Andrus Lake Comparative Lake Survey.

Abstract

Acidification of lake ecosystems has become an increasing problem in recent decades. As this trend continues, it is important to come to a better understanding of both the causes and effects of lake acidification. This study, a survey of Andrus Lake which is located in the Lake Superior State Forest in the Upper Peninsula of Michigan, aimed to further the understanding of the complex relationships between trophic structure and physical parameters; to understand why Andrus Lake is an acidic, dystrophic, oligotrophic lake; and provide a valuable baseline of data from which further changes can be detected and analyzed. Andrus Lake exhibits a complex relationship between its morphology as a seepage lake, conifer dominated watershed, dystrophic and acidic qualities, and low primary productivity. The high hydraulic retention time makes the lake particularly sensitive to acidification, while the conifer dominated watershed decreases the ANC of the water and further increases the acidity of the surface run-off. The high tannin inputs lead to the dystrophic nature of the lake and decrease light penetration and thus productivity. The biological community within the lake reflects these characteristics. While the zooplankton and fish populations show some indications of adaption to acidity, both the phytoplankton and macrophytic communities are dominated by species well adapted to acidic conditions. Species of Spirogyra many of which are well adapted to acidic environments, made up 27% of the algal community, while three of the macrophytes are acidiphiles. Overall diversity within all the groups was decreased and productivity was low.