High definition video from a towed camera system was used to describe the deep-sea benthic habitats within an elongate depression located at the western margin of Rockall Bank in the Hatton–Rockall Basin. At depths greater than 1190 m, an extensive area (10 km long by 1.5 km wide) of what appeared to be reduced sediments, bacterial mats and flocculent matter indicated possible cold-seep habitat. Plumes of sediment-rich fluid were observed alongside raised elongate features that gave topographic relief to the otherwise flat seafloor. In the deepest section of the depression (1215 m) dense flocculent matter was observed suspended in the water column, in places obscuring the seabed. Away from the bacterial mats, the habitat changed rapidly to sediments dominated by tube-dwelling polychaete worms and then to deep-sea sedimentary habitats more typical for the water depth (sponges and burrowing megafauna in areas of gentle slopes, and coral gardens on steeper slopes).

The abundance pattern and species diversity of phytoplankton in the surface waters of the Golden Horn Estuary were investigated between August 2011 and July 2012 in relation to environmental factors. Seventy-eight phytoplankton taxa (38 diatoms, 30 dinoflagellates and 10 phytoflagellates) belonging to eight taxonomic classes were identified in bottle and net samples. Phytoplankton abundance increased in spring and summer (from March to August) and reached its highest (10,429 × 103 cells L−1) during the bloom of Heterosigma akashiwo (Raphidophyceae) in the middle and upper estuary in late May. In general, phytoplankton abundance was higher in the middle estuary indicating more suitable conditions for phytoplankton growth, while species richness and diversity was higher in the lower estuary. The most abundant species were Skeletonema marinoi and Thalassiosira sp. among diatoms; Scrippsiella trochoidea among dinoflagellates; Plagioselmis prolonga and Heterosigma akashiwo among phytoflagellates. Diatoms were more abundant in the lower and middle estuary, while dinoflagellates and phytoflagellates in the upper estuary. The main factors causing the spatio-temporal variation of phytoplankton in the study area were temperature, salinity, water transparency and nutrients. Water transparency in the upper estuary is mostly influenced by organic and inorganic matter carried by two streams. As a result, this area should be considered a potential risk area for future algal blooms.

The Suape coastal zone has suffered since the 1980s the effects of anthropogenic action due to the construction of the industrial complex of Suape. This work aimed to evaluate the environmental conditions and possible eutrophication processes of the area. Six campaigns were carried out, three in the dry season (November 2015, January and April 2016) and three in the rainy season (July 2015, July and August 2016). Water samples were collected at the surface during low tide and high tide, in neap tides. Salinity ranged from 19.75 to 37.20, the dissolved oxygen rate ranged from 61.75 to 125.90% and chlorophyll-a from 0.02 to 3.48 mg m−3. Water transparency, temperature, nitrate and silicate presented significant seasonal variation, the concentrations of nutrients being higher in the rainy season and the others in the dry season. Water transparency, salinity, dissolved oxygen saturation and chl-a <20 µm showed significant differences for tide, being higher at high tide, and at low tide for chl-a of <20 µm. The low content of dissolved inorganic nutrient salts and chl-a were indicative of an area still free of eutrophication. Anthropogenic changes in the environment have led to greater marine interference and consequently to a reduction of the productive capacity of the system.

Based on some coincident morphological characters and distribution, it was believed for a long time that Mica micula was the post-larval stage of a species of Bargmannia, a genus having a very wide geographic distribution. Recent studies, however, have shown that it is much more likely to be the post-larval form of the physonect Pyrostephos vanhoeffeni, which is very common in both Antarctic and sub-Antarctic waters. Until now, molecular evidence to support this theory has been lacking. In the present study 34 nectophores of P. vanhoeffeni and four colonies of M. micula collected from three areas in the Southern Ocean were analysed for the 16S rRNA gene. Five haplotypes were identified, which formed two clearly distinct lineages. Three haplotypes were found exclusively in Admiralty Bay and were shared between individuals of both studied taxa, confirming that M. micula is indeed the post-larval stage of P. vanhoeffeni. Two additional haplotypes were found in one open ocean locality and in Admiralty Bay.

The present study undertaken in the largest coastal lagoon of Asia, Chilika, deals with monthly monitoring of benthic foraminifera assemblages in terms of distribution pattern, diversity and variations in taxonomic composition spanning over a period of 20 months. In total, 13 species of benthic foraminifera represented by eight families were identified in the lagoon. The stations in the Southern sector of the lagoon showed relatively low foraminifera abundance yet high diversity whereas higher abundance and lower diversity were observed in stations located in the Central sector which indicates the spatial patterning of the assemblage. Live foraminifera abundance was sparse in the study area indicating the stressed nature of the lagoon environment. The dissolved nutrient concentration of bottom water reflected significant seasonal variation. The stressed nature of the lagoon is further indicated by the dominance of the genus Ammonia across the inner sectors of the lagoon, a genus known to inhabit impacted habitats. Overall these data can serve as a baseline proxy for understanding palaeontological assemblages of foraminifera in similar shallow-water settings globally.

Despite alterations caused by anthropogenic activities in Singaporean coral reefs, the sponge communities are quite diverse and Xestospongia testudinaria is one of the most common sponge species. In the present study, we used 16S rRNA gene barcoded pyrosequencing to characterize and compare bacterial communities from different biotopes (sponge, seawater and sediment) and to identify dominant bacterial symbionts of X. testudinaria in a Singaporean coral reef ecosystem. Our results showed that biotope appears to affect the richness, composition and abundance of bacterial communities. Proteobacteria was the most abundant phylum in sediment and seawater whilst Chloroflexi was more abundant in X. testudinaria. Members of the order Caldilineales (fermentation of organic substrates), Chromatiales (purple sulphur bacteria), Rhodospirillales (purple non-sulphur bacteria) and Syntrophobacterales (sulphate-reducing bacteria) were relatively more abundant in X. testudinaria samples.

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 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.

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.

Rock oysters of the genus Saccostrea are the dominating group of filter-feeding communities on rocky beaches worldwide. The edible rock oyster (Saccostrea cucullata) is used as food and fish bait along the Indian coast. Morphometric analyses of S. cucullata from Baindur, Karnataka (India) were performed from June 2010 to May 2011, aiming to establish relationships between length and weight (total weight, shell weight, meat wet weight and meat dry weight). Morphometric relationships between length (L)-breadth (B) and length (L)-width (W) were B = 6.4952 + 0.4619 L and W = 3.1806 + 0.3276L, respectively. The equations of the length (L)-total weight (TW), length (L)-shell weight (SW), length (L)-meat wet weight (WW) and length (L)-meat dry weight (DW) were TW = 0.001227L2.3973, SW = 0.001165L2.3164, WW = 0.000037L2.1327 and DW = 0.000030L2.3289, respectively. The allometric growth pattern revealed changes in shell shape and weight variation throughout ontogeny in rocky habitats. The condition index and meat yield of S. cucullata exhibited seasonality, with higher values recorded during the periods post-monsoon and pre-monsoon.

Abalone (Haliotis spp.) are commercially important marine shellfish species worldwide. Knowledge about the physiology of abalone that impacts life-history traits is important for a better understanding of the biology of the species and the impact of stressful husbandry procedures at different seasons. The present study quantified the seasonal and diurnal variations in four physiological parameters of the European species Haliotis tuberculata, i.e. carbon aerial and aquatic respiration, calcification and excretion rates, and the effect of prolonged aerial exposure upon abalone aerial respiration. We also investigated the effect of individual size upon these physiological parameters. Aquatic respiration and calcification rates showed an allometric relationship with biomass. All parameters showed lower rates in cool season and higher rates in warmer season. Temperature was assumed to be the primary driver of the reported seasonal variability in physiological parameters, although reproductive needs and nutrition may also contribute to the observed patterns. Importantly, abalone did not stop calcifying in winter, and calcified more at night than during the day. Abalone did not respire more underwater at night-time than at daytime, however they excreted more overnight. The low air:aquatic ratio (0.2) is likely to be an energy-saving strategy for emerged H. tuberculata individuals. This study highlights the temporal heterogeneity in physiological rates of H. tuberculata, which constitutes a species recently domesticated in Europe.

The shallow sandy marine subtidal ecosystem off Mar del Plata, Argentina, is the scene of multiple fisheries activities, in particular the prawn–shrimp Artemesia longinaris and Pleoticus muelleri grounds. We examined the δ13C vs δ15N isotope signatures of 22 species commonly found in the area in order to understand how this ecosystem supports the fishery, with special emphasis on imposex-affected gastropod populations. Our results indicate that the main food source for Olivancillaria urceus and Buccinanops monilifer were bivalves and crustaceans. Buccinanops duartei and Olivancillaria carcellesi feed on bivalves and also on macroalgae. These findings indicate, for the first time, a slight selectivity of some of the gastropods studied for local drifted algal sources and how gastropods may scavenge available food from by-catch returned to the sea. The fishes Urophysis brasiliensis and Callorhynchus callorhynchus appeared to be the top predators of this area with B. duartei and O. carcellesi constituting important components of their diet.

Time-lapse photography was used to study the timing and duration of foraging activity of a population of the pulmonate gastropod Onchidella celtica on an exposed rocky shore in Cornwall, UK. The pulmonates spent most of their time in their home crevice, emerging onto open rock only during some ebb tides to forage for food and find a mate. Total duration and speed of foraging was highly variable and did not generally conform to a triphasic pattern. The number foraging was also highly variable and was not correlated significantly with the spring/neap tide cycle or weather (air temperature above 12°C, air pressure, solar radiation, precipitation, relative humidity and wind speed). There was a significant negative correlation between foraging and surf height. Although the pulmonates foraged during all hours of the day/night cycle, foraging activity tended to be highest during the afternoon and evening.

The potential use of fatty acid (FA) profile as a dietary tracer in juvenile Chinese horseshoe crab Tachypleus tridentatus was assessed in a feeding experiment. Selected feed was provided to the juveniles at various growth stages according to their food sources in the wild: larval and adult brine shrimp Artemia salina for the first six months, followed by a mixture of short-neck clam Ruditapes philippinarum and greasyback shrimp Metapenaeus ensis for a further six months. Juvenile horseshoe crab haemolymph and tissues of book gill, opisthosomal spine, chelicera and swimming leg were sampled after the feeding experiment. The FA profiles revealed that the juvenile haemolymph and various tissues had a total of 23–24 FA components. The major FA components consisted of saturated (palmitic and stearic) at 22–34%, monosaturated (oleic) at 7–34% and polyunsaturated (eicosapentaenoic and arachidonic) FAs at 9–27%. According to principal component analysis, the FA signatures of juvenile haemolymph were greatly influenced by the shift of food sources from brine shrimp to clam and shrimp meat, whereas the FA profiles of different tissues were more resistant to the nutrient alteration. The present findings confirmed that the FA profile of both juvenile haemolymph and different tissues reflected the FA composition of recent and previous diets, respectively; and thus may be useful in indicating the foraging information of juvenile horseshoe crabs in the field.

This study describes the structure, growth, mortality and stock status of Litopenaeus schmitti in north-eastern Brazil. A total of 1169 specimens were captured (491 males and 678 females) from August 2011 to July 2012. Specimens were weighed and the length of carapace (CL) and total length were measured. The biometric relationships were estimated through regression analysis and growth was described through the von Bertalanffy model. Additionally, total mortality (Z), natural mortality (M), fishing mortality (F), length at first capture (Lc), maximum yield per recruit (ERMY) and longevity were determined. Females were larger (3.07 ± 0.51 cm) than males (2.68 ± 0.25 cm) and dominant in the largest CL classes. The biometric relationships for males, females and both sexes grouped showed a negative allometric growth. Females showed larger L∞ (asymptotic length) and k (coefficient of growth) (L∞ of 5.00–5.16 cm and k of 1.20–1.26 year−1) when compared with males (L∞ of 4.25–4.30 cm and k of 1.00–1.02 year−1). In general, the mortality of males (Z = 1.93–5.48 year−1; M = 1.59–1.61 year−1 F = 0.32–0.3.89 year−1) and longevity (1.11–2.16 years) were higher than those estimated for females (Z = 1.84–3.76 year−1; M = 1.70–1.77 year−1; F = 0.07–1.99 year−1; 1.07–1.78 years). Results indicated that L. schmitti stock is relatively close to the state of full exploitation. Moreover, the CL of first capture of females (2.44–2.51 cm) is below the length of first sexual maturation of the species. The lack of legislation governing shrimp fishing in the area makes this stock even more vulnerable.

During the INDEMARES/CHICA 0610, 0211 and 0412 expeditions, carried out in the northern Spanish sector of the Gulf of Cádiz (Spain), samples were collected with a box-corer in 11 mud volcanoes and their adjacent bottoms. Chemoautotrophic communities were found in nine mud volcanoes. Among Decapoda, a rare eucalliacid, belonging to the genus Calliax and related to the Mediterranean infralittoral species C. lobata (de Gaillande and Lagardère 1966), was present in three of them. Data on its morphology, biogeographic distribution, vertical distribution within the burrows, sediment composition, pH and redox potential values (each in 5 cm intervals) are given; information on the chemoautotrophic communities associated with this species are also provided.

This paper provides data on diversity, zonation and seasonal fluctuations of decapod crustaceans at the northern Gulf of Oman coast, based on quantitative and qualitative samplings. A total of 75 species belonging to four infraorders, 27 families and 48 genera were identified. These species include 20 new records for the entire Gulf of Oman and 13 new records for its Iranian coast. The mid-intertidal zone showed a higher mean diversity and abundance than high- and low-intertidal zones. The mean diversity and abundance in the high-intertidal zone showed significant differences with the mid- and low-intertidal zones. The indices of species richness (Margalef), diversity (Shannon) and evenness (Pielou) showed significant differences among the intertidal zones. Most of the identified species (>60%) that had high values in their frequency of occurrence and relative abundance showed an overlapping vertical distribution, and were present in all three or just in two of the three defined zones. Other species were found only in one of the three zones (non-overlapping vertical distribution). The decapod community in the mid-intertidal zone showed a higher dissimilarity with the high-intertidal zone than with the low-intertidal. Both abundance and diversity were found to be lowest and highest during south-west and north-east monsoons, respectively. During south-west monsoon, the abundance of decapods declined dramatically, but species diversity and ecological indices did not show any statistically significant difference among the sampling periods.

Crustacean decapod assemblages were surveyed in Zostera marina beds adjacent to tidal flats (ET) and rocky shore (ER), and in unvegetated habitats (UV). Decapod samples were collected monthly throughout 2002 using a small beam trawl from northern Jinhae Bay, Korea. Water temperature, salinity, eelgrass biomass, sediment composition and organic matter were also monitored to assess any correlation between environmental variables and decapod fauna. A total of 31 decapod species belonging to five taxa (three prawns, 13 caridean shrimps, one hermit crab, one mud shrimp and 13 crabs) were collected at three different habitats. To assess variations in decapod assemblages in relation to habitat type and season, various multivariate analyses were used. The dominant caridean shrimps were Palaemon macrodactylus, Alpheus digitalis and Crangon uritai, and the dominant crabs were Charybdis japonica, Hemigrapsus penicillatus and Charybdis bimaculata. The number, abundance and diversity of decapod species varied greatly with habitat type and season, peaking in eelgrass beds and during spring, and showing the lowest catch rate in unvegetated habitat and during winter months. The nMDS ordination and multivariate analyses revealed that habitat type and season were determinant factors affecting the structure of decapod assemblages. Seasonal shifts in the abundance of decapods corresponded with changes in eelgrass biomass and loss on ignition (LOI), but not with water temperature or salinity.

Differences between sexes may arise either during development or at the adult stage only. In both cases growth rate during development and level of allometry may influence sexual dimorphism and ontogenetic trajectories. To analyse the period in which sexual dimorphism appears during ontogeny and assess allometric ontogeny in Sesarmidae crabs, we evaluated: (1) sexual dimorphism in shape and size of the carapace and cheliped propodus of juveniles and adult Aratus pisonii and Armases rubripes, and (2) their ontogenetic trajectory, using geometric morphometric (GM) techniques. We tested the hypothesis that sexual dimorphism in sesarmid crab shape takes place before the puberty moult. In Aratus pisonii there was sexual dimorphism in the shape of the carapace in juveniles (before puberty moult) and variation between juveniles and adults was size-dependent, especially in the frontal region of the carapace. For Armases rubripes this shape sexual dimorphism was detected only after the puberty moult (adult phase). For males, carapace variation between juveniles and adults was also size-dependent, especially in the carapace frontal region, but for females, there was a change in shape with different trajectories. Our results also indicated that shape variation is a common pattern during growth for Sesarmidae species. This ontogenetic shape variation may be associated with spatial partitioning between juveniles and adults.