Date of Award

Fall 2010

Document Type

Legacy Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

College

College of Science

First Advisor

John J. Hutchens, Jr.

Second Advisor

Vladislav Gulis

Third Advisor

James O. Luken

Abstract

Ecosystem structure is often used to indicate ecosystem function in studies of stream integrity because structure is usually easier to measure. Whether structure can be substituted for function, however, is seldom assessed. I used ecosystem structural measures (i.e., % of total benthic macroinvertebrates classified functionally as shredders and fungal biomass on leaves) to predict ecosystem function (i.e., leaf breakdown rate). Structural and functional parameters were measured at four sites in each of two forested blackwater streams near Myrtle Beach, SC. Pre-weighed red maple (Acer rubrum) leaves in coarse-mesh bags were sampled monthly from December 2008 to April 2009. Macroinvertebrates colonizing litter bags and fungal biomass (from ergosterol) associated with leaves were quantified. Benthic macroinvertebrates were sampled once using protocols developed for calculating the Coastal Plain-Macroinvertebrate Index and additional leaves were sampled for fungal biomass in each site in March 2009. Despite most sites being acidic (pH ranged from 4.12 to 7.96) and having low dissolved oxygen concentrations (range: 0.82 to 6.03 mg/L), I detected considerable microbial biomass. Leaf breakdown rates varied significantly among sites, with k values ranging from 0.004 to 0.017 d-1. Breakdown rates were not significantly related to mean fungal biomass found in litterbags or to maximum fungal biomass. Percent shredders based on biomass collected during the CPMI sampling and from litterbags were significantly positively related to breakdown rates while percent shredders based on abundance was not. Mean dissolved oxygen across sampling dates and during CPMI sampling was significantly related to breakdown rates. Results of this study suggest that structural metrics of mean dissolved oxygen and percent shredders based on biomass could be used as indicators in Coastal Plain streams. This study also emphasizes the need to use structural metrics specific to the study region and its habitat characteristics when evaluating ecosystem functioning.

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