Date of Award

1999

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Oceanography and Coastal Sciences

First Advisor

Stephen Faulkner

Abstract

Quantitative comparisons of artificially created and natural wetlands are typically confounded by differences in wetland age, with created wetlands being younger than their natural counterparts. Observed differences between these wetlands may be attributed to either age differences or an inability to reproduce natural wetland characteristics. The objectives of this research were to: compare the phosphorus characteristics of similarly aged, created and natural wetlands in the Atchafalaya Delta, Louisiana and determine the controls over phosphorus retention in these wetlands. A phosphorus fractionation procedure was used to identify the phosphorus fractions in sediments from natural and artificially created wetlands in the Atchafalaya Delta belonging to three age classes: young (<1--3 years old), intermediate (5--10 years old), and old (15--20 years old). The young, created wetland was lower in total phosphorus than its natural counterpart due to its higher sand content. The intermediate-aged, created wetland had lower phosphorus contents than its natural counterpart due to higher organic matter and lower bulk density. Phosphorus contents of the old created and natural wetlands were similar. These differences between the created wetlands and their natural counterparts can be explained by the design of the created wetlands. Bedload sediment from the Atchafalaya River, which is dredged to form the created wetlands, had lower phosphorus and oxalate-extractable iron than the river's suspended sediment, which forms the natural wetlands. Sediment recently deposited at both created and natural wetlands had similar phosphorus contents. In the Atchafalaya Delta, wetlands created with dredge sediment will have less phosphorus upon formation than natural wetlands of the same age, but if they are built to mimic the elevation gradient, shape and orientation of the natural wetlands they can develop phosphorus characteristics similar to natural wetlands through the deposition of river sediment.

ISBN

9780599252448

Pages

108

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