Trophic Linkages Between Freshwater Tidal Impoundments and Riverine Fishes in South Carolina

Publication Year:
2011
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Repository URL:
https://digitalcommons.coastal.edu/etd/62
Author(s):
Bayer, Meredith Penland
Tags:
trophic linkage; impoundment; Waccamaw River; fish; tidal river; Ecology and Evolutionary Biology
thesis / dissertation description
Historically, freshwater tidal swamps of the southeastern United States were logged and converted to rice impoundments. Presently, abandoned impoundments are succeeding back to swamps. To assess the connectivity of impoundments differing in dominant plant assemblages and their potential influence on fish in adjacent rivers, I studied six marsh and six swamp impoundments in the Waccamaw River, SC. Fish, organic matter and aquatic invertebrates were sampled at each impoundment during ebb tide. No major differences in fish assemblage composition, structure or diet were found between marsh and swamp sites. Organic matter export at swamp sites was dominated by hardwood litter (26%), seeds and fruits (29%), and herbaceous litter (15%). In contrast, marsh export was dominated by herbaceous litter (38%), coarse particulate organic matter (> 1mm) (23%) and similar proportions (11-13%) of hardwood litter, fine particulate organic matter (<1 mm), and wood. Reproductive plant material was significantly different between the two impoundment types, but did not contribute to fish diet. Total export (mg AFDM/m3) of organic material and invertebrates was similar in both impoundments as well as total biomass (mg) of invertebrates. Basal food resources were sampled at each impoundment and fish material was sampled at one marsh and one swamp impoundment for stable isotope analysis. δ13C and δ15N showed similarities in trophic fractionation (i.e., similar food webs) in both impoundment types. Overall export from both marsh and swamp abandoned rice impoundments contributed similarly to trophic relationships of riverine fish.