RESEARCH - Research Summary

Environmental Integrity Theme

Research Summary

The ascidian Styela clava, the clubbed tunicate, is a recent invader to Prince Edward Island (PEI) waters. It was first identified in 1999 on cultured mussels (Mytilus edulis) in Brudenell River and has since spread to Montague River, Murray River, Orwell Bay, St. Mary’s Bay, Malpeque Bay, areas of substantial mussel aquaculture. The tunicate has especially had a negative impact on mussel culture in Murray River, attaching in high densities to mussel socks and equipment, competing for food resources and fouling equipment. The sheer weight of the tunicates poses challenges for harvesting and farm husbandry. This pest could have a devastating effect on the sustainability of the entire PEI mussel industry. Processing mussel socks with tunicates has proved challenging because of the necessity for physical removal and prevention of spread to other unaffected areas.

S. clava is a solitary ascidian originating from the coastlines of Japan and Korea. It can now be found in Europe and on both coasts of the United States. They are filter feeders with an affinity for colonizing in massive numbers on many substrates found in the water column. The negative impact of the invasion has been much more severe for the PEI mussel industry which utilizes off bottom suspended culture.

This three year research project focuses on determining the cause of death in tunicates to assist in identifying specific, environmentally acceptable chemicals or biological solutions to target only tunicates. The study also investigates the effect of treatment for Styela on the physiological fitness of mussels and the ecology of the mussel sock. Research to date has focused on the effects of 5% acetic acid as a potential treatment and its effects on Mitrella lunata and Caprella linearis.

Network Investigators

Jeff Davidson, University of PEI, Charlottetown, PE
Thomas Landry, Gulf Fisheries Centre, Fisheries and Oceans Canada, Moncton, NB
Gerald Johnson, University of PEI, Charlottetown, PE