The impacts of climate and ocean warming on species distributions

Climate change is altering the geographic distribution of suitable habitat for marine species. These shifts are challenging fisheries management, which is based on the assumption that fish stocks are static over the long term. We conduct research to better understand how variability in climate affects marine species and communities, and also to predict how ocean warming will impact marine ecosystems and fisheries in the future.

​There is a wealth of biological data on marine species from ongoing fisheries surveys that are conducted in ocean and estuarine ecosystems. We use these data to statistically model species distribution in order to answer a variety of questions about species temperature preference, habitat use, and life history. These analyses can be used to better understand how year-to-year variation in climate interacts with species habitat requirements at different life stages. Our goal is to better understand the mechanisms by which species are responding to climate change, and ultimately to help fisheries management progress towards climate adaptive strategies.

Above: We have modeled patterns of brown shrimp abundance for 30+ years in Pamlico Sound, NC. Using enviromental indicators, we are able to explain most of the year-to-year variability in recruitment for this species with statistical models (project lead L. Schlenker). 

How oyster aquaculture impacts ecosystem services in estuaries

Oyster farms occur in estuaries and displace natural habitats. This industry is on the rise in the U.S. and so it is important to understand the net change in habitat function when an area is leased for culturing oysters. Working with colleagues from UNC's Institute of Marine Sciences we are conducting a comprehensive analysis of oyster culture impacts on (1) habitat function for marine animals, (2) seagrass growth, and (3) nutrient cycling in sediments. 

In order to determine species composition, we use a variety of sampling gear around oyster culture gear and on nearby control sites. We also use acoustic imaging technology in order to get unbiased estimates of fish density. The video at right is an example of a sonar sample. The large squares are the tops of oyster-culture cages that rest on the bottom (note the acoustic-shadows behind them). The fish swimming in the foreground were striped mullet, which we determined with net samples. For more examples of our sonar, check out our Oyster Culture Outreach page.  

Left: Aerial view of an oyster farm, where the movements of a tagged fish (red dot) are tracked acoustically over a 24 hour period (project lead A. McMains).
Bottom: Setting up acoustic receivers to track tagged fish. 

Sheepshead life history and population connectivity

Sheepshead are an economically important species in the southeast U.S.  In North Carolina, this species is largely managed based on catch data and little is known about the vulnerability of different life stages or movements of adult fish. Working with colleagues at UNC and NCSU we are filling important data gaps in our understanding of sheepshead. Specifically we are (1) identifying the locations and timing of spawning aggregations, (2) characterizing habitat use throughout the life cycle, and (3) examining the movement patterns of adults to quantify connectivity in the southeast. 

Left: Juvenile sheepshead are captured with open lift-traps filled with oyster shell. Gray snapper are also seen in the video. 
​Right: Cross section of juvenile sheepshead otolith, showing settlement mark (dark ring in middle) and daily growth rings (project lead M. Johnson).