Resistance and resilience of periphyton communities as a function of biomass and physiological state.

Periphyton communities were grown under a gradient of resource regimes to obtain a gradient of mat thicknesses and physiological states. All communities were subjected to a simulated flood event to determine if resistance and resilience are inversely related. Resistance was measured as a lack of a significant decrease between pre-disturbance samples and post-disturbance samples of ash free dry mass (AFDM) and chlorophyll a, both measures of biomass. Resilience was measured as a significant increase in biomass (AFDM and chlorophyll a) between the first post-disturbance sampling day and the second post-disturbance sampling day. Trends were found that indicate high nutrient concentrations influence low resistance and high resilience, and low nutrient concentrations influence high resistance and low resilience.http://deepblue.lib.umich.edu/bitstream/2027.42/54493/1/2931.pdfDescription of 2931.pdf : Access restricted to on-site users at the U-M Biological Station

Douglas Lake - comparative lake survey.

Douglas Lake, located in Cheboygan County, Michigan, has been defined as a moderately eutrophic lake (Bazin and Saunders, 1971). The lake was formed during the late glacial period. As the Wisconsin ice sheets receded, seven or more blocks of ice were left buried in the earth where Douglas Lake now exists. The melting of these ice blocks left seven deep basins which led to the formation of the lake. The deepest of these basins is located on the west side of Pells Island. Other deep depressions are located around South Fishtail Bay (24.1 m deep), and the northwest corner of the lake just west of Roberts Point. These deep holes are broken up by broad shoals where the water is shallow, creating a very diverse lake habitat. This type of lake is technically called a kettle hole lake (Welch, 1935).http://deepblue.lib.umich.edu/bitstream/2027.42/54355/1/2791.pdfDescription of 2791.pdf : Access restricted to on-site users at the U-M Biological Station