Cladophora and an associated community of benthic algae grow to nuisance levels in parts of the Great Lakes nearshore. Historically, these blooms have been controlled by local nutrient reductions. However, large scale disturbance of Great Lakes nutrient cycling by invasive dreissenid mussels has cast into doubt the continued effectiveness of nutrient limitation as a tool for Cladophora community control. Dreissenid mussel filter feeding and excretion concentrates available nutrients in near bottom waters; increases light penetration, increasing the potential depth distribution of benthic algae; and increases the surface area of hard substrate for algal attachment. We are integrating information from scuba supported benthic assessments, autonomous underwater vehicle (AUV) surveys, and satellite remote sensing to assess Cladophora community distribution and growth limiting factors, including testing hypotheses related to the nutrient, light, and substrate effects of dreissenids. This work supports ecosystem status assessments and decision making around lake nutrient targets to support desired levels of algal growth.

Primary Presenter: Mary Evans, U S Geological Survey (maevans@usgs.gov)

Authors:

Mary Evans, U. S. Geological Survey  (maevans@usgs.gov)

Jennifer Wardell, U. S. Geological Survey   (jwardell@usgs.gov)

Kasia Przybyla-Kelly, U. S. Geological Survey  (kprzybyla-kelly@usgs.gov)

Peter Esselman, U. S. Geological Survey  (pesselman@usgs.gov)