Nutrient cycling in Brazos River Oxbow Lakes, with emphasis on the importance of benthivorous fish /
Experimental mesocosm studies revealed that the presence of
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739363791&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Experimental mesocosm studies revealed that the presence of benthivorous smallmouth buffalo (Ictiobus bubalus) significantly enhanced turbidity, phytoplankton biomass, NH4', and total N and P in a shallow, aerobic, hypereutrophic oxbow lake. The effects of ktiobus on water quality are similar to the results of experiments done with other benthivorous fish species. Prior studies have suggested that enhanced phytoplankton biomass in the presence of benthivorous fish may be a result of P excretion by fish and physical relocation of sediment P to the water column. However, results of experiments done on ktiobus revealed that enhanced microbial NH4' regeneration and subsequent uptake by phytoplankton also may be an important factor causing increased phytoplankton biomass levels in the presence of benthivorous fish. Seasonal measurements of NH4' and PO4'- regeneration rates of sediments, zooplankton, benthivorous fishes, planktivorous fishes, and grass shrimp were conducted in Big Bend and Moehlman's Slough, two oxbow lakes of the lower Brazos River floodplain of Texas. Multiple regression equations indicated that temperature was the main factor affecting temporal variation in remineralization rates in Big Bend. An internal nutrient cycling model was developed using data on NH4' and PO4 regeneration rates between the two oxbow lakes, along with data from the literature. The model showed that sediment and water column microbes typically supplied over 70% of NH4 in both oxbows. On the other hand, P04 3- was supplied mainly by zooplankton (primarily rotifers) in Big Bend, and benthivorous fishes (primarily ktiobus, Dorosoma, and Cyprinus) in Moehlmans. Model results also showed that oxbow lakes which are less frequently flooded have lower NH4':PO4 3- supply ratios, and a greater abundance of nitrogen fixing cyanobacteria. Because benthivorous fishes commonly comprise more than 50% of the ichthyomass in lakes and reservoirs, management of these species may be an important tool for controlling phytoplankton biomass and species composition. |
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| Item Description: | Vita. "Major Subject: Wildlife and Fisheries Science". |
| Physical Description: | ix, 77 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 65-76. |