In order to develop effective management strategies to alleviate shoreline-fouling events caused by nuisance-level filamentous benthic algal growth throughout the Great Lakes, we need to understand what is controlling benthic algal growth. By focusing on the benthic filamentous algae linked to shoreline-fouling in Saginaw Bay, Lake Huron, I examined how nutrient and light limit benthic algae biomass, and how this limitation varies across gradients of light and nutrient availability. Using active fluorometry and benthic algal internal nutrient content, the benthic algal community was found to be both light and nutrient limited over a large spatial range along the southwest region of Saginaw Bay in the summer of 2009. In addition, active fluorometry indicated that algal health decreased as site distance from the Saginaw River increased. Further, photosynthetic efficiency decreased as depth decreased, suggesting shallower depths are less conducive to growth than more protected, deeper depths. Analysis of light saturation indicated that light availability close to the river is sporadic and relatively constant at further distances. Furthermore, internal phosphorus significantly decreased as distance from the river increased along a 3.0 m depth contour, supporting the existence of a phosphorus gradient. My research sheds light on the degree to which key factors limit benthic algae growth in Saginaw Bay, and how their role varies along gradients common in systems with nuisance beach algae.
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