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.

The bryozoan Uschakovia gorbunovi was initially characterized as a constituent member of benthic communities of the Kara and East-Siberian Seas. The academic literature reports this species in the Barents Sea, but without accurate information on sampling locations. Also, there are no previous records of this species in the northern Greenland Sea near Svalbard. Our analysis of benthic collections obtained during the past two decades revealed the occurrence of four distribution records of Uschakovia gorbunovi within the Barents and Greenland Sea specifying its distribution: one in the northwestern part of the area and three others in the waters surrounding Svalbard. The new distribution records may be related to inadequate sampling efforts or the expansion of this Arctic species into the Barents Sea, which may be due to either natural processes such as ocean currents, or introduction by mobile benthic species such as snow crabs.

Saccular otoliths (sagittae) have long been shown to be species-specific and exhibit inland geospatial intra- and interpopulation morphological differences with variations in environmental conditions. Here, we analysed inland and outland geospatial variations in sagittae shape, length (Lo), width (Wo), perimeter (Po), and area (Ao), and fluctuating asymmetry (FA) in Chelon auratus males and females collected from Ghar El Melh (Tunisia) and Etoile Bay (Mauritania) stations to assess whether sagittae shape and morphometry differ between these two niches having different environmental conditions. At the intrapopulation level, a significant otolith shape asymmetry was observed between left and right and left–left and right–right otoliths among males and females of the Ghar El Melh (Tunisia) population and a significant symmetry among those of the Etoile Bay (Mauritania) population. At the interpopulation level, a significant asymmetry was found between left and right otoliths' shape among males and females of the two populations. Besides, a discriminant function analysis of otoliths' contour shape separated left and right otoliths among males and females at the intra- and interpopulation levels and also separated those of the two populations. Moreover, differential significant asymmetry in Lo, Wo, Po, and Ao between left and right otoliths was observed among males and females at the intra- and interpopulation levels. Therefore, the geospatial variations in environmental conditions between the two ecological niches effectively induced differences in otolith morphology. These significant asymmetries were discussed in terms of FA caused by environmental stress conditions resulting from variations in abiotic factors between the two ecological niches.

Ergasilid copepods represent one of the commonest groups of fish parasites in Brazil. Within Ergasilidae, three genera share a peculiar latching mechanism on the antenna that completely encircles the gill filament, one of which is Acusicola Cressey, 1970. During a survey of estuarine fish from the Brazilian Amazon Coast, a new species of Acusicola was found on the gills of the largescale foureyes Anableps anableps (Linnaeus, 1758) (Actinopterygii: Anablepidae) in São Marcos Bay, State of Maranhão. Acusicola rochai n. sp. can be distinguished from its closest congeners mainly by three protrusions on the dorsal surface of third and fourth pedigerous somites, and by smooth interpodal plates. This work is the first report of a parasitic copepod infesting a fish from Anablepidae and, consequently, the host An. anableps. The existing dichotomous key proposed for the genus Acusicola includes only ten species, excluding the eight species subsequently described. Therefore, in the present work, a new dichotomous key is provided based on reliable and well-documented features.

The morphology of female bopyrids is adapted to parasitism, but understanding the function of their thoracic and mouth appendages is hindered by their small size and cryptic lifestyle, limiting detailed examination. This study aimed to clarify the function of the first oostegites and maxillipeds in bopyrid isopods infesting the branchial chamber of caridean shrimp through behavioural observations and morphological examination. We tested whether the movement of these structures was exclusive to ovigerous female parasites during brood ventilation. The results revealed that the beating of the maxillipeds and flapping of the first oostegites were not restricted to ovigerous females. However, the frequency of these movements was significantly higher in ovigerous females than in non-ovigerous females. The frequency of maxilliped beating increased with embryonic development, whereas that of flapping the first oostegites exhibited the opposite trend. Microscopic observation using dye showed that the movements of the maxillipeds and the first oostegites expelled residual dye from the female brood chamber through the dorsal surface or beneath the first oostegites. The dye was then transported by the water current generated by the scaphognathite of the host shrimp. These findings suggest that these structures not only facilitate ventilation but also serve as a grooming mechanism for female parasites, which is critical for embryonic survival. The results of the present study represent the first observation of embryo grooming in bopyrid isopods. This study also provides new information on the functional morphology of bopyrid isopods, which is important for understanding their ecological dynamics and adaptation to parasitism.

Eve Caroline Southward (1930–2023) was a multi-talented scientist, motivated by her curiosity and love of nature. Since she was never paid as a scientist, Eve was an amateur, in the best sense of the word. She was highly proficient at transmission electron microscopy and made lasting contributions to polychaete taxonomy, morphology and ecology. Eve was internationally respected, especially for her studies on the Siboglinidae, mouthless and gutless tubeworms (formerly called Pogonophora) that are found worldwide in the deep-sea. She described how the siboglinids obtained nutrition from symbiotic, sulphur-oxidising bacteria and described similar symbiotic relationships in several bivalve species. Eve wrote over 140 scientific publications and described 56 new benthic species, 47 being mouthless and gutless ‘pogonophores’. Eve assisted her husband Alan Southward in starting broad-scale intertidal surveys around the British Isles and Northwest Europe. These surveys formed the foundation for the time-series, later continued by others, that allowed assessments of the influence of climatic fluctuations, using intertidal rocky shore biota as indicators. Eve contributed, with Alan, to what became a 50-year study describing the long-term effects on intertidal communities of the oil pollution and excessive dispersant use resulting from the Torrey Canyon oil spill in 1967. Eve also co-wrote the Linnaean Society Synopsis on Echinoderms of the British Isles and helped complete unpublished work by Alan Southward and others on barnacle taxonomy.

This study describes the presence of the royal cucumber Parastichopus regalis (Cuvier, 1817) in The Natural Park of Ria Formosa (NPRF), Portugal. A single individual was observed during a monitoring scuba dive at a depth of 3 m inside this shallow mesotidal lagoon. The most plausible explanation for this occurrence is attributed to the rejection by trawlers when returning to their home port from their fishing grounds. This marine species has a deeper distribution outside the lagoon and is commonly captured as by-catch and subsequently discarded. This study also alerts us to the growing presence of non-indigenous species and the emergent threat of new invasions, highlighting the need to adopt biosecurity measures, like good practices for fishers when dealing with discards to avoid new species introductions in this fragile coastal marine habitat.

Lough Hyne (LH) Marine Nature Reserve in Ireland is a globally recognised biodiversity hotspot that hosts mesophotic-like communities in shallow water, however, major changes have occurred to most of the rocky cliff (>6 m) communities in one or more events between 2010 and 2015. To provide insights into these changes, we compared the sponge assemblage composition on the undersides of different sized, shallow (<1 m) subtidal boulders between 2000 and 2022 at two sites in LH. We also measured sponge species richness at seven sites in 2018. We found that unlike earlier reports from the deeper subtidal reef sponge assemblages, there was no evidence for changes in sponge assemblage composition on the undersides of boulders at either site. We also found high levels of sponge species richness at all seven sites sampled in 2018. We did find differences in sponge assemblages between sites and for different boulder sizes, which we propose is a result of site-specific environmental conditions and disturbance and size–area relationships. Since we found no changes in the shallow subtidal sponge assemblages between 2000 and 2022, our results support the hypothesis that changes to the deeper subtidal sponge assemblages at LH are driven by local processes associated with deeper water in LH, potentially related to the seasonal oxythermocline that forms within LH. Given the national and global importance of LH, understanding the drivers of change is critical to determine if management actions can prevent any future alterations to the LH sponge assemblages and support wider mesophotic community management.

To capture prey more efficiently, cetaceans can display a wide range of foraging tactics to separate individual prey. Barrier feeding tactics are performed to restrict prey movements, using natural and non-natural barriers and some species can even create barriers with their own bodies. Mud ring feeding has been observed in bottlenose dolphins in Florida Bay and in Chetumal-Corozal Bay, where ring-maker dolphins create ring-shaped mud plumes to encircle fish schools. Here, we document for the first time Guiana dolphins performing the mud ring feeding behaviour in the Cananéia estuarine system, in the southern portion of the state of São Paulo, Brazil. A total of 11 dolphins were recorded in four expeditions through aerial footage engaging in the behaviour. These findings expand our knowledge about the behavioural plasticity of the species and builds upon existing records of mud ring feeding behaviour in cetaceans.

Omobranchus sewalli is a native Indo-Pacific blenniid recently introduced and established along the Brazilian coast. The putative introduction was through ballast water and/or ship hull biofouling. Herein, we report the presence of the species for the first time inside of the Paranaguá Estuarine Complex (PEC) which is recognized as a RAMSAR site and listed as a Wetland of International Importance. The mature specimens of O. sewalli were found in intertidal and shallow subtidal waters in the mixture zone in the estuary, suggesting the establishment of the population. The presence of port terminals in this area indicates that O. sewalli colonize PEC using ship hull fouling or larval dispersal from the shallow inner shelf.

Tanaidaceans have a worldwide distribution, with 36 families, 316 genera, and 1575 extant species described. This study aimed to compile the resulting taxonomic information for Brazilian waters obtained to produce the available online catalogue Taxonomic Catalogue of the Brazilian Fauna. Results show 63 species described for Brazilian waters: 30 Apseudomorpha and 33 Tanaidomorpha, distributed in 46 genera and 18 families. For apseudomorphan, Kalliapseudidae is the most diverse family (12.7%), followed by Apseudidae and Parapseudidae (9.5% each). For tanaidomorphan, Typhlotanaidae is the most diverse (15.9%) followed by Leptocheliidae (9.5%) and Tanaididae (7.9%). In Brazilian waters, more than 60% of Tanaidacea species are distributed in shallow waters (42 species; 63.6%), including continental areas, and about 1/3 are recorded from deep-sea (24 species; 36.4%). Southeast Region of Brazil holds most records with 46 occurrences, followed by the Northeast Region with 19 occurrences. Our results highlight the increasing number of publications and new Brazilian tanaids species in the last 15 years, and this is directly correlated to where specialists in alpha-taxonomy, systematics/phylogeny, and ecology are based in. Our current dataset also indicates an important aspect regarding the lack of taxonomic experts of Tanaidacea worldwide, but especially in Brazil. This study gives an overview of all the information that may help elucidate future research on the taxonomic diversity of tanaidaceans in Brazil, thus it is expected that this may encourage further studies and specialists for the group.

The importance of habitat-forming species, particularly cold-water corals like Dendrophyllia ramea, cannot be overstated as they provide crucial physical structures that offer shelter, food, and breeding habitat for a range of other species. We studied the spatial distribution and abundance of D. ramea, its associated species and the impact of human activities in a population of the Herradura, Granada in the western Mediterranean. Video transects were conducted at different depths, and epibiont samples were collected to describe the coral assemblage and the diversity of associated organisms. Dendrophyllia ramea presented high abundances at an unusually shallow depth in the Mediterranean, ranging from 30 to 48 m, despite typically being found between 50 and 500 m, with recordings indicating occurrences as deep as 1000 m, and hosting a high number of epibionts and macro-benthic organisms associated with coral reefs. Bryozoans showed a close relationship with D. ramea as they are important components of both the reef and the epibiont community. This study identified 63 new species and 15 new genera associated with cold-water corals. This study showed the importance of D. ramea as a nursery site, even for other habitat-forming species. The major threat to this community is human activity (fishing, littering and free anchoring), with the most abundant types of waste being rubber, glass/ceramics, and plastic polymers, and many fishing lines and nets damaging the corals. Overall, this study emphasises the urgent need to protect cold-water corals and their associated species and reduce the impact of human activities on marine ecosystems.

The oceanic archipelago of Fernando de Noronha represents one of the most important regions for Brazilian marine biodiversity, and is considered a ‘no-take’ marine area under law. More than 130 crustacean species have already been registered in the archipelago, with a significant number of caridean shrimps. Almost half of these shrimps belong to the family Alpheidae, making them an important marker of the species composition of the region. This study provides five new records of alpheids for the archipelago. Samples were taken in 2019 and 2022 from six locations around Fernando de Noronha, using active search during low tide and SCUBA diving in subtidal zones. The new records are Alpheus agilis, A. angulosus, A. rudolphi, Automate dolichognatha sensu lato, and Salmoneus ortmanni, and their DNA sequences have been made available alongside geographical distribution, photographs, ecological notes, and species remarks. All DNA sequences (mitochondrial 16S and cytochrome oxidase I genes) generated were compared with sequences available in Genbank and, in some cases, our sequences are the first for the species. Through this update, a total of 46 species of caridean shrimps have been recorded from Fernando de Noronha. Here we highlight the importance of checklists as a tool to keep an updated record of species' distributions. Continuous study of the native fauna of one of the most important biodiversity hotspots on the Brazilian coast is essential to establish effective management and conservation plans for the region.

The Pacific bryozoan, Smittoidea prolifica Osburn, 1952, is reported for the first time from the Northwest Atlantic coast. Colonies were discovered during routine benthic sampling of Casco Bay, Maine, encrusting mussel shells and barnacles. Aiming to compare specimens from native and introduced locations, uncertainties about the Pacific range of S. prolifica were resolved by re-examining specimens from Japan, southern Korea, the United States west coast, and Mexico. The occurrence of this species in Japan was confirmed but southern Korea specimens were found to be Smittoidea spinigera (Liu, 1990). Comparisons of biometrics among specimens from widely dispersed locations where S. prolifica is native and introduced showed significant trends in variation with most characters largest for California and smallest for Germany. Zooid width was largest for Maine specimens. Comparisons between oceans showed that Pacific and Atlantic specimens differed significantly in all measures except zooid length and orifice width. Low substrate specificity and broad range of temperatures and salinities in occupied habitats suggests the potential for successful introduction is high. Smittoidea prolifica was most likely introduced through commercial shipping from the North Sea where it is an established non-native species. This was the third non-indigenous species found in Casco Bay discovered within the same timeframe and which shared the same likely region of origin. This spike matched a rise in commercial shipping from the Northeast Atlantic to Portland, Maine, suggesting this seaport is shifting towards becoming a bioinvasion hotspot.

In 2013 and 2019, two separate encounters with a white shark (Carcharodon carcharias) were documented within Indonesian waters. Of particular importance was ca. 6.0 m male C. carcharias that was captured in Lombok, Indonesia in 2013, where an upper lateral tooth was retained. Using the D-loop sequences of the mitochondrial DNA (mtDNA) associated with this captured white shark, the mtDNA was compared to the available mtDNA sequences in GenBank® associated with the Northwest Pacific and Australian (i.e. Southern-Western and Eastern) C. carcharias subpopulations to determine its point of origin. Results from the mtDNA analyses suggest that the point of origin for this captured C. carcharias is from one of the Australian subpopulations. When compared to primary literature, this migration presents a northerly range extension for this species; however, since it is unclear what Australian subpopulation this shark was from it is uncertain what subpopulation this range extension applies to. Although C. carcharias presence within Indonesian waters is likely a rare occurrence, being that Indonesia represents the largest shark fin exporter in the world, the utilization of these waters and potential unsustainable exploitation poses a definitive threat to this highly migratory top predator. Therefore, further research investigating the purpose and site fidelity of C. carcharias within these waters is critical to future multijurisdictional protection of this top predator.

Little is known about the Chondrichthyes fauna of the state of Espírito Santo, southeastern Brazil, notably on the species composition, distribution, and biology. Historically, only a few studies have focused on these issues. Basic taxonomy is one of the main tools employed in cataloguing, organizing, and initiating other, more specific, assessments regarding regional diversity. In this context, this study presents the most comprehensive list of shark and ray species occurring in the state of Espírito Santo to date. The compiled data were obtained from specimens deposited in ichthyological collections, literature reviews, and samplings conducted at fisheries landings and onboard commercial fleet vessels. The findings indicate 79 species, comprising 51 sharks and 28 rays. A total of 53.2% of threatened Brazilian marine elasmobranch species occur in the area, indicating the importance of carrying out local studies focusing on this group. A first record for the Brazilian large-eyed stingray, Hypanus marianae, was also observed for the state, increasing the southern limit of the species known distribution, previously considered restricted to the North and Northeast coasts.

Long-term marine monitoring programmes have provided numerous quantitative data on the composition of North Sea benthic communities and their changes over time, including species introductions. Particularly in the German Bight, the rapid environmental and hydrographical changes are promoting the spreading (usually anthropogenically mediated) of neobiota, with more than 150 species being registered to date. During routine seafloor monitoring, grab samples taken on the subtidal sandbank of the Borkum Reef Ground revealed the presence of the polychaete Streptosyllis nunezi in different years, a species previously unreported in the southern North Sea. In this paper, these individuals are described morphologically and the population status is discussed. Our finding demonstrates the importance of intensive and regular environmental monitoring programmes for the assessment of regional biodiversity and its potential changes.

Trophic competition among top predators is also influenced by environmental variability. However, the magnitude of the changes in contrasting events such as El Niño Southern Oscillation (ENSO) is poorly studied. The stomach contents of striped marlin (Kajikia audax), blue marlin (Makaira nigricans), and dolphinfish (Coryphaena hippurus) were analysed. We included the ENSO effect on the diet because we analysed organisms captured during 2010–2011 and 2014–2015, periods that, according to the Ocean Niño Index, were defined as the cold phase (CP) and warm phase (WP), respectively. Trophic diversity, feeding habits and strategy, trophic position (TP), trophic niche amplitude, and diet overlap were calculated. It was found that, despite a wide trophic spectrum, all three species were specialist predators in both phases. The most important prey species during both phases for striped marlin was Dosidicus gigas, while Auxis spp. was the most important prey of blue marlin. Dolphinfish fed mainly on Oxyporhamphus micropterus during the CP and Pleuroncodes planipes during the WP. Our results indicated that during both ENSO phases, all species maintained a trophic position similar to previous reports for the study area. However, for striped marlin, these differences were significant. Greater trophic competition was found during the CP (seven prey taxa shared) than in the WP (three prey taxa shared). These species often share the same environment, but their preference for feeding on different prey makes them occupy different trophic spaces, an aspect that allows their coexistence in time and space.

Jellyfishes have ecological and societal value, but our understanding of taxonomic identity of many jellyfish species remains limited. Here, an approach integrating morphological and molecular (16S ribosomal RNA and cytochrome oxidase I) data enables taxonomic assessment of the blubber jellyfish found in the Philippines. In this study, we aimed to resolve doubt on the taxonomy of Acromitoides purpurus, a valid binomen at the time of our research. Our morphological findings confirm that this jellyfish belongs to the genus Catostylus, and is distinct from known species of the genus inhabiting the Western Pacific, such as Catostylus ouwensi, Catostylus townsendi, and Catostylus mosaicus. Detailed morphological and molecular analyses of the type specimens from the Philippines with the other Catostylus species revive the binomen Catostylus purpurus and invalidate A. purpurus. Genetic analysis also distinguishes this Philippine jellyfish from C. townsendi and C. mosaicus. Through this study, we arranged several Catostylidae taxa into species inquirendae (Catostylus tripterus, Catostylus turgescens, and Acromitoides stiphropterus) and one genus inquirenda (Acromitoides) and provided an identification key for species of Catostylus. This comprehensive study confirms the blubber jellyfish as C. purpurus, enriching our understanding of jellyfish biodiversity. The integration of morphological and genetic analyses proves vital in resolving taxonomic ambiguities within the Catostylidae family and in the accurate identification of scyphozoan jellyfishes.

Extending over warmer environments in the Brazilian waters, the exotic vermetid Eualetes tulipa was first recorded from Ceará State (3°S) in 2005. In 2009, it was reported in cold-water environments in Rio de Janeiro State (22°S). Seven years later, E. tulipa was recorded from Rio Grande do Norte State (6°S) on rocky pools in sandstone reefs. In the present study, E. tulipa is for the first time recorded from Bahia State (12°S), associated with a biofouling community in the Todos-os-Santos Bay, co-occurring with exotic dendrophylliid corals (Tubastraea). The vermetid community recorded from Bahia State shows a great diversity of epibionts, mostly bivalves, cirripeds and sponges. The co-occurrence of Eualetes and Tubastraea corals must be monitored, once these exotic species are co-occurring in a protected environmental area, bringing concern on possible impacts on native benthic fauna.