Midwest Fish & Wildlife Conference 2019

AUTHORS: Kishore Gopalakrishnan, Donna Kashian, Anna Boegehold, Nick Johnson – Wayne State University

ABSTRACT: Dreissenid mussels are successful invaders in a wide variety of freshwater environments. As biofoulers, they create serious economic and recreational problems. In addition, these rapid filter feeders alter their invaded ecosystem by disrupting the entire food web. Their rapid colonization rate and environmental resilience make them difficult to control. Many management options have been explored for combating the spread of dreissenid mussels, but an effective management strategy is elusive.  In an effort to identify a novel management tool, we investigated the impacts of cyanobacteria, commonly associated with Harmful Algal Blooms (HABs), on reproduction in dreissenid mussels. Mussel populations may be regulated by HABs through several reproductive mechanisms including spawning and fertilization. Specifically we tested the impacts of several bloom forming cyanobacterial species on quagga mussel reproduction through a series of bioassays examining quagga mussels’ spawning, fertilization and sperm motility. Mussel were induced to spawn using serotonin, then the effect of five cyanobacterial species spawning and sperm motility was examined. Sperm motility was determined by recording the movement of sperm from five males per treatment at 400X, tracking velocity and distance travelled. Fertilization success was determined through assays combining quagga mussels’ egg and sperm in individual vials containing cyanobacteria species cultures (n=5), and enumerating zygote formation marked by cellular cleavage. Some cyanobacteria species inhibited reproductive endpoints; spawning was inhibited by Microcystis wesenbergii and M. ichthyoblabe, sperm motility was reduced by Aphanizomenon flos-aquae and two strains of M.aeruginosa and fertilization ratio decreased with exposure to five unique species of cyanobacteria including two strains of M. aeruginosa. These results show the HABs may negatively impact dreissenid populations. Determining the class of compounds and understanding the mechanism by which the cyanobacteria disrupts reproduction may inspire new dreissenid control tactics.