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Science Serving Maryland's Coasts


Application of an Individual Based Model to Understand the Effects of Climate Change on Blue Crab, Callinectes sapidus, Population

Principal Investigator: 

Thomas Miller

Start/End Year: 

2015 to 2016


Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science

Strategic focus area: 

Resilient ecosystem processes and responses


Climate change is a long term, global problem caused by the emission of combustion products, particularly carbon dioxide. The influence of these emissions is already quantifiable and their full impact will likely not become apparent for decades. Research on climate change stressors can help society to understand likely future ecological and economic scenarios to help society become better equipped to respond to these stressors. The blue crab, Callinectes sapidus, serves an important ecological and economic role in the Chesapeake Bay. The blue crab is both an important predator and prey species and can also serve as an important pathway for energy in the Chesapeake Bay ecosystem. From an economic viewpoint, blue crab supports one of the most important fisheries in the Bay; crabs are a key income source to coastal communities from spring to autumn. However, projected climate scenarios will fundamentally disrupt the existing ecological and economic pattern and this may have profound impacts on management regimes and social patterns that have had to traditionally rely on other income during winter months.

Researchers propose to use crab growth and energetics data collected in experiments that simulated the joint and interactive effects of temperature change and acidification to re-parameterize and extend an existing individual-based model (IBM) to forecast the population level impacts of climate change on blue crab in the Bay. They will re-parameterize the model based on experimental data they have collected in the last two years that explore the growth trajectories of juvenile blue crab exposed to the individual and interactive effects of global warming and acidification. Next, they will use the re-parameterized model to predict the size distribution of crabs exposed to acidification and warming, in the absence of fishing mortality. Specifically, three different scenarios of global warming (current conditions, temperature predicted in year 2100 (4.8oC increase), and temperature that would prevent winter dormancy (9°C increase)) and two different acidification scenarios (current conditions, pCO2=800 ppm, and an acidified estuary future, pCO2= 8,000 ppm), will be simulated in model runs over 24 months. Finally, they will evaluate the sustainability of alternative fishery management scenarios (exploitation rates) that include: (i) current fishing practice, (ii) male only fisheries and (iii) hard-shell only fisheries for the current fishing season and for year round fisheries. Sustainability will be assessed within the model by calculating the yield-per-recruit of each strategy.

Currently, no published data exist on the impact of climate change on blue crab from either an ecological or a fisheries perspective. The proposed project will not only determine the fundamental physiological response of crabs to climate change, but will also estimate the sustainability of the blue crab fishery in the face of a changing Chesapeake Bay climate. The data from the proposed project will improve the resilience of the Chesapeake Bay region by providing increased scientific knowledge as well as employment information through predictions about blue crab fishery yields in the changing climate of the future.

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