Barnacles of the genus Conopea are obligate epibionts of gorgonians and antipatharians. The species Conopea saotomensis Carrison-Stone et al. 2013, previously only known from the islands of São Tomé and Príncipe and the coast of Gabon, is reported from the Bijagós archipelago, Guinea-Bissau, based on morphological examination and DNA barcoding of specimens. The new record extends the known range of the species about 3000 km to the northwest.

Sea turtle populations have significantly declined in recent years due to anthropogenic causes. Historical stranding records in the Canary Islands archipelago (Spain) reveal a high frequency of Caretta caretta and Chelonia mydas strandings. Our study aims to comprehensively characterize and explore these stranding records. Additionally, we have investigated the interactions between sea turtles and the island's professional fishers, seeking insights from small-scale artisanal fishers to understand the current state of sea turtle populations. The results have shown that Tenerife stands out with the highest number of sea turtle strandings, recording 1875 strandings over a span of 23 years. The primary cause of sea turtle stranding's is the interaction with fishing gear, specifically nets and hooks. Moreover, our research has highlighted the need for improved knowledge and training on how to handle stranded sea turtles within the fishing sector. Consequently, raising awareness and implementing conservation plans for sea turtle populations in Tenerife is of outmost importance in addressing and improving the current situation.

Understanding the relationships between cetaceans and their environment is crucial for conservation. This study examined humpback whales in Bahía de Banderas, Mexico, identifying key calving habitats. From 2018 to 2023, 1066 sightings were recorded, including 242 mother–calf groups, 109 mating groups, and 715 other groups. Spatial analysis revealed a non-random distribution; both the Kruskal–Wallis and Wilcoxon–Mann–Whitney tests detected significant differences (P < 0.05) in site preferences. Calving mothers favoured habitats with a mean depth of 59 m and a distance of 2 km from the coast, while mating groups preferred locations at 126 m and 4 km, and other groups chose areas at 149 m and 4 km. All groups were found in relatively flat areas around 2° seafloor slope. A dispersion test indicated a significant relationship between the location of calving mothers and environmental factors. K-means clustering showed 83.6% of calving mothers' sightings at depths less than 40 m and 2 km from the coast. Ensemble species distribution models identified three critical calving areas: one large area (261.8 km2) along the north coast and two smaller areas (9.5 and 5.4 km2) at the southern end of the bay. This study highlights Bahía de Banderas as a vital breeding habitat for humpback whales, providing insights for conservation strategies to protect calving grounds during the breeding season.

Synthesising knowledge on the health of marine ecosystems and the human activities is crucial to informing holistic marine management. In many coastal states, however, research is conducted in an ad hoc manner and rarely compiled into accessible repositories making it challenging for marine managers to identify knowledge gaps when allocating resources. Here we conduct a structured review of existing literature to identify the current state of marine and coastal knowledge in the Isles of Scilly, an oceanic archipelago in the UK. The archipelago's marine flora and fauna are biogeographically unique in the Northeast Atlantic, with a distinct mosaic of warm and cold temperate habitats and species and are also considered a rare example of a near pristine marine environment in the otherwise highly degraded Northeast Atlantic Ocean. We found 150 sources relating to the marine biodiversity and relevant human activities in the Isles of Scilly with increasing diversification of research topics in recent years. Sources however remain dominated by specific taxa and habitats, suggesting the Isles of Scilly would particularly benefit from future research into: (1) anthropogenic impacts associated with warming waters and intense seasonal vessel activity; (2) development of repeatable survey protocols that can underpin long-term, ecosystem-based monitoring and management (notably for reef and sediment habitats and the European spiny lobster); and (3) data gaps associated with marine teleost fish and elasmobranch communities including identifying core habitat. This review can therefore act as a baseline biological synthesis for the region and importantly, can inform future research priorities.

Effluent waste generated from the intensive production of vannamei shrimp is known to play an essential role in increasing phytoplankton abundance and the alteration of environmental quality. This alteration is characterized by the presence of various organic compounds and their derivatives. The northern coastal area of Bangka Island represents a region in Indonesia that has witnessed significant growth and development as a vannamei shrimp cultivation zone. Therefore, this study aims to evaluate phytoplankton abundance and environmental quality in the waste of shrimp ponds in the northern coastal area of Bangka Island. The investigation procedures were carried out in four specific locations within this area, namely BL1, BL2, BL3, and BL4. The results showed the presence of five–six distinct phytoplankton groups, including a total of 11–18 genera, within the effluent discharge from these ponds. The highest abundance of phytoplankton was recorded at BL3, with a value of 2,418,375 cells ml−1. The phytoplankton groups identified at all locations included Chlorophyta, Cyanophyta, Chryptophyta, Bacillariophyta, and Pyrrophyta. Euglenophyta was found at BL1 and BL3 but was not observed at BL2 and BL4. Furthermore, the most abundant group found in this study was Chlorophyta. The genera Nanochloropsis, Chlorella, Microcystis, and Nitzschia were consistently found in all the surveyed ponds. The calculation results showed that all locations had a moderate level of diversity, high evenness, and the absence of dominance. Based on the findings of principal component analysis, there was a commonality in parameters that exerted a strong influence on phytoplankton abundance, including nitrate, orthophosphate, and magnesium.

Harbour seals were extensively hunted in Denmark, but have only been driven to local extinction in one larger area, the South Funen Archipelago and Little Belt, where the species has been absent throughout the 20th century. Despite high growth rates of the Danish harbour seal populations after protection from hunting in 1976, seals have only been observed sporadically in the South Funen Archipelago and Little Belt until recent years, where recolonisation now causes conflicts with fisheries. Here, we review historical sources documenting the local extinction of harbour seals in the area during the 19th century and report the results of aerial surveys of haul-out sites during moulting seasons of 2021–2023 and pupping seasons of 2022 and 2023. Historical sources reveal that seal hunting was a common practice in southern Denmark, but catches dwindled to rarities during the 19th century. During recent surveys, seals were detected at six of the identified potential haul-out sites. Around Aarø Island, an average of 141 (range: 92–186) harbour seals were recorded over four moulting season surveys, constituting the majority (90%) of the total counts of the surveyed area. During the pupping seasons, a total of five pups was encountered at two different haulouts. As none of the haulouts are protected during the pupping and breeding seasons, protective measures may support this recolonisation of the historic harbour seal breeding range.

Microcosmus squamiger, an ascidian with high invasion potential, is recorded for the first time in the Brazilian western Atlantic, between Rio de Janeiro and Espírito Santo. The species was found near ports and marinas, and its introduction may have been favoured by intense nautical activity and climatic events such as La Niña. Coexistence with Microcosmus exasperatus, a morphologically similar species, was observed in all localities where M. squamiger was recorded. This discovery implies that a more rigorous process of species identification is necessary during monitoring activities, given that both species can be easily confused (only the syphon spinules differentiate them) and M. exasperatus is widely distributed with collection records dating back more than half a century on the Brazilian coast. The preference of M. squamiger for colder waters suggests that researchers in the Southeast and South Brazil, Uruguay, and Argentina should closely monitor the arrival and possible environmental impacts of this species. The identification of M. squamiger in locations close to bivalve mariculture areas in Rio de Janeiro raises concern, as the species has the potential to compete with bivalves. This study highlights the importance of continuing to monitor the potential spread and the implications of the introduction of M. squamiger into Brazilian waters, as well as its relationship with M. exasperatus, a species already established in this same region.

A single Stygiomedusa gigantea was caught by demersal crab trawl off Namibia at a fishing depth of 750 m. Although widely considered to be globally distributed in meso- and bathy-pelagic waters, this represents the first record of the species from the SE Atlantic and only the second from around Africa. The photographed specimen differs slightly from previous observations and attention is drawn to accurately recording future material.

The first insights on habitat and phylogenetic origin of a newly found population of Solen marginatus are provided in the mid-North Atlantic Azores archipelago, in the bay of Praia da Vitória, Terceira Island. Distribution is confined to the northern portion and most sheltered part of the bay down to 14.2 m depth. Densities with an average of 12.69 individuals/m2 were found at 8.4 m depth, using 4 × 20 sqm visual transects. Sizes of shell length between 10 and 12 cm comprised 60% of collected specimens (n = 118), ranging between 8.79 and 15.4 cm and averaging 11.28 cm. Considering shell length, the high densities and dispersion area, a settlement period above 20 years is estimated. Greater genetic affinity was found in the Ria de Aveiro (North of Portugal) and the Asturias populations (North of Spain). The source origin remains undetermined, with intentional or non-intentional anthropogenic introduction, as well as natural dispersion remaining possible, although more unlikely. Due to the commercial value of this species, a new clam fishery is likely to develop in the area, requiring further studies and immediate conservation measures.

In the present study, we assessed the sponge fauna, sponge-associated, and planktonic prokaryotic communities residing in Burgers' Zoo Ocean aquarium, Arnhem, the Netherlands. The Ocean aquarium consisted of separate displays and life support systems, and included fish-only systems in addition to a large, 750,000 L tank containing a living, tropical coral reef ecosystem. Sponges were observed throughout the aquarium system and were identified as belonging to the genera Chalinula, Chondrilla, Chondrosia, Cinachyrella, Stylissa, Suberites and Tethya. There was a highly significant difference in composition between sponge-associated and planktonic prokaryotic communities. The tanks in which the sponges were sampled appeared to have a secondary structural effect on prokaryotic composition with sponges and water from the same tanks sharing several microorganisms. Both sponge-associated and planktonic prokaryotic communities housed prokaryotic taxa, which were highly similar to microorganisms previously recorded in sponges or coral reef environments, including taxa potentially involved in nitrification, denitrification, sulphur oxidation, and antibiotic biosynthesis. Several abundant microorganisms were only recorded in sponges and these may play a role in maintaining water quality in the aquarium system. Potential pathogens, e.g. related to Photobacterium damselae, and beneficial organisms, e.g. related to Pseudovibrio denitrificans, were also detected. The present study showed that Burgers' Zoo Ocean aquarium housed diverse free-living and host-associated prokaryotic communities. Future research should focus on identifying conditions and microbial communities conducive to a healthy aquarium environment.

Although mesopelagic fish dominate the oceanic ecosystem, they remain one of the least investigated components. From the vertically stratified sample collections, we investigated community structure, vertical distribution and diel/ontogenetic vertical migration covering four seasons for larval and juvenile/adult mesopelagic fish at the time-series station K2 in the Western Subarctic Gyre of the North Pacific. We collected 10 and 20 species of larval and juvenile/adult fish, respectively. Among the larval fish community, Leuroglossus schmidti was the most abundant; total abundances except L. schmidti were low throughout the year; species richness of myctophids were low. Among the 20 species of juvenile/adult fish, larvae of only six species were collected; thus, most mesopelagic fish species do not use the Western Subarctic Gyre as their nursery. In the juvenile/adult fish community, Stenobrachius leucopsarus and Stenobrachius nannochir were abundant. Species diversity and total abundance in the warm seasons (summer and autumn) were higher than in the cold seasons (winter and spring). The decreasing of species diversity and total abundance during the cold seasons was probably affected by horizontal migrations of fish for reproduction toward the southern transition or subarctic slope areas. Stenobrachius leucopsarus was distributed at shallow depths with opportunistic diel vertical migration (DVM); in contrast Stenobrachius nannochir occurred at greater depths, without DVM. The distribution depths of S. leucopsarus during day and those of S. nannochir changed seasonally and synchronously; shallowest in autumn, deepest in spring.

This study provides the first records of the upside-down jellyfish Cassiopea andromeda (Forskål, 1775) in the eastern Atlantic supported by molecular analysis. Specimens were observed, recorded, and sampled in an inland aquaculture facility in September 2023 in Tenerife Island (Canary Islands). This new record officially demonstrates the geographical expansion of C. andromeda, and the introduction of a new potential invasive species in the Macaronesia oceanic island system.

Species in the genus Engraulis show extensive intraspecific as well as interspecific morphological and genetic diversity. Since morphological differences do not necessarily correspond to genetic differences, it is necessary to clarify the relationship between morphological differences and genetic differences for a better understanding of the population structure. Fish morphology at a given standard length differs between cohorts of Japanese anchovy Engraulis japonicus during the early life stages in the Kii Channel, but it is unknown whether the differences are caused by genetic differences or not. The Kii Channel includes the boundary between the Pacific (southern side of the Kii Channel) and the Seto Inland Sea stocks (northern side), but stock separation is based primarily on demographic characteristics. In the present study, genetic analyses were conducted to examine the genetic differences among samples (month and area) based on mitochondrial DNA cytochrome b region (Cyt b), control region (CR) and microsatellite markers. AMOVA revealed that the percentage of genetic variation among samples was low at 0.11% for Cyt b, 0.30% for CR and 0.00% for microsatellite, and no significant genetic variation was observed among samples. Although two clades were identified in the unrooted neighbour-joining tree for Cyt b and CR, both Cyt b and CR sequences were similar between months and between areas. Accordingly, the morphological differences among cohorts can be attributed to phenotypic plasticity. Additionally, there were no genetic differences between samples from the southern side and the northern side of the Kii Channel, suggesting strong genetic connectivity in these areas.

During our research programme about mussel spat in Amsa Bay, we found some specimens of Hesione sicula delle Chiaje, 1830 and noted as the first record for Mediterranean Moroccan coasts and for the Mediterranean coastlines of North Africa. Five specimens of this species were collected for the first time in the Amsa shellfish farm on October 30, 2021, and we provide some characteristics and illustrations for the species. This new record from the bay contributes to the Polychaeta list of North Africa and expands the geographical distribution range of species within the Mediterranean Sea.

This study presents the first Korean records of two subtropical fish species, Pseudojuloides paradiseus and Diplogrammus xenicus, collected around Jeju-do Island, as well as one boreal fish species, Erilepis zonifer, collected in Busan (approximately 200 km away from Jeju-do Island). In this study, we discuss the implications of the species’ habitat range expansion. Previously, P. paradiseus was known as an endemic species of Japan, while D. xenicus was known to inhabit the Eastern Indian Ocean and the Pacific Ocean excluding around the equator, and E. zonifer was only known to inhabit the Pacific Ocean between eastern Japan and the western USA. Their habitat range expansions might be attributed to the expansion of the Tsushima Warm Current at the surface layer and/or the North Korean Cold Current at the bottom layer. Our findings may suggest that habitat of marine fish is being changed continuously by climate change or oceanic currents. Therefore, it needs to conduct integrated and systematic monitoring of fish fauna to response changing marine biodiversity.

Burmeister's porpoise (Phocoena spinipinnis) is an endemic species found in both the South Pacific and Atlantic Oceans, along the coastal regions of South America. In the Southwestern Atlantic Ocean, the species is reported from Tierra del Fuego, Argentina to Santa Catarina, Brazil, and the Falkland Islands. This study provides new insights on two stranded P. spinipinnis specimens in Southeastern Brazil, including the first occurrence in the state of Rio de Janeiro. Despite the advanced decomposition of the carcasses, which limited necropsy findings, we provide new data on the general characteristics of the specimens found in this extralimital geographical range, such as total body length, age, sex, vertebral count, and cranial measurements.

Small and medium pelagic fish (SMPF, i.e. Scomber colias, Trachurus spp, Sardina pilchardus, and Sardinella spp) in the Canary Islands are mainly targeted by the artisanal purse-seine fleet. The waters in the archipelago (located in the coastal transition zone of the Canary Current Eastern Boundary Upwelling System) are monitored since the late nineties by a hydrographic section (RAPROCAN) designed to study the temporal variability of the eastern subtropical gyre. In this study we analyse the relationship between the SMPF abundance assumed from official sale notes (reported since 2007) and several oceanographic parameters obtained for the outermost water layer (Sea Surface Temperature, SST, and concentration of chlorophyll a, Chla) and from the 200–800 m depth waters (Sea Temperature, ST_200–800, and salinity, Salinity_200–800). Except for SST, statistically significant correlations occur between environmental variables and SMPF landings when one-year time-lag is considered, matching with the time period necessary for these species to attain legal catchable sizes and, hence, being catchable by the fishery. However, in the GLM only Chla resulted a significant explaining variable for the SMPF landings during the following year, probably because this strong correlation overshadows the ST_200–800 influence. Keeping the monitoring systems is crucial to understand, foresee and anticipate potential variations in the fishery resources and to aim the sustainable exploitation of the SMPF populations, even more challenging in the current climate change scenario.

To explore relationships between spatial distributions of northern shrimp Pandalus eous and environmental factors along the coastline of Honshu Island in the Sea of Japan, we built delta-type two-step generalized additive models (delta-GAM) based on bottom trawl surveys conducted in 2013–2022. The models provide the first quantitative analysis of the species’ habitat, showing that its distribution is associated with bottom sediment type, depth, slope and topographic position index (TPI) alongside the effects of year and region. From the delta-GAM response plots, species habitat preferences in the Sea of Japan were estimated as follows: seafloor deeper than 283 m; muddy rather than sandy bottoms; gently sloped to flat bottoms (<0.8° in slope); and valleys rather than ridges (TPI < 0.9). These results were reviewed in detail along with previously reported distribution records of northern shrimp. Standardized density (s-density) per fishing grid cell (10′ square latitude–longitude mesh) estimated from the delta-GAM results indicated that this species is widely distributed on the continental slope along the coast of Honshu Island. To test plausibility of the s-density analysis, we compared s-density per fishing grid cell with nominal CPUE (kg per haul) per fishing grid cell based on official logbook data from large offshore trawl fisheries. The two were generally positively correlated by year, and the delta-GAM results were assumed to be fairly robust. Finally, potential fishing grounds were explored based on the delta-GAM results.

In Northeastern Brazil, successful release programmes have been implemented for the conservation of West Indian manatees (Trichechus manatus) since the 1990s. Recently, the non-government organization AQUASIS started releasing manatees in the state of Ceará, where oceanographic conditions and the absence of sheltered places pose new challenges for the release and monitoring of manatees. This research investigates the movement of a manatee named Tico, released in Icapuí, Ceará, Brazil, that travelled approximately 4017 km over 62 days through deep oceanic waters. Correlating Tico's trajectory and velocity with surface currents revealed the influence of the North Brazil Current (NBC) and its vortices on his movement. Tico crossed the diluted Amazon River plume with surface salinity as low as 26 g kg−1 in early August, potentially encountering areas of even lower salinity. Additionally, Tico experienced several storms, with significant rainfall during his journey, which may have provided freshwater. The erratic movement patterns and significant weight loss prompted the rescue of Tico on Isla la Blanquilla, Bolivarian Republic of Venezuela. Tico is currently being temporarily housed in Parque Zoológico y Botánico Bararida in Venezuela. Understanding the nature of Tico's long-distance movement could help inform decisions about his future. AQUASIS proposes to return Tico to Brazil, a region with an ecologically and genetically distinct population from Venezuela, for a second release attempt, incorporating lessons learned from the first release. Furthermore, AQUASIS has the necessary human and financial resources to ensure the continuous monitoring of Tico during his readaptation to the wild.

The symbiotic relationship between the syllid polychaete, Haplosyllides floridana Augener, 1922, and the barrel-shaped sponge Xestospongia muta (Schmidt, 1870), originally documented solely in the Caribbean, is presumed to be species-specific. Recently, the host sponge has been found as a single species distributed across approximately 8000 km (from 26°N to 22°S). Herein we addressed new spatial and bathymetric population records of H. floridana to question the persistence of the association with X. muta, and whether, in the case of an association, the polychaete remains as a single species throughout this extensive distribution. Our findings change the restricted distribution of H. floridana, revealing a remarkable association with X. muta from Tropical north-western to south-western Atlantic including records in the Fernando de Noronha Archipelago and the Almirante Saldanha Seamount, at 270 m deep. The populations analysed in this study are morphologically consistent. The study underscores the need for further investigations into the connectivity of Xestospongia species, the presence of Haplosyllides in other ocean basins, and the shared evolutionary history between Xestospongia and Haplosyllides. The observed life cycle completion of H. floridana within the host sponge suggests a potential co-evolutionary relationship, offering insights into the intricate dynamics of symbiotic associations in marine ecosystems.