In order to confirm the genetic relationship between the Yellow Sea and East China Sea populations of mantis shrimps Oratosquilla oratoria, fragments of mitochondrial DNA COI gene samples were analysed. A total of 212 individuals from nine localities in the East China Sea and Yellow Sea were collected and 108 haplotypes were detected. Neighbour-joining analysis revealed a complete genetic break between the Yellow Sea and East China Sea, which was consistent with the previous mtDNA 16S rRNA. Pleistocene isolation and the current physical barrier were responsible for the complete genetic break between the East China Sea and Yellow Sea. Furthermore, local adaptation in the COI gene may also be contributed to by the genetic differentiation between the populations of the Yellow Sea and East China. The different Ka/Ks ratios between the two clades may reflect different selection pressures and local adaptation on the fragment of COI gene.

The syllid genus Anguillosyllis is relatively rare and mainly restricted to deep waters. The phylogenetic position of the genus was only recently inferred, while its reproductive mode, an important trait in the classification of the Syllidae, remains unknown. We describe herein our finding of one specimen of Anguillosyllis lanai with fragile egg capsules dorsally attached to some parapodial lobes, the first observation to date providing information about reproductive aspects of animals of the genus, and discuss possible evolutionary and phylogenetic implications of this finding.

Macrophytes provide a habitat for many species of marine invertebrates, the gastropods being one of the main components. This study provides new information about Sargassum-associated gastropod biodiversity, through characterization of the fauna from a highly impacted area of Brazil, investigating its variation at a small spatial scale and between two main seasons of the year, as well as its relationship with macroalgae parameters. Density of gastropods was higher during the warmest season and varied throughout sampling sites. A significant and positive, however weak, relationship between gastropod density and Sargassum dry weight was found in all localities. For all sites, a marked and unusual dominance of Bittiolum varium was observed. The high dominance of this species seems to be related to the impacts caused by shipping activities and highway construction in the 1970s and 1980s, which caused a decline in local species diversity that seems to have continued until now. Many species, both typical of these habitats and characteristic of other, nearby habitats, benefit from Sargassum sp. These macrophytes allow gastropods to establish and grow during their most vulnerable stages, as shown by the growth series and juvenile forms found for most species of gastropods. The present data highlight the importance of macrophyte habitats for gastropod biodiversity in coastal areas and call attention to the importance of raising knowledge on this fauna, especially in impacted areas, thus contributing to the conservation of these highly diverse and ecologically important macrophyte–gastropod systems.

Despite global deterioration of coral reef health, not all reef-associated organisms are in decline. Bioeroding sponges are thought to be largely resistant to the factors that stress and kill corals, and are increasing in abundance on many reefs. However, there is a paucity of information on how environmental factors influence spatial variation in the distribution of these sponges, and how they might be affected by different stressors. We aimed to identify the factors that explained differences in bioeroding sponge abundance and assemblage composition, and to determine whether bioeroding sponges benefit from the same environmental conditions that can contribute towards coral mortality. Abundance surveys were conducted in the Wakatobi region of Indonesia on reefs characterized by different biotic and abiotic conditions. Bioeroding sponges occupied an average of 8.9% of available dead substrate and variation in abundance and assemblage composition was primarily attributed to differences in the availability of dead substrate. Our results imply that if dead substrate availability increases as a consequence of coral mortality, bioeroding sponge abundance is also likely to increase. However, bioeroding sponge abundance was lowest on a sedimented reef, despite abundant dead substrate. This suggests that not all forms of coral mortality will benefit all bioeroding sponge species, and sediment-degraded reefs are likely to be dominated by a few resilient bioeroding sponge species. Overall, we demonstrate the importance of understanding the drivers of bioeroding sponge abundance and assemblage composition in order to predict possible impacts of different stressors on reefs communities.

The aim of the present study is to test the resource economic monopolization hypothesis and the hypothesis of monogamy using the shrimp Alpheus estuariensis as a model. The shrimps were collected in two areas in the Vaza-Barriz estuary, north-east Brazil, from August to November 2016. The average abundance of refuges was obtained through 30 random replicates. The shrimp presented a random distribution in both areas. Males and females found together showed a weak relation between their sizes, with males being larger than females. In addition, the cheliped of males grows proportionally more than that of females. The great abundance of refuges present in the environment, added to the aforementioned results, do not support the idea of refuge-guarding behaviour or monogamy. These results, which are in disagreement with those already found for some shrimps of the same family, genus, and even species, reinforce the idea that Alpheidae can be used as a model in the study of how environmental conditions are capable of shaping the social behaviour of a species.

Details on size at first maturity, embryo number and size, brood chamber volume and reproductive output of deep-sea armoured shrimp, Glyphocrangon investigatoris caught off the south-east coast of India by using EXPO trawl from 633 m depth in FORV ‘Sagar Sampada’ are reported here. Eighty-four female shrimps ranging from 17.29–36.31 mm carapace length and 2.28–16.54 g weight formed 7.73% of total catch, 30% of which was constituted by embryo-bearing females. Regression of weight on carapace length revealed negatively allometric growth (r2 = 0.85, P < 0.01). The size at first maturity was estimated as 19.96 mm. The embryo number ranged from 55 to 233 with a mean of 120.24 ± 34 embryos and showed a positive correlation to body size. Embryo diameter varied between 1.0 to 3.34 mm and more than 50% of embryos constituted the 2.0–2.5 mm size class. Brood chamber volume and percentage frequency of embryo stage development revealed a linear relationship with carapace length. Based on dry weight, mean reproductive output was estimated to be 0.16. The female armoured shrimps showed a high reproductive investment evidenced from few, large, yolky embryos, indicating their deep-sea adaptation.

The amphinomid fireworm Hermodice carunculata is a potentially invasive species reported throughout the subtropical Atlantic Ocean and the Mediterranean Sea, which is known as a generalist predator and opportunistic feeder. The ongoing climate changes and seawater warming may favour fireworm poleward range expansions and density increases. Our results provide the first investigation into a population which has purportedly been spreading widely in the Salento Peninsula (Apulia, Italy). The specimens were analysed using allometric variables and molecular markers. The best morphometric parameters to estimate individual size were determined as key information for future studies on fireworm population dynamics. To phylogeographically characterize the Apulian population, sequences of the mitochondrial COI and 16S rDNA regions were obtained from a pool of individuals and treated together with those of Atlantic specimens retrieved from GenBank. The estimates of genetic variability for Apulian population were consistent with those recently reported in the literature. Inferences on demographic history analysis confirmed a recent expansion event in Apulia, as has been recounted by fishermen and scuba divers during recent years. Overall, these results constitute a crucial step in the characterization of present-day H. carunculata populations, and provide greater insight into fireworm population ecology.

The functional morphology of Pinna nobilis is described, with special reference to the uniquely pinnid pallial organ, the similarly unique buccal (formerly pallial) gland, the stomach and its contents. The pallial gland produces sulphuric acid which as well as functioning as a shell cleaning swab may be involved in prey capture. The buccal gland discharging into the oesophagus has proteolytic digestive functions while the stomach is adapted for the reception and digestion of captured, mucous-bound, mesozooplanktonic and epi- and endo-benthic, prey items. Pinna nobilis is thus not simply either an accidental or incidental predator of such species but is opportunistic. The buccal glands and stomachs of other Pinnidae are not so specialized as in P. nobilis, possibly indicating that in the particular, oligotrophic, environment of the Mediterranean and Adriatic Seas, and in which it is endemic, P. nobilis has, in addition to being a typical ctenidial suspension feeder, become an opportunistic predator. Although the deep sea representatives of the Septibranchia (Anomalodesmata) and Propeamussidae are obligate predators, this is the first record of any bivalve functioning as an opportunistic predator with unique morphological adaptations to facilitate this.

Edwardsiidae is one of the most speciose families within order Actiniaria with ~75 valid species of burrowing sea anemones. Five edwardsiids have been recorded in South Atlantic waters with only two species known for Brazil: Nematostella vectensis and Edwardsia migottoi. Such low diversity is probably the result of a historical small number of specialists in the region combined with difficulties in collecting and identifying these small burrowing animals. Although edwardsiids have been reported from Brazil since at least the 1960s, these reports did not include proper descriptions or specific identification, making comparison to other valid species impossible. Here we describe a new genus, Isoscolanthus gen. nov., and two new species: Isoscolanthus iemanjae sp. nov., Isoscolanthus janainae sp. nov. and we also describe Scolanthus crypticus sp. nov., the first species of the genus for Brazil. Isoscolanthus gen. nov. is easily distinguished from other edwardsiid genera by a combination of external (i.e. presence of periderm and nemathybomes in proximal end and 12 tentacles), microanatomical (i.e. four microcnemes) and cnidom features (i.e. pterotrichs in nemathybomes). In addition to the description of the new genus and species, we expand the range distribution of Nematostella vectensis and Edwardsia migottoi in the South-western Atlantic. The number of edwardsiids known from Brazil is raised from two to five species, substantially increasing the diversity of soft-bottom sea anemones for South Atlantic waters.

Boring sponges are an important component of bioeroder assemblages in tropical coral reefs. They are considered as a potential threat for coral reef health, and the increase of dead corals is expected to promote their abundance. The relationship between the availability of dead coral substrata and the development of boring sponge assemblages was evaluated during El Niño 2015–16 at five reefs from Zihuatanejo, Guerrero, Mexico. Environment and substrate quality were assessed. Overall, environment conditions remained normal in relation to previous studies in the area. Only water temperature showed unusually high records at all sites and coincided with bleaching and mortality of corals, possibly caused by the effects of the El Niño event. Abundance of boring sponges in dead corals and coral rubble was lower than during previous studies. Although sponge abundance was not directly related to cover of both dead corals and coral rubble, cover of dead corals showed a high correlation with the variation in the structure of sponge assemblages across sites. Cliona vermifera dominated sponge assemblages at all sites, and its abundance was high under conditions of high cover of live corals and low cover of bleached corals. Since overall sponge abundance responded in a similar way, these results suggest that boring sponge assemblages dominated by C. vermifera are enhanced by conditions favourable for corals. Our results imply that El Niño events in the Mexican Pacific are not likely to cause immediate population outbreaks of boring sponges.

Limpets and barnacles are important components of intertidal assemblages worldwide. This study examines the effects of barnacles on the foraging behaviour of the limpet Patella vulgata, which is the main algal grazer in the North-west Atlantic. The behaviour of limpets on a vertical seawall on the Isle of Man (UK) was investigated using autonomous radio-telemetry, comparing their activity patterns on plots characterized by dense barnacle cover and plots from which the barnacles had been removed. Limpet behaviour was investigated at mid-shore level, but two different elevations were considered. This experiment revealed a significant effect of barnacle cover on the activity of P. vulgata. Limpets on smooth surfaces spent a greater proportion of total time active than did limpets on barnacles. Movement activity was also greater in areas that were lower down in the tidal range. In general, limpets were either predominantly active during diurnal high or nocturnal low tides and always avoided nocturnal high tides. Individuals on barnacles at the higher elevation concentrated their activity during nocturnal low water. All the other groups of limpets (smooth surfaces on the upper level and all individuals on the lower shore) had more excursions centred around daylight hours with an equal distribution of activity between periods of low and high water. Inter-individual variability was, however, pronounced.

Many studies have already assessed how wave action may affect morphology of intertidal species among sites that vary in wave exposure, but few attempted to look to this issue in smaller scales. Using the most common limpet of the Brazilian coast, Lottia subrugosa, and assuming position on rocky boulders as a proxy for wave action at small scale, we tested the hypothesis that waves may also influence limpet morphology at a smaller spatial scale by investigating how individual size, foot area and shell shape vary between sheltered and exposed boulder sides on three shores in the coast of Ubatuba, Brazil. Limpets consistently showed a proportionally larger foot on exposed boulder sides for all shores, indicating that stronger attachment is an important mechanism to deal with wave action dislodgement at a smaller scale. Shell shape also varied in the scale investigated here, with more conical (dissipative) shells occurring in exposed boulder sides in one exposed shore across time and in the other exposed shore in one year. Shell shape did not vary regarding boulder sides across time in the most sheltered shore. Although we did not assess large spatial scale effects of wave action in this study, variations of the effect of waves at small spatial scale observed for shell shape suggest that it may be modulated by the local wave exposure regime. Our work highlights the importance of wave action at small spatial scales, and may help to understand the ecological variability of limpets inhabiting rocky shores.

The present study describes the variation in the benthic macrofauna related to the presence of Sabellaria wilsoni (Polychaeta: Sabellariidae) reefs on a sandy beach of the Brazilian Amazon Coast. The study also investigated whether the erosion of parts of the reef by intense wave action results in differences in the fauna. Samples were collected from a patch of reef and the adjacent sandy sediment for the analysis of the zoobenthos and substrates (granulometry and organic matter content) on Algodoal-Maiandeua Island (northern Brazil coast). The reef had more heterogeneous sediments and a higher organic matter content, and its fauna was distinct from that of the beach, with a higher density, species richness and diversity. The reef fauna included taxa typical of both consolidated and unconsolidated substrates. The portion of the reef more exposed to wave action had a lower density of reef-building worms, and these worms were smaller in size than those of the more protected portion, although the associated fauna of the exposed portion was denser and richer in species. These results confirmed that S. wilsoni is an important ecosystem engineer on the Amazon coast, and that the diversity and unique features of the fauna associated with these reefs emphasize their importance as a substrate for the local benthic communities, in particular in areas where consolidated bottoms are naturally scarce.

Recruitment of the limpet Patella ulyssiponensis was investigated in relation to the presence of living crustose coralline algae (CCA) in rocky-shore habitats. Juvenile limpets (≤10 mm maximum shell length) were counted in CCA-present and CCA-absent habitats, on three shores in SW Portugal during summer 2007 and winter 2009. Furthermore, the settling response of laboratory-reared larvae of P. ulyssiponensis to CCA-covered substratum, and bare-rock, was examined. Across the intertidal zone, we found a clear association between the distribution and abundance of juveniles and the presence of CCA. Although the presence of CCA was not an absolute requisite for juvenile occurrence, null juvenile densities were mostly recorded in CCA-absent areas. The highest juvenile densities (maximum of 64 individuals in 15 × 15 cm) were consistently found in CCA-dominated habitats, namely steep wave-exposed areas at low-shore and rock-pools. The hypothesis of CCA-enhanced settlement was not supported, as settlement intensities of laboratory-reared larvae were similar between chips of rock encrusted by CCA and chips of bare-rock. From the overall number of settlers onto CCA-encrusted rock chips, 51% were found in tiny pits lacking CCA. This was the first study of the settlement patterns of larvae of the genus Patella using naturally occurring rocky substrata. These results are preliminary and should be confirmed with choice-experiments and improved monitoring of the position of settlers. We suggest that CCA plays a role in the recruitment of P. ulyssiponensis, potentially promoting survivorship of early benthic stages, but possibly not enhancing settlement.

The population and reproductive characteristics of the hermit crab Pagurus proximus Komai, 2000 have been examined in the northern part of the species range (Vostok Bay, Peter the Great Bay, Sea of Japan). The average population density was 4–5 ind m−2 in winter and spring, 10 ind m−2 in summer and autumn; the biomass was 7–9 and 18–19 g m−2, respectively. Hermit crabs were found at a depth of 0 to 12 m but were most numerous at about 3 m depth with an average population density of up to 26 ± 7 ind m−2. The shield length of males varied from 1.3 to 7.8 mm and females from 1.2 to 6.7 mm. The male to female ratio was close to 1 but varied with size and season. Females attained sexual maturity at a shield length of more than 1.3 mm. Ovigerous females were found from December to August. The proportion of ovigerous females increased from 7% in December to 93% in late April; however, the embryos in clutches remained at early developmental stage until May. The mass release of larvae was observed at the beginning of June. A subsequent spawning probably took place in July. The main factors contributing to the high abundance of P. proximus in the investigated area are the presence of the embryonic diapause synchronizing the release of larvae at the most favourable time for their development, high fecundity, the presence of at least two egg clutches during the reproductive season, and total absence of parasites.

The regulatory framework of the red octopus (Octopus maya) fishery includes total allowable catches (TAC), which are based on studies conducted on the population that occurs in shallow waters. In fact, most of the biological studies of this species refer to the fraction of the population that occupies waters less than 30 m deep; however, O. maya can occur up to a 60 m depth. The aim of this study is to assess the stock of O. maya that occupies waters between 30 m and 60 m deep. Four research cruises were carried out during the closed and fishing seasons, from May 2016 to January 2017. An average of 29 sampling sites were surveyed in each cruise (±2 sampling sites) using a commercial vessel with a uniform sampling effort. In each sampling site, the swept area, the total number of octopuses captured, the total weight of the catch, and the individual weight of octopuses were recorded. Biomass was obtained with four methods: stratified random method, swept area method, geostatistical biomass model, and an unpublished method of weighted swept area. The four methods provided consistent results. The distribution pattern of species was in patches, although before the fishing season started it was more homogeneous. The fraction of the population that occurs between 30 m and 60 m deep consisted mostly of adult organisms, so it could be contributing significantly to the recruitment of the entire population, even to the fraction that is exploited.

This study addresses aspects of the phylogenetic relationships of the commercial Tehuelche scallop, Aequipecten tehuelchus s.l. (Bivalvia: Pectinidae), from southern South America using molecular techniques. The Tehuelche scallop presents two different putative subspecies, A. t. tehuelchus and A. t. madrynensis, and a potentially related sympatric species, Flexopecten felipponei. The Tehuelche scallop is a very important component of ecosystems and is the target of artisanal fisheries in the northern Patagonian gulfs of Argentina. Despite its importance, the systematic relationships of these taxa have not been fully addressed. The main goal of this study is to place the Tehuelche scallop within a partial phylogenetic framework of the family Pectinidae. Scallops were sampled at 10 localities distributed along the south-western Atlantic Ocean. Phylogenetic reconstructions were carried out from two mitochondrial (12S rRNA and 16S rRNA) and two nuclear markers (28S rRNA and H3) using Bayesian, maximum likelihood and maximum parsimony analyses. Our phylogenetic analysis indicates that the two putative subspecies of the Tehuelche scallop together with F. felipponei form a monophyletic clade, without differentiating at the specific level. Observed differences would be the result of phenotypic plasticity, probably caused by environmental factors. However, further analysis using genes with faster evolution rate are needed to corroborate it. Our phylogenetic analysis resolved to Aequipecten as polyphyletic. The Tehuelche scallop has a basal position within the Argopecten group and we recommend that it should be transferred to this genus. The relationship between the hypotheses about the origin of the Tehuelche scallop implicit in the literature and our results are discussed.

Mud volcanoes are singular seafloor structures classified as ‘sensitive habitats’. Here we report on the sponge fauna from a field of eight mud volcanoes located in the Spanish margin of the northern Gulf of Cadiz (North-eastern Atlantic), at depths ranging from 380 to 1146 m. Thirty-eight beam-trawl samplings were conducted (covering over 61,000 m2) from 2010 to 2012, in the frame of a EC-LIFE + INDEMARES grant. A total of 1659 specimens were retrieved, belonging to 82 species, from which 79 were in the Class Demospongiae and three in Hexactinellida. Two species were new to science (Jaspis sinuoxea sp. nov.; Myrmekioderma indemaresi sp. nov.) and three others recorded for the first time in the Atlantic Ocean (Geodia anceps, Coelosphaera cryosi and Petrosia raphida). Five additional species were ‘Atlantic oddities’, since this study provides their second record in the Atlantic Ocean (Lanuginella cf. pupa, Geodia cf. spherastrella, Cladocroce spathiformis, Cladocroce fibrosa and Haliclona pedunculata). Basic numerical analyses indicated a significant linear relationship between the species richness per m2 and the number of sponge individuals per m2, meaning that in most volcanoes many species occur in equivalent, moderate abundance. Likewise, sponge species richness increased with depth, while the abundance of hard substrata resulting from carbonate precipitation and the fishing activities around the volcanoes had no detectable effect on the sponge fauna. However, in the latter case, a negative trend – lacking statistical support – underlaid the analyses, suggesting that a more extensive sampling would be necessary to derive more definitive conclusions in this regard.

Understanding variations in the reproductive cycle of commercial and ecologically important bivalve species is essential to address fisheries management and climate oscillation issues. Spatial and temporal trends in the reproductive cycle of Callista chione were analysed using standard histological procedures and gonadosomatic index (GSI) for two consecutive years at two coastal sites in the Adriatic Sea. Reproductive output and fecundity were analysed quantitatively to gain better insight into the seasonal energy balance with respect to gametogenesis. A seawater temperature difference of ~4°C between the two sites likely influenced the onset and duration of spawning. At Cetina (milder temperatures), spawning was prolonged and occurred between spring and July, whereas at Pag there was only one main spawning peak in July. Both histology and GSI showed similar trends, indicating GSI to be a reliable method for analysing the main characteristics of the reproductive cycle. Conversely, the use of the body mass index (BMI) as an indicator of gonad development should be addressed carefully. Intraspecific variation in energy allocation between populations suggested life strategies modified to different habitat conditions. A higher reproductive investment and output in the Pag population directed gonadal resorption to ensure the generation of a new cycle, whereas the higher fecundity at the Cetina site indicated the production of gonads from newly available food. These results suggest successful physiological acclimatization to recent increasing temperatures.

During the period from April to September for the years 2014–2016, 998 swordfishes caught by the Moroccan artisanal longline fishery in the Strait of Gibraltar were sampled to study the reproduction of this species in this mixing area between the Mediterranean Sea and the North Atlantic. The results showed that the sex ratio is slightly in favour of males for sizes smaller than 130 cm LJFL (Lower jaw-fork length), whereas females are more numerous in sizes larger than 140 cm LJFL. Fifty per cent of females were estimated to be mature at 170 cm LJFL, while for males, the size at first maturity was estimated to be 95 cm LJFL. The swordfish spawn from June to September, probably in the Mediterranean Sea. The findings of this study suggest that the reproductive characteristics of swordfish caught in the Strait of Gibraltar are similar to those of the Mediterranean swordfish, and a high mixing rate between the Mediterranean and the North Atlantic stocks occurs in the study area.