Preliminary Investigations of Biofouling of Ships' Hulls: Non-Indigenous Species Investigations in the Columbia River
2006
Davidson, Ian | Sytsma, Mark | Ruiz, Gregory
Hull biofouling is an important vector of non-indigenous species (NIS) but has received very little attention compared to ballast water. This was a preliminary examination of hull biofouling arriving to the Lower Columbia River (LCR) using three components of study. First, we examined the potential magnitude of transfers, using wetted surface area (WSA) of vessel arrivals as a proxy measure of potential colonizable surface. Second, we examined vessel hulls on drydock and by archival video footage to assess hull fouling densities. Third, we examined the existing fouling community trends and environmental receptiveness of the LCR to hull mediated organisms. Over 40.5 million m2 of wetted surface area arrived to the LCR in a three year period from 66 different countries. Fouling levels on vessels examined were highly variable, ranging from less than one percent to more than ninety percent. Thirty two unique taxa (species) were found on ten drydocked vessels. Vessels that frequently traversed different salinity regimes (sea to river and vice versa) were observed to have lower levels of fouling than those which remained in either marine or riverine environments for extended periods. Overall, the threat of hullmediated introductions to the LCR is probably not limited by propagule (organism) supply. Despite a low number of replicates, the data suggest that propagules are being delivered to the system and the cumulative surface area arriving is substantial. However, salinity and habitat availability are more likely to limit the establishment of NIS. More data are required on hull fouling densities, here and elsewhere, to answer even the basic questions regarding biofouling transfers on commercial ships.
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