This paper reports one mytiloid species, Amygdalum anoxicolum P. G. Oliver, 2001 from the summit of a seamount located in the eastern Arabian Sea. This species was encountered from the core of the Arabian Sea oxygen minimum zone at a depth of 340 m and possessed several adaptations to low-oxygen concentration. This paper presents the first-ever DNA barcodes for this species.

The family Dendrophylliidae comprises a genus of azooxanthellate corals, Tubastraea (also known as ‘sun corals’ or ‘cup corals’), native from the Indo-Pacific and introduced into the Atlantic Ocean in the early 1940s. In Brazil, Tubastraea colonies were first registered on oil platforms on the northern coast of Rio de Janeiro state (22°S) in the late 1980s. Two decades later, these corals were for the first time identified in the Todos-os-Santos Bay (Bahia state, 13°S), a warmer environment with diverse marine ecosystems including estuaries, mangroves, and coral reefs. Intending to describe the biological cycle of exotic dendrophylliids from the Brazilian northeastern coast, histological analyses revealed three new reproductive structures for Scleractinia: (1) a mucin layer composed of acid glycoproteins surrounding immature sun coral oocytes, (2) trophonema or specialized cells connecting the oocyte to the adjacent gastrodermis, and (3) nucleolini, small condensations in nucleoli.

Providing nursery habitats to a number of marine fish larvae that recruit after prolonged pelagic larval duration, has been identified as one of ecosystem services rendered by estuaries and protected inshore water bodies like mangroves, mudflats, swamps, and marshes. Larval fish congregation and survival are largely dependent on abiotic and biotic potential of such systems and many migrant marine fishes are adapted to them. However, occurrences of larval forms of tropical reef-associated vagrant species which are known for extensive range adaptations generate considerable academic interest. The present study provides the first report of ontogenic habitat utilization of yellow fin surgeon fish, Acanthurus xanthopterus Valenciennes 1835 in a tropical microtidal positive estuary, the Vembanad lake, South India. Surface plankton collections from the downstream part of the estuary revealed considerable proportions of acanthurid larvae in post monsoon (mean 354 ± 180 numbers/100 m3) and pre monsoon (mean 217 ± 120 numbers/100 m3) while they were absent in monsoon season. These acronurus larval forms were morphologically identified and sorted before being subjected for DNA barcoding. Mitochondrial DNA COI sequences developed from morphologically characterized acronurus larvae exhibited genetic congruency to sequence of A. xanthopterus which was evident from phylogram (bootstrap support of 100) and genetic distance data (intraspecific distance of 0%). The study indicates that Acronurus larvae of A. xanthopterus, after extensive cross-habitat dispersal, utilize the estuarine habitat to promote potential growth.

A specimen of Prionotus punctatus was caught in Bahía Engaño, Chubut Province, Patagonia, Argentina. This extends the known distribution by 900 km and a 5.5° further south from its previous southernmost record. This record increases the number of species of the genus Prionotus and the fish diversity of central Patagonia. The presence of P. punctatus along with other recent reports of fish of tropical and subtropical lineages in central Patagonia adds new evidence on the ongoing tropicalization of the Patagonian Sea.

Feather stars (Echinodermata: Crinoidea) are known to host a diversified associated fauna. Surprisingly, very few accounts on the crinoid epiphytic communities from the coasts of the India are available. The present contribution reports for the first time the crinoid-associated scale worm Paradyte crinoidicola (Potts, 1910) from Gujarat coastline, India. The species has been so far recorded from the southern part of Indian subcontinent, the Lakshadweep Islands as its first record from Indian coastline. Further research and documentation of these species will contribute to enhance our understanding of the diverse associations and complex interactions within Indian marine ecosystems. This highlights the necessity for more thorough field surveys and ongoing monitoring, as the region remains surprisingly underexplored.

In this study the finding of the sponge Clathria (Clathria) unica in coastal waters of Mar del Plata city (38°14′24″S, 57°27′30″W), Argentina, at the formation called ‘Banco de Afuera’, is reported. This record constitutes the northernmost record of the species, which was known until the present study only from its type locality in San Antonio Oeste, Río Negro province. Additionally, the bathymetric range of the species is updated from intertidal to 20 m. Other two common sponge species, Cliona aff. celata and Spongia (Spongia) magellanica, were also recorded in this environment for the first time.

In order to evaluate the seasonal responses of periphytic protozoan fauna to the antibiotic nitrofurazone at sensitive concentration, a 1-year baseline survey was carried out in Chinese coastal waters of the Yellow Sea. To assess the nitrofurazone (NFZ)-induced toxicokinetics in different season, the test protozoan samples were collected using microscope slides and exposed to the sensitive NFZ concentration of 8 mg ml−1. Differences in species composition and typical species were observed in the test organism fauna in the control and treatment among four seasons. However, the community patterns were significantly shifted under the sensitive concentration, with a part of stressed test samples significantly departed from a respected taxonomic pattern. Therefore, it is suggested that periphytic protozoan fauna may be significantly changed at the same sensitive concentration in both the species composition and community pattern, although there were significant differences in tolerant species among four seasons in marine environments.

We report the first non-indigenous dottyback Pseudochromis persicus record in the Mediterranean Sea. A single individual was documented several times at the same location on October 2024 in Bat Galim reef, a shallow rocky shelf of Rosh Carmel underwater ridge on the northern coast of Israel. This record represents the first sighting of Pseudochromidae, a family native to the Indo-Pacific Ocean, in the Mediterranean Sea. It is also the first record of P. persicus beyond its native range in the Persian Gulf and the Arabian Sea.

This research focuses on pteropods of the family Cavoliniidae, which remains an under-studied taxa in Indian waters. Sediment samples collected by the FORV Sagar Sampada from the Andaman Islands, India, yielded eight species of the family Cavoliniidae, representing the genera Cavolinia and Diacavolinia of the subfamily Cavoliniinae, and the genus Diacria of the subfamily Diacriniinae. Notably, four species – Diacavolinia aspina, D. bandaensis, D. deblainvillei and Diacria erythra represent new distributional records for India. Furthermore, Cavolinia uncinata, Diacavolinia angulata, D. bicornis and D. flexipes are recorded for the first time in the Andaman Sea. This study is significant in expanding the understanding of pteropod diversity in the Indian Ocean, contributing to a better understanding of their ecosystem and geographical range.

The ghost shrimp Audacallichirus mirim had been previously recorded along the Brazilian coast. However, this study marks its first report in southern Espírito Santo and northern Rio de Janeiro, in southeastern Brazil. Two male specimens were collected at Piúma Beach (Espírito Santo) and Guaxindiba Beach (Rio de Janeiro) in March 2023, using a steel suction pump in the intertidal zone. The individuals were identified in a laboratory based on taxonomic characteristics. Abiotic factors such as salinity, temperature, and dissolved oxygen were measured at the collection sites, revealing distinct environmental conditions between the two beaches. Granulometric analysis showed significant differences in sediment composition, with Piúma characterized by finer sands and Guaxindiba by a more poorly sorted sediment, with a higher contribution of coarser grains. This record contributes to understanding the biogeographical distribution of A. mirim, emphasizes its ecological role, and highlights the need for further research on its population dynamics and habitat preferences in southeastern Brazil.

The brachyuran crab fauna (Crustacea: Decapoda: Brachyura) collections in the extensive exploratory fishery survey cruises from the northeast coast of India was studied from June 2018 to March 2020. During the study period, 81 species of brachyuran crabs belonging to 19 families and 46 genera were recorded. Among these, 21 species were newly recorded from the northeast coast of India, and 1 species, Naxioides taurus (Pocock, 1890) represents a new record for the mainland coasts of India. This study serves as a baseline for understanding the diversity and distribution of brachyuran crabs in the region. It provides valuable insights for future research and conservation efforts.

In the Caribbean Sea, orcas (Orcinus orca, also known as killer whales) are present throughout the year. The most recent review confirmed seven strandings of the species in the Caribbean Sea in the period May 1851 to January 2023, all of which were single strandings and only one of which occurred in Venezuela. In this publication we document the circumstances of the successful rescue, by local fishers and authorities, of seven orcas that stranded in August 2023 on the coast of the State of Sucre, north-eastern Venezuela. Worldwide, this is only the second mass stranding of the species within the tropics (23.5°N to 23.5°S). We also documented the presence of a probable whalesucker (Remora australis) on a juvenile orca. The present case represents the first mass stranding event of orcas in Venezuela and the Caribbean Sea and only the second in a tropical location worldwide.

Monthly sampling of cephalopod at Port-en-Bessin fish market (Normandy, France) over a 30-year period, combined with commercial fishery statistics, provides essential insight into the exploitation patterns, composition and size frequencies of these resources. Port-en-Bessin cephalopod landings are shown to decrease which is consistent with the decline observed in the entire French fleet operating in the English Channel. Cuttlefish landings exhibit a bimodal length distribution which is expected for this 2-year life cycle (and two-cohort) population. Juveniles of the year are recruited from October (from 8 cm). By the end of their second year of life, cuttlefish reach their maximum size (on average about 22 cm in April–May) prior to dying following spawning. Cuttlefish average size of the second cohorts has decreased from 20 to 17 cm over the period 1996–2022. This seems to be a reduction in size rather than a change in the timing of catches. Squids are not segregated in commercial landings, and the protocol was developed to inform on the prevalence of Loligo forbesii and L. vulgaris in the catch. Both species have a 1-year life cycle with a 3-month offset (recruitment of L. forbesii occurs in June and L. vulgaris in September). Over the 30 years of data, an increase in L. vulgaris landings is observed, while L. forbesii landings have decreased. These findings, in line with climate change, consider biases such as fishermen behaviour determining landings geographical origin.

Surface migratory myctophids migrate nocturnally from the mesopelagic to the near-surface layers and are the dominant components of oceanic neuston fish assemblages. We examined the horizontal distribution and habitat conditions of juvenile surface migratory myctophids in the Kuroshio region in late winter from 2003 to 2016. In total, 9098 myctophid juveniles, including 17 species, were collected in the surface layer at night. Of these, the eight most abundant species accounted for 99.0%. They showed five distinct distribution patterns closely related to the position of the Kuroshio axis. Dasyscopelus orientalis was restricted to the inshore side of the Kuroshio axis (INK), where sea surface temperature (SST) was lowest but zooplankton biomass (ZPB), a proxy for food availability, was highest. The centre of distribution of D. asper and D. obtusirostris was in the area of the axis (KUA), where the highest SST and intermediate ZPB were observed, although they were also abundant in INK. Dasyscopelus spinosus was collected mainly in the area south of Kyushu Island adjacent to upstream of the Kuroshio. The distributions of Symbolophorus evermanni, Centrobranchus nigroocellatus, and Myctophum nitidulum were restricted to the offshore side of the axis (OFK), where intermediate SST and lowest ZPB were observed. Hygophum reinhardtii was collected abundantly in both OFK and KUA. Spatial habitat segregation of juveniles would result from differences in spawning grounds and larval and juvenile transport routes. The Kuroshio contributes to the biodiversity of myctophids along the Pacific coast of southern and central Japan by creating adjacent but distinct habitat conditions.

We document the first recorded nesting attempt by a green sea-turtle (Chelonia mydas) in Pemba located in the Cabo Delgado Province of northern Mozambique – an urban area with a population of 200,529 inhabitants. This sighting expands the known nesting range of sea-turtles by 40 km south of the Quirimbas Archipelago, highlighting Pemba’s potential as a critical nesting site. In July 2021, local fishermen were observed by a tourism operator killing the turtle and selling its meat. Consequently, the absence of eggs at the presumed nesting site suggests that the turtle was intercepted before it could lay eggs. This incident highlights the threats to sea-turtles and the need for conservation while emphasising the importance of collaboration among communities, government, and researchers to protect nesting activity.

The distribution pattern of species and habitats protected by the Habitat Directive is one of the main parameters used to assess their conservation status. According to the European guidelines, the assessment must be carried out at a biogeographical scale by implementing monitoring activities. The results of a national monitoring programme conducted on five invertebrates during the last reporting cycle (2018–2024) are presented and discussed. Monitoring activities on Patella ferruginea, Pinna nobilis, and Lithophaga lithophaga were performed using on a spatial design based on Italian administrative regions, whereas Scyllarides latus and Centrostephanus longispinus were surveyed within six marine protected areas (MPAs) representing the different Italian marine subregions.

The most critical situations, due to different reasons, were observed in the distribution pattern of P. ferruginea and P. nobilis, which were confined to few areas with very small populations. Data on the distribution of L. lithophaga, collected by assessing the quality of the habitat for the species, indicate the persistence of illegal fishing activities, at least in some of the areas investigated. The use of ‘opportunistic’ methodologies, typical of citizen science, to collect semi-quantitative data on the distribution of C. longispinus and S. latus in the six MPAs, chosen to conduct this type of monitoring, confirmed the effectiveness of this approach. Some differences in the number of individuals recorded emerged among MPAs for both species, likely due to an uneven sampling effort. Overall, our results revealed significant interspecific differences linked to intrinsic and extrinsic factors, providing valuable insights into the vulnerability of the investigated species.

Bobtail squids of the family Sepiolidae, which includes the genus Euprymna, are closely related to, but distinct from the true squids (Teuthoidea). Despite their ecological importance, there have been few studies on the age and growth of bobtail squids using hard parts. This study is the first to use statolith increments to estimate the age of Euprymna hyllebergi collected from the southeastern Arabian Sea. Statoliths were extracted from 80 individuals (24 males, 56 females) of dorsal mantle length (DML) 8–50 mm and total weight 0.45–37 g and assessed for their age. Statolith size ranged from 328 to 836 μm. Assuming a daily deposition of increments, growth was rapid and adult sizes were attained in around 2 months. The age of the individuals varied between 25 days (DML = 8 mm) and 91 days (DML = 37 mm) for males; 33 days (DML = 10 mm) and 92 days (DML = 44 mm) for females. The daily growth rate ranged from 0.20 to 0.49 mm DML day−1 for males and 0.23–0.59 mm DML day−1 for females. The lifespan of E. hyllebergi is short, based on the statolith increment analysis.

The present study describes a new Mediterranean terebellid, Spinosphaera latachaeta sp. nov., found along the Aegean coast of Türkiye and the Sea of Marmara, between 27 and 80 m depth in soft substrata. It can be morphologically distinguished from all other species of Spinosphaera having 18 pairs of notopodia, double rows of uncini present until the last notopodia, and 11 pairs of Spinosphaera-chaetae. A dichotomous taxonomic key and a table summarizing the morphological characters that distinguish all species of Spinosphaera are provided. This study also reports, for the first time, the transformations of Spinosphaera-chaetae and saw-like chaetae from the anterior to posterior segments of body.

ZooBank: urn:lsid:zoobank.org:pub:628B1F01-166A-4E26-9C42-39D0CBFDE998.