Vessel biofouling management in Antarctica

Vessel biofouling refers to the accumulation of marine organisms on the submerged surfaces of a vessel, such as the hull, recessed or niche areas and the internal seawater pipework [1-3]. A wide variety of marine species can form the biofouling community on a vessel, with biofouling accounting for more than 50% of marine non-native species introductions worldwide [4]. Another major vector for marine non-native species is ballast water, which vessels take onboard to maintain stability and can transport non-native species to new locations when the ballast water is discharged. Vessel operators are motivated to manage biofouling growth, as increasing biofouling loads will reduce the vessels’ efficiency moving through water, resulting in higher fuel consumption and costs. Various management strategies exist, such as anti-fouling coatings and marine growth prevention systems, which can be paired with in-water cleaning to minimise biofouling accumulation [3]. Niche areas of vessels can pose additional biosecurity risks compared to the hull, with substantial biofouling communities able to develop within these areas protected from water flow; and substantial growth can be present before causing a problem for vessel operators [5]. Niche areas on the hull include sea chests, which are large, recessed areas with seawater intake points for engine cooling and firefighting systems. Additionally, vessels have extensive internal seawater pipework that can be subject to biofouling [6]. There have been a limited number of published reports or research articles on the biofouling communities present on Antarctic-bound vessels. However, a wide variety of species, including those with distributions in the sub-Antarctic or Arctic, have been reported as part of those biofouling communities [2, 6-9].

An example of the increasing risk of marine non-native species establishment in Antarctica are the mussels Mytilus spp. Live individuals of Mytilus galloprovincialis were identified in the sea chest of an icebreaker following an Antarctic voyage [7], indicating that the individuals could survive exposure to Antarctic marine conditions within niche areas on the hull. In 2019, juvenile specimens of Mytilus cf. platensis were detected on the seabed close to the South Shetland Islands, Antarctic Peninsula [10]. A subsequent survey of the same location did not detect any more mussels, suggesting that the population did not persist. Genetic analysis and vessel activity patterns suggested that the population may have resulted from spawning by adult Mytilus present on a visiting vessel [10]. Physiology experiments of the closely related Mytilus chilensis suggest that under future warming scenarios, waters along the western Antarctic Peninsula will be within the thermal tolerance range of this species [11]. These three Mytilus species were previously identified as some of the species presenting the highest risk of invading Antarctica [12], thereby highlighting the rising likelihood of non-native species being able to survive and establish populations in a warming Antarctic climate.

A remarkably challenging problem is the frequently visited inner bay (Port Foster) of the volcanic Deception Island where seawater is warmer [13] and thus could easily allow for the survival of non-native species (Figure 1). Deception Island was one of the top 20 locations in Antarctica visited by IAATO vessels between 2019-2024, with 194 vessel landings at Whalers Bay, Port Foster in the 2024-25 season [14]. Viable non-native species have been identified arriving on kelp rafts at Deception Island, including the bryozoan Membranipora membranacea [15], suggesting that this location could provide a stepping stone for marine non-native species into the wider Antarctic region.

Vessels in the Antarctic are governed by the Antarctic Treaty system (ATS), including the Antarctic Treaty, Protocol on Environmental Protection (The Protocol), Committee for Environmental Protection (CEP) and the Convention for the Conservation on Antarctic Marine Living Resources (CAMLR Convention), as well as the conventions of the International Maritime Organization (IMO). Substantially more countries are members of the IMO (176 member states) than the Antarctic Treaty (58 member states, 29 consultative parties and 29 non-consultative parties) in 2026. The main types of vessels that visit the Antarctic are tourism, research, resupply and fishing vessels [16]. Many parties to the Antarctic Treaty operate research and resupply vessels through their National Antarctic Programmes, with most operators’ members of the organisation Council of Managers of National Antarctic Programs (COMNAP). Some National Antarctic programmes may however use military vessels to conduct their research and resupply operations. Tourism vessels can be flagged under countries that are not signatories to the Antarctic Treaty [17, 18], but most operators are members of the industry body, the International Association of Antarctica Tour Operators (IAATO). IAATO membership requires adherence to the IAATO bylaws including “To advocate and promote operation by the Membership within the parameters of the Antarctic Treaty System, including the Antarctic Treaty and the Protocol on Environmental Protection to the Antarctic Treaty, as well as IMO Conventions and similar international and national laws and agreements” [19]. Tourism vessels will generally be flagged to countries that are members of the IMO, with the IMO’s International Code for Ships Operating in Polar Waters (Polar Code) setting out mandatory requirements for safety and pollution prevention for vessels operating in polar regions, and providing guidance on biofouling management, focusing on appropriate anti-fouling systems for vessels operating either year-round or intermittently within ice-covered waters [20]. Operators of vessels that encounter sea ice are advised not to apply biocide-containing anti-fouling systems to the hull due to the likelihood of ice scour removing some of the paint, as evidenced by the detection of the now banned anti-fouling compound tributyltin (TBT) in Antarctic sediments [21]. Abrasion-resistant coatings are recommended instead, with regular cleaning required to remove any accumulated biofouling from this type of coating.

Ballast Water discharge is regulated within the Antarctic Treaty area to reduce the likelihood of marine non-native species introduction. In 2004, the IMO adopted the International Convention for the Control and Management of Ships’ Ballast Water and Sediments, which came into force in 2017 [22]. Given the length of time between adoption and enforcement of the Convention, and the risks associated with ballast water discharge in Antarctic waters, the ATCM adopted the Practical Guidelines for Ballast Water Exchange in the Antarctic Treaty Area in 2006 [23], which provided interim guidance before the IMO regulations came into force. Under these regulations, standards are set for the exchange and discharge of ballast water for vessels operating in the Antarctic.

There are currently no mandatory international regulations for the management of biofouling, with voluntary guidelines produced by the IMO and national legislation in New Zealand [24], Australia [25] and California (US) [26], for example. The voluntary biofouling guidelines produced by the IMO [27], which were adopted in 2011 and updated in 2023, set out information to facilitate globally consistent biofouling management and record keeping. It was recently indicated by the IMO Marine Environment Protection Committee (MEPC) that the development of a legally binding framework for biofouling management will commence in 2026 to bring biofouling management in line with ballast water management [22]. The top ten departure ports of all Antarctic-bound vessels, accounting for 91% of departures between 2014-2018, are in Argentina, Chile, Falkland Islands (Malvinas), Australia, New Zealand, South Africa, and Uruguay [16]. Aside from the Falkland Islands (Malvinas) and Uruguay which have no biofouling regulations, mandatory biofouling regulations exist in Australia, New Zealand and South Africa, while Argentina and Chile have voluntary guidelines [28]. The level of implementation and enforcement varies across these countries, with the biofouling legislation in place in Australia and New Zealand the most stringent and consistent with the IMO recommendations.

Many of the tourism companies and national Antarctic programmes that operate vessels within the Antarctic are members of the industry body IAATO or organisation COMNAP, respectively. Following a request by the CEP to IAATO and COMNAP for updated information on the biofouling and ballast water management practices of their members, these organisations conducted independent surveys to identify the current management practices in place [29, 30]. While the questions were not identical between the two surveys, the data revealed some inconsistencies across vessel operators in how biofouling was managed and records kept (Figure 2). A recommendation of the IMO biofouling guidelines is that all vessels produce and use vessel-specific biofouling management plans (BFMP) and record books (BFRB), that set out how and when biofouling management should occur [27]. The survey results showed that while a large proportion of IAATO member vessels have implemented BFMP and keep BFRB, a much lower proportion of COMNAP vessels do so (Figure 2). While a large proportion of these vessels were reported as having anti-fouling technologies, the lack of consistent recording of biofouling management procedures is concerning and would make any enforcement action more challenging.

Biofouling poses a substantial risk to the Antarctic under a warming climate, with the Antarctic Treaty Parties currently considering how to best manage and mitigate the risks [31]. Article 4 of Annex II to the Protocol on Environmental Protection to the Antarctic Treaty states that “No species of living organisms not native to the Antarctic Treaty area shall be introduced onto land or ice shelves, or into water, in the Antarctic Treaty area except in accordance with a permit”. The CEP, established through the Protocol, has a non-native species manual for the Antarctic, which is currently under review [32]. The implementation of biofouling management regulations for Antarctic-bound vessels would assist in reducing the likelihood of marine non-native species introduction, through ensuring that vessels are taking the appropriate steps to minimise biofouling presence before transit to Antarctica [28]. Given the variety of vessel types and operators involved and the many countries with links to the Antarctic, coordinated international effort across all these stakeholders would be key for ensuring effective and feasible biofouling management measures can be introduced.