Identifier

etd-06082004-232601

Degree

Master of Science (MS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

The Barataria-Terrebonne estuary has been eroding at a rate of up to 103.6 km2 yr-1 for several decades. If the current rate of loss is not reduced, an additional 2,550 km2 of coastal wetlands will be lost by the year 2050. Currently, stormwater in Terrebonne Parish is pumped into canals, ultimately discharging into the Gulf of Mexico. An opportunity exists to use this stormwater for wetland restoration; however, the ecological impacts of stormwater diversions on wetlands are unknown. The objectives of this project were to 1) to investigate the seed banks of a degraded marsh to determine if a viable seed source exists, 2) to gather baseline soil chemistry of a degraded marsh prior to receiving stormwater input, and 3) to compare the soil P chemistry, metal concentrations and accumulation rates, and sedimentation rates for different wetlands receiving stormwater input. An existing degraded marsh that is scheduled to receive stormwater input in the fall of 2004 was selected for the baseline study. These results will be compared to conditions after a new stormwater pump becomes operational. Coastal wetlands that have been receiving stormwater for <10 years and 30 years were selected to carry out the sediment chemistry study. A total of 370 stems germinated from the seed banks from the vegetated areas and a total of 2 stems were counted in the seed banks from the mudflat. These results suggest that replanting will be necessary for establishment of vegetation in the mudflat areas. There was a significant increase (p<0.05) in P concentrations in soil that had been receiving stormwater for 30 years when compared to soil that had been receiving for stormwater for <10 years, which may lead to alteration of plant communities as seen in the Everglades. Sediment profiles indicated a significant difference in Fe, Al, Zn, and Pb concentrations when comparing the age of the pump (P<0.05). However, soil metal concentrations were found below EPA toxicity thresholds even in coastal wetlands receiving stormwater input for 30 years. The results from this study will be used as a foundation for future studies of stormwater input to coastal Louisiana wetlands.

Date

2004

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Stephen Faulkner

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