations, we examined the relationship between environmental temperature change and body temperature of the intertidal mussel Mytilus californianus over 1,600 km of its geographic distribution. We found that at all locations examined simulated changes in air or water temperature always produced less than equivalent changes in the daily maximum mussel body temperature. Moreover, the magnitude of body temperature change was highly variable, both within and among locations. A simulated 1 degrees C increase in air or water temperature raised the maximum monthly average of daily body temperature maxima by 0.07-0.92 degrees C, depending on the geographic location, vertical position, and temperature variable. We combined these sensitivities with predicted climate change for 2100 and calculated increases in monthly average maximum body temperature of 0.97-4.12 degrees C, depending on location and climate change scenario. Thus geographic variation in body temperature sensitivity can modulate species' experiences of climate change and must be considered when predicting the biological consequences of climate change.
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Affiliation(s)
- Sarah E Gilman
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA.
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25
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Abstract
Many activities by infauna, including burrowing and feeding, involve hydraulic mechanisms. We expected these activities to generate low-frequency pressure waves that would propagate through sediments and be detectable at some distance from the source. Pressure sensors in intertidal sediments recorded large-amplitude porewater pressure signals. Laboratory recordings of single individuals allowed us to identify characteristic signals of arenicolid and nereidid polychaetes and tellinid bivalves. In the bivalve Macoma nasuta, these high-amplitude signals were associated with burrowing, expulsion of pseudofeces, and siphon relocation. In the polychaetes Neanthes brandti and Abarenicola pacifica, the high-amplitude pressure signals were associated with burrowing, burrow construction, burrow ventilation, and defecation. These signals were detectable in the field at distances of at least 20 cm. Since the waveforms are species-specific as well as activity-specific, they may provide a mechanism for prey detection, for predator avoidance, for competitor detection, and perhaps even for mate detection.
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Affiliation(s)
- David S Wethey
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208, USA.
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26
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Abstract
The selfish herd hypothesis predicts that aggregations form because individuals move toward one another to minimize their own predation risk. The "dilemma of the selfish herd" is that movement rules that are easy for individuals to follow, fail to produce true aggregations, while rules that produce aggregations require individual behavior so complex that one may doubt most animals can follow them. If natural selection at the individual level is responsible for herding behavior, a solution to the dilemma must exist. Using computer simulations, we examined four different movement rules. Relative predation risk was different for all four movement rules (p<0.05). We defined three criteria for measuring the quality of a movement rule. A good movement rule should (a) be statistically likely to benefit an individual that follows it, (b) be something we can imagine most animals are capable of following, and (c) result in a centrally compact flock. The local crowded horizon rule, which allowed individuals to take the positions of many flock-mates into account, but decreased the influence of flock-mates with distance, best satisfied these criteria. The local crowded horizon rule was very sensitive to the animal's perceptive ability. Therefore, the animal's ability to detect its neighbors is an important factor in the dynamics of group formation.
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Affiliation(s)
- Steven V Viscido
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA.
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27
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Abstract
According to the selfish herd hypothesis, animals can decrease predation risk by moving toward one another if the predator can appear anywhere and will attack the nearest target. Previous studies have shown that aggregations can form using simple movement rules designed to decrease each animal's Domain of Danger. However, if the predator attacks from outside the group's perimeter, these simple movement rules might not lead to aggregation. To test whether simple selfish movement rules would decrease predation risk for those situations when the predator attacks from outside the flock perimeter, we constructed a computer model that allowed flocks of 75 simulated fiddler crabs to react to one another, and to a predator attacking from 7 m away. We attacked simulated crab flocks with predators of different sizes and attack speeds, and computed relative predation risk after 120 time steps. Final trajectories showed flight toward the center of the flock, but curving away from the predator. Path curvature depended on the predator's size and approach speed. The average crab experienced a greater decrease in predation risk when the predator was small or slow moving. Regardless of the predator's size and speed, however, predation risk always decreased as long as crabs took their flock-mates into account. We conclude that, even when flight away from an external predator occurs, the selfish avoidance of danger can lead to aggregation.
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Affiliation(s)
- S V Viscido
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, U.S.A.
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28
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Grove MW, Finelli CM, Wethey DS, Woodin SA. The effects of symbiotic crabs on the pumping activity and growth rates of Chaetopterus variopedatus. J Exp Mar Biol Ecol 2000; 246:31-52. [PMID: 10699217 DOI: 10.1016/s0022-0981(99)00171-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This study investigates how the presence of symbiotic crabs (Pinnixa chaetopterana or Polyonyx gibbesi) in the tubes of the polychaete Chaetopterus variopedatus affects the worms' pumping activity and growth rates under laboratory and field conditions. In the field, worms whose tubes are inhabited by Pinnixa beat their fan segments significantly more frequently than do worms hosting Polyonyx, but other measures of pumping activity do not differ according to symbiont species. In the lab, worms tend to move water through their tubes at higher rates when crabs are present. In 7-month laboratory experiments, growth rates of worms hosting either species of crab did not differ from growth rates of worms without crab symbionts. Although worms hosting Polyonyx are, on average, significantly larger than worms hosting Pinnixa, this appears to be due to competition between the crab species for hosts and not due to differential effects on host growth. Unlike the crabs in this study, pea crab species inhabiting bivalves are known to have strong deleterious effects on host growth and reproduction, suggesting that the evolution of virulence in symbiotic interactions is dependent upon specific ecological context.
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Affiliation(s)
- MW Grove
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
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Tamburri MN, Finelli CM, Wethey DS, Zimmer-Faust RK. Chemical Induction of Larval Settlement Behavior in Flow. Biol Bull 1996; 191:367-373. [PMID: 29215928 DOI: 10.2307/1543009] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The ability of dissolved chemical cues to induce larval settlement from the water column has long been debated. Through computer-assisted video motion analysis, we quantified the movements of individual oyster (Crassostrea virginica) larvae in a small racetrack flume at free-stream flow speeds of 2.8, 6.2, and 10.4 cm/s. In response to waterborne chemical cues, but not to seawater (control), oyster larvae moved downward in the water column and swam in slow curved paths before attaching to the flume bottom. Effective stimuli were adult-oyster-conditioned seawater (OCW) and a synthetic peptide analog (glycyl-glycyl-L-arginine) for the natural cue. The chemically mediated behavioral responses of oyster larvae in flow were essentially identical to those responses previously reported in still water. Our experimental results therefore demonstrate the capacity of waterborne cues to evoke settlement behavior in oyster pediveligers under varying hydrodynamic conditions.
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31
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Lindsay SM, Wethey DS, Woodin SA. Modeling Interactions of Browsing Predation, Infaunal Activity, and Recruitment in Marine Soft-Sediment Habitats. Am Nat 1996. [DOI: 10.1086/285947] [Citation(s) in RCA: 20] [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: 11/03/2022]
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Abstract
In marine sediments, many of the processes associated with high post-settlement mortality of infauna have similar effects on the sediment surface. In most cases the original sediment surface is either removed, buried, or mixed with subsurface sediment. The experiments reported here tested the ability of new juvenile infauna to discriminate between undisturbed and recently disturbed sediment surfaces (i.e., subsurface sediment exposed). Recently settled juveniles of two polychaete species (Nereis vexillosa and Arenicola cristata) and one bivalve species (Mercenaria mercenaria) were exposed to simulated erosional and mixing events as well as to fresh feces, burrow tailings, and feeding tracks. Where the disturbance buried or removed several millimeters of the sediment surface, the time to initiate burrowing or the percentage of individuals failing to burrow increased significantly over times and percentages for juveniles on undisturbed surfaces. In all cases the results were consistent with the hypothesis that new juveniles reject (or are significantly slower to burrow into) disturbed sediment surfaces, if the disturbance is less than several hours old. For example, 51% of nereid juveniles did not burrow when placed on subsurface sediments, whereas 100% burrowed into surface sediments; their average burrowing time on surface sediments was 29.3 s compared with 109.7 s on fecal mounds of arenicolid polychaetes or 106.1 s on burrow tailings of thalassinid crustaceans. Individuals that did not indicate acceptance of a sediment surface by burrowing were all rapidly eroded from the surface in the presence of flow. Erosion of nonburrowing individuals occurred within 90 s of initiation of flow. Burrowing individuals were not eroded. The decision as to the acceptability of a sediment was made within 30 s. These data imply that the new juveniles are utilizing cues associated with a process, the disturbance of surface sediments, in addition to the species-specific cues described elsewhere.
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33
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Zimmer-Faust RK, Finelli CM, Pentcheff ND, Wethey DS. Odor Plumes and Animal Navigation in Turbulent Water Flow: A Field Study. Biol Bull 1995; 188:111-116. [PMID: 29281358 DOI: 10.2307/1542075] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Turbulence causes chemical stimuli to be highly variable in time and space; hence the study of animal orientation in odor plumes presents a formidable challenge. Through combined chemical and physical measurements, we characterized the transport of attractant released by clam prey in a turbulent aquatic environment. Concurrently, we quantified the locomotory responses of predatory crabs successfully searching for sources of clam attractant. Our results demonstrate that both rheotaxis and chemotaxis are necessary for successful orientation. Perception of chemical cues causes crabs to move in the upstream direction, but feedback from attractant distributions directly regulates movement across-stream in the plume. Orientation mechanisms used by crabs difler from those employed by flying insects, the only other system in which navigation relative to odor plumes has been coupled with fluid dynamics. Insects respond to odors by moving upstream, but they do not use chemical distributions to determine across-stream direction, whereas crabs do. Turbulent eddy diffusivities in crab habitats are 100 to 1000 times lower than those of terrestrial grasslands and forests occupied by insects. Insects must respond to plumes consisting of highly dispersed, tiny filaments or parcels of odor. Crabs rely more heavily on spatial aspects of chemical stimulus distributions because their fluid dynamic environment creates a more stable plume structure, thus permitting chemotaxis.
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Walters LJ, Wethey DS. Settlement, Refuges, and Adult Body Form in Colonial Marine Invertebrates: A Field Experiment. Biol Bull 1991; 180:112-118. [PMID: 29303633 DOI: 10.2307/1542434] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We examine the relationship between adult body form (sheet vs. arborescent) and larval settlement in colonial animals. Because thin sheet forms are more susceptible to overgrowth than arborescent forms, we predict that larvae of sheet forms should preferentially settle in refuges from competitors. On both natural and artificial substrata, the larvae of the sheet form (Membranipora membranacea) settled more often on high spots, which could serve as refuges from competition. The arborescent forms (Bugula neritina and Distaplia occidentalis) settled around the bases of bumps more frequently than would be expected by chance. For many arborescent forms, their most vulnerable periods are the days immediately following settlement, when individuals can be consumed easily by predators or dislodged by physical disturbances. Settlement in a crevice (base of a bump) would provide protection from the bulky mouthparts of predators. Moreover, dislodgment would be less likely than if settlement had occurred on flat locations, such as the tops of bumps or the areas between bumps.
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Wethey DS. Effects of crowding on fecundity in barnacles: Semibalanus (Balanus) balanoides, Balanus glandula, and Chthamalus dalli. CAN J ZOOL 1984. [DOI: 10.1139/z84-261] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Phenotypic plasticity of relative investment in shell, eggs, and somatic tissue was examined with experimental population density manipulations in field populations of the intertidal barnacles Semibalanus (Balanus) balanoides from Massachusetts and Balanus glandula and Chthamalus dalli from Washington State, U.S.A. Individuals of S. balanoides of comparable somatic tissue weights produced larger clutches of eggs when crowded and columnar than when conical and uncrowded. Individuals of C. dalli showed a similar pattern. Individuals of B. glandula showed the opposite pattern: at comparable somatic tissue weights, conical uncrowded individuals made slightly larger clutches of eggs than did crowded, columnar individuals. In all cases the greatest shell investment per unit somatic tissue weight was associated with the greatest clutch investment per unit somatic tissue weight.
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Wethey DS. Intrapopulation Variation in Growth of Sessile Organisms: Natural Populations of the Intertidal Barnacle Balanus balanoides. OIKOS 1983. [DOI: 10.2307/3544195] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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