Identifier

etd-07022014-151226

Degree

Master of Science (MS)

Department

Biological Sciences

Document Type

Thesis

Abstract

Barataria Bay, in southeast Louisiana is home to productive oyster reefs that are both ecologically and economically important, but was threatened by the Deepwater Horizon oil spill in April 2010. This study was designed to determine how the oil spill affected long- and short-term oyster recruitment, and spat (juvenile oysters) cellular health. I also investigated how predators in the bay affect spat survival. Four study sites were selected in Barataria Bay: two control and two oiled, each with a low and high salinity location. To determine whether there were long-term effects of the oil spill on oyster recruitment, tiles were placed at each site in 2012 and 2013 and spat recruitment quantified monthly. Results indicate that in 2012, recruitment varied more with salinity, but in 2013 when early summer salinity was lower, recruitment only occurred at the control sites. Tiles with 5 mL of light crude oil absorbed were used to study the short-term effects of oil on oyster and barnacle recruitment in 2013. Spat recruitment was lower on oiled tiles but there was no difference in spat size between treatments; alternately, there was a slight tendency for oil to increase barnacle recruitment. The effect of No (0 ppm), Low (500 ppm) or High (25,000 ppm) oil concentrations in 10 and 20 PSU seawater on spat cellular function was determined. Lysosomal stability was lower in low and high oil treatments suggesting oiling can affect spat health after just 10 days of exposure. The effect of predators on spat survival at each site was determined by quantifying predation on spat with no cage or in predator exclusion cages with 0.5, 1.0, or 3.0 cm mesh openings. The presence of a cage reduced predation of oyster spat. Predation rates were greatest on spat without cages suggesting larger predators such as blue crabs and oyster drills, with access to exposed spat, may play greater roles in post-settlement spat mortality than other predators such as mud crabs. Oyster recruitment and spat survival seems to depend more on salinity and predation than long-term hydrocarbon contamination. However, the short-term effect of hydrocarbon contamination can detrimentally impact spat recruitment and health; thus, clean-up efforts immediately following an oil spill and continuous monitoring efforts are necessary to maintain healthy oyster populations.

Date

2014

Document Availability at the Time of Submission

Student has submitted appropriate documentation to restrict access to LSU for 365 days after which the document will be released for worldwide access.

Committee Chair

Brown, Kenneth M.

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