Posts Tagged 'communitymodeling'

Climate shapes population variation in dogwhelk predation on foundational mussels

Trait variation among populations is important for shaping ecological dynamics. In marine intertidal systems, seawater temperature, low tide emersion temperature, and pH can drive variation in traits and affect species interactions. In western North America, Nucella dogwhelks are intertidal drilling predators of the habitat-forming mussel Mytilus californianus. Nucella exhibit local adaptation, but it is not known to what extent environmental factors and genetic structure contribute to variation in prey selectivity among populations. We surveyed drilled mussels at sites across Oregon and California, USA, and used multiple regression and Mantel tests to test the effects of abiotic factors and Nucella neutral genetic relatedness on the size of mussels drilled across sites. Our results show that Nucella at sites characterized by higher and less variable temperature and pH drilled larger mussels. Warmer temperatures appear to induce faster handling time, and more stable pH conditions may prolong opportunities for active foraging by reducing exposure to repeated stressful conditions. In contrast, there was no significant effect of genetic relatedness on prey size selectivity. Our results emphasize the role of climate in shaping marine predator selectivity on a foundation species. As coastal climates change, predator traits will respond to localized environmental conditions, changing ecological interactions.

Continue reading ‘Climate shapes population variation in dogwhelk predation on foundational mussels’

Potential socioeconomic impacts from ocean acidification and climate change effects on Atlantic Canadian fisheries

Ocean acidification is an emerging consequence of anthropogenic carbon dioxide emissions. The full extent of the biological impacts are currently not entirely defined. However, it is expected that invertebrate species that rely on the mineral calcium carbonate will be directly affected. Despite the limited understanding of the full extent of potential impacts and responses there is a need to identify potential pathways for human societies to be affected by ocean acidification. Research on these social implications is a small but developing field. This research contributes to this field by using an impact assessment framework, informed by a biophysical model of future species distributions, to investigate potential impacts facing Atlantic Canadian society from potential changes in shellfish fisheries driven by ocean acidification and climate change. New Brunswick and Nova Scotia are expected to see declines in resource accessibility but are relatively socially insulated from these changes. Conversely, Prince Edward Island, along with Newfoundland and Labrador are more socially vulnerable to potential losses in fisheries, but are expected to experience relatively minor net changes in access.

Continue reading ‘Potential socioeconomic impacts from ocean acidification and climate change effects on Atlantic Canadian fisheries’

Effects of coastal acidification on North Atlantic bivalves: interpreting laboratory responses in the context of in situ populations

Experimental exposure of early life stage bivalves has documented negative effects of elevated pCO2 on survival and growth, but the population consequences of these effects are unknown. We substituted laboratory responses into baseline population models of northern quahog Mercenaria mercenaria and bay scallop Argopecten irradians. The models were constructed using inverse demography with time series of size-structured field data from New York, USA, whereas the stress-response relationships were developed using data from published laboratory studies. We used stochastic projections and diffusion approximations of extinction probability to estimate cumulative risk of 50% population decline during 5 yr projections at pCO2 levels of 400, 800, and 1200 µatm. Although the A. irradians field population exhibited higher growth (12% yr-1) than the declining M. mercenaria population (-8% yr-1), cumulative risk was higher due to variance in the stochastic growth rate estimate (log λs = -0.02, σ2 = 0.24). This 5 yr risk increased from 56% at 400 µatm to 99 and >99% at 800 and 1200 µatm, respectively. For M. mercenaria (log λs = -0.09, σ2 = 0.01), 5 yr risk was 25, 79, and 97% at 400, 800, and 1200 µatm, respectively. These estimates could be improved with detailed consideration of harvest, disease, restocking, compensatory responses, and interactions between these and other effects. However, results clearly indicate that early life stage responses to plausible levels of pCO2 enrichment have the potential to cause significant increases in risk to these marine bivalve populations.

Continue reading ‘Effects of coastal acidification on North Atlantic bivalves: interpreting laboratory responses in the context of in situ populations’

Multispecies yield and profit when exploitation rates vary spatially including the impact on mortality of ocean acidification on North Pacific crab stocks

A multi-species size-structured population dynamics model that can account for spatial structure and technical interactions between commercial fisheries was developed and applied to the snow and southern Tanner crab fisheries in the eastern Bering Sea. The model was then used as the basis for forecasts to calculate reference points related to yield and profit under the effects of ocean acidification on snow and southern Tanner crab. Stochastic projections that account for variation about the stock-recruitment relationship were undertaken for a constant F35% harvest strategy, a strategy that sets effort to maximize profit ignoring the effects of environmental variability such as ocean acidification, and the Acceptable Biological Catch control rule, which includes a reduction in fishing mortality rate when stocks are below target levels. Single- and four-area models led to similar fits to abundance and catch data, and provide similar estimates of time-trajectories of mature male biomass. The model is used to compute Maximum Sustainable Yield (MSY) and an upper bound on Maximum Economic Yield (uMEY). The effort levels that achieve MSY and uMEY were sensitive to whether a spatial or non-spatial model was used to calculate reference points and hence how technical interactions among species were accounted for. Dynamic projections based on various management strategies indicated that adopting a uMEY target level of effort leads to some robustness to the effects of ocean acidification, although similar results can be obtained using the Acceptable Biological Catch control rule, which reduces harvest rates as biomass levels decline.

Continue reading ‘Multispecies yield and profit when exploitation rates vary spatially including the impact on mortality of ocean acidification on North Pacific crab stocks’

Modeling climate-dependent larval growth rate and duration of Olympia oysters in the Salish Sea

Most invertebrates in the ocean begin their lives with a planktonic larval phase that is of utmost importance for dispersal and distribution of these species, especially for organisms that are sessile or otherwise mobility-limited during adult life. As larvae are particularly vulnerable to environmental change, holistic understanding of interacting climate stressors on larval life is important to predict population persistence and vulnerability of species. However, traditional experimental designs are often limited by resolution in understanding multiple stress relationships, as environmental variables in the ocean do not occur in discrete interacting levels. Here, I use a novel experimental approach to model growth rate and duration of Olympia oyster larvae and predict the suitability of habitats for larval survival in interacting gradients of temperature, salinity, and ocean acidification. I find that temperature and salinity are closely linked to larval growth and larval habitat suitability, but larvae are resistant to acidification. Olympia oyster larvae from populations in the Salish Sea exhibit higher growth rate and greater tolerance to habitats in near-future climate change conditions compared to present-day conditions in the Salish Sea, suggesting that this species will benefit from some degree of global ocean change. Using generalized linear modeling, I predict larval growth and duration in present-day and future oceanographic conditions in the Salish Sea, finding a vast decrease in mean pelagic larval duration by the year 2095. Using these data, I explore implications of these relationships for Olympia oysters across their range now and in the future.

Continue reading ‘Modeling climate-dependent larval growth rate and duration of Olympia oysters in the Salish Sea’

Spatial patterns in aragonite saturation for the north central California shelf

Ocean acidification is exacerbated along the California shelf due to the upwelling of deep CO2 rich waters. This process of upwelling is driven by along-shore winds, which vary in strength by season. We present the relationship between along-shore wind and aragonite undersaturation utilizing an empirical formula to determine aragonite saturation from salinity, temperature, and dissolved oxygen. Our models show that stronger along-shore winds are correlated with a higher percentage of the water column undersaturated in aragonite. In addition, pteropod and juvenile krill density decrease in upwelled water which is cold, salty, and low in aragonite. With a predicted increase in along-shore winds, California shelf waters will become more undersaturated in aragonite and lead to a decrease in pteropod and krill density.

Continue reading ‘Spatial patterns in aragonite saturation for the north central California shelf’

Effects of an aquaculture pesticide (diflubenzuron) on non-target shrimp populations: extrapolation from laboratory experiments to the risk of population decline

Highlights

• Diflubenzuron (DFB) in salmon lice treatment can kill non-target crustaceans.

• We developed an age-structured model to assess effects of DFB on shrimp populations.

• The model predicts decline in shrimp abundance by 8%–99%, depending on DFB scenario.

• Environmental fluctuations contribute to the risk of shrimp population decline.

• Future environmental warming and ocean acidification may further impact populations.

Abstract

Marine aquaculture production has lately experienced high economic growth, but also concerns related to production and environmental contamination. For the Atlantic salmon aquaculture industry, the ectoparasitic crustacean salmon louse (Lepeophtheirus salmonis) has become a major problem. A common method to control populations of salmon lice within farm cages is treatment by various pharmaceuticals. One of the pesticides used in medicated feed for salmon is diflubenzuron (DFB), which acts as a chitin synthesis inhibitor and thereby interferes with the moulting stages during the development of this crustacean. However, DFB from fish feed may also affect non-target crustaceans such as the northern shrimp (Pandalus borealis), which is an economically and ecologically important species. Nevertheless, the actual risk posed by this chemical to shrimp populations in nature is largely unknown. Laboratory experiments have demonstrated that both larval and adult shrimp exposed to DFB through medicated fish feed have reduced survival compared to control. Moreover, the effects of DFB exposure are more severe under conditions of higher temperature and reduced pH (ocean acidification), which can be expected in a future environment. The aim of this study is to make the individual-level information from laboratory studies more relevant for risk assessment at the population level. We have developed a density-dependent age-structured population model representing a northern shrimp population located in a hypothetical Norwegian fjord containing a fish farm, under both ambient and future environments. Our model is based on thorough documentation of shrimp biology and toxicological effects from the laboratory experiments. Nevertheless, extrapolating the reported individual-level effects of DFB to the population level poses several challenges. Relevant information on shrimp populations in Norwegian fjords is sparse (such as abundances, survival and reproductive rates, and density-dependent processes). The degree of exposure to DFB at different distances from aquaculture farms is also uncertain. We have therefore developed a set of model scenarios representing different DFB application schemes and different degrees of exposure for the shrimp populations. The model predicts effects of DFB exposure on population-level endpoints such as long-term abundance, age structure and the probability of population decline below threshold abundances. These model predictions demonstrate how the risk of DFB to shrimp populations can be enhanced by factors such as the timing (season) of DFB applications, the percentage of the population affected, future environmental conditions and environmental stochasticity.

Continue reading ‘Effects of an aquaculture pesticide (diflubenzuron) on non-target shrimp populations: extrapolation from laboratory experiments to the risk of population decline’


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Ocean acidification in the IPCC AR5 WG II

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