Detection and quantification of Microcystis spp.and microcystin-LR in Western Lake Erie duringthe summer of 2007

摘要

Microcystis spp. blooms have occurred annually in western Lake Erie since about 1995.Microcystis produce a group of toxins known as microcystins which can be harmful to livestockand to humans. In this study, surface water samples were collected from six sites during sixsampling events from July to October in 2007. In situ environmental data (e.g. pH, temperature)and laboratory analyses (e.g. nutrients) were carried out to characterize the six sites. TheMicrocystis spp. density ranged from 10~2to 10~7cells/ml. Microcystin-LR concentration of 20 of all36 samples were below the detection limit (0.15-5 ppb), while the microcystin-LR concentration --in the 16 remaining samples ranged from 0.5 to 3 x 10~3μg per gram dry weight. The aim of thisresearch was to investigate the relationships between sampling location, environmentalparameters, Microcystis spp. concentration, and microcystin-LR concentration. The resultssuggest that temperature, nutrient concentration, turbidity, and wind speed and direction(P < 0.05) are factors which affected Microcystis spp. density. Sampling site 8M, located 13 mfrom the Maumee River, provided an advantage for Microcystis spp. growth, presumably due tointermediate water depth (5.5 m) combined with impact from the river. No relationship was foundbetween Microcystis spp. density and microcystin-LR concentration. Temperature, nutrientconcentration and DO (P < 0.05) were associated with the production of microcystin-LR.