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Thesis - University Access Only
Master of Science (MS)
Wildlife and Fisheries Science
Leigh H. Fredrickson
This study took place on 3 lower Missouri River sandbars near Columbia, Missouri during June 2004 to June 2005. The objectives of the study were to describe sandbar microhabitats and determine the abundance and distribution of macroinvertebrates and fish using these microhabitats as a source of food for migratory shorebirds. Nearly 40 species of shorebirds migrate between breeding and wintering grounds through interior North America every year. There are documented cases of significant threats to 36 species (72%) during migration. Migratory shorebirds need stopover sites to refuel for the final stages of their journey and one major source of food is Missouri River sandbars, especially during dry years because sandbars provide preferred feeding sites with sparse vegetation and shallow water. Thus the future well-being of migratory shorebirds rests with habitat condition at stopover sites such as lower Missouri River sandbars. Sandbars were sampled seasonally for microhabitat and weather (environmental) conditions at four or more locations at each sandbar region to determine differences among sandbars, sampling periods, regions, and substrates. Very few microhabitat variables were significantly different among sandbars. Substrates were among the variables that were different with coarse substrates being more than twice as abundant as fine substrates within sandbars. Furthermore, fine substrates were more common at the tertiary region and on wing-dike sandbars. In contrast the head had a higher occurrence of coarse substrates. Many environmental variables were significantly different among sampling periods and times of day but not among sandbar regions or between substrate types. Macroinvertebrates and larval fish were collected in aquatic habitats with a sweep net and stovepipe sampler and invertebrates were collected in terrestrial habitats with a core sampler and sticky traps. A total of 3169 macroinvertebrates were collected over six sampling periods, 2055 were captured in aquatic habitats and 1114 in terrestrial habitats. Split-plot Analysis of Variance was used to detect significant differences (p-value 0.0500) in invertebrate and fish abundance among sandbars, sampling periods, sandbar regions, and water depths/distance from the shoreline while Kruskal-Wallis Analysis of Variance was used to identify significant differences (p-value 0.0500) in abundances between environmental variables as well as substrate types. Stepwise Regression Analysis (p-value 0.0500) determined which variables had the most effect on macroinvertebrate abundance and distribution while a Shannon- Weiner Diversity Index measured differences in family diversity among sandbars, sampling periods, regions, and substrate. Aquatic macroinvertebrate abundance was significantly different among sandbar regions and substrates but not among sandbars or sampling periods. Average macroinvertebrate abundance was highest at the tertiary for both sampling methods and lowest at the tail for sweep samples and at the secondary for stovepipe samples. Abundances were higher in fine substrates regardless of method. Substrate type, time of day, and cloud cover were the environmental variables that had the most effect on aquatic macroinvertebrate abundance. The most common aquatic Orders collected were Diptera, Hemiptera, Coleoptera, Bivalvia, and Ephemeroptera with the most frequent Families being Chironomidae, Ceratopogonidae, Corixidae, Heteroceridae, and Sphaeriidae. Above ground terrestrial macroinvertebrate numbers were significantly different among sandbar regions and sampling periods although they were not among sandbars or substrates and surface macroinvertebrate abundance was not significantly different for any of these tests. Wind speed as well as temperatures and substrate type had the most effect on terrestrial macroinvertebrate distribution. The most frequently collected terrestrial Orders included Diptera, Hemiptera, Hymenoptera, and Araneae while the most common Families collected were Chironomidae, Dolichopodidae, and Ephydridae. There was not a significant difference in larval fish abundance among sandbars but there was among regions regardless of sampling method as well as among sampling periods and substrates for fish collected with sweeps. Sweep fish abundance was highest at the secondary and tail and lowest at the head while stovepipe fishabundance was highest at the tertiary and lowest at the tail and primary. For nearly all environmental variables, larval fish had a range or a preference for a certain environmental condition. Temperatures (air, substrate, and water) had the strongest effect on fish distribution. Macroinvertebrate and fish abundance and distribution on sandbars was dependent upon fine substrates, habitat complexity (i.e., presence of tertiary channels), low current velocity and temperature. Thus, management of lower Missouri River sandbars for migrant shorebirds requires an understanding of these variables in relation to seasonal variation in river hydrographs, location within the river channel, and location in association with structural features on the floodplain.
Library of Congress Subject Headings
Shore birds -- Food -- Missouri River
Freshwater invertebrates -- Missouri River
Sand bars -- Missouri River
Includes bibliographical references (page 172-184)
Number of Pages
South Dakota State University
Copyright © 2007 Jessica F. Lee. All rights reserved.
Lee, Jessica F., "Community Compostition and Microhabitats of Macroinvertebrates on Sandbars within the Lower Missouri River as a Food Source for Foraging Migratory Shorebirds" (2007). Theses and Dissertations. 519.