Abstract
Invasive, non-indigenous ascidians have been a significant biofouling problem for the aquaculture industry in Nova Scotia and Prince Edward Island since the mid-1990's. The problematic species in Atlantic Canada include Styela clava, Ciona intestinalis, Botryllus schlosseri and Botrylloides violaceus. Newfoundland harbour surveys that we have performed over the past three years revealed the presence of B. schlosseri and B. violaceus. As of yet, neither of these species has reached invasive abundance in Newfoundland. Portions of the COI genes of two non-indigenous ascidians (Botryllus schlosseri and Botrylloides violaceus) and two indigenous ascidians (Boltenia echinata and Halocynthia pyriformis) were cloned and sequenced. We then determined intraspecific and interspecific COI sequence variation. The BLASTN results showed that Botryllus schlosseri and Halocynthia pyriformis match the other listings for these species in GenBank. However, the BLAST results from Botrylloides violaceus were more similar to B. schlosseri than B. violaceus. While there were no other entries for Boltenia echinata, it was similar to other species in the Pyuridae family. Intraspecific similarity in the COI sequence for Newfoundland populations was >99.7% for B. violaceus, H. pyriformis and B. echinata, and 86.5-96.6% for B. schlosseri. Interspecific similarities among all four species were <80.3 %. This indicates that the COI gene should be an effective species-specific molecular marker for the identification of eggs and larvae of these Newfoundland ascidians.
Highlights
Bioinvasions are some of the leading marine environmental issues in the world and represent a serious global threat (Ruiz et al 2000; Stachowicz et al 2002; Occhipinti-Ambrogi and Galil 2004; Campbell et al 2007)
We initially discovered Botryllus schlosseri on the bottom of a small, local fishing vessel in Argentia harbour in December 2006, and Botrylloides violaceus on wharf pilings in Belleoram harbour in October 2007 (Figure 1)
As of January 2010, we have found B. violaceus only in Belleoram, where it is growing on boat hulls, wharf pilings, as well as on mussel shells and natural substrates
Summary
Bioinvasions are some of the leading marine environmental issues in the world and represent a serious global threat (Ruiz et al 2000; Stachowicz et al 2002; Occhipinti-Ambrogi and Galil 2004; Campbell et al 2007). Impacts of invasive ascidians on the aquaculture industry include biofouling of the harvested species themselves as well as fouling of the growing and processing equipment (Carver et al 2003). These impacts lead to decreased economic performance of the farms due to increased production costs (Carver et al 2003). This prediction is based on the fact that Newfoundland has many shipping links with the other Maritime provinces and that some areas of the coastline have environmental conditions within the tolerance limits of these nonindigenous ascidians (Locke et al 2007; Therriault and Herborg 2008b)
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