Date of Award

Spring 2018

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Chair

Dr. M. Zachary Darnell

Committee Chair Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 2

Dr. Kelly M. Darnell

Committee Member 2 Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 3

Dr. Chester F. Rakocinski

Committee Member 3 Department

Coastal Sciences, Gulf Coast Research Laboratory

Abstract

Coastal marshes are important nursery habitats for many commercially important invertebrate species, yet these marshes are being lost worldwide at an unprecedented rate due to subsidence, erosion, climate change, and human activity. As marsh is lost, it creates the opportunity for submerged aquatic vegetation (SAV) colonization and establishment in newly created open water areas. Blue crabs, Callinectes sapidus, use both marsh edge and SAV habitat during the juvenile stages and support one of the largest fisheries in the Gulf of Mexico, worth over $70 million in 2015. This thesis studied the linkages between habitat type, SAV cover, benthic prey availability, and blue crab abundance and mortality due to predation. In different habitat types and across a gradient of marsh fragmentation, crab pots and throw traps were used to conduct monthly crab abundance surveys and benthic cores sampled benthic invertebrate communities. This study found that blue crab abundances, benthic invertebrate biomass, and benthic invertebrate community composition were insensitive to marsh fragmentation but did vary significantly with habitat type. These results have implications for future blue crab populations in coastal Louisiana where if marsh loss occurs as projected, poor recruitment by juvenile blue crabs into the adult population due to less available nursery habitat and food availability may lead to time-lagged decreases in the commercial blue crab fishery, unless SAV colonizes areas of high marsh fragmentation to serve as an alternative nursery habitat for juvenile blue crabs.

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