Identifier

etd-03252014-170304

Degree

Doctor of Philosophy (PhD)

Department

Oceanography and Coastal Sciences

Document Type

Dissertation

Abstract

Saltmarsh loss is occurring at high rates in Louisiana (LA), but understanding the impacts that marsh degradation has had on historical abundance of estuarine nekton in Barataria Bay, LA is lacking. I first examined the differences between fishery independent and fishery dependent data as indices of relative abundance. Previous studies used landings data to evaluate the importance of marsh habitat (e.g. distance of marsh edge and area of intertidal marsh) to fisheries production, but for most species, landings and survey data showed differing patterns of abundance through time. These findings emphasize the importance of using survey data (not landings data) to conduct habitat-related analyses in Louisiana and elsewhere. Next, I investigated the influence of a suite of environmental and fishery related predictors on fishery independent catch-per-unit-effort (CPUE) and developed descriptive models for these relationships. The descriptive models show that abundance of estuarine nekton varied only marginally with marsh habitat related predictors. Using both parametric and non-parametric statistical analyses, I then tested previous hypotheses that explained the relationship between marsh habitat and fish abundance, in addition to exploring community level effects. Results indicated that marsh and marsh edge distance do not appear to be driving nekton abundance. However, differences were found when comparing the community structure of Barataria Bay from different time periods over the last 44 years. Finally, I developed an ecosystem model to test the influence of marsh loss on nekton abundance, while accounting for changes in salinity and trophic interactions. Results indicate that marsh edge accounted for only a small portion of historical variation in nekton abundance. While this study suggests the influence of marsh loss on fisheries may be less significant than once thought, the importance of protecting coastal saltmarshes remains vital to the health and prosperity of Louisiana’s deltaic ecosystem.

Date

2014

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Cowan, James H. Jr.

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