Resource contributions from dreissenid mussels to the benthic algae Lyngbya wollei (Cyanobacteria) and Cladophora glomerata (Chlorophyta)

Dreissena spp. (zebra and quagga mussels) are invasive to North America and increase light to the benthos, provide hard structure for algal attachment, and may contribute limiting nutrients to benthic algae, thereby facilitating algal blooms. We conducted experiments to determine how Dreissena affect nutrient stoichiometry and growth of Lyngbya wollei and Cladophora glomerata, two benthic algal species recently increasing in biomass in parts of the Laurentian Great Lakes, combined with a field survey to determine the likelihood of L. wollei co-occurrence with Dreissena. L. wollei had a significantly higher concentration of carbon, nitrogen, phosphorus, potassium, and sulfur when grown with live Dreissena. C. glomerata had greater biomass in tanks with live Dreissena, but did not have significant increases in nutrient concentration like L. wollei did. Neither algal species increased in growth due to the added structure of Dreissena shells. L. wollei biomass was greater in the presence of Dreissena during 1 year (of two) of our field survey. This field survey also showed that L. wollei and Dreissena are likely to co-occur. These results suggest that Dreissena provide several nutrients to benthic algae, and these added resources can promote algal growth and consequently blooms.