Ashley D.M. Coutts

A preliminary investigation of biosecurity risks associated with biofouling on merchant vessels in New Zealand

Abstract Biofouling on international vessels is an important mechanism for the inadvertent transfer of non‐indigenous marine species around the globe. This paper describes the nature and extent of biofouling on 30 merchant vessels (ranging from 1400 to 32 000 gross registered tonnes) based on analysis of hull inspection video footage collected by two New Zealand commercial diving companies. A new method for measuring biofouling communities is applied, which aims to incorporate the potential for various hull locations to house non‐indigenous marine species. Our analysis revealed that out‐of‐service vessels and vessels plying trans‐Tasman routes possessed greater levels of biofouling than more active vessels. Dry‐docking support strips and sea‐chest gratings generally had the highest levels of biofouling and may pose relatively high biosecurity risks. Any future biosecurity surveillance should target these hull locations for non‐indigenous species.

Ships' sea-chests: an overlooked transfer mechanism for non-indigenous marine species?

Historically, hull fouling associated with slow-moving, wooden-hulled vessels has been recognized as the primary transport mechanism responsible for the dispersal of non-indigenous marine species (NIMS) around the world and the fouling of hulls may have contributed significantly to the current patterns of bi-ogeographic distributions of many marine organisms (e.g., Carlton and Hodder, 1995). Over the past three decades however, ballast water has been identified as the primary causal mechanism and has been the focus of international concern (e. suggest that the attachment of organisms on the hulls of vessels remains a significant vector in modern times, possibly equal to ballast water, although further conclusive evidence is required. Currently , there is no concerted effort to evaluate the relative importance of these disparate mechanisms in the transfer of NIMS to new locations. The discussion of transfer mechanisms has identified that numerous locations within and on a vessel may afford distinct environments (e. discussed sea-chests (sea inlet boxes, or suction bays) as environments linked with hull fouling assemblages. Similarly, Gollasch (2002) has discussed the role of sea-chests in the transport of fouling organisms. Sea-chests provide a unique part of the vessel for the transport of marine organisms, dissimilar to ballast water and the exposed surface of the hull. Sea-chests are recesses built into a ships hull located beneath the waterline on the side and/or on the bottom near the engine room. They are designed to reduce water cavitation, and thus increase pumping efficiency when seawater is pumped aboard the vessel for engine cooling, ballast, and fire fighting purposes. The size, number and dimensions of sea-chests vary considerably with vessel size and type. As a general rule, the larger the vessel, thus increasing demand for ballast water, the greater the size and number of sea-chests. Sea-chests are protected by metal grates, which have holes (15–25 mm in diameter) or slots (20–35 mm width) to prevent foreign matter entering and damaging the ships pumps. These grates are held in place by a number of bolts, and therefore sea-chests are usually only accessible during dry-docking. In order to ascertain the extent to which sea-chests provide a unique habitat and contribute to the transport of NIMS, we undertook a preliminary investigation of the passenger ferry Spirit of Tasmania, which operates in southeastern Australia. The hull of the Spirit of Tasmania was surveyed for fouling at the Australian Defence Industries Limited dry-dock at Garden Island, Sydney, on …

Effect of vessel voyage speed on survival of biofouling organisms: implications for translocation of non-indigenous marine species

This study experimentally determined the effect of different vessel voyage speeds (5, 10 and 18 knots = 2.6, 5.1 and 9.3 ms−1, respectively) and morphological characteristics including growth form (solitary or colonial), profile (erect or encrusting) and structure (soft, hard or flexible) on the survival of a range of common biofouling organisms. A custom built hydrodynamic keel attached to the bottom of a 6 m aluminium powerboat was used to subject pre-fouled settlement plates for this purpose. Vessel speeds of 5 and 10 knots had little effect on the species richness of biofouling assemblages tested, however richness decreased by 50% following 18 knots treatments. Species percentage cover decreased with increasing speed across all speed treatments and this decrease was most pronounced at 10 and 18 knots, with cover reduced by 24 and 85% respectively. Survival was greatest for organisms with colonial, encrusting, hard and/or flexible morphological characteristics, and this effect increased with increasing speed. This study suggests that there is predictive power in forecasting future introductions if we can understand the extent to which such traits explain the world-wide distributions of non-indigenous species. Future introductions are a certainty and can only provide an increasing source of new information on which to test the validity of these predications.

The effect of vessel speed on the survivorship of biofouling organisms at different hull locations.

This study used a specially designed MAGPLATE system to quantify the en route survivorship and post-voyage recovery of biofouling assemblages subjected to short voyages (<12 h) across a range of vessel speeds (slow, medium, fast; in the range 4.0–21.5 knots). The effect of hull location (bow, amidships and stern) was also examined. While no significant differences were evident in en route survivorship of biofouling organisms amongst hull locations, biofouling cover and richness were markedly reduced on faster vessels relative to slower craft. Therefore, the potential inoculum size of non-indigenous marine species and richness is likely to be reduced for vessels that travel at faster speeds (>14 knots), which is likely to also reduce the chances of successful introductions. Despite this, the magnitude of introductions from biofouling on fast vessels can be considered minor, especially for species richness where 90% of source-port species were recorded at destinations.

Non-native Aquaculture Species Releases: Implications for Aquatic Ecosystems

* Corresponding author Abstract Aquaculture is undergoing a rapid worldwide expansion. Of significant concern is the increasing use of non-native species, with subsequent escapes of these species and their associated pathogens and parasites posing a serious threat to native biodiversity, economic value and ecosystem function, particularly in regions rich in endemic species. The contribution of non-native species to the growth of the global aquaculture industry and the economic benefits that it has brought to many developing countries cannot be underestimated. However, minimizing the escapes of non-native aquaculture species must be a high priority for resource managers, conservationists and the aquaculture industry. This paper reviews intentional and unintentional non-native aquaculture introductions and the environmental consequences that escapes can have on the aquatic environment and presents a potential system of risk evaluation, management and funding mechanisms to assist in the long term sustainable development of the aquaculture industry.

Potential ramifications of the global economic crisis on human-mediated dispersal of marine non-indigenous species.

The global economy is currently experiencing one of its biggest contractions on record. A sharp decline in global imports and exports since 2008 has affected global merchant vessel traffic, the principal mode of bulk commodity transport around the world. During the first quarter of 2009, 10% and 25% of global container and refrigerated vessels, respectively, were reported to be unemployed. A large proportion of these vessels are lying idle at anchor in the coastal waters of South East Asia, sometimes for periods of greater than 3 months. Whilst at anchor, the hulls of such vessels will develop diverse and extensive assemblages of marine biofouling species. Once back in service, these vessels are at risk of transporting higher-than-normal quantities of marine organisms between their respective global trading ports. We discuss the potential ramifications of the global economic crisis on the spread of marine non-indigenous species via global commercial shipping.

The effectiveness of rotating brush devices for management of vessel hull fouling.

The present study tested two diver-operated rotating brush systems, coupled with suction and collection capabilities, to determine their efficacy in the management of vessel biofouling. Both rotating brush systems proved effective (>80%) in removing low-to-moderate levels of fouling from flat and curved experimental surfaces (Perspex plates). However, performance was generally poorer at removing more advanced levels of fouling. In particular, mature calcareous organisms were relatively resistant to the rotating brushes, with a high proportion (up to 50%) remaining on plates following treatment. On average, >95% of defouled material was collected and retained by both systems. The amount of lost material generally increased when treating curved plates with increasing biomass, whereas the material lost from flat plates was typically less and remained relatively constant throughout the trials. The majority (>80%) of fouling not captured by the systems was crushed by the brushes (ie non-viable). However, a diverse range of viable organisms (eg barnacles and hydroids) was lost to the environment during the defouling trials. When defouling a vessel, unintentional detachment of fouling organisms is likely to be high through physical disturbance by divers operating the devices and by associated equipment (eg hoses). Furthermore, residual biosecurity risks are also likely to remain due to diver error, persistent fouling remaining on treated surfaces and the inaccessibility of niche areas to the brush systems. To address these limitations, further research into alternative treatment methods is required.