Abstract
Invasive species such as ascidians have negative effects on aquaculture operations worldwide. Prince Edward Island, Canada, in particular has seen high fouling levels of non-native tunicates including the colonials Botryllus schlosseri and Botrylloides violaceus. Previous research indicated that high-pressure seawater spraying of mussel socks fouled with colonials is an effective mitigation strategy. Those results, however, were based on a year (2009) with unseasonably low water temperatures at the beginning of the colonial tunicate growing season in June and July; therefore, we repeated part of that study in the following year (2010) to determine whether typical (warm) early season water temperature affected tunicate fouling levels and how both treatment efficacy and fouling effect on mussel productivity differed between the two years. In 2010, Botryllus schlosseri fouling (in terms of biomass) was four-fold higher than in the colder year (2009), reaching an average biomass of 600-800 g per full-length mussel sock (up to 2.4 m long), but it still did not affect mussel productivity. B. violaceus was also present on mussel socks, but only in very low amounts (<50 g per mussel sock), so that results for this species were inconclusive. Highpressure water spraying was at least as effective in 2010 as in 2009 at removing B. schlosseri tunicate fouling from mussel socks, though in 2010, treatment also negatively affected mussel productivity by reducing mussel biomass by 30% in the frequently (5×) treated group. Considering these results along with the potential risk of increased tunicate spread (through fragmentation) and the cost of treatment, frequent application of high-pressure water spray is unnecessary.
Highlights
Worldwide, marine invasions are on the rise (Ruiz et al 1997; Cohen and Carlton 1998), including those that negatively affect aquaculture production (e.g. Lee and Gordon 2006; Ramsay et al 2008; Carman et al 2010)
Highpressure water spraying was at least as effective in 2010 as in 2009 at removing B. schlosseri tunicate fouling from mussel socks, though in 2010, treatment negatively affected mussel productivity by reducing mussel biomass by 30% in the frequently (5×) treated group
While some studies have speculated about mussels and other bivalves being smothered by colonial tunicates, we found no evidence for this phenomenon in the case of B. schlosseri in either 2009 (Arens et al 2011) or 2010
Summary
Marine invasions are on the rise (Ruiz et al 1997; Cohen and Carlton 1998), including those that negatively affect aquaculture production (e.g. Lee and Gordon 2006; Ramsay et al 2008; Carman et al 2010). The Prince Edward Island (PEI) blue mussel (Mytilus edulis Linnaeus, 1758) aquaculture industry has faced multiple challenges in recent years due to the introduction and proliferation of several nonnative tunicate species (Carver et al 2003; Locke et al 2007; Locke et al 2009). These highly invasive tunicate species rapidly colonize the artificial substrates created by the suspension of mussel long lines within the water column (Lambert and Lambert 2003; Forrest et al 2007; Tyrrell and Byers 2007). The tunicates’ high reproductive capacity combined with other modes of dispersal such as rafting on dislodged seaweeds and attachment to boat and barge hulls (Lambert and Lambert 2003; MacNair et al 2006) has resulted in these species spreading to most of the major aquaculture-containing bays and estuaries on PEI
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
