Cladophora ecology in changing ecosystems: an assessment guided by management information needs

Session: Connecting Management Needs and Science Information (2)

Emily Wimmer, USGS - Great Lakes Science Center, [email protected]
Mary Anne Evans, USGS, Great Lakes Science Center, [email protected]
Meredith Nevers, U.S. Geological Survey - Great Lakes Science Center, [email protected]

Abstract

Cladophora, a native benthic filamentous algae, and non-native dreissenid mussels are both ecosystem engineers in the nearshore Great Lakes ecosystem; affecting habitat and nutrient availability for many species. Despite successful management programs to reduce external Phosphorus (P) loading, Cladophora blooms have recently returned to nuisance levels in the Great Lakes, a possible result of dreissenid mussels altering abiotic factors that support Cladophora growth. Research suggests dreissenid mussels may shift production to the benthos in the Great Lakes; facilitating Cladophora habitat and growth by 1) increasing light penetration, 2) increasing benthic Phosphorus levels, and 3) providing suitable Cladophora habitat (dreissenid shells). These factors may increase Cladophora growth by increasing nutrient availability and allowing Cladophora to colonize habitat previously unsuitable. During the growing season of 2018, abiotic factors (temperature, light, DO, etc.) were monitored at multiple sites (6 m) in Lakes Michigan, Huron, Erie, and Ontario. Monthly sampling was conducted to collect Cladophora and dreissenid biomass samples and supporting variables (nutrients, light, temperature, etc.). Study results will assist management in understanding the ecology behind the cause of recent nuisance Cladophora nearshore fouling events and how to reduce nuisance blooms in the Great Lakes.