A new species of the cyclorhagid genus Meristoderes is described. Meristoderes zmaj sp. n. is distinguished from its congeners by its unique arrangement of spines and tubes. It possesses acicular spines on segments 4, 6 and 8 in middorsal position and on segments 6–9 in lateroventral position; and tubes on segment 2 in subdorsal, midlateral and ventrolateral position, on segment 5 in lateroventral position and on segment 10 in laterodorsal position. With the formal description of M. zmaj sp. n., the number of species within the genus is increased to 10. In addition, the appearance of a new species and its accompanying fauna within the North-Eastern Adriatic Sea fauna, extensively studied by Kinorhyncha taxonomists, is discussed.

The Falkland Shelf is a highly productive ecosystem in the Southwest Atlantic Ocean. It is characterized by upwelling oceanographic dynamics and displays a wasp-waist structure, with few intermediate trophic-level species and many top predators that migrate on the shelf for feeding. One of these resident intermediate trophic-level species, the Patagonian longfin-squid Doryteuthis gahi, is abundant and plays an important role in the ecosystem. We used two methods to estimate the trophic structure of the Falkland Shelf food web, focusing on the trophic niche of D. gahi and its impacts on other species and functional groups to highlight the importance of D. gahi in the ecosystem. First, stable isotope measurements served to calculate trophic levels based on an established nitrogen baseline. Second, an Ecopath model was built to corroborate trophic levels derived from stable isotopes and inform about trophic interactions of D. gahi with other functional groups. The results of both methods placed D. gahi in the centre of the ecosystem with a trophic level of ~ 3. The Ecopath model predicted high impacts and therefore a high keystoneness for both seasonal cohorts of D. gahi. Our results show that the Falkland Shelf is not only controlled by species feeding at the top and the bottom of the trophic chain. The importance of species feeding at the third trophic level (e.g. D. gahi and Patagonotothen ramsayi) and observed architecture of energy flows confirm the ecosystem's wasp-waist structure with middle-out control mechanisms at play.

The rocky intertidal zone of sheltered shores in Breiðafjörður, north-west Iceland is dominated by monospecific stands of canopy-forming brown algae Ascophyllum nodosum, which provide habitat for mobile organisms and has been subjected to long-standing rotational harvesting. We investigated the assemblage composition of little-studied mobile brachyuran crabs in this area, to track distributional shifts in a native species responding to climate change and extent of occupancy of the intertidal by a primarily subtidal invasive non-native species. Potential interactive effects of seaweed harvesting were explored. Breiðafjörður was compared with two reference sites in Faxaflói, south-west Iceland. The study revealed clear poleward expansion of the native European green crab Carcinus maenas in the region, displacing the native spider crab Hyas araneus particularly at mid-shore levels. The invasive non-native Atlantic rock crab Cancer irroratus had negligible occupancy in the intertidal zone, indicating limited effects on the intertidal crab assemblage, composition, and abundance. The current harvesting regime of A. nodosum in Breiðafjörður did not affect the composition and abundance of the brachyuran crab assemblage in the rocky intertidal zone. H. araneus is likely being squeezed by displacement subtidally by C. irroratus, and intertidally by C. maenas. Overall, we provide insights into the potential interactions between climate change, invasive species, and human activities in the rocky intertidal zone.

Despite attacks of bottlenose dolphins towards conspecifics and other species of dolphins being reported worldwide, inside the Mediterranean Sea these behaviours are still considered sporadic and have been, to date, only recorded in Spain and France, mostly directed to striped dolphins. In this work, we reported the necropsy outcomes of a dead striped dolphin that suggest a fatal interaction with bottlenose dolphins inside the Italian side of the Pelagos Sanctuary, Western Ligurian Sea. Results from the post-mortem examination showed multiple, multifocal external rake marks spaced 1–1.2 cm and several internal injuries, consisting of subcutaneous and muscular haematomas and haemorrhages, multiple vertebral and rib fractures, haemothorax and lung laceration. The inter-tooth distance and all the internal findings were consistent with a fatal traumatic interaction with bottlenose dolphins as reported in similar cases in other parts of the world where the same results were found. No other significant gross and microscopic findings and concurrent significant pathogens were detected. This case highlights the existence of negative interspecific interactions in an area where they have never been reported before and adds new important information to the literature for understanding their occurrence, expanding the geographical range of observation in the western Mediterranean Sea.

The unsolved systematics of the genus Cardiomya has led to a sequence of astonishing identification mistakes. This scenario is a result of the rarity of specimens and, more importantly, the lack of knowledge about which characters are relevant to the genus taxonomy. In this study, we developed a method based on standard linear discriminant analysis to identify the smallest number of morphological characters that efficiently distinguish individuals at the species level of Brazilian Cardiomya. Starting from 29 morphometric measurements obtained from photographed Cardiomya shells, we were able to identify only five characters: the dorsal inflection of the rostrum, the distance from the posterior most rib end to the umbonal posterior margin and the distance from the central point of the valve to the anterior margin at 45°, 15° and −30° angles. Surprisingly, all these characters are related to the shell outline and not the ornamentation, which is a remarkable character in Cardiomya. We performed a one-way ANOVA with post-hoc Tukey HSD test specifically using the total number of ribs to verify its discriminant power in species identification. Our analysis demonstrated that the number of ribs does not show a significant difference between the analysed species.

In this study, we applied generalized additive model to investigate the influence of spatial temporal variables and vessel length on catch per unit-effort (CPUE) of Atlantic bluefin tuna (ABFT) purse seine fishery using catch and effort data from commercial logbooks and field surveys from 1992 to 2006. The vessel lengths of sampled purse seines ranged from 20 to 64 m. The number of ABFT caught within each operation varied between 1 and 2000. A total of 386 CPUE values for ABFT were calculated 0.05 and 60 t ⋅ (haul day)–1 with mean CPUE of 5.51 ± 0.54 t ⋅ (haul day)–1. Although the sea surface temperature had little influence on the CPUE, the effect of time and spatial variables, vessel length and salinity was found as significant. In conclusion, the spatial dynamics of ABFT should be considered if the impact of fisheries on the ecosystem is to be reduced.

We report the first record of Ramari's beaked whale (Mesoplodon eueu) from the temperate Southwestern Atlantic. Our analysis is based on an adult female and a plausibly associated calf/juvenile that stranded on the coast of Canelones Department, Uruguay. The species of the two individuals was identified via a combination of morphometric and molecular mitochondrial data and provide new insights into the Ramari's beaked whale, including previously unknown polymorphisms in the mitochondrial genome and a re-estimated date of divergence from Mesoplodon mirus at 2.5902 Mya.

Sharks are scarce in much of the Caribbean due to widespread depletion. Trinidad and Tobago, in the southern Caribbean, is a shark meat consumer and international exporter of dried shark fins. Despite limited fisheries management there is a small Marine Protected Area (MPA; 7 km2) in urbanised southwest Tobago, but its effect on sharks and rays (elasmobranchs) is unknown. The rural northeast is a recently designated UNESCO Man and the Biosphere Reserve with a significant marine component and plans for a large MPA, but no baseline data for elasmobranchs exist. Given the local importance of elasmobranchs and a newly drafted Sustainable Shark and Ray Management Plan, we used baited remote underwater video stations within a 40 m depth contour at 270 randomly generated points around Tobago to: (i) establish a baseline of species richness and relative abundance, (ii) investigate the influence of season, habitat relief, depth and water temperature on relative abundance, and (iii) investigate spatial variation in relative abundance. Caribbean reef sharks, nurse sharks, and southern stingrays were observed at all sites, the latter two more frequently in the urbanised southwest. Shark diversity was unexpectedly high in the northeast, driven by rarer species (sharpnose, smoothhound, tiger, scalloped hammerhead, great hammerhead) only observed there. Habitat relief, depth and season likely influence relative abundance of elasmobranchs around Tobago, but research is needed to elucidate species-level effects. Shark species richness in northeast Tobago is high for the Caribbean, warranting research attention, while the larger MPA presents an opportunity to strengthen elasmobranch management.

Several individuals of the sea anemone Telmatactis cricoides (Duchassaing, 1850) (order Actiniaria) were observed in the Mediterranean continental Spanish coast (Almeria) and the Balearic Islands (Mallorca) showing an expansion of the species, possibly related to rising sea water temperatures. This finding contributes to increase the knowledge on the geographical distribution range of this actiniarian in the Mediterranean basin.

Pseudechinus magellanicus is an ecologically important and small sea urchin in coastal and nearshore habitats off southern South America. We provide the first growth assessment for the species using tag (calcein) and recapture procedures in central Patagonia (Argentina). The individual growth rate of P. magellanicus ranged 0.05–1.3 mm year−1. The Brody–Bertalanffy and Richards growth models provided asymptotic maximum diameters of 29.89 and 26.01 mm, respectively. Both models yielded low values for the growth constant (k), with 0.046 (Brody–Bertalanffy) and 0.062 (Richards). Maximum instantaneous growth rate was estimated at 1.36 mm year−1 for the Brody–Bertalanffy model, and 2.69 mm year−1 for the Richards model. Model selection (corrected Akaike information criterion) showed a slight better fit for the Brody–Bertalanffy growth model compared to the Richards model. A significant variability in growth was observed within the studied population, which can be attributed to genetic factors and micro-environmental effects. P. magellanicus displays a combination of slow growth and small body size, with the lowest recorded growth performance index (θ = 3.72) recorded so far in sea urchins. The species has a long lifespan, with the most common adult sizes estimated to range from 15 to 21 years according to the Brody–Bertalanffy model. Due to the broad geographic distribution and occupation of contrasting habitats, further studies are necessary to explore growth of P. magellanicus under different environmental conditions and/or along a bathymetric gradient.

Historic species records of the families Onuphidae and Eunicidae, from the Falkland Islands region, are reviewed and updated, new records added from intertidal and nearshore localities on and around the Falkland Islands, and a new species of Hyalinoecia described. Eight genera are reported from around the region including eight taxa of Onuphidae and two of Eunicidae, although most are only known from deep offshore waters. Kinbergonuphis dorsalis is re-described from type material, Kinbergonuphis sp. from the Falkland Islands is described and discrepancies between the two descriptions are examined. Hyalinoecia falklandica sp. nov. is described and the history of the genus and its misidentification in the region is discussed. The new species is distinguished from all other species in the genus through a combination of simple, unidentate falcigers on chaetigers 1 and 2, ventral cirri present to chaetigers 3 or 4, and branchiae present from chaetigers 26 or 27 to the end of the body. The historic record of Marphysa aenea from the Falkland Islands is also shown to be a misidentification and the actual, as-yet-undetermined species present is described. Problems surrounding a correct identification of Marphysa species, other species that do not quite fit current descriptions, and additional Eunicoidea taxa that might be expected to occur in the region are also discussed.

We describe Pericelis nivea sp. nov. from sunken wood collected 330 m deep, off the coast of Owase, Japan. This is the first record of Pericelis from the bathyal zone. Unlike other congeners, P. nivea sp. nov. is characterized by the absence of eyespots. We provide a partial sequence of the mitochondrial cytochrome c oxidase subunit I gene as a DNA barcode for the new species. Phylogenetic analyses based on concatenated sequences of nuclear 18S and 28S ribosomal DNA showed that P. nivea sp. nov. was nested in the clade of Pericelis with high support; however, the relationship between P. nivea sp. nov. and other Pericelis species was unclear.

Variations in sagittal otolith shape and morphometry, including length (Lo), width (Wo), area (Ao), and perimeter (Po), were investigated in two populations of Chelon ramada collected from the Boughrara and El Bibane lagoons located in southeastern Tunisia. The objective was to assess the geographic variation in the sagittal otoliths' shape and morphometry and the effect of potential fluctuating asymmetry (FA) in morphometry on the stock structure of C. ramada in the two lagoons to inform on appropriate management procedures. At the interpopulation level, analysis of sagittal otolith shape showed a statistically significant difference (P = 0.0001), i.e. there was a bilateral asymmetry, in the shape of left and right otoliths between individuals of the two populations. In addition, significant FA was found only in Lo between the left and right otoliths. At the intrapopulation level, a significant shape difference (P < 0.0001), particularly asymmetry, was observed in both left and right otoliths between males and females, indicating sexual dimorphism in shape within the Boughrara lagoon. However, significant shape similarity, i.e. symmetry, was observed in the left and right otoliths among individuals of the El Bibane lagoon. Moreover, a significant FA was detected in Lo between the left and right otoliths only among males, as well as between males and females of the Boughrara lagoon. However, a significant FA between the left and right otoliths was found only in Wo among males and in all morphometric dimensions among females and Wo between males and females of the El Bibane lagoon. Discriminant function analysis of the otolith contour shape confirmed the presence of two separate C. ramada stocks, one corresponding to the Boughrara lagoon and the other representing the El Bibane lagoon, which should be managed separately. The possible cause of morphological variation in the sagittal otoliths' shape and morphometry due to FA between individuals of the two populations was discussed in relation to the biotic and abiotic factors.

The Cuvier's beaked whale, Ziphius cavirostris, is a cosmopolitan species and the only beaked whale species commonly found in the Mediterranean Sea. Five strandings of Cuvier's beaked whale were reported along the Aegean/Mediterranean Seas coasts of Türkiye and northern coast of Cyprus in 2016–2017. Mitochondrial DNA (mtDNA) control region (430–444 bp) and cytochrome b (cytb) (382–424 bp) sequences each revealed two different haplotypes (four out of five individuals had the same haplotype for each locus) on these stranded animals. The control region haplotypes were identical to two previously identified haplotypes from the Ionian (Greece) and Adriatic (Croatia) Seas. Only one of the cytb haplotypes had previously been described from the Adriatic Sea (Italy) and the other one was detected for the first time. In a comparison of these haplotypes with Cuvier's beaked whale haplotypes previously reported from outside the Mediterranean Sea, the Mediterranean subpopulation shows genetic differentiation based upon the presence of two unique haplotypes. Additional mtDNA sequences from the Mediterranean Sea are needed for a better understanding of the genetic population structure of this species and to elaborate more concrete conservation measures.

Entanglement in static fishing gear is the largest cause of non-natural mortality for minke whales (Balaenoptera acutorostrata) in Scottish waters. To mitigate whale entanglement, one priority is to identify areas where the risk of entanglement is consistently high. Sightings data for minke whales and creel fleets were collected by the Hebridean Whale and Dolphin Trust, during vessel line transect surveys conducted between 2008 and 2014. Habitat modelling was used to relate survey, environmental, and temporal variables to the co-occurrence of minke whales and creels in coastal waters of western Scotland. This revealed that minke whale occurrence was related to depth, peaking around 70 m. Using predictive habitat modelling, the overlap between minke whale habitat and the creel fishery was measured as risk of entanglement. A method was developed to quantify the consistency of risk over the seven-year time period. This allowed for the identification of areas where there had been a consistently low, medium, or high risk of entanglement from 2008 to 2014. The three areas with a consistent high risk of entanglement were identified: Inner Sound and Sound of Raasay, east of North and South Uist, and north of The Small Isles. The method presented here could be used to guide management to areas where mitigation efforts will be the most consistently effective over time.

In the present study, 15 new records from Kavaratti Atoll are added to the ichthyofaunal diversity of the Lakshadweep Archipelago and six to the Indian fish fauna based on underwater photographs and videos. Fishes were recorded from both lagoon and forereef areas off Kavaratti. The new records include Cirripectes auritus (Blackflap blenny), Cirripectes polyzona (Barred blenny), Ecsenius bicolor (Bicolor blenny), Glyptoparus delicatulus (Delicate blenny), Amblyeleotris wheeleri (Gorgeous prawn-goby), Eviota punyit (Punyit dwarfgoby), Eviota cf. teresae (Viridescent dwarfgoby), Cirrhitichthys falco (Dwarf hawkfish), Halichoeres leucoxanthus (Canarytop wrasse), Pseudocheilinus evanidus (Disappearing wrasse), Coris latifasciata (Broad banded wrasse), Pomacentrus xanthocercus (Yellowtail damsel), Plectroglyphidodon luteobrunneus (Indian gregory), Pomacentrus indicus (Indian damsel) and Synodus dermatogenys (Sand lizardfish). Six species, G. delicatulus, E. cf. teresae, E. punyit, P. xanthocercus, P. evanidus and C. latifasciata represent new records for Indian waters. The genus Amblyeleotris is recorded for the first time from Lakshadweep.

Tonic immobility is considered an anti-predator defence, wherein prey adopts a motionless state in a characteristic posture elicited by external stimuli. The marine isopod Cleantiella isopus exhibits tonic immobility with an arch-like posture and motionless state lasting several seconds or minutes in response to external stimuli such as predatory attacks by fish. In this study, we describe tonic immobility by wild-caught C. isopus and examine the influence of body size, sex, and colour morph on the frequency and duration of tonic immobility. All individuals exhibited tonic immobility regardless of body size, sex, or colour morph, suggesting that the behaviour plays a major role in predator avoidance following detection by a predator. In males, smaller individuals exhibited more prolonged tonic immobility than larger individuals, whereas the relationship between the duration of tonic immobility and body size was unclear in females. Colour morph had no effect on the duration of tonic immobility. These findings provide a detailed documentation of tonic immobility in C. isopus and suggest that the factors affecting tonic immobility differ between males and females.

The aim of the present study was to report canid attacks on sea turtles in northeastern Brazil. The study was conducted on the Sergipe-Alagoas Basin coastline between March 2010 and October 2019. Injured-stranded sea turtles or carcasses were recorded through systematic beach monitoring. The specimens were submitted for clinical or postmortem assessments, providing evidence for the identification of injuries caused by canids. In the study period, 9841 stranded sea turtles were recorded, with the diagnosis of canid attacks in 55 (0.55%) events. Lepidochelys olivacea was the species with the largest number of events (90.90%), followed by Chelonia mydas (7.27%), and Caretta caretta (1.81%). The attacked sea turtles were clinically healthy, with a good body score and no apparent diseases; most were in the reproductive stage. The injuries were mainly found on the front flippers, with considerable loss of musculature affecting the brachial plexus, with the rupture of large blood vessels, and in some cases, exposure of the humerus or oesophagus. Thus, these events hampered the reproductive cycle, limiting the egg-laying process and preventing the hatching of hundreds of new turtles. Therefore, mitigating measures should be implemented, addressing the consequences of abandoning pets and their unsupervised presence on beaches.

The reproductive cycle of Marphysa sanguinea is described for a population at Mount Edgecombe, Plymouth, near the type location in Southwest England, using a data set obtained previously (October 1999 to September 2000). The species is iteroparous without schizogamy, spawning prior to October 1999 and during a short breeding season in 2000 from end August through September. The sexes are separate with a sex ratio of 1:1. Mature oocytes and spawned eggs are 215 μm in diameter and spermatozoa of the ectaqua sperm type. Mature gametes of both sexes are discharged through paired coelomoducts, and the diploid chromosome number is 28. Proliferation of new coelomic gametes from paired gonads began within a month of spawning and continued for 8–9 months but ovulation was suppressed in June and July. Attempts to undertake fertilisation using spawned oocytes and active spermatozoa were unsuccessful. The size of discharged oocytes suggests a short pelagic larval duration of a few days. This is the first publication about the reproduction of this species, and our results suggest that M. sanguinea is restricted to intertidal areas in SW England, NW France and southern North Sea. The highly synchronised pattern of reproduction observed is not compatible with a quasi-cosmopolitan species range indicating that this species has been mistakenly reported from around the world. Future studies of the genus should combine rigorous taxonomy with observations of reproduction to facilitate comparison among Marphysa spp.

Bobtail squids (Family Sepiolidae) have a variety of sperm storage patterns, but their reproductive biology has not been studied in many species, especially those in Japanese waters. Two species, Austrorossia bipapillata (Subfamily Rossiinae) and Sepiolina nipponensis (Subfamily Heteroteuthinae) inhabit Suruga Bay in Japan. These were sampled approximately bimonthly by trawling at around 500 m between the end of September, 2020 and May, 2022. They were measured for body size (dorsal mantle length) and weighed for gonadosomatic index (GSI) calculation, and their sperm storage mechanism was investigated. The reproductive season occurs from May to October in A. bipapillata and from December to February in S. nipponensis. In both species, spermatangia were deposited inside the mantle cavity as implanted spermatangia. In A. bipapillata, 5.7 ± 6.5 spermatangia were deeply implanted in the opening of the oviduct, and in S. nipponensis 62.7 ± 61.5 spermatangia were attached to the left gill and surface of the connective-tissue capsule enclosing the digestive gland. The GSI was lower and there were fewer spermatophores stored in the spermatophoric sac of A. bipapillata males compared to S. nipponensis, leading us to suggest that it is exposed to weaker sperm competition than S. nipponensis, irrespective of similar sperm storage mechanism in the two species.