Diapterus brevirostris (Sauvage, 1879) is a fish of the family Gerreidae, native to the tropical and subtropical waters of the Pacific coast of America. A specimen of this species was captured off the coast of Asturias, Spain. To the best of our knowledge, this is the first record of the genus Diapterus in the North Atlantic. Given its small size (6.4 cm), it is likely that the species was present in the area for a relatively short time. Although the introduction pathway is unknown, the species' native area and the proximity of a major port to the site of capture suggest that ship's ballast water is the most likely vector of introduction.

Otoliths are an excellent tool in studies on ecological connectivity of fish species populations. Opsanus beta is an invasive species introduced on the Brazilian coast, but not native from the Gulf of Mexico. The present study aimed to compare the otolith contours of specimens collected in Mexico (Celestún, CEL) and in two Brazilian estuaries (Santos Bay, STB, and Paranaguá Estuarine Complex, PEC). In the laboratory, 99 otoliths were extracted, photographed and compared using wavelet analysis. The otolith contours varied between sites (39 from CEL, 26 from STB and 34 from PEC). The linear discriminant analysis correctly reclassified 87.9% of otoliths by sites, with the best reclassifications in the CEL (97.36%), followed by PEC (88.23%) and SBT (73.07%). MANOVA showed significant differences in otolith contours between sites (F = 5.37; P < 0.005). The otolith contour from CEL was significantly different from those from the PEC and SBT. However, the otolith contour of the two Brazilian estuaries did not significantly differ among them (MANOVA, P > 0.005). Our results indicate O. beta populations on the Brazilian coast are connected, and probably isolated from the Mexican population.

The introduction of non-native predator fish is thought to have important negative effects on native prey populations. Opsanus beta is a non-native toadfish that was originally described in the Gulf of Mexico, between the west coast of Florida and Belize. In the present study, we describe, for the first time, the occurrence of O. beta in Sepetiba Bay (22°55′S), south-eastern Brazil, probably brought into the bay through ships' ballast water. Thirteen specimens were recorded in this area near to Sepetiba Port. Similarly, three other records of this species in the Brazilian coast were also reported near to port areas at Rio de Janeiro (22°49′S), Santos (23°59′S) and Paranaguá (25°33′S) ports. To confirm the species identity, we employed DNA barcoding and compared our samples with sequences deposited on public databases, which indicated that our samples are highly similar (>99.9% of genetic similarity) to O. beta samples collected near its type locality. Several individuals were found in the capable spawning phase, according to histological analysis of the reproductive cell stages. The environmental plasticity of this species and the favourable local environmental conditions probably enabled the establishment of O. beta in this region. This raises concerns of potential high invasion impact due to this species' diet and reproductive capacity.

Ballast water from commercial ships engaged in international trade has been implicated as the primary invasion pathway in over 60 percent of new introductions of invasive alien species (IAS) in the Great Lakes since 1960. Recent policies have recognized that IAS are a form of biological pollution and have become focused on preventing new introductions. Given that emissions-based incentives are infeasible for the case of biological emissions, we investigate the cost-effectiveness of various performance proxy-based and technology-based economic incentives to reduce the threat of new invasions of Ponto-Caspian species in the Great Lakes.

We report, for the first time, the occurrence of the muzzled blenny, Omobranchus punctatus, on the coast of São Paulo, South-Eastern Brazil, partially filling a record gap within the species’ expected distribution in Brazil. One individual was found on 16 June 2014 in a sand-bottom tide pool of a tidal flat ecosystem, adjacent to the port of São Sebastião.

The Southern Ocean around Antarctica is no longer free from invasive marine species. The North Atlantic spider crab Hyas araneus (Linnaeus, 1758) (Crustacea: Decapoda: Majidae) has been recorded for the first time from the Antarctic Peninsula. Isolated for at least 25 million years, the endemic Antarctic Southern Ocean marine fauna is now being exposed to human-mediated influx of exotic species. Invasive species and polar warming combined can foster the probability of arrival and colonization by non-indigenous species, with unpredictable consequences for the Antarctic marine biota.