Abstract
Abstract. Biofouling is a major vector in the transfer of non-native species around the world. Species can be transported on virtually all submerged areas of ships (e.g. hulls, sea chests, propellers) and so antifouling systems are used to reduce fouling. However, with increased regulation of biocides used in antifoulants (e.g. the International Maritime Organization tributyltin ban in 2008), there is a need to find efficient and sustainable alternatives. Here, we tested the hypothesis that short doses of low salinity water could be used to kill fouling species in sea chests. Settlement panels were suspended at 1.5 m depth in a Plymouth marina for 24 months by which time they had developed mature biofouling assemblages. We exposed these panels to three different salinities (7, 20 and 33) for 2 hours using a model sea chest placed in the marina and flushed with freshwater. Fouling organism diversity and abundance were assessed before panels were treated, immediately after treatment, and then 1 week and 1 month later. Some native ascidian Dendrodoa grossularia survived, but all other macrobenthos were killed by the salinity 7 treatment after 1 week. The salinity 20 treatment was not effective at killing the majority of fouling organisms. On the basis of these results, we propose that sea chests be flushed with freshwater for at least 2 hours before ships leave port. This would not cause unnecessary delays or costs and could be a major step forward in improving biosecurity.
Highlights
Biofouling is a major vector in the transfer of non-native species around the world (Carlton et al, 1995; Ruiz et al, 1997; Gollasch et al, 2002; Coutts and Taylor, 2004; Castro et al, 2017)
Biofouling communities were similar on panels before and immediately after treatment but thereafter there were marked differences since low salinity treatments killed most of the organisms present
For vessels which stay for long periods in berth we suggest low salinity flushing of sea chests is applied shortly before vessels depart for the port of call
Summary
Biofouling is a major vector in the transfer of non-native species around the world (Carlton et al, 1995; Ruiz et al, 1997; Gollasch et al, 2002; Coutts and Taylor, 2004; Castro et al, 2017). Some areas of ships hulls, such as sea chests and chain lockers, are difficult to access and coat with antifoulants These areas often get heavily fouled by a wide variety of marine organisms such as hydroids, serpulid polychaetes, barnacles, mussels, bryozoans and tunicates (Coutts and Taylor, 2004; Murray et al, 2011). In 2011, the IMO Marine Environment Protection Committee issued Resolution MEPC.207(62) outlining measures to minimize the risk associated with ship biofouling. These regulations are directed at many stakeholders (e.g. states, shipmasters, operators and owners, shipbuilders, port authorities, ship repair, dry-docking and recycling facilities, and antifouling paint manufacturers and/or suppliers). Two subsequent sets of guidance on biofouling have since been released: one for recreational craft less than 24 m in length (MEPC.1/Circ.792, 2012), and the second evaluating the 2011 guidelines for the control and management of ship biofouling to minimize the Published by Copernicus Publications on behalf of the European Geosciences Union
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