The influence of biofilms on the attachment of the zebra mussel, Dreissena polymorpha

The European mollusk Dreissena polymorpha , also known as the zebra mussel, rapidly became a major fouling nuisance in North American fresh waters, since its introduction to the Great Lakes in the mid-1980s. The literature contains numerous examples of marine invertebrate larvae using environmental cues to determine where to attach. These cues can be chemical and/or physical factors. Chemical factors can be produced by other species (associative cues) or by members of the same species (conspecific cues). The biological factors involved in zebra mussel attachment have not been extensively studied. The purpose of the research was to determine if biofilms provided larval and adult forms of the zebra mussel with information on where to attach, i.e., associative cues. Field research studied the effects of natural biofilms on the attachment of zebra mussel postveligers. Biofilms were developed on substrata in the field. Postveliger attachment to initially filmed and initially clean surfaces was compared. The results indicated that postveligers could use associative cues from biofilms when determining where to attach. The results did not indicate that larval conspecific cues were influencing postveliger attachment. Also, substratum wettability was not detected to be a factor in postveliger attachment. Laboratory research studied the effects of natural biofilms (multi-species), single-species biofilms, and bacterial extracellular products (BEP) isolated from single-species biofilms on the reattachment of young adult zebra mussels. Natural biofilms were developed in Petri dishes using field samples. Single-species biofilms were developed in Petri dishes with bacteria isolated from surfaces where zebra mussels were found attached. Petri dishes were also treated with BEP. The reattachment locations of zebra mussels in initially filmed, or treated, and initially clean Petri dishes were compared. The results indicated that substratum wettability and biofilms are factors in the reattachment of young adult zebra mussels. The results also indicated that BEP could be the associative cues used by the zebra mussels. The results of the completed research can be applied towards the development of new control strategies for the zebra mussel, e.g., commercial antifoulants