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Biological invasions are a major driver of biodiversity loss and socioeconomic burden globally. As invasion rates accelerate worldwide, understanding past invasion dynamics is essential to inform predictions of future invaders and impacts. Owing to a high diversity of pathways and current biosecurity gaps, aquatic systems near urban centres are especially susceptible to alien species establishments. Here, we compiled and compared alien species lists for three different aquatic recipient regions spanning the North Atlantic: Chesapeake Bay, Great Lakes‐St. Lawrence River and North and Baltic Seas. Each system is a major trade centre, with a history of invasions, and characterized by a strong natural salinity gradient. Our goal was to compare the alien species across systems, to test for similarities in the taxonomic composition and geographic origin as well as species overlap among the three regions. We selected specific macroinvertebrate, algal and fish taxa for analysis, to control for uneven taxonomic and biogeographic resolution across regions. Cumulatively, we identified 326 individual alien species established in these aquatic systems, with the North and Baltic Seas most invaded overall (163), followed by Great Lakes‐St. Lawrence River (84) and Chesapeake Bay (79). Most invasions were from Ponto‐Caspian, Eurasian, Northwest Pacific, Northwest Atlantic and North American origins, and mostly comprised Arthropoda, Chordata, Mollusca and Annelida. However, origins and taxonomies differed significantly among destinations, with Ponto‐Caspian species particularly successful invaders to the North and Baltic Seas then Great Lakes‐St. Lawrence River, but less so to Chesapeake Bay. Nevertheless, approximately eight‐tenths of invaders established in only one region, indicating disparate invasion patterns and a high potential for future aliens to accrue from increasingly diverse source pools and pathways. These results support biosecurity strategies that consider a broad range of geographic origins and taxonomic groups to limit the translocation, arrival and spread of alien species worldwide. [ABSTRACT FROM AUTHOR]

We confirm the presence of the Indo-West Pacific barnacle Amphibalanus amphitrite (Darwin, 1854) in Chile, based on the discovery of a population in Tongoy estuary in northern-central Chile, and following upon an obscure report of its presence in Chile as of 1980 at unidentified sites. [ABSTRACT FROM AUTHOR]

International marine reserves should be established in the open ocean. The reserves would be areas with no commercial shipping, little or no pressure from fishing, no weapons deployment or testing, and no floating cities. They should represent the different biogeographic regimes of the open oceans, including boreal, temperate and tropical oceans.

A marine bioinvasions Rapid Assessment Survey in August 2019, focused on marina floating pontoons in Rhode Island, Connecticut and New York recorded 21 nonindigenous, 22 cryptogenic and 2 range-expanding species. Five non-indigenous species (NIS) were found at more than 70% of the 10 sampled sites: three ascidians, Botryllus schlosseri (Pallas, 1766) (a probable mixture of introduced and native populations), Botrylloides violaceus Oka, 1927, and Styela clava Herdman, 1881; a crab, Hemigrapsus sanguineus (de Haan, 1835), and a sea anemone, Diadumene lineata (Verrill, 1869). The sea anemone Aiptasiogeton eruptaurantia (Field, 1949), native to the southern United States, is newly reported from New York. The southern U.S. barnacle Amphibalanus subalbidus (Henry, 1973) was detected for the first time in Connecticut in Long Island Sound. It had been six years since the last rapid assessment survey of marinas in Rhode Island and 16 years for marinas in Connecticut and New York. During this six to 16 year hiatus, we found northern range expansions, expansion of recent invaders and generally consistent presence of previous NIS at high levels of occurrence. [ABSTRACT FROM AUTHOR]

Hydroids were examined from surveys of marine fouling communities undertaken during 2018 in Ecuador. Specimens were collected on settlement panels in harbours at Salinas and La Libertad on the mainland, and at Isla San Cristóbal in the Galapagos Islands. Of 27 species in the samples, 18 were present in collections from the mainland and 14 from San Cristóbal. Most frequent in samples from the mainland were Bougainvillia cf. muscus (20 samples), Obelia microtheca (20), Clytia delicatula (19) and Pennaria disticha (10). In collections from San Cristóbal, most frequent were Obelia alternata (27), Bougainvillia cf. muscus (16), Ectopleura crocea (13) and Cirrholovenia tetranema (11). Based on genetic evidence, Ectopleura media Fraser, 1948 is assigned to the synonymy of E. crocea (L. Agassiz, 1862). In addition, a COI reference sequence is deposited for the first time for Tridentata turbinata. Male gonophores of Eudendrium breve, previously unknown, were discovered and illustrated. The cnidome of the species comprises small and large microbasic euryteles. Five of the species have not been reported before from the Tropical Eastern Pacific. Of these, three (Amphinema cf. rugosum, Egmundella humilis, and Campanulinida, undetermined) were found only in the Galapagos, one (Clytia delicatula) occurred at both mainland sites and the Galapagos, and one (Opercularella sp.) was collected only from a station on the mainland. Six other species [Ectopleura integra, Coryne repens, Clytia irregularis, C. seriata, Obelia alternata (resurrected here from the synonymy of O. dichotoma), and O. microtheca] are known only from the Tropical Eastern Pacific. Three of them, E. integra, C. irregularis, and C. seriata, are new to the Ecuadorian mainland. Species numbers were similar (range of 6 to 11 taxa) across all stations. One-third (nine species) were found only in Galapagos samples, whereas nearly half (13 species) were found only at mainland sites. More than half (15 species) were restricted to a single station. Previous studies, together with this work, bring the total of introduced and cryptogenic hydroid species in the Galapagos Islands to 12 (previously eight) and nine (previously five) taxa, respectively. We recognize four introduced and eight cryptogenic hydroid species from the coast of mainland Ecuador. [ABSTRACT FROM AUTHOR]

The biological diversity of the world ocean is subject to unprecedented alterations that are largely due to potentially irreversible effects of human activities. What do we know about the pattern [...]

There have been few surveys of intertidal invertebrates in San Francisco Bay, California, USA. Most prior intertidal surveys were limited spatially or taxonomically. This survey of the intertidal invertebrates of San Francisco Bay was conducted over 13 months between 1970 and 1971, generating what is now a legacy data set of invertebrate diversity. Specimens were hand collected at land access points at 34 sites around the Bay. In all 139 living species in 9 phyla were collected; 28.8% were introduced species, primarily from the Atlantic Ocean (62.5%) and the Northwest Pacific and Indo-West Pacific Oceans (30%). [ABSTRACT FROM AUTHOR]