Twin Cities WRS Seminar
Double Trouble: Harmful cyanobacterial blooms, invasive mussel species, and carbon cycling in lakes and reservoirs
Biogeochemical cycling in lakes and reservoirs is influenced by multiple, and potentially counter-active, anthropogenic forces (e.g., nutrient inputs leading to eutrophication, increasing temperatures due to global climate change). The enrichment of nutrients in lakes and reservoirs coupled to rising global temperatures is leading to an increase of eutrophication-induced blooms (EIBs) of cyanobacteria and associated harmful cyanobacterial blooms (blooms with elevated toxin production). Collectively, blooms increase water column phytoplankton biomass, alter food webs and biogeochemical cycles, and negatively impact water quality. However, the effects of EIBs on carbon cycling and sequestration in lakes and reservoirs may be obfuscated by the presence of a filter-feeding, invasive mussel species (i.e., Dreissena spp.). To help elucidate the influence of nutrient enrichment and invasive mussel species on microbial communities and carbon cycling, we examined biogeochemical attributes (including carbon stable isotopes) and microbial community composition in eutrophic lakes, reservoirs, and rivers in western Ohio, eastern Indiana, and northern Kentucky during the cyanobacterial bloom period of the summer of 2015. Our results suggest that the presence of invasive mussel species did not result in changes in overall microbial community composition during EIBs. However, we find evidence that invasive mussels may influence carbon cycling in eutrophic lakes based on differences in the δ13C signal of carbon pools in the water column and sediments. As invasive mussels are predicted to spread, more intensive study of the interacting effects of EIBs and invasive mussel species on the carbon sequestration potential of lakes and reservoirs is warranted.