Document Type

Thesis - University Access Only

Award Date

2003

Degree Name

Master of Science (MS)

Department / School

Wildlife and Fisheries Science

First Advisor

Steven R. Chipps

Abstract

Regulated river flows and land-use activities have altered the floodplain ecosystem within the Upper Missouri River basin. These changes have led to decreased connectivity between the floodplain and main river and enhanced land-use activities (i.e., agriculture) within the floodplain. Knowledge of floodplain wetland attributes and their response to anthropogenic disturbances is limited. In this study, I developed a macroinvertebrate index of biotic integrity (M-IBI) that evaluated the effects of disturbances in seasonal floodplain wetlands. I also examined differences in macroinvertebrate community structure in forested and emergent seasonal floodplain wetlands. As part of a U. S. EPA REMAP study, aquatic macroinvertebrates were sampled to develop biomonitoring criteria for seasonal floodplain wetlands in the Garrison Reach of the Missouri River. Twenty-six seasonal wetlands were sampled in the summers of 2000-2001. Wetlands were designated as reference (n=6) or impaired (n=5} based on land-use characteristics. Candidate metrics were first identified using univariate t-tests (e.g., reference versus impaired) and then subjected to a stepwise discriminant function analysis to develop a predictive suite of variables that distinguished reference and impaired wetlands. The final macroinvertebrate index of biotic integrity consisted of seven metrics that included: 1) proportional abundance of Chironomidae, 2) proportional abundance of Lymnaeidae, 3) proportional abundance of predators, 4) proportional abundance of dominant taxa, 5) proportional biomass of Hydraenidae 6) proportional biomass of univoltine taxa and 7) number of Odonata taxa. These metrics were then scored from 0-10 (high scores indicated similarity to the reference condition), summed and standardized for a final M-IBI that ranged from Oto 100. The M-IBI was found to be robust to inter-year variation, but displayed considerable intra-year variation implying that time of year wetlands are sampled is critical for accurate wetland assessment. Randomly selected wetlands (n = 15) were used to determine the overall condition of seasonal floodplain wetlands within the Garrison Reach and yielded an average condition rating of fair (mean M-IBI score = 52). This study demonstrated the usefulness of macroinvertebrate data for assessing floodplain wetlands of the upper Missouri River. Riparian forests and their associated wetlands have disappeared throughout much of the Upper Missouri River basin. Information on seasonal forested wetland invertebrate communities and how they compare to surrounding emergent wetlands are limited. Twelve seasonally flooded forested (n = 6) and emergent (n = 6) floodplain wetlands were sampled in the summer of 2001. Physical attributes, periphyton biomass, macrophyte coverage and water chemistry were analyzed along with invertebrate community attributes. Forested wetlands had significantly higher pH (8.16) and lower macrophyte coverage than emergent wetlands. Numerous differences in taxa richness and biomass occurred between the invertebrate communities of forested and emergent wetlands. In general, emergent wetlands had higher taxa richness and biomass than forested wetlands. The most important finding was the general increase in total invertebrate biomass as macrophyte coverage increased. Macrophytes are known to increase invertebrate abundance by affecting the physical environment (i.e., habitat complexity, shading, etc.), food availability and predation. Differences observed in invertebrate community structure suggest that biomonitoring criteria be developed separately for forested and emergent wetlands.

Publisher

South Dakota State University

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Rights Statement

In Copyright