Document Type

Thesis - University Access Only

Award Date

2002

Degree Name

Master of Science (MS)

Department / School

Biology

Abstract

The objective of this project was to characterize lake littoral habitat and macroinvertebrate community structure between two ecoregions in eastern South Dakota and determine invertebrate response signatures to physical disturbance in the littoral zone. Water temperature, conductance, dissolved oxygen, pH, substrate particle size, vegetation biomass, vegetation percent cover, shoreline slope and invertebrate samples were collected from fourteen lake basins in the Northern Glaciated Plains (NGP, n=8) and Northwestern Glaciated Plains (NWGP, n=6) ecoregions. Five random locations were sampled during the growing season from ten basins on one date in 1996, from twelve (1997-1998) basins and fourteen basins (1999-2000) on two dates. NGP sites had higher means for dissolved oxygen, sand-gravel substrate, cobble-boulder substrate, shoreline slope and canopy cover. NWGP sites had higher means for water temperature, specific conductance, pH, clay-silt substrate and littoral vegetation variables (dry weight, ash free dry weight, percent cover). A total of 179 macroinvertebrate taxa were identified. All organisms were identified to genus and 43% were identified to species. Seventy-three candidate community metrics were evaluated and their central tendencies and variance were described for use in ecoregion classification. NGP harbored a greater number of macr6invertebrates, while NWGP sites had a higher percentage of Annelida. Percent Insecta was higher for NGP sites and percent Mollusca was higher for NWGP sites. NWGP sites had a higher mean for total taxa richness. ETSD and ETO metrics were also higher for NWGP sites. NGP sites harbored greater numbers of predators, while NWGP sites had more collector-gatherers. Spearman rank correlations were conducted for invertebrate metrics and physiochemical data. Dominant metrics in NWGP sites (% Gastropoda etc.) were positively correlated with fine substrates and littoral vegetation. An optimization procedure was done using the coefficient of variation for each metric in each ecoregion and the discriminatory power of each metric between ecoregions to establish a suite of viable metrics to compare ecoregion differences. The Hilsenhoff Biotic Index (HBI), percent collector-gatherers, total taxa, Crustacean+Mollusca (CM) richness, percent Insecta, percent dominant taxon, percent swimmers, percent non- Insecta, percent crawlers and percent shredders were the ten optimized metrics developed for the NGP ecoregion. Scraper abundance, Hydracarina richness, percent intolerant, Odonata richness, percent Chironorninae, percent collector-gatherers, percent Insecta, sprawler abundance, percent burrowers and HBI were the optimized metrics developed for NWGP ecoregion sites. An experimental manipulation study was conducted at Oak Lake, Brookings County, South Dakota, where overland drainage areas had been classified as "prone" or "not prone" to non-point source disturbance. Three prone _and three not prone were manipulated. Littoral invertebrates, vegetative cover, water temperature, conductance, dissolved oxygen, and pH were collected on two-week intervals from May to September 1999 and 2000, with four pre-disturbance and eight post-disturbance sampling dates. Percent Ephemeroptera, percent Odonata, percent Tanypodinae, ET: Chironomidae, percent collector-filterers, percent sprawlers, Ephemeroptera richness and ETO richness metrics all had significant differences between treatments. Percent Ephemeroptera was found significantly higher for scour treatment compared to control and sedimentation treatments. ETO and Ephemeroptera richness were significantly lower for sedimentation treatments compared to control and scour treatments, while no differences were found between control and scour treatments. Percent sprawler was significantly higher for scour treatments than controls and significantly lower for sedimentation treatments than control and scour. These metrics and eleven other community metrics were all found significantly greater at not-prone sites. An optimization procedure was used to determine viable metrics in detecting scour and sedimentation disturbances. Diptera richness, percent gliders, percent swimmers, percent dominant taxon, Ephemeroptera richness, percent Chironorninae, percent Insecta, HBI, percent collector-gatherers and percent predators exhibited the highest discriminatory power and lowest reference site variability and should be used in detecting physical disturbance in littoral zones. Index of Biotic Integrity (IBI) scores exhibited different patterns between treatments and disturbance potential sites. IBI scores declined sharply after sedimentation at prone sites, while IBI scores were virtually unimpaired following sedimentation at not prone sites. A decline in IBI scores was found at prone sites following scour treatment, while an initial increase in IBI scores was· found for not prone sites. Results of this effort demonstrate differences in littoral habitat and invertebrate community structure between these two landscape regions. Identified signatures will aid in lake management efforts.

Library of Congress Subject Headings

Invertebrates -- South Dakota -- Geographical distribution Invertebrates -- Habitat -- South Dakota Ecological disturbances Lake ecology -- South Dakota

Format

application/pdf

Number of Pages

273

Publisher

South Dakota State University

Download

Share

COinS