Effects of agriculture, urbanization, and climate on water quality in the northern Great Plains

Article Abstract:

Three distinct biological assemblages have been found in Pasqua Lake in the northern Great Plains in Canada through fossil analyses with variance partitioning analysis. The effects of agriculture, urbanization, and climate on water quality of the area were studied. Before agriculture came to the area the lake was eutrophic. Diatom and chronomid communities did not change much before Europeans settled the area, but changed rapidly at the time of settlement. Elevated biomass, nuisance cyanobacteria, and low levels of deep-water zoobenthos characterized the assemblage around 1930-60. Resource use and urbanization were more important determinants of algal and chronomid community change than climatic factors. Urban impact was lower when the distances to point sources were higher.

Agriculture, Climatic changes, Climate change, Great Plains, Marine ecology, Europeans, Urbanization, Water acidification, Acid water pollution, Europeans in foreign countries

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Direct and interactive effects of allochthonous dissolved organic matter, inorganic nutrients, and ultraviolet radiation on an alpine littoral food web

Article Abstract:

Allochthonous dissolved organic matter (DOM) affects littoral food webs, with mediation by UVR and differences between benthic and planktonic habitats. Experiments conducted in an alpine lake indicate that DOM amendments result in significantly increased epilithon biomass, but the abundance of epipelon or phytoplankton is not affected. The positive effect of DOM on epilithon is enhanced by natural UV irradiance, which also increases epipelon abundance. Epilithon abundance was also increased by additions of nitrogen and phosphorus. Omnivorous copepod nauplii also became more dense due to DOM amendments.

Ultraviolet radiation, Food chains (Ecology), Food chains

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Long-term dynamics of algal and invertebrate communities in a small, fluctuating tropical soda lake

Article Abstract:

Long-term dynamics of invertebrate and algal communities as seen in a small, fluctuating tropical alkaline-saline crater lake in Kenya, Lake Sonachi. Reduction in algal biomass favored benthic and planktonic invertebrates by cutting down on complete water-column anoxia that goes with intense nighttime respiration of cyanobacterial blooms. Decline of filamentous cyanobacteria increased water-column transparency, but did not apparently increase benthic diatom abundance.

United Kingdom, United States, Australia, Belgium, Kenya, Statistical Data Included, Algae, Invertebrates, Biogeochemistry, Lakes

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