Identifier

etd-04152013-152031

Degree

Master of Science (MS)

Department

Renewable Natural Resources

Document Type

Thesis

Abstract

Benthic intertidal bivalves play an essential role in estuarine ecosystems by contributing to habitat provision, water filtration, and promoting productivity. As such, ecosystem level changes that impact population distributions and persistence of local bivalve populations may have large ecosystem level consequences, making it important to better understand the population distribution and ecology of native bivalve populations. Gametogenesis, recruitment, growth, mortality, size structure and density of the ribbed mussel, Geukensia demissa, were examined across a salinity gradient in southeastern Louisiana. In summer 2012, 100-m transects were placed at interior and edge marsh plots to collect data on mussel density, and vegetation data at duplicate sites in upper (salinity ~4), central (salinity ~8) and lower (salinity ~15) Barataria Bay, LA. Caged growth and recruitment plots were established adjacent to each transect, in April, and growth, mortality and recruitment of individually marked mussels within plots were recorded in November 2012. Mussels were randomly sampled monthly from low (~ 5) and high (~25) salinity marsh sites, and histologically processed to determine the seasonal progression of gametogenesis. Mussel densities were greatest within mesohaline marsh (66.6 + 18 m-2), J. roemerianus vegetation (191.2 + 42.7 m-2) and plots experiencing 20-60% annual flooding rates (46.7 + 13.8 m-2). Mussel recruitment, growth, size and survival were significantly higher at mid and high salinity marsh edge sites as compared to all interior and low salinity sites. Peak gametogenic ripeness occurred between April and September, positively correlated with temperature, and coincidental with seasonal shifts in salinity. The observed patterns of density, growth and mortality in Barataria Bay may reflect detrital food resource availability due to local site flooding rates, vegetation community distribution along the salinity gradient, and reduced predation at higher salinity edge sites.

Date

2013

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

La Peyre, Megan

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