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Non-native ascidians have long dominated the artificial structures in southern California's (United States) marinas and harbors. To determine the change in ascidian abundance and community composition over the last several decades, in 2019-2020 we replicated surveys from 1994-2000. We then created nMDS plots using the abundance data collected in the 1994-2000 and 2019-2020 surveys to compare the two groups. Range and average abundance per species were analyzed to determine trends and changes in ascidian community composition. Of the species used for comparison, four are native, three are cryptogenic, and 12 are non-native. As predicted by Lambert and Lambert, non-native species have persisted in southern California; however, ranges and abundances have changed. The only native species found consistently in both sets of surveys, Ascidia ceratodes, remained rare in 2019-2020, with an unchanged average abundance. Several non-native species increased in abundance or remained common. The non-native colonial species Polyandrocarpa zorritensis had the greatest influence on the dissimilarity between the surveys, increasing from rare in 1994-2000 to more common in 2019-2020, and spreading north to Santa Barbara. Several non-native species confined to San Diego in the 1994-2000 surveys have also spread north, such as Botrylloides giganteus and Styela canopus which were found in Santa Barbara in 2019-2020. A formerly unidentified Aplidium sp. has now been identified as the non-native Aplidium accarense. There have also been additional introductions since 2000, including Ascidia cf. virginea and the first report of Ascidiella aspersa in the NE Pacific. The overwhelming trends of the surveys indicate that we will continue to see an increase and persistence of newly introduced non-natives in Southern California marinas, with possible continued northward expansion. [ABSTRACT FROM AUTHOR]

Non-indigenous species may drive declines in global freshwater biodiversity. Japanese mystery snails, Heterogen japonica (previously Cipangopaludina / Bellamya / Viviparus japonica), have invaded numerous freshwater systems in North America. To resolve questions about its population demography and genetics, we surveyed ponds and rivers from six Mid-Atlantic USA locations (Richmond, Virginia to Washington, D.C.) in 2018 and 2019 for mystery snails and co-occurring indigenous snails. A random subset of each snail species (max N = 80) per location was assessed for population demographics (size, sex), and brooding embryos were counted in mystery snails. Because morphological identification can be difficult to discern from its congener, the Chinese mystery snail (Cipangopaludina chinensis), we used a mitochondrial barcoding gene (COI) to confirm identity of H. japonica and also serve as a population genetics marker. Our barcoding confirmed that the mystery snails detected in our surveys were H. japonica, and that, compared to the indigenous range, its populations have low genetic diversity and limited genetic structure. Even so, H. japonica had the highest overall catch-per-unit-effort among all snails and sites. In demographic analyses, H. japonica populations skewed towards females, and females brooding live young were the largest across all sites. The number of live young ranged from 14 to 101/female (average: 52 live young/female). Further, a linear relationship existed between brooding female shell length and the number of live young for all sites, except one. Possible explanations could include site-level differences in abiotic or biotic parameters, but this requires further research. Altogether, the snail's reproductive capacity documented here suggests that H. japonica has the potential to undergo additional population growth, especially if large females spread to new locations. Moreover, it highlights another example of an invasive species with high population abundance, demographic performance, and distributional range even with depauperate genetic diversity. [ABSTRACT FROM AUTHOR]

The palaemonid shrimp Palaemon sinensis, a species native to China, was first discovered as an established non-native species in Japan in 2005, and it has since been reported in 25 of 47 prefectures. To genetically elucidate that P. sinensis was introduced to Japan from China via importation as a live fishing bait species, this study analyzed partial nucleotide sequences of the mitochondrial 16S rRNA gene of 165 specimens collected in 7 geographical regions in Japan (Tohoku, Kanto, Chubu, Kinki, Chugoku, Shikoku and Kyushu), and from 18 imported specimens from China purchased at a fishing store. All sequences were classified into 11 haplotypes, which included one widespread haplotype shared by more than half of the P. sinensis samples. Almost all of the samples of imported specimens possessed the dominant haplotype. Analysis of molecular variance showed no genetic differentiation between the Japanese local and imported samples or among regions in Japan. The overall results suggest that P. sinensis was introduced through human-mediated dispersal; furthermore, the haplotype distributions of P. sinensis established in Japan reflected the intensity of the species' importation from central and northern China. This is the first study to document the genetic structure of non-native P. sinensis in Japan. [ABSTRACT FROM AUTHOR]

The increasing rate of marine invasions to Western Europe in recent decades highlights the importance of addressing the central questions of invasion biology: what allows an invader to be successful, and which species are likely to become invasive? Consensus is currently lacking regarding the key traits that determine invasiveness in marine species and the extent to which invasive and indigenous species differ in their trait compositions. This limits the ability to predict invasive potential. Here we propose a method based on trait profiles which can be used to predict non-indigenous species likely to cause the greatest impact and native species with a tendency for invasion. We compiled a database of 12 key biological and life history traits of 85 non-indigenous and 302 native marine invertebrate species from Western Europe. Using multivariate methods, we demonstrate that biological traits were able to discriminate between native and non-indigenous species with an accuracy of 78%. The main discriminant traits included body size, lifespan, fecundity, offspring protection, burrowing depth and, to a lesser extent, pelagic stage duration. Analysis revealed that the typical non-indigenous marine invertebrate is a mid-sized, long-lived, highly fecund suspension feeder which either broods its offspring or has a pelagic stage duration of 1-30 days, and is either attached-sessile or burrows to a depth of 5 cm. Biological traits were also able to predict native species classed as "potentially invasive" with an accuracy of 78%. Targeted surveillance and proactive management of invasive species requires accurate predictions of which species are likely to become invasive in the future. Our findings add to the growing evidence that non-indigenous species possess a greater affinity for certain traits. These traits are typically present in the profile of "potentially invasive" native species. [ABSTRACT FROM AUTHOR]

Ficopomatus enigmaticus (Fauvel, 1923) is a reef-building serpulid polychaete that has invaded estuaries worldwide, causing environmental and economic harm. Although Australia has long been suggested as a place of origin for the species, this remains unclear. We tested for genetic patterns across the range of F. enigmaticus in southern Australia, predicting that if the species is an Australian native, it would show evidence of (east-west) phylogeographic patterns often observed in native marine species in southern Australia. Unexpectedly, concordant patterns from mitochondrial (Cyt B) sequencing and nuclear marker (iSSR) profiles suggested the presence of at least three genetic groups (putative species), not distributed simply as "east" or "west". Two common (and closely related) groups were present across Australia and were often found together in the same aggregations. A third group was only found in southeast Australia and was morphologically similar to F. uschakovi (Pillai, 1960), a species previously reported from tropical areas. The discovery of multiple cryptic species with overlapping ranges means that more work is needed to resolve whether any of the F. enigmaticus sensu lato group has an Australian origin and to determine how they are related to invasive populations of F. enigmaticus elsewhere. [ABSTRACT FROM AUTHOR]

The majority of bryozoans possess short-lived larvae with limited dispersal potential, yet many species of bryozoans have obtained global distributions. The marine bryozoan Tricellaria inopinata d'Hondt and Occhipinti-Ambrogi, 1985 was first described from specimens collected in 1982 in the Lagoon of Venice, but is thought to be native to the northeast Pacific. By 2009, it could be found in various locales in the eastern Atlantic including Spain, France, England, and Ireland. In 2010, T. inopinata was found for the first time in the western Atlantic in Eel Pond, Woods Hole, Massachusetts, and shortly thereafter was collected in several other locales in the area. A newly developed suite of polymorphic microsatellite loci was used to investigate this recent range expansion of T. inopinata in an effort to understand what makes these animals such successful invaders. We examined various aspects of the population genetics of adult colonies collected from four sites in eastern Massachusetts: Eel Pond, Boston Harbor, Marblehead and Gloucester. There was significant genotypic differentiation between all sites. Higher homogeneity between the Eel Pond and Boston Harbor populations, as well as the potential for Eel Pond acting as a source of migrants for Boston Harbor, suggest that Eel Pond was a source population for the Boston Harbor population. In contrast, levels of genotypic differentiation and a lack of migrants suggested that the Marblehead and Gloucester populations likely did not originate from animals in Eel Pond. Thus, the recent range expansion by T. inopinata in the western Atlantic appears to be a result of multiple introduction events. [ABSTRACT FROM AUTHOR]

The R/V Oceanus completed a 9,789 km, 28 day passage from Woods Hole, Massachusetts, in the Atlantic Ocean, through the Panama Canal to Yaquina Bay, Oregon, in the Pacific Ocean on 21 February 2012. The Oceanus had previously operated in the Mediterranean Sea and Atlantic Ocean (including the Caribbean Sea). We document the sequential acquisition of the barnacles Balanus trigonus and Amphibalanus venustus and the oyster Ostrea equestris on the Oceanus on its high and low latitude transoceanic, intra-oceanic, and inter-oceanic travels before she was surveyed in Yaquina Bay. The close correspondence between hull fouling accumulations and the detailed two year Oceanus working history reveals B. trigonus settlement occurred in every tropical port visited by the Oceanus, that some populations survived through two of three Woods Hole winters, and that some of these populations passed through the freshwater Panama Canal. These results suggest that marine hull-fouling species are continuously transported globally between most ports of call by most ship passages. [ABSTRACT FROM AUTHOR]

Here we present the known distribution and population demography of the most northern known population of the North American whitefingered mud crab, Rhithropanopeus harrisii, from southwest Finland in the Baltic Sea. This species was first reported in Finland in 2009 from the archipelago close to Turku and has been found from 82 locations within a 30 km radius since then. Due to the presence of young of year, juveniles, and gravid females observed at three sites in Finland, R. harrisii has established successful populations that are able to overwinter under ice and can opportunistically occupy diverse habitats, such as shafts of dead marsh plants, self-made burrows in muddy bottoms, and the brown algae Fucus vesiculosus in hard bottoms. In its native range, a rhizocephalan barnacle parasitizes R. harrisii, but this parasite was not found in the introduced Finnish population. While R. harrisii is expected to expand its range along the coast of the northern Baltic Sea, the ultimate impact of this species on food web dynamics, both as a predator and prey item, remains to be seen. [ABSTRACT FROM AUTHOR]

Specimens of small (< 1 mm) cyclopoid copepods of the genus Oithona were collected from Sevastopol Bay and an offshore area of the Black Sea. On the basis of a combination of characteristics such as those in the maxillule and the genital double-somite, the specimens were identified as O. davisae Ferrari and Orsi, 1984. The identity of "O. brevicornis" that was reported in the Black Sea and the possible origin of O. davisae in the Black Sea are discussed. [ABSTRACT FROM AUTHOR]