The amathillopsid subfamily Cleonardopsinae Lowry, 2006 is reviewed. The only species of the subfamily, Cleonardopsis carinata K.H. Barnard, 1916, should be regarded as a species-complex. A new genus and species of the subfamily, Carinocleonardopsis seisuiae gen. et sp. nov., is described from the Sea of Kumano, Japan as the second species of the subfamily Cleonardopsinae as well as the first record of the subfamily from the North Pacific. This new genus can be easily distinguished from Cleonardopsis by the presence of distinct large eyes and the dorsal carination on head, pereonites and pleonites.

There is an important small-scale fishery using mechanized dredges and targeting clams (mainly wedge clam Donax trunculus and striped venus clam Chamelea gallina) along the Catalan coast (NW Mediterranean Sea). This study evaluated for the first time the discards and impact of mechanized clam dredging on the Catalan coast. To this end, three surveys were performed on board standard clam vessels (September and November 2016 and January 2017). Surveys were conducted in the three main clam fishing areas (Rosas Bay, South Barcelona and Ebro Delta). The composition of discards and the impact caused to discarded species was assessed using a three-level scale (undamaged; minor or partial damage; and lethal damage). Our study revealed that a large proportion of the catch (between 67–82% weight) is discarded. Even though about 63% of the discarded species were undamaged, 11% showed minor or partial damage and 26% lethal damage. Infaunal and epifaunal species with soft-body or fragile shells were the most impacted by the fishing activity (e.g. the sea urchin Echinocardium mediterraneum (~89%) and the bivalve Ensis minor (~74%)). Our results showed different levels of impact by target species and fishing area.

The Pacific sleeper shark Somniosus pacificus is one of the largest predators in deep Suruga Bay, Japan. A single individual of the sleeper shark (female, ~300 cm in total length) was observed with two baited camera systems deployed simultaneously on the deep seafloor in the bay. The first arrival was recorded 43 min after the deployment of camera #1 on 21 July 2016 at a depth of 609 m. The shark had several remarkable features, including the snout tangled in a broken fishing line, two torn anteriormost left-gill septums, and a parasitic copepod attached to each eye. The same individual appeared at camera #2, which was deployed at a depth of 603 m, ~37 min after it disappeared from camera #1 view. Finally, the same shark returned to camera #1 ~31 min after leaving camera #2. The distance between the two cameras was 436 m, and the average groundspeed and waterspeed of the shark were 0.21 and 0.25 m s−1, respectively, which were comparable with those of the Greenland shark Somniosus microcephalus (0.22–0.34 m s−1) exhibiting the slowest comparative swimming speed among fish species adjusted for size. The ambient water temperature of the Pacific sleeper shark was 5.3 °C, which is considerably higher than that of the Greenland shark (~2 °C). Such a low swimming speed might be explained by the ‘visual interactions hypothesis’, but it is not a consequence of the negative effects of cold water on their locomotor organs.

The present study reports polychaetes that bore into limestone rocks along the east coast of the Aegean Sea (eastern Mediterranean). Rock materials were collected at two depth intervals (0–5 and 5–10 m) at 15 stations in four localities of Ildırı Bay. A total of 276 specimens belonging to 12 species and four families (Eunicidae, Spionidae, Cirratulidae and Sabellidae) were recorded. Specimens belonging to Dodecaceria and Pseudopotamilla were identified at the genus level, because they differ from described species, were few in number or were in poor condition. Dipolydora giardia is a new species to the marine fauna of Turkey. The most dominant and frequent family in the area was Eunicidae, followed by Spionidae. Lysidice ninetta and L. margaritacea comprised 59% of the total number of individuals. The number of species and individuals, and the diversity index did not change with regard to depth or locality. Two species assemblages were found in the area, mainly formed by Dipolydora and Lysidice species. The Lessepsian species, Palola valida, which is a new record for the Aegean Sea, occurred abundantly at the study sites, posing a risk of damage to limestone rocks in the Mediterranean Sea. The morphological features of the species identified at the generic level and the burrow structure of these species are presented. The burrow shapes of Palola siciliensis and P. valida were described for the first time in the present study; they constructed complicated galleries, including more than four entrances.

The demographic histories, genetic relationships and population structure of sedentary fish Pomatoschistus marmoratus (Risso, 1810), which was sampled from the north-eastern basin of the Mediterranean Sea (including the Turkish coasts of the Black Sea, Aegean Sea, Levantine Sea and Sea of Marmara), were investigated by mitochondrial cytochrome c oxidase subunit I (652 bp) and cytochrome b (526 bp) regions. It was found that the population groups had high haplotype diversity while the nucleotide diversity was quite low for both gene regions. Phylogeographic analyses of the haplotypes indicated that the Levantine population (LEV) were genetically different from other populations. Also, the gene flow between LEV and the other populations was very limited. The results of the analyses of neutrality and mismatch distributions that were applied to the population groups were evaluated as a whole. It was determined that the haplogroup that represents the Black Sea and Sea of Marmara populations (BLAMAR) was stable, but the Levantine population (LEV) was under the sudden demographic expansion model following the population bottleneck. The genetic variance indices indicated sudden demographic expansion following population contraction. This was supported by star-shaped haplotype networks. The reason for this limited gene flow and differentiation between the Levantine population (LEV) and the others was linked with wind-driven offshore transport of the larvae and surface currents in these sub-basins. The timing of the differentiation, demographic histories of populations associated with geological and palaeo-climatic events and current ecological conditions were discussed.

In this study, we investigated ontogenetic and sexual changes of the brain scaling as well as the scaling and the relative size of six major brain areas in the small-spotted catshark Scyliorhinus canicula from the Mediterranean Sea. The brain somatic index (0.31–1.25%) did not differ significantly between sexes but was significantly affected by size with smaller specimens exhibiting higher values. Brain growth exhibited negative allometry (allometric coefficient 0.634), not affected by sex or maturity status. The brain growth rate was found to be higher compared with a previous study from the Atlantic Ocean. Regarding the scaling of the brain areas, the olfactory bulbs scaled with positive allometry, the telencephalon and the diencephalon scaled with the same rate of negative allometry, the mesencephalon exhibited even higher negative allometry, while the cerebellum and the medulla oblongata both followed a close-to-isometric growth pattern. Immature S. canicula possessed a larger mesencephalon and diencephalon, highlighting the importance of vision in this life period, while mature specimens had enlarged olfactory bulbs, indicating that olfaction may be more important after the animal attains sexual maturity. In respect of sexual dimorphism, males had a larger cerebellum and medulla oblongata, while females had enlarged telencephalon and olfactory bulbs.

The slipper lobster Scyllarus arctus is an important fishery resource in Galicia (NW Iberian Peninsula), with a large reduction of its populations in recent decades in the North-east Atlantic and Mediterranean, but only limited information on its reproduction. This study provides an analysis of the reproductive potential of this scyllarid during two breeding cycles (2008 and 2009) in the NE Atlantic (43°20′N 8°50′W). We studied several reproductive traits (fecundity, brood weight, egg weight and volume) in broods with eggs both in an early and late embryonic stage, in relation to female size and temporal variations. Total output (fecundity and weight) and egg weight were closely linked to maternal size, and this relationship remained in broods with late-stage eggs. In relation to temporal variations, our data revealed an important seasonal variability in fecundity and egg weight, showing an inverse pattern in the reproductive strategy in the first two seasons of the reproductive period, with a maximum egg weight in winter (December–February) and a maximum number of eggs produced in spring (April–May). A predictive model for realized fecundity was developed: log (FE) = 0.064 + 2.907 log (length)−0.018 Month2 + 0.174 Month, which accounted for over 90% of variation in the total data.

Increased numbers of great cormorants (Phalacrocorax carbo) in the Baltic Sea may have local impacts on fisheries and salmonid hatcheries. We studied spatial and temporal variability in cormorant diet, and potential consumption of hatchery salmonids, by analysing knee subcutaneous adipose tissue fatty acids (FA) of specimens (N = 77) collected along Swedish and Finnish coasts in different seasons during 2013–2017. The FA profiles of the subspecies sinensis and carbo were similar, with large individual variation. The proportion of C18 polyunsaturated FAs (PUFAs) was the largest in the north, whereas the proportion of C20–22 monounsaturated FAs (MUFAs) increased towards the south, reflecting diminishing freshwater and increasing marine food web characteristics towards the south. As an exception, the C20–22 MUFA percentage was high in sinensis collected in June 2017 from the northern Baltic Sea. The source of C20–22 MUFAs was probably hatchery salmonids, raised on ocean fish hatchery feed and released 10 days before, near the cormorant capture site. The FA profiles of northern and southern cormorants differed from each other both in early and late summer samples, suggesting spatially different diets. The largest individual variation was found in 22:1n-11, characteristic of ocean zooplanktivorous fish, and likely originating from Atlantic wild or Baltic Sea hatchery-reared fish. This study shows that adipose tissue FA profiles can be used as proxies for seabird diet monitoring and indicators of predation on hatchery-reared fish. Obtaining quantitative estimates on the proportions of dietary fish species requires future feeding experiments, allowing calibration between the FA compositions and diet.

An extensive review of cephalopod fauna in the Central and North Atlantic coast of Africa was performed based on material collected during 10 research cruises in these waters. In the Canary Current Large Marine Ecosystem (CCLME) area, a total of 378,377 cephalopod specimens was collected from 1247 bottom trawl stations. Of those specimens, 300 were sampled for subsequent identification in the laboratory and found to belong to 65 different species and 23 families. After an exhaustive review of the existing literature on the cephalopods and new data obtained from the surveys, an updated checklist of 138 species was generated for the CCLME area. Our knowledge of the known geographic distribution ranges of several species has been expanded: Muusoctopus januarii has been sighted from Guinea–Bissau waters, passing through Western Sahara, to Morocco waters for the first time; Lepidoteuthis grimaldii and Octopus salutii have been sighted off Morocco waters for the first time; Austrorossia mastigophora, Abralia (Heterabralia) siedleckyi, Abralia (Pygmabralia) redfieldi and Sepiola atlantica have been cited off Western Sahara waters for the first time; Magnoteuthis magna, Abralia (Asteroteuthis) veranyi and Octopoteuthis megaptera have been sighted off Moroccan and Western Sahara waters for the first time; Ancistroteuthis lichtensteinii, Opisthoteuthis grimaldii, Onykia robsoni, Muusoctopus levis and Bathypolypus valdiviae have been cited in the Guinea–Bissau coast for the first time; the northern geographic limit of Bathypolypus ergasticus has been expanded to Morocco, Western Sahara and Mauritania and southward to Guinea–Bissau waters. The presence of Muusoctopus johnsonianus in Senegalese waters has been reported for the first time. A Chtenopteryx sicula specimen was reported in Western Sahara waters. A specimen belonging to the poorly known Cirrothauma murrayi species was found in South Moroccan waters. Amphitretus pelagicus, a probably cosmopolitan species, has been reported in the Western Sahara and Guinea–Bissau waters. Some species that were previously recorded in the area, Sepia angulata, Sepia hieronis, Heteroteuthis dagamensis, Helicocranchia joubini and Tremoctopus gelatus, were removed from the final checklist and considered to be not present in the CCLME area. Cycloteuthis akimushkini was substituted with Cycloteuthis sirventi, its senior synonym, in the final checklist. Similarly, Mastigoteuthis flammea and Mastigoteuthis grimaldii were substituted with Mastigoteuthis agassizii.

Twelve hyper-β carotene-producing strains of algae assigned to the genus Dunaliella salina have been isolated from various hypersaline environments in Israel, South Africa, Namibia and Spain. Intron-sizing of the SSU rDNA and phylogenetic analysis of these isolates were undertaken using four commonly employed markers for genotyping, LSU rDNA, ITS, rbcL and tufA and their application to the study of Dunaliella evaluated. Novel isolates have been identified and phylogenetic analyses have shown the need for clarification on the taxonomy of Dunaliella salina. We propose the division of D. salina into four sub-clades as defined by a robust phylogeny based on the concatenation of four genes. This study further demonstrates the considerable genetic diversity within D. salina and the potential of genetic analyses for aiding in the selection of prospective economically important strains.

Sea turtles are partners in commensal relationships with a variety of epibionts, including barnacles. The acorn barnacle Chelonibia testudinaria is one species commonly found associated with sea turtles and other marine fauna throughout temperate to tropical waters including the Indo-Pacific. We conducted a study to assess the occurrence of this barnacle, relative to host life stage and species in a mixed foraging population of green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles (juvenile, sub-adult, adults (female and male)) in Mabul Island, Sabah, Malaysia (Celebes Sea). Expecting similar relative abundance by life stage, we found instead a significant effect between the combined dependent variables (abundance and size of barnacles) and the life stages of sea turtles in Mabul after controlling for the covariates of size and species of sea turtles (F(8, 428) = 5.77, P < 0.001, Pillai = 0.19). Among green turtles with barnacles, though adult males had larger barnacles compared with the female turtles, the mean barnacle abundance on adult females (43.4 individuals ± 5.19 SD) was higher than all other life stages. Most of the barnacles (85.6%; N = 1931) were found on the plastron of the sea turtles. The highest number of barnacle reacquisition was found among the juvenile turtles. In assessing the complemental males of the barnacles, we found they were consistently attached to the shells of the larger of the hermaphrodites from each region of the host's body despite average shell-size differences with each region.

Members of Clibanarius virescens show considerable intraspecific colour variation, including colouration of the second/third pereopods (green/white) and the dactyls of the second/third pereopods (with or without dark bands/patches). However, factors inducing these colour variations have not yet been elucidated. Here, we investigated the occurrence of colour variation in this species with particular emphasis on change of colouration associated with growth stage and region in specimens from tropical/subtropical to warm temperate areas in the Indo–West Pacific, including evidence from molecular phylogeny based on the cytochrome c oxidase subunit I (COI). We have, then, clarified that the colouration on the pereopod dactyls gradually changed from solid colour (yellow/white) to having dark-coloured area(s) or transverse band(s) as a result of the growth stage. The frequency of occurrence of the solid colour dactyls was higher than those of other colour types in tropical regions. Our results also indicated that the white ambulatory leg type was the colouration type that was frequently seen in juvenile stages. However, significant genetic differences were not detected between each colouration determined by molecular analysis of samples from 14 localities in the Indo-West Pacific region; in contrast, two genetically differentiated regional populations (North Australia; Phuket, Thailand; and Lombok, Indonesia) were detected. The present study, therefore, emphasizes the necessity for further study on the colour variation of marine animals focusing on growth stages and regional differences, with molecular data to facilitate the research on adaptation and/or speciation, especially in geographically widely distributed species.

The evaluation of symbiotic microbial communities occurring in the intestinal tract of animals has received great interest in recent years. However, little is known about gut microbial communities in cetaceans, despite their relevance in the ecology of marine communities. Here, we report an investigation using 16S rRNA gene amplicon sequencing of the resident gut microbiota of the two cetacean species Stenella coeruleoalba and Tursiops truncatus by sampling intestinal mucosa from specimens retrieved stranded along the Tyrrhenian coast of Tuscany (Italy). We found an abundance of members from Clostridiaceae and Fusobacteriaceae, which in total accounted for more than 50% of reads, in agreement with gut microbiota composition of other carnivorous mammals. Probably due to the limited number of samples available, sex, preservation status and also species, did not correlate with overall differences in the microbiota. Indeed, a high similarity of the taxonomic (family-level) composition between the gut microbiota of the two species was found. However, Pedobacter spp. was found abundant in amplicon sequencing libraries from S. coeruleoalba, while clostridia were more abundant from T. truncatus samples. Our results shed some light on the gut microbiota composition of two dolphin (S. coeruleoalba and T. truncatus) species, with specimens collected in the wild. Studies with a larger number of individuals are now needed to confirm these first results and evaluate the interspecific differences in relation to sex and age.

With over a century of records, we present a detailed analysis of the spatial and temporal occurrence of marine turtle sightings and strandings in the UK and Ireland between 1910 and 2018. Records of hard-shell turtles, including loggerhead turtles (Caretta caretta, N = 240) and Kemp's ridley turtles (Lepidochelys kempii, N = 61), have significantly increased over time. However, in the most recent years there has been a notable decrease in records. The majority of records of hard-shell turtles were juveniles and occurred in the boreal winter months when the waters are coolest in the North-east Atlantic. They generally occurred on the western aspects of the UK and Ireland highlighting a pattern of decreasing records with increasing latitude, supporting previous suggestions that juvenile turtles arrive in these waters via the North Atlantic current systems. Similarly, the majority of the strandings and sightings of leatherback turtles (Dermochelys coriacea, N = 1683) occurred on the western aspects of the UK and the entirety of Ireland's coastline. In contrast to hard-shell turtles, leatherback turtles were most commonly recorded in the boreal summer months with the majority of strandings being adult sized, of which there has been a recent decrease in annual records. The cause of the recent annual decreases in turtle strandings and sightings across all three species is unclear; however, changes to overall population abundance, prey availability, anthropogenic threats and variable reporting effort could all contribute. Our results provide a valuable reference point to assess species range modification due to climate change, identify possible evidence of anthropogenic threats and to assess the future trajectory of marine turtle populations in the North Atlantic.

Structure and diversity of sessile zoobenthic assemblages seem to be driven not only by chemical-physical constraints and biological interactions but also by substrate lithology and its surface features. Nevertheless, broadly distributed crustose epilithic corallines could mask the role of substrate on animal settling. To evaluate the direct influence of different rocky substrates, occurrence and coverage of several sessile species, growing on the dark (i.e. coralline-free) face of sublittoral limestone and granite boulders were compared in the Tavolara MPA (Mediterranean Sea). The analysis of photographic samples demonstrated significant differences in terms of species composition and coverage, according to lithology. Moreover, limestone boulders were widely bare, while the cover per cent was almost total on granite. The leading cause of observed patterns could be the different level of dissolution of the two types of rocks, due to their different mineral composition and textural characteristics. Limestone has previously been shown to have higher dissolution compared with granite, and consequently, a more unstable surface. Our results suggest that, in dark habitats, the absence of the crustose coralline layer allows more rock dissolution and consequent lower stability of the limestone compared with granite, which, in turn, reduces the zoobenthos colonization.

Sardinella aurita has become an important source of fish protein-intake in NW African countries, where one stock is considered from Morocco to south Senegal, performing seasonal reproductive migrations along the coast. Although data are limited for the fisheries involved and for life-history knowledge of the species in the area, a precautionary approach is recommended to avoid overexploitation. Commercial landings of round sardinella produced by the European freezer-pelagic trawlers operating in Mauritanian waters were analysed between May 2004 and February 2012. The length-weight relationships (LWRs) (N = 40,725) did not show significant differences between sexes. Ripening round sardinellas were present throughout the year, but spawning effort rose between June and December. The length at first maturity for males and females was estimated at 27.7 cm TL (2.1 years) and 28.1 cm TL (2.2 years), respectively. Ages were interpreted from otoliths, varying from 0 to 8 years. Von Bertalanffy growth parameters resulted in non-statistically significant differences between sexes (P = 0.28). Natural mortality was estimated at ~0.63 year–1. The results provide important biological information for fisheries assessment of a species that plays an important key role in the current climate change scenario and for the economies of the riparian countries.

Since the mid-1980s, swarms of the rhizostome Rhopilema nomadica have been an annual phenomenon in Israeli Mediterranean coastal waters during the summer months. Despite its annual prominence and the potential impact on food webs and ecosystem services, studies concerning its feeding ecology and its interactions with other biota in the marine food web have not been conducted. During summer 2015 gut contents of 41 R. nomadica were analysed as well as ambient plankton assemblages. More than 60% of the medusae diet was found to consist of microzooplankton <150 μm. Size correlations revealed that larger R. nomadica consumed faster swimming prey while smaller medusae relied more on the slower swimming taxa. The medusan diet reflected most of the ambient plankton taxa, but no statistically significant correlations between the relative abundance in diet and ambient plankton were found. As summer progressed, there was a gradual decrease in both mean medusa bell diameter (from 42.2–16 cm) and integrity of feeding structures. These findings suggest that R. nomadica, at least at the time of its appearance in Israeli coastal waters, may exert less predatory pressure on the plankton than we might otherwise expect.

This work aimed to test whether the colour variability featured by the European nudibranch Polycera quadrilineata is consistent with the concept of a single polychromatic species or may hide multiple lineages. Samples from across the geographic range of P. quadrilineata together with representatives from worldwide species with a focus on Atlantic diversity, were gathered and studied using an integrative taxonomic approach. Morpho-anatomical characters were investigated by light and scanning electron microscopy. Bayesian molecular phylogenetics using MrBayes, the Automatic Barcode Gap Discovery species delimitation method, and haplotype network analysis using the PopArt software were employed to help delimit species using the mitochondrial gene cytochrome c oxidase subunit I (COI). The results supported the existence of a second species, here described and named Polycera norvegica sp. nov., only known from Norway where it is sympatric with P. quadrilineata. The COI uncorrected p-genetic distance between the two species was estimated at 9.6–12.4%. Polycera norvegica sp. nov. differs by exhibiting a black dotted or patchy dotted pattern occasionally with more or less defined orange/brown patches, but never black continuous or dashed stripes as in P. quadrilineata. The two species share a common colouration with a whitish base and yellow/orange tubercles. Anatomically, P. norvegica sp. nov. has a weaker labial cuticle, a smaller radula with fewer rows, and only four marginal teeth, a reproductive system with a single lobed bursa copulatrix, shorter reproductive ducts, and a penis armed with two kinds of spines: needle-like and hook-shaped penile spines.

Moulting is essential for crustacean growth, but is one of the causes of mortality, because a crustacean cannot move during and just after its ecdysis. In the cases of ectosymbiotic crabs, escape from the host's hostile response may also be a problem during its own ecdysis. In this study, Sestrostoma sp. (Varunidae), an ectosymbiotic crab which clings to the ventral abdomen of upogebiid shrimps with legs that can walk, was studied to clarify how the crab moults and maintains association with the host. Five cases of crab ecdysis were observed, where the crab moulted with its legs clinging to the host abdomen, without detaching from the host body. Time required for moulting was 14–21 min. Shedding of the old exoskeleton (active phase) took only 40–59 s. Sestrostoma sp. detached from the host abdomen and waited in the burrow tube during shrimp ecdysis. The crab then reattached at the same location on the host when shrimp moulting was complete. Our results suggest that Sestrostoma sp. are able to maintain a symbiotic relationship with the same shrimp host after its own ecdysis as well after ecdysis of its host.

The continental shelf edge of the NW Gulf of Mexico supports dozens of reefs and banks, including the West and East Flower Garden Banks (FGB) and Stetson Bank that comprise the Flower Garden Banks National Marine Sanctuary (FGBNMS). Discovered by fishermen in the early 1900s, the FGBs are named after the colourful corals, sponges and algae that dominate the region. The reefs and banks are the surface expression of underlying salt domes and provide important habitat for mesophotic coral ecosystems (MCE) and deep coral communities to 300 m depth. Since 2001, FGBNMS research teams have utilized remotely operated vehicles (e.g. ‘Phantom S2’, ‘Mohawk’, ‘Yogi’) to survey and characterize benthic habitats of this region. In 2016, a Draft Environmental Impact Statement proposed the expansion of the current sanctuary boundaries to incorporate an additional 15 reefs and banks, including Elvers Bank. Antipatharians (black corals) were collected within the proposed expansion sites and analysed using morphological and molecular methods. A new species, Distichopathes hickersonae, collected at 172 m depth on Elvers Bank, is described within the family Aphanipathidae. This brings the total number of black coral species in and around the sanctuary to 14.