PARR-2011-G-05
Identifying critical ecological thresholds for tunicate infestations on mussel farms

Bio-fouling is a well documented shellfish aquaculture industry challenge and the recent introduction of several invasive tunicate species has greatly inflated its impact.  The PEI mussel aquaculture industry has been particularly affected by the introduction of four new tunicate species: Clubbed Tunicate (Styela clava) in 1998 in the eastern end of the province; Golden Star Tunicate (Botryllus schlosseri) in 2001 and 2002 and Violet Tunicate (Botrylloides violaceus) were both reported on the north coast of PEI; and in 2004, the Vase Tunicate (Ciona intestinalis) was first reported on the east coast of the island. Efforts to control the spread of these tunicate species have been relatively successful, but presently most mussel producing areas in PEI are infested with at least one tunicate species. Currently, high pressure water spray is the main technique used by the mussel industry to control tunicate fouling. Lime dipping is also used to control tunicates, particularly the Clubbed Tunicate, on mussel socks.  Efforts to develop the most cost-effective treatment strategy are continuing while specific ecological thresholds are not yet established.  The establishment of both economical and ecological thresholds are key to the sustainability of the mussel industry in PEI and could lead to the creation of the first Integrated Pest Management approach for Aquatic Invasive Species. The goal of this project is to investigate the ecological impact of tunicate treatment with the following objectives: 1) develop a method to estimate the tunicate biomass on mussel farm structures; 2) develop a model to predict the impact of tunicates fall-off, pre- and post-treatment, on the benthic environment; and 3) assess the impact of tunicate filtration and biodeposition on ecosystem productivity. Results from this project will also provide information on timing and coordination of treatment.

Principal investigator: Thomas Landry, 343 Ave Université Ave, Moncton, NB; Tel.: (506) 851-6219; Email: Thomas.Landry@dfo-mpo.gc.ca

Team members: Andrea Locke, DFO-Gulf region; Jeff Davidson, AVC-UPEI; Chris McKindsey, DFO-Québec region; Aaron Ramsay, DFARD-PE; Monique Niles, DFO-Gulf region; Daniel Bourque, DFO-Gulf region; Thitiwan Patanastienkul, AVC-PEI; Thomas Guyondet, DFO-Gulf region; Luc Comeau, DFO-Gulf region

2-year project (2011/12, 2012/13)