Seasonal changes in spatial structure of biomass of submerged aquatic vegetation (SAV) and environmental variables were evaluated in Celestun Lagoon, an estuarine habitat in Mexico. Geostatistical techniques were used to evaluate spatial autocorrelation and to predict the spatial distribution by kriging. The relative contribution of 11 environmental variables in explaining the spatial structure of biomass of SAV was evaluated by canonical correspondence analysis. Spatial partitioning between species of SAV was evident: the seagrasses Halodule wrightii and Ruppia maritima dominated the seaward and central zones of the lagoon, respectively, whereas the green alga Chara fibrosa was constrained to the inner zone. The spatial structure and seasonal variability of SAV biomass were best explained by organic carbon in the sediments, salinity and total suspended solids in the water column. Analysis at different spatial scales allowed identifying the importance of spatial structure in biotic and abiotic variables of this estuarine habitat.

In this work, we evaluated the influence of long rocky jetties (~5 km) on fish abundance and diversity between sheltered and exposed marine sandy beaches. We also described and compared the fish community structure and investigated the relationships between environmental variables and fish assemblages. Fish were collected monthly with a beach seine net from May 2001 to May 2002 at the Cassino and Mar Grosso beaches. Twenty-nine taxa were caught and the fish assemblage showed similar composition between beaches (Sj = 62.1%; %Min = 52.3%), with 18 species in common. Most of the fish were juveniles, mainly young-of-the-year with sizes ≤60 mm total length. Eight species (Trachinotus marginatus, Mugil liza, Brevoortia pectinata, Menticirrhus littoralis, Menticirrhus americanus, Odontesthes argentinensis and Oncopterus darwinii) were the most abundant, accounting for 95.6% of the total catch. At both beaches, only T. marginatus, M. liza and M. littoralis were frequent and abundant, but with some differences in their relative abundance. The canonical correspondence analysis results showed that temperature had the highest correlation with fish abundance. Seasonal changes in fish assemblage structure were evident, with a greater species diversity and abundance in the spring and summer. The overall results indicate that the presence of jetties had no effect on fish assemblages of adjacent sandy beaches. Moreover, differences between beaches were related to some species abundance and not to differences in the number and composition of species between beaches.

Near-shore recent benthic foraminifera from three ecologically important (Olive Ridley turtle congregation sites) but vulnerable sites encompassing 23 sampling stations (12 in Rushikulya, 5 in Devi and 6 in Gahirmatha) along coastal Orissa, north-west Bay of Bengal (BoB) in India were studied for the first time for their composition, distribution and assemblage patterns. Thirty-nine species of benthic foraminifers (from 6 orders and 23 families) were identified of which all 39 were present in Rushikulya, 22 in Devi and 12 in Gahirmatha with abundance ranging from 35–2620 individuals/10 cm3 in the sediments. The communities across the sites were dominated by eurytopic rotalids followed by miliolids and textularids. Benthic foraminifer assemblages were found to be dominated by Ammonia species complex (up to 38% in Rushikulya, 64% in Devi and 22% in Gahirmatha). Agglutinated foraminifers were infrequent in the sediments (7 species in Rushikulya, 4 species in Devi and 3 in Gahirmatha) on the other hand, being dominated by Quinqueloculina agglutinans in Rushikulya and Trochammina macrescens and Ammobaculites agglutinans in Devi and Gahirmatha. The substrates along the study sites were found mostly to be sand dominated and in some of the stations sediment composition influenced the foraminifer distribution pattern. The present findings on the assemblage patterns of benthic foraminifers from three coastal settings in Orissa along the BoB are comparable with previous reports from other sandy coastal ecosystems in the world. Overall these data provide valuable insights into the distribution and assemblage patterns of benthic foraminifers from the BoB coastal regions.

Sponges (phylum Porifera) are important components of the benthic marine fauna known for their interactions with vertebrates and a large number of invertebrates seeking for food, shelter or substrate for attachment. Studies on this subject, however, were restricted only to the macrofauna inhabiting sponges of the class Demospongiae. In the present work, we describe the macrofauna associated with a calcareous sponge in Brazil, Paraleucilla magna. Individuals of this allegedly non-native species were monthly collected during one year in Rio de Janeiro (Brazil). Fifty-one taxa representing ten animal phyla were found associated with P. magna. The most frequent and abundant taxa were Crustacea, Mollusca, Polychaeta and Bryozoa, while echinoderms, cnidarians, ascidians, nemerteans, platyhelminthes and sponges were less frequent or even rare and less abundant. Juveniles of several taxa and pregnant females of Crustacea were found associated with P. magna, but these associations were not exclusive. The macrofauna associated with P. magna did not present a clear seasonality, although it was possible to observe a change in the community composition alongside the year. The volume of the sponges was significantly related to the diversity index (H′) and number of taxa, but not with evenness (J′) and number of individuals. Our results show that P. magna is used as a substrate for attachment and/or shelter by its associates and that most of these associations are just opportunistic. The data presented here reiterate a previous proposal that sponges are important biodiversity reservoirs and that they should be seriously considered in conservation programmes.

Haliclona indistincta has in some respects, a typical reproductive cycle for a marine haplosclerid sponge. We suggest that oocytes originate from archaeocytes and that spermatozoa originate from choanocytes. Oocytes were first seen in November and matured as eggs by May and June. Immature spermatic cysts were identified from February and mature cysts were present in May and June only. Of the individuals surveyed that had reproductive elements present (150/200), reproductive elements from a single sex were reported in over half of the specimens (59%) but there were also many hermaphrodites (41%). Embryos were first seen in June. Larvae were distributed throughout the mesohyl and were released from the end of June to the end of July. Three mobile larval stages and fusing of sibling larvae were observed. Post-settlement stages from early settlement to the development of oscula and excurrent canals are also shown. However, some elements of the larvae (uniform ciliation and no spicules at posterior pole) are not consistent with larvae from this genus.

Virus-like particles were observed in thin sections of partially bleaching colonies of the scleractinian Acropora cytherea, collected in the Hon Mun Marine Protected Area (Vietnam). The most common particles were found in the cytoplasm of epidermal cells, exhibiting icosahedral symmetry and measuring 90–140 nm in diameter. Some had a tail-like structure resembling that of certain Hepadnaviridae such as the hepatitis B virus. Some others were tailless with a virion size. Overall, less than 10% of the cells showed obvious signs of infection. Images of virally-parasitized tissues of A. cytherea provide further evidence that corals are a target for viral infection. However, more research is required into their pathogenicity and involvement in bleaching events.

The majority of biochemical studies in corals has been focused on the lipidic composition and little attention has been given to the amino acid profile of these invertebrates. The objectives of this work were to investigate, for the first time, the temporal variations in the total amino acid (AA) composition of an octocoral, namely the sea pen Veretillum cynomorium, and to evaluate possible interspecific differences in AA profile between this octocoral and hexacorals. The quantitatively most important AAs in V. cynomorium colonies were: glutamic acid, varying from 3.92 to 5.94% dry weight (dw) and representing around 14–15% of total AA content; aspartic acid (3.34–4.99% dw; 11–12%); and glycine (2.87–4.57% dw; 9–12%). On the other hand, the minor AAs were methionine (0.41–0.73% dw; 1–2%) and histidine (0.54–0.76% dw; 2%). Almost all AAs showed the same significant seasonal variations, with the highest values in February, second highest in October and the lowest in June. Some AAs, namely lysine, phenylalanine and methionine did not follow this trend and showed the major peak in October. Most of the AA variations seemed to be linked to changes in food availability and/or gametogenesis. Principal component analysis clearly separated the octocoral from the group of hexacorals, mainly due to the higher percentages of arginine, tyrosine and glycine in V. cynomorium, and valine, serine, histidine, isoleucine and alanine in hexacorallia species. We speculate that this differentiation possibly derived from physiological differences related to phylogeny, and was not affected by reproductive or environmental seasonality.

Jellyfish display strong population variability. Competitive interactions between fish and jellyfish have been depicted as a major mechanism controlling this variability. Biological associations involving jellyfish are, however, more diverse than predation–prey interactions and remain poorly understood. Parasitic associations in particular may have relevant effects on jellyfish host populations. We studied basic patterns (temporal patterns of parasite intensity–biomass and the distribution pattern of parasites among hosts) of the association between the parasitic anemone Peachia chilensis and its scyphozoan host, Chrysaora plocamia. The mean number of parasites per host (MI) was high (average = 465) and showed significant differences during the pelagic life phase of the medusa. The mean biomass of parasites per host was also significantly different among months but showed a different temporal pattern to that of MI, which may reflect recruitment pulses of parasitic larvae. The mean biomass of P. chilensis per host averaged 56.3 mg ash-free dry mass, which represents a trophic flow of energy probably linking pelagic and benthic food webs. The distribution of parasites among hosts was best fitted to the negative binomial distribution model, as typical for host–parasite systems. We concluded that the parasite-induced host mortality and reduction of fecundity, represented by parasitic castration, is restricted to a few hosts and is therefore under the expected levels that characterize the dynamic equilibrium of host–parasite systems.

Two new free-living marine nematodes belonging to the family Thoracostomopsidae, subfamily Enoplolaiminae and the genera Epacanthion are described from Patagonian coastal areas, Río Negro and Chubut provinces of Argentina. In Epacanthion bicuspidatum sp. nov. the main features are: two cusps on distal mandible end; presence of two rings of eight setae in the cervical region; and eight crown-shaped setae along the body, presence of one supplement distant two cloacal body diameter (cbd) from cloacae, gubernaculum and short spicule. Epacanthion ampullatum sp. nov. is characterized by having a tubular and long pre-cloacal supplement, short spicule, presence of gubernaculum, presence of three long setae on the tip of the tail, the presence of one supplement distant three cbd from cloacae and the presence of two small cusps on the distal end of the mandible.

The genus Acantholaimus (Chromadoridae: Nematoda) is one of the most species-rich deep-sea nematode genera. The descriptions of two new species and supplemental descriptions of five known species from the Angola Basin (south-east Atlantic Ocean) and a depth of about 5500 m are given. Acantholaimus formosus sp. nov. is characterized by a spindle-shaped body with narrow elongated anterior end, the position of amphideal fovea on the apical tip of the body and by robust rugae and onchia. Acantholaimus skukinae sp. nov. is characterized by its cylindrical body shape; short outer labial, cephalic, cervical, and somatic setae; large amphideal fovea; the position of its amphideal fovea (situated relatively far from the head end); and relatively small onchia. Acantholaimus angustus was previously found in the Peru Basin (central-eastern Pacific) and the Clarion–Clipperton Nodule Province (Equatorial Pacific), about 13,000 km apart from the nearest previous location of finding. The type location of A. verscheldi is the Kenyan coast of the Indian Ocean. New specimens of this species were found about 8000 km apart from the type location. Acantholaimus akvavitus, A. iubilus and A. quintus were previously found in different parts of the Atlantic and the Pacific.

A new marine tardigrade of the genus Tanarctus is described from Japan. Tanarctus diplocerus sp. nov. was collected from Shimabara Bay, Kumamoto and Tanabe Bay, Wakayama. It is characterized by simple leg IV appendages, the lack of the internal–external relation in the dorsal and ventral cirri and the lack of the club-shaped secondary clavae. The secondary sexual dimorphism of the primary clavae and probable two-digit juveniles of the new species are reported. The problematic terminology of the so-called ‘internal’ and ‘external’ cirri is also discussed. A taxonomic key for the species of Tanarctus is provided.

Nuchalosyllis Rullier & Amoureux, 1979 is an extremely rare syllid genus, only known from the holotype of its type species, N. lamellicornis Rullier & Amoureux, 1979. The genus is characterized by the dorso-ventrally flattened body and the unique comb-like nuchal epaulettes. We herein describe the second specimen of this genus ever found, which is also a new species, Nuchalosyllis maiteae sp. nov.; it differs from N. lamellicornis in having different morphology of nuchal epaulettes, spinose papillae on cirrophores of dorsal cirri throughout and sub-bidentate posterior body falcigers.

The small polychaete family Trochochaetidae is monogeneric and had been recorded almost exclusively in the northern hemisphere before this study. During a benthic investigation in the coastal shelf zone off Angola at 15°S several specimens were collected from 84 m depth differing from other members of the family and we described it as a new species herein. The only known African species so far was Trochochaeta kirkegaardi from the eastern Atlantic. Trochochaeta ankeae sp. nov. is characterized by having four minute eyes, a small conical antenna, a nuchal crest projecting through chaetiger 2, by lacking notochaetae on chaetiger 2, by having acicular spines on neuropodia 2 and 3 and a pair of conical papillae ventral on abdomen. A key to all 11 known species (including an unnamed one) is given.

Several studies have been conducted to explain patterns of the abundance, richness and diversity of sandy-beach macrofauna; however, such analyses have ignored the overall functional structure of macrofauna communities. Few studies have examined polychaete feeding guilds on sandy beach environments. To examine the effects of environmental factors on polychaete feeding guilds on sandy beaches, 12 sandy beaches from five islands in Sepetiba Bay were sampled. A total of 24 polychaete morphospecies, grouped among 21 families, were identified in these sandy beaches. The polychaete species were classified into 10 feeding guilds, and the SDT guild (suspended-deposit feeders, discretely motile, with tentacles) was the most abundant feeding guild, with 34.2% of total number of organisms. The highest trophic importance index and index of trophic diversity values were recorded on the sheltered beaches. A canonical correspondence analysis showed that the exposure rate, beach length, and grain size of the beach sediment significantly affected the polychaete feeding guild distribution and abundance. We can conclude that sheltered beaches have a higher diversity of feeding guilds than exposed beaches and that the biological descriptors of the feeding guilds are directly associated with the grain size of the sediment.

Mooreonuphis bidentata, a new species of onuphid polychaete, is newly described from the Mexican Caribbean. It was found in dead coral rocks at depths of 2.2 m and can be distinguished from its congeners by having simple filaments branchiae from chaetigers 19–24, as well as bi- and tridentate pseudocompound falcigers and large median simple tridentate hooded hooks in the first four chaetigers. Including M. bidentata sp. nov., the genus Mooreonuphis includes 19 species, which have been exclusively collected on the American coasts, mainly in tropical and temperate waters. From the Caribbean Sea, six species have been recorded. Of these, M. bidentata sp. nov, M. cirrata, M. dangrigae and M. intermedia are the only species having their locus typicus in this tropical region. A taxonomic key is presented for all the species of Mooreonuphis recorded from both sides of the American seas.

A new species of deep water Epimeria is described based on material collected in 1526–1586 m depth during the TALUD X expedition in the central Gulf of California, Mexico. It is the sixth species of this genus reported for the East Pacific. Epimeria morronei sp. nov. is morphologically similar to E. norfanzi Lörz, 2011 (New Zealand, 1268 m depth) and E. cora J.L. Barnard, 1971 (off Oregon, USA, 2086 m depth). Epimeria morronei sp. nov., however, differs from these two species by a combination of several characters, including: vestigial eyes; multidentate mandibular lacinia mobilis; a distinct setae arrangement in palm and dactylus of gnathopods 1–2; the shape and relative size of coxae 1–5; and the shape of the telson.

The mud shrimps of Iran are not well known. Material for the present study was collected from 21 out of 51 intertidal localities from the Persian Gulf and Gulf of Oman, Iran. In total, 11 species were found along the Iranian coast. These were belonging to three families, including Upogebiidae (Upogebia carinicauda, U. darwinii and U. pseudochelata), Callianassidae (Neocallichirus jousseaumei, N. calmani, Callichirus masoomi, Corallianassa coutierei, Michaelcallianassa indica, Paratrypaea bouvieri and Gourretia coolibah) and Callianideidae (Callianidea typa). Geographical distributions of the species were considered and the results show that each species is totally dependent on a special type of habitat. Comparing different types of habitat, sandy and muddy substrates of the intertidal and shallow subtidal zone are found as the dominant habitat type for all species, but some species have a preference for boulder dominated coasts or occupy already existing holes and crevices in the boulder and bedrocks. In addition, the world distribution of each species was considered, and according to their present recorded localities, these are grouped into two distributional categories including the Indo-West Pacific region and one in a broader area of the Indo-Pacific.

We investigated morphological differences in specimens of the arcid bivalve Scapharca kagoshimensis collected from two sites differing in turbidity in the inner part of Ariake Bay. First, we confirmed if the specimens collected from the two sites were the same species by comparing the sequences of their nuclear 18S ribosomal DNA (18S rDNA) and cytchrome c oxidase subunit I gene (COI) of mitochondrial DNA (mtDNA), since the closely related species S. inequivalvis could be distributed in one site. The results of DNA analyses showed that specimens from both sites belonged to the same species. Shell morphology, gill and posterior adductor muscle size did not differ between the two populations. However, the size of the labial palp was significantly larger in bivalves living in an area of high turbidity compared with those living in an area with low turbidity. This difference could not simply be attributed to differences in meat content because the total weight of the soft body parts did not differ between the two populations. The labial palp is an organ functioning in preingestive particle selection. Hence, the large palps would presumably be a response to high turbidity conditions in which the need for particle processes increases. To the best of our knowledge, this is the first study demonstrating palp size flexibility in arcid bivalves, and such flexibility could be a factor enabling S. kagoshimensis to successfully exploit a wide area of shallow water in the inner part of Ariake Bay.

Iheyaspira bathycodon sp. nov. is described from the Von Damm Vent Field on the world's deepest spreading centre, the Mid-Cayman Spreading Centre (MCSC), Caribbean, at 2300 m depth. The new species is defined and illustrated from 11 specimens, with brief notes on habitat and known distribution. Molecular phylogenetic data from partial COI mDNA, 16S rDNA and nuclear 18S rDNA regions are used to analyse the species’ phylogenetic position and its morphology is compared with previously described skeneid and vent taxa. The new species is distinguished from the most closely allied vent species, Iheyaspira lequios Okutani, Sasaki & Tsuchida, 2000 by morphological differences in radula diagnosis and appendage structure of the head-foot. Iheyaspira bathycodon sp. nov. is the tenth turbinid to be described from a hydrothermal-vent environment and the second species to be named from recently discovered hydrothermal vents on the MCSC. Determining the faunal composition of assemblages at the vent fields of the MCSC will help to elucidate the vent biogeography of the region.

Animal movements in heterogeneous environments shape most ecological processes from individuals to ecosystems. The identification of the processes underlying animal movements thus has critical implications in a wide range of fields. Changes in the motion behaviour of free-ranging species have mainly been reported across different spatial scales but have been less investigated over time. Here the processes potentially triggering temporal changes in movement, microhabitat occupation and distribution patterns of the intertidal herbivorous gastropod Nerita atramentosa were examined on a south Australian rocky shore during 8 successive daytime low tides considered in four different months. The observed temporal shift in microhabitat occupation and aggregation behaviour was likely an adaptation to both abiotic and biotic stressors such as temperature and food distribution. In contrast, the temporal changes observed in N. atramentosa motion behaviour are consistent with optimal foraging strategies driven by the presumed variability in both microalgal density and distribution. Individuals seemed to switch from an extensive foraging strategy in February and May to an intensive strategy in August and October. Specifically, N. atramentosa seemed to adopt two different foraging strategies, a Lévy-like foraging strategy in May and a ballistic foraging strategy in February when the resources are expected to be respectively non-depleted and depleted. The Brownian foraging strategy theoretically expected under high food density conditions was however not observed. The potential role of the behavioural flexibility observed in N. atramentosa motion behaviour is discussed in relation to the persistence of this species under disrupted environmental conditions.