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Como Lake, Minnesota: The Long-Term Response of a Shallow Urban Lake to Biomanipulation

 

作者: T.A. Noonan,  

 

期刊: Lake and Reservoir Management  (Taylor Available online 1998)
卷期: Volume 14, issue 1  

页码: 92-109

 

ISSN:1040-2381

 

年代: 1998

 

DOI:10.1080/07438149809354113

 

出版商: Taylor & Francis Group

 

关键词: biomanipulation;urban lake;Daphnia;macrophytes

 

数据来源: Taylor

 

摘要:

Como Lake, a shallow hypereutrophic 29-ha lake, located in St. Paul, MN, was biomanipulated by fisheries renovation using rotenone in September 1985, to reduce algal standing crop, improve aesthetics, and increase recreational use. Long-term monitoring (1982–97) indicates a cyclic water quality and biologic response following the initial biomanipulation. Algal standing crop, as measured by chlorophylla(CHLA), varied positively with total phosphorus (TP) and total nitrogen (TN) for the post-biomanipulation years (1986–97), with marked changes in phytoplankton community composition and population abundance. Nutrient-phytoplankton (“bottom-up”) interactions are a strong and consistent force in Como Lake following biomanipulation due to continued high normalized areal phosphorus loading (~735 mg m−2yr−1). “Top-down” influences have not yet stabilized, but appear to have dampened with time due to decreased effectiveness of sportfishing regulations and fish stocking, along with partial winterkill due to aerator failure, to maintain piscivore abundance. Planktivorous fish abundance and size-selective feeding pressure on large-bodied herbivorous zooplankton grazers, as well as Daphnia biomass, have fluctuated cyclically over the study period. Recent decreased macrophyte abundance suggests a return to phytoplankton dominance as the long-term stable state for Como Lake. Monitoring results suggest that future management efforts in Como Lake should include renewed emphasis on fisheries and watershed management to promote the presence of macrophyte growth and a reduction in the magnitude of “bottom-up” forces, particularly nutrients, that effect the size of the algal population.

 

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