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Document Type

Dissertation - University Access Only

Award Date

2001

Degree Name

Doctor of Philosophy (PhD)

Department

Wildlife and Fisheries Science

First Advisor

Daniel E. Hubbard

Keywords

invertebrates, aquatic invertebrates, wetlands, prairie pothole region, sedimentation, hydrophytes

Abstract

Sediment is the major pollutant of wetlands, lakes, rivers, and estuaries in the United States and it poses unique threats to wetlands of the Prairie Pothole Region (PPR). Sediment may impact the success of wetland restorations because burial of invertebrate and plant propagules may impact hatching and germination success, and hence, may hamper successional changes throughout interannual climate cycles. Sedimentation also reduces the pool depth and volume, further exacerbating the recovery of hydrophyte communities in restored wetlands. I evaluated the potential impacts of sedimentation on prairie wetlands from several perspectives. First, I evaluated the effects of sedimentation on loss of wetland pool depth and volume, and secondly, I examined the effect of sediment load on emergence of plants and invertebrates from seed and invertebrate egg banks. Additionally, I compared the seed and invertebrate egg bank composition of high quality reference wetlands (i.e., having no history of cultivation) to previously farmed nondrained, restored, and drained seasonal and semipermanent wetlands in the Missouri and Prairie Coteau, and Glaciated Plain physiographic regions of the PPR. My results demonstrated that previously farmed wetlands of all categories had greater mean (± SE) accretion (0.26 ± 0.02 cm yr·1) and mass accumulation (0.268 ± 0.027 g cm·2 yr·1) rates of sediments than non-farmed reference wetlands (0.08 ± 0.03 cm yr·1, 0.068 ± 0.034 g cm·2 yr-1). Projected over the next 200 years, I estimated that cultivated and reference wetlands would accrete significant quantities of sediment, resulting in a 57% and 18% loss, respectively, in the number of wetlands capable of attaining water depths ≥ 1 m. Wetland pool depths ≥ 1 m are important for the establishment of vegetative zones during seasonal and interannual wet and dry periods. Also, over the next 200 years, I estimated that 50% and 20% of the wetland volume (203 hectare-meters) would be lost based on my estimated accretion rates for cultivated and reference wetlands, respectively. Egg bank hatching success in seasonal wetlands was lowest in drained wetlands. Drained and restored semipermanent wetlands in the Glaciated Plain and Missouri Coteau also had poorer hatching success than reference and nondrained wetlands. More restored seasonal wetlands in the Coteau regions attained taxon richness similar to reference and nondrained wetlands than in the Glaciated Plain. Within 5 years after restoration, most restored seasonal wetlands contained viable invertebrate egg banks, but I was unable to detect a significant increase in taxon richness and invertebrate abundance with restoration age. Hatching success and abundance of invertebrate egg banks in restored semipermanent wetlands were lower than in seasonal wetlands. Trends indicated that for all regions and wetland classes, reference wetlands had greater perennial-native seed density, tax on richness, floristic quality, and fewer annual species than nondrained, restored, and drained wetlands. However, most comparisons of perennial-native response variables were found to be similar among nondrained, restored,and drained wetlands. I found no increase in the floristic quality of seed banks as restored wetlands aged. Sediment load experiments showed burial of seed and egg banks with sediment depths as little as 0.5 cm virtually halted invertebrate and seedling emergence. My results show that intensive agriculture has negatively impacted seed and invertebrate egg banks in both restored and nondrained wetlands, and that active planting or donor material will be needed to restore certain wetland communities. Results of my burial experiments on seedling emergence corroborated prior research; however, my research also demonstrated that invertebrate emergence is equally impacted by sediment burial. Agricultural activities in the PPR appear to have caused significant loss in wetland volume and depth that have potential to alter the success of wetland restorations. Agricultural conservation strategies need to be implemented to reverse this trend and keep valuable topsoil in place for agricultural production.

Library of Congress Subject Headings

Wetlands -- Prairie Pothole Region
Sedimentaiton and deposition -- Prairie Pothole Region,br>Aquatic invertebrates -- Prairie Pothole Region
Aquatic plant -- Prairie Pothole Region

Description

Includes bibliographical references (page 144-152)

Format

application/pdf

Number of Pages

180

Publisher

South Dakota State University

Rights

Copyright © 2001 Robert Andrew Gleason. All rights reserved.

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