Date of Award

Fall 2013

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Chair

Kevin Dillon

Committee Chair Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 2

Chet Rakocinski

Committee Member 2 Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 3

Patrick Biber

Committee Member 3 Department

Coastal Sciences, Gulf Coast Research Laboratory

Abstract

Artificial reefs are primarily used to provide a suitable habitat for target fish populations, but the structures can also improve water quality and benefit non-target organisms. Laboratory incubation experiments were conducted in the presence of biofilm on rubble and in its absence to examine bacterial growth, community respiration, and nutrient dynamics at four artificial reef habitats in the Mississippi Sound. Biofilm samples were also collected from settlement plates deployed at each site and were analyzed for 813C and 81sN stable isotope content. Respiration rates were always higher in the presence of biofilm but bacterial abundance often declined over time, and rates of decline were higher in the presence of biofilm. This suggests that heterotrophic activity was high but bacterial abundance was limited by some factor, such as grazing pressure. P04 and NH4 production were often observed in incubation experiments, and production rates were higher in the presence of biofilm, indicating that the benthic community supplements microbial water column nutrient regeneration. Respiration, P04 production, and NH4 production were higher in low profile reef incubations than high profile reef incubations when biofilm was present, which reflected the higher biofilm growth observed at low profile reefs. Seasonal effects were also observed. Respiration and nutrient production rates were positively correlated with temperature, and 813C and 81sN values were enriched during warmer seasons, all of which indicate higher benthic and water column productivity. Further studies are needed to compare productivity and nutrient regeneration at other artificial reefs and natural reefs.

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