Atlantic ribbed mussels (Geukensia demissa) are candidates currently under consideration for microbial pollution remediation in urban estuaries due to their tolerance of degraded environments and their ability to clear bacteria. But the extent and efficacy of this clearance in the face of environmental conditions associated with pollution events, such as rapid salinity decline, are not well characterized. Furthermore, continuous assessment of clearance activity in situ is challenging. Hall effect sensors, which can be used to measure valve gaping, represent an appealing approach to continuously monitor bivalve activities in situ. However, the relationship between valve gaping and clearance is not well described in ribbed mussels. This work explores the impact of salinity fluctuations on mussel feeding activities and the potential of valve gaping to serve as a proxy for bacterial clearance.
Ribbed mussels in individual chambers were outfitted with hall effect sensors and magnets on opposing valves. They were then exposed to a gradual, but rapid, salinity fluctuation, with simultaneous delivery of a constant concentration of Escherichia coli and 5µm polystyrene microspheres. Valve gaping was monitored continuously via sensors and water samples were collected at the inflow and outflow of each chamber at 15-minute intervals. Particle concentration was then quantified via flow cytometry and percent reduction of particles at each interval was calculated for each individual mussel.
Ribbed mussels were shown to effectively clear E. coli. Preliminary results suggest that salinity depression triggers valve closure which corresponds with decreased clearance. These results highlight the role that ribbed mussels can play in remediating pathogen pollution from impacted waterways. Furthermore, they support the potential for hall effect sensors to serve as a proxy for mussel clearance, making continuous monitoring of mussel response to microbial pollution events feasible under field conditions. Ongoing work contrasts response to salinity fluctuations between different mussel populations to evaluate potential local adaptations to different salinity regimes.