Global marine biosecurity and ship lay-ups: intensifying effects of trade disruptions

Assessment of ship hull-attached marine diatoms: species composition and reattachment

Ship biofouling is a primary pathway for the introduction and global spread of non-indigenous species, posing significant risks to marine ecosystems. However, the extent to which ship hull-attached diatoms survive and disperse following in-water hull cleaning (IwHC) remains poorly understood. Here, we analyzed the attached diatoms compositions in the in-water hull cleaning water (IwHCW) from three international ships entering Korea as well as benthic diatoms at nearby stations, using both morphological and molecular methods. In addition, we assessed the survival of ship hull-attached diatoms using reattachment analysis. Water temperature and salinity varied during sampling of the IwHCW of the ships, while the conditions at the four nearby stations were more consistent. The diatom Halamphora spp. was most abundant in the IwHCW of the ships, whereas Achnanthes species dominated at the nearby stations. Non-metric Multidimensional Scaling (NMDS) revealed significant variation in species composition between the IwHCW and the stations, suggesting limited dispersal of ship-associated diatoms or spatiotemporal influences. Survival and reattachment analyses revealed that Halamphora oceanica survived for over 21 days in unfiltered IwHCW, with no attached diatoms observed in IwHCW filtered through 5 and 32 μm filters. These findings indicate that diatoms in an unfiltered IwHCW may survive and reattach to substrates, highlighting the need for IwHC risk assessment and biofouling management in coastal waters.

Small sea with high traffic - what is the biofouling potential of commercial ships in the Baltic Sea

Despite the Baltic Sea being one of the most intensive shipping regions in the world the potential magnitude of the biofouled hulls in this region is unknown. This study estimated the biofouling load to Baltic Sea Region (BSR) based on the wetted surface area (WSA) method with regard to country, ship type and donor bioregion. WSA flux reached 656 km2, of which 86% was associated with ships operating inside and 14% was WSA flux brought by ships from outside of the Baltic Sea. Most of the WSA was transported to Swedish, Finnish and Danish ports as well. The highest WSA flux was assigned to roll-on/roll-off, passenger and general cargo ships. The high biofouling potential in BSR indicates a potential high risk to the environment and, therefore there is an urgent need for appropriate guidelines to be introduced into daily use by the commercial shipping community.

Ship Hull-Fouling Diatoms on Korean Research Vessels Revealed by Morphological and Molecular Methods, and Their Environmental Implications

Ship biofouling is one of the main vectors for the introduction and global spread of non-indigenous organisms. Diatoms were the early colonizers of ship hulls; however, their community composition on ships is poorly understood. Herein, we investigated the diatom community on the hull samples collected from two Korean research vessels Isabu (IRV) and Onnuri (ORV) on September 2 and November 10, 2021, respectively. IRV showed low cell density (345 cells/cm2) compared to ORV (778 cells/cm2). We morphologically identified more than 15 species of diatoms from the two research vessels (RVs). The microalgae in both RVs were identified as Amphora, Cymbella, Caloneis, Halamphora, Navicula, Nitzschia, and Plagiogramma. Of them, the genus Halamphora was found to be predominant. However, both RVs had a varied dominant species with a significant difference in body size; Halamphora oceanica dominated at IRV, and Halamphora sp. at ORV, respectively. Molecular cloning showed similar results to morphological analysis, in which Halamphora species dominated in both RVs. The hull-attached species were distinct from species found in the water column. These results revealed diatoms communities that are associated with ship hull-fouling at an early stage of biofilm formation. Moreover, ships arriving from different regions could show some variation in species composition on their hull surfaces, with the potential for non-indigenous species introduction.

Knowledge needs in economic costs of invasive species facilitated by canalisation

Canals provide wide-ranging economic benefits, while also serving as corridors for the introduction and spread of aquatic alien species, potentially leading to negative ecological and economic impacts. However, to date, no comprehensive quantifications of the reported economic costs of these species have been done. Here, we used the InvaCost database on the monetary impact of invasive alien species to identify the costs of those facilitated by three major canal systems: the European Inland Canals, Suez Canal, and Panama Canal. While we identified a staggering number of species having spread via these systems, monetary costs have been reported only for a few. A total of $33.6 million in costs have been reported from species linked to European Inland Canals (the fishhook waterflea Cercopagis pengoi and the zebra mussel Dreissena polymorpha) and $8.6 million linked to the Suez Canal (the silver-cheeked toadfish Lagocephalus sceleratus, the lionfish Pterois miles, and the nomad jellyfish Rhopilema nomadica), but no recorded costs were found for species facilitated by the Panama Canal. We thus identified a pervasive lack of information on the monetary costs of invasions facilitated by canals and highlighted the uneven distribution of costs.