Identifier

etd-06102008-194156

Degree

Master of Science (MS)

Department

Environmental Sciences

Document Type

Thesis

Abstract

The purpose of this project was to monitor the recovery of marsh vegetation following Hurricane Katrina in the Breton Sound estuary, which is directly influenced by the Caernarvon freshwater diversion. From March 2006 until October 2007, we measured above- and belowground biomass, soil porewater nutrients (NOx, NH4, and PO4), porewater salinity, porewater sulfide concentrations, and soil redox potential bimonthly at duplicate Near (N), Intermediate (M), and Far (F) sites (with respect to the diversion), as well as at a Reference (C) site. End of season live (EOSL) below and above ground biomass was measured at 26 separate stations where vegetation studies had been done previously. Peak standing crop ranged from 423 g/m2/yr at site M2 to 1515 g/m2/yr at F1. Aboveground biomass was significantly greater at N1 than at N2, M1, or M2. Peak belowground biomass ranged from 8315 g/m2/yr at C2 to 17890 g/m2/yr at N1. Multiple regression analysis showed that sulfide levels were related to the amount of belowground biomass (p < 0.05; R2=0.13). PO4 concentration was related to the amount of aboveground biomass (p<0.05; R2=0.09). Short term vertical marsh accretion measurements ranged from 0.49 cm y-1 at N2 to 1.25 cm y-1 at N1, suggesting that all the study sites are stable or accreting at a rate which offsets local RSLR. Analysis of the results of short term accretion compared to regional relative sea level rise (RSLR) indicates that all Caernarvon sites are keeping pace with RSLR. Analysis of porewater parameters showed that stress on plants was low to moderate while nutrient concentrations were greatest at the Near sites.

Date

2008

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Day, John W.

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