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Ballast water is recognized globally as a major vector of aquatic nonindigenous species (NIS) introductions; domestic ballast water transfers, however, have generally been considered low risk in North America. We characterize ballast operations of domestic ships in the Great Lakes--St. Lawrence River system (Lakers) during 2005-2007 to examine the risk of primary and secondary introductions associated with ballast water transfers over short distances. Results indicate that Lakers transported at least 68 million tonnes of ballast water annually. Approximately 71% of ballast water transfers were interregional, with net movement being from lower to upper lakes. A small proportion of ballast water discharged in the Great Lakes ( Resume: L'eau de ballastage est reconnue a l'echelle planetaire comme un vecteur primordial d'introduction d'especes non indigenes (NIS) aquatiques; cependant, on considere generalement que les transferts locaux d'eau de ballastage presentent peu de risques en Amerique du Nord. Nous decrivons les operations de ballastage des navires domestiques du systeme Grands-Lacs--Saint-Laurent (cargos hors mer) en 2005-2007 afin d'evaluer le risque d'introductions primaires et secondaires associees aux transferts d'eau de ballastage sur de courtes distances. Nos resultats indiquent que les cargos hors mer transportent au moins 68 millions de tonnes d'eau de ballastage chaque annee. Environ 71% des transferts d'eau de ballastage se font entre des regions, le deplacement net ayant lieu entre les lacs d'aval vers les lacs d'amont. Une petite proportion ( [Traduit par la Redaction], Introduction Human-mediated invasions by nonindigenous species (NIS) result from a sequence of steps or stages from uptake by a vector in a donor region to eventual live release and establishment [...]

Laboratory microcosm experiments are carried out for the quantitative comparison of the colonization of two copepod species, Acartia tonsa and Eurytemora affinis, by each of the epidemic serogroups. The difference in colonization is significant in the general predominance of Vibrio cholera O1 in cholera epidemics in rural Bangladesh where water supplies are taken directly from the environment.

Research on biological invasions within North American marine habitats reveals that the encroachment of non-indigenous species within coastal ecosystems has risen exponentially since the early 1800s. Other findings show that these invasions are primarily the result of shipping, and are typically composed of mollusks and crustaceans; invasions were also discovered to be more prevalent on the coast of the Pacific Ocean rather than the Atlantic, and the origins of invasive species correspond to trade patterns.

Invasion impacts and interactions have been assessed in non-indigenous species (NISs) in the Chesapeake Bay region. In marine and estuarine communities NISs may act as stressors and available data on their roles have been evaluated with interactions with anthropogenic stressors of various kinds assessed. Reported ecological impacts of 196 species that are known invaders or of uncertain origin in tidal waters of the bay have been reviewed, and impacts for the same 54 species of plants and fish from the group that regularly occur in the region are compared. Evidence for interaction in distribution or performance of the 54 plant and fish species within the bay and other stressors is discussed. NIS-stressor interactions likely have an important role in pattern and impact of invasions.

Aims: The present study is the first attempt to grasp the scale and richness of marine biological invasions in Macaronesia. We pioneered a comprehensive non‐native species (NNS), inventory in the region to determine their diversity patterns and native distribution origins. NNS were defined here as the result of both introductions and range expansions. We also used statistical modelling to examine relationships among NNS richness, anthropogenic activities, demographic and geographical variables across Macaronesia. Location: Macaronesia. Methods: A comprehensive literature search was conducted for marine NNS records in Macaronesia, registering the first record's location and year from 1884 to 2020. We used univariate and multivariate analyses to evaluate differences and similarities in community composition. By applying a Generalized Linear Model (GLM), we tested hypotheses regarding NNS richness as a function of anthropogenic activities, demographic and geographical variables. Results: A total of 144 marine non‐native species (NNS) were recorded for the whole of Macaronesia. The highest NNS richness was registered in the Canary Islands (76 NNS), followed by the Azores (66 NNS), Madeira (59 NNS) and finally Cabo Verde (18 NNS). Some differences amongst archipelagos were observed, such as the high number of non‐native macroalgae in the Azores, fishes in the Canary Islands and tunicates in Cabo Verde. Overall, macroalgae, tunicates and bryozoans were the predominant taxonomic groups in the Macaronesian archipelagos. Madeira and Canary Islands were the archipelagos with more similarity in marine NNS, and Cabo Verde the most divergent. Finally, GLM suggested that non‐native richness patterns across Macaronesia were dependent on the considered archipelago and strongly affected by (1) minimum distance to the mainland, (2) the total number of ports and marinas and (3) total marinas area (km2). Conclusions: The model results and NNS listing in the present study will likely raise the awareness and response regarding marine NNS in the whole Macaronesia region, serving as a baseline for future research as well as implementing and enforcing regulations related to the introduction of marine NNS in oceanic islands. [ABSTRACT FROM AUTHOR]

Recreational boats and their marinas are important components of the hub-and-spoke model of invasion in coastal marine systems. Like most vectors, however, species transfers by boats are under-sampled and the extent of invasion among coastal bays is patchily sampled, with a bias towards larger urbanized bays with commercial port systems. We assessed both the hubs (bays with marinas) and the spokes (recreational boat movements and their vector biota) that form the basis of a non-shipping hub-and-spoke system for the coast of California. Non-native invertebrates and algae have been reported from most bays in California (26 of 27), with only five of these having commercial shipping ports. Recreational boats offer frequent opportunities for transfers of species among bays; 292,000 recreational boats were registered in coastal California, and more than half (54%) of surveyed recreational boat owners made voyages outside their home bays. Destinations for recreational boaters often included bays without commercial ports and areas of conservation value inside National Marine Sanctuaries. We recorded 158 taxa from the hulls and niche areas of 49 transient recreational boats upon arrival at Californian marinas. These included several non-native species that are already well-established at arrival locations and four that are not known from the state or sampling location. Biofouling abundance on vessels ranged from zero to remarkably high levels (estimated at 106 organisms) for vessels that traverse open coastal systems. Management opportunities and models exist for the recreational boat vector but, absent operational incentives, these are challenging to implement broadly. An initial management focus on areas recognised for their distinct marine habitats and biodiversity may be an effective implementation approach. [ABSTRACT FROM AUTHOR]

Established non-native species can have significant impacts on native biodiversity without any possibility of complete eradication. In such cases, one management approach is functional eradication, the reduction of introduced species density below levels that cause unacceptable effects on the native community. Functional eradication may be particularly effective for species with reduced dispersal ability, which may limit rates of reinvasion from distant populations. Here, we evaluate the potential for functional eradication of introduced predatory oyster drills (Urosalpinx cinerea) using a community science approach in San Francisco Bay. We combined observational surveys, targeted removals, and a caging experiment to evaluate the effectiveness of this approach in mitigating the mortality of prey Olympia oysters (Ostrea lurida), a conservation and restoration priority species. Despite the efforts of over 300 volunteers that removed over 30,000 oyster drills, we report limited success. We also found a strong negative relationship between oyster drills and oysters, showing virtually no coexistence across eight sites. At experimental sites, there was no effect of oyster drill removal on oyster survival in a caging experiment, but strong effects of caging treatment on oyster survival (0 and 1.6% survival in open and partial cage treatments, as compared to 89.1% in predator exclusion treatments). We conclude that functional eradication of this species requires significantly greater effort and may not be a viable management strategy in this system. We discuss several possible mechanisms for this result with relevance to management for this and other introduced species. Oyster restoration efforts should not be undertaken where Urosalpinx is established or is likely to invade. [ABSTRACT FROM AUTHOR]

Non-indigenous species (NIS) are increasingly conspicuous in marine and estuarine habitats throughout the world, as the number, variety, and effects of these species continue to accrue. Most of these NlS invasions result from anthropogenic dispersal. Although the relative importance of different dispersal mechanisms varies both spatially and temporally, the global movement of ballast water by ships appears to be the largest single vector for NlS transfer today, and many recent invasions have resulted from this transfer. The rate of new invasions may have increased in recent decades, perhaps due to changes in ballast water transport. Estuaries have been especially common sites of invasions, accumulating from tens to hundreds of NIS per estuary that include most major taxonomic and trophic groups. We now know of approximately 400 NlS along the Pacific, Atlantic and Gulf coasts of the U.S., and hundreds of marine and estuarine NIS are reported from other regions of the world. Although available information about invasions is limited to a few regions and underestimates the actual number of NIS invasions, there are apparent differences in the frequency of NIS among sites. Mechanisms responsible for observed patterns among sites likely include variation in supply of NIS, and perhaps variation in properties of recipient or donor communities, but the role of these mechanisms has not been tested. Although our present knowledge about the extent, patterns and mechanisms of marine invasions is still in its infancy, it is clear that NIS are a significant force of change in marine and especially estuarine communities globally. Taxonomically diverse NlS are having significant effects on many, if not most, estuaries that fundamentally alter population, community, and ecosystems processes. The impacts of most NlS remain unknown, and the predictability of their direct and indirect effects remains uncertain. Nonetheless, based upon the documented extent of NIS invasions and scope of their effects, studies of marine communities that do not include NIS are increasingly incomplete.