Benthic communities form an important component of the marine food chain. Their occurrence also provides information on the health of the ecosystem. A study was carried out to understand the distribution and abundance of macrobenthos along with sediment characteristics and physicochemical parameters in Visakhapatnam Harbour, a major port along the east coast of India. In all 84 macrobenthic taxa were reported from the port area of which 60 were polychaetes and 24 were other invertebrate taxa. Our observations revealed an increase in the number of polychaete species observed over the last 20 years from this region. An earlier study reported 38 polychaete species in 1975 and a year later the number of polychaete species reported was 12, indicating an increase in the number of polychaete species in the present study by about 150%. The macrobenthic abundance and dominance of species varied with the seasons. Pre-monsoon was dominated by Cirratulus sp., during monsoon tanaids were dominant indicating a seasonal shift in the occurrence and dominance of macrobenthos. During post-monsoon, Cossura coasta was dominant followed by Nephtys dibranchis and amphipods. Sediment characteristics (sand, silt and clay), organic carbon and dissolved oxygen were the important factors influencing the abundance and species diversity. The abundance of macrobenthic forms also varied with inner and outer harbour region. Higher species diversity was observed in the outer harbour suggesting the outer harbour has semi-polluted conditions such as higher dissolved oxygen (DO) and salinity, low nutrients (nitrite, nitrate and silicate) and low organic carbon in the sediment.

The variations in the composition and structure of macroinvertebrate benthic communities in relationship with the marine sediment enrichment with heavy metals were investigated in the Gulf of Gabes, Tunisia. Standard community parameters as well as the trophic and ecological structure were analysed in 18 stations sampled in six localities. Highest values of diversity descriptors (S, N and H′) were recorded in the less-polluted localities and vice versa. Besides, the results of AMBI and BENTIX indexes were also concordant with those obtained with the classical diversity parameters and matched with the sediment heavy metals distribution in the Gulf of Gabes. Compared with the northern and southern parts of the Gulf, the central area was found to be the most polluted and to host the most-affected benthic community. In addition, biotic indexes were found to be very useful tools to monitor the ecological quality status of benthic assemblages.

The Adriatic Sea, being a semi-closed and shallow basin, is more sensitive to anthropogenic impact than other areas of the Mediterranean Sea. Given the crucial role of meiofauna in the marine ecosystems, temporal series of data on this benthic assemblage are fundamental to give new insights into the health status of this basin. A data set (decade 2002–2012) on the meiofauna of two river mouths (Foglia and Metauro) close to a Natural Park (Monte San Bartolo, Central Adriatic Sea) has been analysed and related to several environmental parameters. In particular, changes in the meiofaunal structure, abundance and diversity have been investigated in order to evaluate possible variations of ecological quality status (EQS), in accordance with the Water Framework Directive. The structure of the meiofaunal assemblage appeared significantly different in the period studied, with a higher abundance of annelids in 2002 and an increase of nematodes in the following sampling campaigns. Among the faunal parameters, the Shannon and Pielou indices suggested a decline of the EQS over time, likely mainly due to the negative effect of chlorophyll-a peaks, which may highlight the influence of eutrophication phenomena and an enhancement of the organic matter supply. The lowering of the EQS of the study area suggests the need to intensify management and conservation efforts in the coastal systems, and supports the use of the meiofaunal assemblage as a useful bioindicator.

Sea-cage fish farms impact the seabed within their immediate vicinity, potentially affecting recipient communities. We assessed whether proximity to three sea-cage fish farms at the Canary Islands altered patterns in the abundance, assemblage structure and richness of soft-bottom macrofauna. We related among-farm variability in dissimilarities in macrofaunal assemblage structure between seabeds beneath cages and controls to differences in hydrodynamics, production and seabed topography. Contrasting patterns of species abundances with varying proximity to fish farms were observed: some species decreased while other species increased their abundances with increasing distance at some farms. Although faunal assemblages at 0 m (i.e. beneath the cages) were different, in terms of assemblage structure, from those found at controls, pairwise differences in assemblage structure among distances away varied among the studied fish farms. Species richness showed inconsistent patterns with proximity to cages among fish farms. In summary, inconsistent patterns of macrofaunal assemblages with varying proximity to aquaculture facilities preclude confident predictions on the way offshore aquaculture alters macrofauna in the study region.

Thraustochytrids, the exclusively marine organisms of kingdom Stramenopila and a source of essential fatty acids in the marine milieu, possess an osmoheterotrophic mode of nutrition and are therefore affected by type and source of available organic matter and pollution. To study their response to heavy metal pollution, they were isolated from the brown alga Sargassum cinereum from the coastal waters of Dona Paula, Goa, India. A total of 22 isolates were obtained from two samples collected during February and March 2012. Based on their 18S rRNA gene sequencing, the majority of the isolates were identified as Thraustochytrium kinnei. The rest were identified to be Sicyoidochytrium minutum, Ulkenia visurgensis and species of Thraustochytrium and Aurantiochytrium. Six isolates were screened for various enzymatic activities. Characteristic and distinctive enzyme profile was obtained from isolates of different genera. All isolates were also screened for their tolerance to heavy metals. They showed good growth in the presence of Mn2+. The other metals that were tolerated by most of the isolates were in the order Ni2+ > Cr6+ > Zn2+. Seven isolates grew in the presence of Cu2+, and six in the presence of Cd2+. The isolates growing on metals showed vast differences from their normal morphology such as small colony size, shrunken cells etc. Scanning electron micrographs revealed holes or depressions in the cell wall in the presence of metals. On the whole, the isolates belonging to Ulkenia visurgensis and Aurantiochytrium sp. showed tolerance to more metals than Thraustochytrium kinnei. Cluster analysis showed no peculiar trend of metal tolerance to any particular genus as the characters were scattered in the clusters.

Ciliates are a primary component of the periphyton microfauna and play a crucial role in the functioning of microbial food webs. Seasonal variation in community structures of periphytic ciliate communities was studied, using glass slides as an artificial substratum, during a 1-year cycle (August 2011–July 2012) in coastal waters of the Yellow Sea, northern China. Samples were collected monthly at a depth of 1 m from four sampling stations. A total of 144 ciliate species representing 78 genera, 43 families, 17 orders and eight classes were recorded. Among these species, 31 distributed in all four seasons, while 11, 11, 13 and two forms occurred only in spring, summer, autumn and winter season, respectively. The species number and total abundance peaked in spring and autumn, with minimum values in winter. Ciliate community structures differed significantly between seasons, and were significantly correlated with the changes in environmental variables, especially temperature, pH, dissolved oxygen (DO) and the nutrients. Of 36 dominant species (top 15 ranked contributors in each season), nine (e.g. Pseudovorticella paracratera, Trochilia minuta and Zoothamnium sp.) were significantly correlated with pH, DO or nutrients. Species richness, evenness and diversity measures were significantly correlated with temperature, pH, DO or soluble reactive phosphates. Results demonstrated that periphytic ciliates exhibited a clear seasonal variation in community structures in response to environmental conditions and potentially might be used as a robust bioindicator for assessing environmental quality status in coastal waters.

The near-cosmopolitan genus Clytia is abundantly found in coastal waters, but difficulties of identification in this genus make nearly all species records of medusae suspect. Complex life histories, ambiguous taxonomic characters, and phenotypic plasticity pose serious problems for accurate species-level identifications and future revisions of Clytia species. In the present study, morphological investigations and molecular analyses of Clytia specimens from the coastal waters of the East China Sea revealed Clytia gulangensis sp. nov. as a new species. DNA barcoding based on the mitochondrial cytochrome oxidase I (COI) gene supported the new species as a separate species within Clytia, and phylogenetic analyses based on mitochondrial 16S rDNA and nuclear 18S rDNA further confirmed this new species to be a distinct lineage. Moreover, detailed observation of medusae and polyps of this species showed sufficient morphological differences from other Clytia species for a diagnosis. Our results indicated that life cycle and DNA-based studies should be a standard approach in future biodiversity investigations of Clytia species.

This study examined the trophic ecology of the zoanthid Palythoa caribaeorum in tropical reefs and evaluated its role in the energy flow in that ecosystem. Colonies of this species were sampled in the infralittoral zone of reefs in north-eastern Brazil in 2008. We calculated the richness, total abundance, relative abundance and frequency of occurrence of prey items. The biovolumes and weighted biovolumes of prey were calculated to characterize the most important food items in terms of their biomasses. To evaluate the selectivity, zoanthid and plankton samples were collected in 2010. Pennate diatoms were the most abundant and most frequent prey and, together with invertebrate eggs, constituted the most important food items in terms of their biomasses. There were no significant differences in abundance or richness among the different beaches studied, nor between the different seasons. The mean size of prey items within the polyps was significantly smaller than of the general plankton, indicating that P. caribaeorum selected for (or limited) certain prey sizes. This species predominantly fed on diatoms, and did not take advantage of many other prey items abundant in the plankton. Our results indicate that P. caribaeorum is suspensivorous and feeds principally on small phytoplankton. As this species is prey for benthic organisms such as polychaetes and nektonic organisms, our results indicate the importance of this zoanthid in tropical reef ecosystems as a primary consumer that serves as an energy transfer link between the planktonic environment and the nektonic and benthic spheres.

The Iberian Peninsula is part of the South European Atlantic Shelf within the Lusitanian ecoregion. Given the characteristics of this region, a great invertebrate biodiversity is expected. Nevertheless, no literature records of Polycladida are known for the Cantabrian Sea. Here, we report the presence of six polyclad species, including one new species. Notoplana vitrea, considered endemic to the Mediterranean Sea, was found in the Cantabrian Sea, demonstrating its presence in Atlantic waters. This species was previously reported for these waters on two natural history photographic websites: the importance of searching, indexing and disseminating this type of record for the scientific community is discussed. Discocelis tigrina is reported for the first time for the Cantabrian Sea, and is the northernmost record to date. In this paper, Pleioplana atomata is reported for the second time for the Iberian Peninsula, yet is the first record for the Cantabrian Sea. Although a literature record of Leptoplana tremellaris for the Iberian Peninsula exists, it is considered a misidentification of L. mediterranea; therefore, this work provides the first record of L. tremellaris for the Iberian Peninsula. The cosmopolitan species Cycloporus papillosus is also reported for the Cantabrian Sea. A new species, Imogine fafai sp. nov., is described and taxonomically compared with other species of the genus.

Terebellides stroemii Sars, 1835, the type species of the genus, was originally described from the south-west coast of Norway. Over the past 170 plus years this species has been reported from around the world often without a detailed description; in some cases, schematic illustrations of the anterior end with the distinctive branchiae were given. Identifications were likely based mainly on the branchiae consisting of 4–5 lobes but recent work has shown that this character alone has led to misidentifications and confusion of a number of morphologically similar species. Michael Sars (1835) did not designate type specimens for this species. In order to provide an accurate definition of the genus it is necessary to redescribe and characterize the type species including the designation of a neotype. This will provide a baseline against which the potentially undescribed sibling species in the area can be compared and fully described. A large collection of specimens identified as T. stroemii from locations along the coasts of Norway was studied in the Natural History Museum, University of Oslo. This has prompted us to locate material collected by M. Sars (1835) from the vicinity of the type locality and to designate a neotype and provide a comprehensive description of the type species of the genus.

A new species from the subfamily Comesomatinae is described from the back-reef platforms of the central part of the Maldivian archipelago. Paracomesoma susannae sp. nov. is characterized by a large-sized body, very long cephalic sensilla (72–91 µm long), lateral differentiation of punctuations, and, in the males, 19–22 minute precloacal supplements, relatively short spicules (2.3–2.9 anal body diameter) and a hook-like structure in the distal end of the gubernaculum. Paracomesoma susannae sp. nov. is the only species so far described of the genus which appears to have such a low ratio of the outer labial and cephalic sensilla (about 0.02). An emended diagnosis of P. paralongispiculum is proposed, along with an updated and modified key to all the valid species of the genus Paracomesoma.

The small-sized copepod community structure (<1  mm) and its response to environmental variability was examined during an annual cycle in Kalloni Gulf, a semi-enclosed coastal system in the NE Aegean Sea. Α 90 µm net was used in order to adequately sample the smaller copepod fractions. In the copepod ecology the spatial patterns dominated over the seasonal. Total copepod abundance increased towards the inner gulf area while diversity indices followed the opposite trend. The inner gulf copepod assemblage area was affected by the increasing magnitude of eutrophication, characterized by high abundance values, low species richness and dominance of a single species (e.g. Oithona nana). A clear seasonal succession of species was observed, ordered by temperature, salinity, chlorophyll a, heterotrophic bacterial biomass, organic and inorganic nutrients. Freshwater inputs and the subsequent nutrient inflow was a dominant phenomenon enhancing copepod production and negatively affecting the biodiversity of the assemblage. The great contribution of copepod larval stages in the total community and their year-round presence indicate the continuous production of copepods during the annual cycle, highlight the importance of the smaller size fraction and encourage the use of finer mesh-size nets when assessing the structure and dynamics of copepod communities.

Crabs are thought to play a vital role in structuring gastropod populations. Studies quantifying the frequencies with which crabs attack gastropods in natural settings are, however, scarce. Although a wide variety of techniques exist with which predator–prey interactions can be investigated (e.g. laboratory experiments, exclusion caging, tethering and population surveys), there is a need for methods that can provide large amounts of quantitative data, particularly documenting the frequency with which crabs attack gastropods. This study examines the utility of using wax replicas of gastropods to determine crab attack frequencies. Replicas of Chlorostoma funebralis, Nucella ostrina and Nucella lamellosa were bolted to mesh screens and deployed in the rocky intertidal. Crabs attacked wax replicas of gastropods, leaving characteristic marks in the wax. In most cases, the appendage used in the attack could be identified from the marks (i.e. chelae vs walking legs). The effectiveness of this technique was verified using surveys of repair scar frequencies of the gastropod populations; patterns in attack frequency, determined from the number of marked wax replicas, were consistent with those of repair frequency, in that both were greater at the wave protected, quiet water locality. This study confirms the value of wax replicas in investigations of crab predation to determine the frequency and type of attack, and illustrates the potential of this method for quantifying predation intensity. The development of techniques that quantify the magnitude and exact nature of the effects of crab predation on intertidal communities is pivotal, given the intensity of commercial fishing of some species of crabs.

Coastal lagoons are highly variable environments that may act as hotspots of genetic diversity as a consequence of their ecological role as nursery habitats of marine species with both ecological and fisheries importance. The edible cockle (Cerastoderma edule) is a commercially important shellfish resource inhabiting coastal lagoons in Europe and their fisheries management urgently needs genetic studies to design appropriate strategies to promote the recovery of exploited populations. The aim of this study was to assess the C. edule genetic diversity and population structure at a small geographic scale, inside Ria Formosa coastal lagoon (southern Portugal) using mitochondrial cytochrome oxidase I sequences in six locations. Outcomes pointed to a common pattern of high haplotype diversity and non-significant genetic structuring inside the Ria Formosa lagoon. A high level of gene flow was detected between all localities and the presence of a single stock from a genetic point of view may be considered for fisheries management purposes. The existence of a high number of haplotypes and high values of haplotype diversity of C. edule in Ria Formosa lagoon could be consistent with the hypothesis that higher genetic diversity is expected in populations occurring in coastal lagoons, suggesting that lagoons could increase standing genetic variation and an adaptive potential of lagoon populations as an ecological response to a highly variable environment.

Length-weight relationship, growth parameters and mortality rates of Anadara granosa in the intertidal zone of Balik Pulau, Penang Island, West Coast of Malaysia were investigated based on monthly length-frequency data (December 2011 to November 2012). A total of 548 individuals ranging from 11.25 to 33.13 mm size were subjected to analysis. Logarithmic relationship between the length and weight was Log W = 2.328 Log L − 2.537 (R2 = 0.922) for combined sexes. From this equation it was clear that the exponent ‘b’ value for A. granosa showed a negative allometric growth (b < 3). A von Bertalanffy growth function with an asymptotic length (L∞) of 35.40 mm and a growth constant (K) of 1.1 year−1 was established from length frequency distributions. The t0(−0.140) was estimated by substituting the L∞and K in the Pauly's equation. The sizes attained by A. granosa were 10.13, 14.36, 17.89, 20.82, 23.56 and 25.29 mm at the end of 2, 4, 6, 8, 10 and 12 months, respectively. The estimated growth performance index (Ø) was 3.13 while the estimated lifespan of the cockles was about 2.72 years at the study area. The estimated value of total mortality based on length-converted catch curve was Z = 3.02 year−1. The natural mortality (M) and fishing mortality (F) rates were 1.84 and 0.48 year−1, respectively. The exploitation level (E) of A. granosa was 0.20, which indicated slight fishing pressure on the stock.

Red vent syndrome (RVS) has previously been reported in returning wild Atlantic salmon, Salmo salar from Canada, Iceland, Ireland, Norway and the UK. Affected fish show reddening and swelling in the perianal/vent area, with scale loss, ulceration and bleeding in severe cases. Studies in the UK and elsewhere report the condition to be induced by Anisakis simplex sensu stricto (s.s.) larvae. This parasite, commonly reported in several marine fish species, is typically found in the body cavity and the skeletal muscle, but has recently been reported within the vent tissues of salmon. This latter finding may reflect greater efforts in examining this body portion due to current awareness of the parasite presence in this atypical location. Based on clinical observations, affected fish are classified into three categories according to the severity of the external lesions, but quantification of the vent parasite numbers in relation to the categories, and assessment of the relative importance of this area as a site of infestation, are missing to date. This investigation aimed to provide data on parasite number and distribution in the viscera, skeletal muscle, peduncle and vent area and to confirm the identity of the larvae found in the vent and the viscera. The study showed the perianal/vent region harbours the highest total number of A. simplex larvae per fish and, proportionally to fish biomass, is the most heavily infested body location irrespective of external severity levels of RVS.

Blue jack mackerel Trachurus picturatus monthly samples were collected between 1998 and 2011 to determine morphometric relationships, maturity, growth rates, reproduction and spawning seasonality in north-east Atlantic waters (ICES area Xa2). A total of 2895 specimens were sampled, ranging from 98 to 542 mm in fork-length (LF). The morphometric relationships (length-length and length-weight) showed statistically significant differences between sexes. Ages were estimated by counting growth bands on otoliths and verified by marginal increment analysis, with specimens ranging from 0 to 18 years. The von Bertalanffy models used to estimate growth parameters for both observed and back-calculated length-at-age data gave good fits. The gonads were analysed macroscopically and the spawning season found to occur from December to May. The length at 50% maturity for females and males occurred at 277 mm LF (4.3 years) and 288 mm LF (5.1 years), respectively. The results provide important biological information for fisheries assessment of a species that plays an important key role in the surrounding ecosystem.

Latitudinal patterns of composition, biogeographic affinity and indicators of taxonomic diversity are described for the by-catch fish community in five typical shrimping areas in the Mexican Pacific (Upper Gulf of California, Sinaloa-Nayarit, Jalisco-Colima, Michoacán-Guerrero and Gulf of Tehuantepec). The taxonomic composition included two classes, 20 orders, 65 families, 147 genera and 292 species. The family Sciaenidae was the best represented with 33 species, whereas at the genus level, Anchoa was represented with eight species. A high percentage of the species showed wide distribution ranges (30.2% for Cortez Province ~ Panamic Province; 21.3% for San Diego Province ~ Panamic Province); nevertheless, each ecosystem included a characteristic combination of species, apparently related to the physiographic conditions of the ecosystems. Species richness showed a pronounced decrease from the Upper Gulf of California, which has warm-temperate features, to the Gulf of Tehuantepec, which has tropical conditions; this is an opposite trend to that observed in the taxonomic diversity indicators, suggesting that a taxonomic redundancy was present in tropical areas and higher taxonomic diversity was present in the Upper Gulf of California, despite the lower species richness. This is explained by the prevailing environmental conditions and isolation processes generated during the formation of the Gulf of California.

The stomach contents of juvenile Magellanic penguins, Spheniscus magellanicus, stranded along the Atlantic coast (21–23°S) during the extreme mortality event of 2008 were analysed. The isotopic profiles of this species and their prey in a wintering area are presented to identify trophic relationships and to evaluate whether the prey species recovered in the stomach contents were assimilated. The prey groups recorded were molluscs (cephalopods and gastropods), teleost fish, and, to a lesser extent, crustaceans (decapods and isopods). Cephalopods were the most representative prey, and Argonauta nodosa was the most abundant species. Plant remains and solid waste were atypical items found in the stomach contents. The nitrogen isotope (δ15N) values found in this study confirm the higher trophic position of the penguins (14.5‰) relative to their prey (11.7–12.3‰). The carbon isotope (δ13C) measurements of all species are characteristic of marine coastal environments (−18.7 to −16.8‰). A Bayesian approach applied to stable isotope mixing models showed that cephalopods are assimilated to a greater extent than fish. However, the poor nutritional condition of specimens that reach the Brazilian coast, especially at the northern limit of migration (~21°S), indicates that prey ingestion is not sufficient for the maintenance of body weight.