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.

To study zooplankton–phytoplankton relationships in the diatom-dominated plankton communities of the northern Adriatic we performed feeding experiments with diatoms and zoea I larvae of the brachyuran Xantho poressa. We found that zoea I of X. poressa feed on diatoms of different forms (centric, pennate, colony forming, single celled, with or without setae) and size classes. In a laboratory setup, we presented the zoeas with a mix of diatom species similar to communities observed during blooms regularly found in the northern Adriatic. We report that the grazing activity resulted in a decrease of the relative abundance of the toxic diatom Pseudo-nitzschia calliantha. For the colonial, bloom-forming diatom Skeletonema marinoi our results show a chain length reduction in the presence of zoea I. Of particular interest is the observation that the presence of larvae also resulted in an increased growth rate and abundance of S. marinoi, which resembles bloom induction by grazer presence.

The mole crab Emerita brasiliensis inhabits exposed sandy beaches, both reflective and dissipative, along the Atlantic coast of South America, where it usually attains high biomass and production. We assessed the effects of physical characteristics of beaches (mean grain size, beach width and slope) on production and turnover rate (P/B ratio) of E. brasiliensis. Six production and P/B ratio datasets, estimated with cohort-based and size-based methods, were gathered from studies carried out on subtropical (~25°S) and temperate beaches (~32°S). Based on the estimates available, general trends were identified. Production was positively related to the intermediate/dissipative conditions of wider beaches with finer sand grains and gentler slopes. P/B ratio was negatively related to grain size (mm) and positively related to beach width. These results suggest that P/B ratios also increase towards intermediate/dissipative features due to higher growth rate, as indicated by higher values of the curvature parameter of the von Bertalanffy growth function (K) in more benign conditions (wider beaches with finer grains). In addition, the recurrent pattern of size structure on intermediate/dissipative beaches, with high frequency of recruits, leads to higher P/B ratio estimates on these beaches than on reflective beaches. The relationship of production and P/B ratio with physical features, such as mean grain size, beach width and slope indicates that a ‘short-cut’ approach to estimate Emerita brasiliensis production is a promising prospect and, therefore, more data on the production of this species should be provided.

An earlier study of metals in the polychaete Owenia fusiformis showed that individuals within intertidal populations were remarkably variable in terms of whole-body concentrations of zinc and copper. Four populations have now been studied, two in south Cornwall (Fal Estuary and Par Sands) and one each in east Devon (Torre Abbey Sands) and north Brittany (Grève de St Michel). Investigations of the distributions of zinc and copper within the body have demonstrated that consistently zinc is concentrated in the middle body whilst copper increases to a maximum posteriorly. Zinc is accumulated in the mid-gut cells in the form of numerous spherules, 1–2 μm in diameter: X-ray microanalysis shows these to be largely composed of zinc phosphate but containing also magnesium, calcium and iron, together with sulphur and chlorine. Viewed under the microscope the spherules are greenish due to a pigment identified by high performance liquid chromatography absorption scanning as a pheophorbide-like chlorophyll-degradation product. In contrast, copper is widely distributed throughout the body and much is deposited as small granules, 0.2–0.3 μm in diameter, in laminar groupings in hypodermal and peri-intestinal tissues. The identity of the green pigment responsible for the characteristic body colour of O. fusiformis has not been specifically determined but it appears to have a copper basis since dark-green tissues have a significantly higher copper content than those with a light-green colour. The possible role of chlorophyll degradation products in zinc and copper uptake is discussed.

This paper describes two new species from the genus Dorymenia (Mollusca: Solenogastres: Proneomeniidae): D. hesperidesi sp. nov. and D. menchuescribanae sp. nov., collected during the Spanish oceanographic expeditions for the study of Antarctic benthos, BENTART'94 and BENTART'95, carried out in the area of the Livingston Island (South Shetland Islands, Antarctica). A comparative study of main specific characteristics of species belonging to the genus Dorymenia found off the South Shetland Islands and in the Bransfield Strait (Antarctica), is also included.

The fine-scale structure of a bloom of the coccolithophorid Emiliania huxleyi has been mapped for the first time with an airborne thematic mapper (ATM) scanner (visible bands at 420–450 nm, 450–520 nm, 520–600 nm, 605–625 nm and 630–690 nm). The airborne results are in close agreement with simultaneous satellite observations from the visible band (580–680 nm) of the advanced very high resolution radiometer (AVHRR

The following short paper is based upon the results of very extensive experiments made with both surface-floating and bottom-trailing drift bottles, by the Ministry of Agriculture and Fisheries during 1920–21.

Malmgrenia louiseae sp. nov. is described from both the western Mediterranean in the Gulf of Lions, and the north-east Atlantic from off Portugal and the Bay of Biscay. The species was found in muddy sediments in shallow water and is possibly associated with echiurids or synaptid holothurians. Malmgrenia louiseae sp. nov. can be clearly distinguished from all other known Malmgrenia species by the presence of an infra-acicular process in addition to the supra-acicular process on the acicular lobe of the neuropodia, the lack of microtubercules on the elytra, two kinds of notochaetae (stout with blunt tip and slender with fine pointed tip), and exclusively unidentate neurochaetae. An identification key to the north-east Atlantic and Mediterranean Malmgrenia species is provided.

The known distribution of the Northern Rockling, Ciliata septentrionalis (Collett, 1875) is discussed and several additional occurrences reported. These greatly extend the range of the species. Notes on the biological background of the fish are provided, as are synoptic descriptions of it and its relative C. mustela.

Investigation of parasites and diseases affecting molluscs of ecological and economic interest is critical for the management of native stocks and aquaculture. In recent years, much attention has been devoted to investigating the World Organisation for Animal Health listed infectious diseases, so that communities can be prepared to attend public health emergencies and avoid severe income losses. In this context, the health status of Mytilus galloprovincialis Lamarck, 1819 was analysed in two aquaculture sites (Strunjan Bay and Piran Bay, Slovenia), and in four natural mussel beds (Adriatic Croatia International Marinas Pula and Rovinj and St Catherine, Croatia; Marina Koper, Slovenia) along the coast of the northern Adriatic Sea. The mussels were sampled in February and April 2014, and processed for histological examination of several endosymbionts and pathogens that frequently occur in mytilid mussels. Endosymbionts and pathogens were not detected in farmed mussels. Prokaryotic inclusion bodies, the protozoan Nematopsis, Ancistrocoma-like ciliates, haplosporidian-like plasmodia, turbellarian Urastoma cyprinae, and basophilic inclusion bodies were observed in digestive gland cryosections of wild mussels from the coastal region of the northern Adriatic. Fungal spores of Psilocybe sp., Ulocladium sp. and Alternaria sp. were detected between the digestive tubules based on their morphology. Diagnostic PCR did not reveal infection with Marteilia refringens during the studied period, neither in wild nor farmed mussels. We confirmed the site effects on prevalence of infected mussels. Thus, we can conclude that wild areas are more exposed to endobionts and parasites than aquaculture sites.

There are two marine species in the genus Ozobranchus. Ozobranchus branchiatus mainly parasitizes green turtles and O. margoi parasitizes most turtle species. We used sequences for the mitochondrial cytochrome c oxidase subunit I gene (COI sequence analysis), along with morphological diagnosis, to compare the population genetic structures of O. branchiatus and O. margoi collected near Taiwan to those of their populations in the Atlantic. The results provide estimates of the genetic divergence between these leeches in the two regions. Ozobranchus branchiatus had a greater pairwise distance within Taiwan (0.0031–0.0141) than O. margoi (no differences). Phylogenetic tree analysis identified one O. branchiatus clade and one O. margoi clade in Taiwan. The better environmental adaptability and lower host specificity of O. margoi might result in lower genetic divergence among populations.

An opportunistic sighting of an Indo-Pacific humpback dolphin (Sousa chinensis) was reported in the nearshore waters off the east Liaodong Peninsula, China. This is the first at-sea sighting in this area, and the northern-most sighting record of this species with a distance >3000 km away from the nearest described conspecific population located in the mid-China. The present sighting occurred in close proximity to the location at which another Indo-Pacific humpback dolphin was found by-caught in 2003. The sighted individual could not be identified through the existing photo-identification catalogues of this species in China (>3500 individuals). Therefore, we suggest that a population of Indo-Pacific humpback dolphins that was never reported might exist in the north of the Yellow Sea.

Dirivultus spinigulatus sp. nov. (Copepoda: Siphonostomatoida) is described from vestimentiferans at a deep-water hydrothermal site near Lihir Island in the South Pacific. The species is characterized by several features: sexual dimorphism in the second segment of the antennule, the rostrum with lateral spines, the oral cone with four conspicuous spines, the mandible without palp, the maxilla without an axillary seta, the endopod of leg 1 with segments 1 and 2 partly fused, and leg 5 in the female represented by a conspicuous ventrally located spine but in the male by a free segment having setae. A key is included to the 11 genera of the family Dirivultidae, whose members are endemic to hydrothermal vents and cold seeps.

The genetic relationship between fiddler crab Uca crassipes populations from the continental coast, continental islands, and oceanic islands in the west Pacific was investigated using 1039 bp (base pairs)-long combined 12Sr-RNA–16Sr-RNA sequences and a 504-bp mitochondrial DNA control region. The combined 12Sr-RNA–16Sr-RNA sequences indicated that the Vietnamese population, located along the continental coast, and the Chichi-jima population, which is located on an oceanic island north of the Northern Mariana Islands, formed different clades than populations from the other Ryukyu Islands and Moorea Island. Conversely, the Ryukyu Islands and Moorea Island populations exhibited a close genetic relationship, although the mtDNA control region indicated significant differentiation between the Ryukyu Islands and Moorea Island populations. The isolated Vietnam and Chichi-jima populations exhibited higher genetic diversity in the control region than the other populations.

The present work provides a first description of three planktonic larval stages of Chorismus tuberculatus which were obtained from plankton samples collected in the south-western Atlantic during the expeditions of the RVs ‘Walther Herwig’ and ‘Shinkai Maru’ in 1978 and 1979, respectively. Three early developmental stages of C. tuberculatus are described and compared with those of the second species of this genus, C. antarcticus which is known to be distributed in the southern Atlantic Ocean and Antarctica. Both species are distinguishable by the presence/absence of supraorbital spines at the carapace, an anal spine and the exopodite on pereiopod 4. The rostrum is less developed in C. tuberculatus, the shape of the somites is less pronounced, and the number of posterior spines at the telson is lower than in C. antarcticus. Due to an abbreviated larval development as a physiological adaptation to it wider distribution into the Polar region, we assume C. antarcticus to have phylogenetically separated from C. tuberculatus, represented by the well developed first larval stages in contrast to that of the species described herein.

The suggestion that the enfeeblement of Zostera marina due to lack of sunshine in 1931–2 is the fundamental cause of the epidemic is not supported by the meteorological data available from 1897 onwards, or by the known extinction coefficients of the water.

The objective of this study was to identify potential recruitment sources of Prochilodus lineatus from freshwater areas (Paraná and Uruguay rivers) to estuarine population of the Río de la Plata Estuary (La Plata Basin, South America), considering young (age-1) and adult (age-7) fish. LA-ICP-MS chemical analysis of the otolith core (nine element:Ca ratios) of an unknown mixed sample from Río de la Plata Estuary (2011 and 2017) was compared with a young-of-year baseline data set (same cohort) and classified into freshwater nurseries (Paraná or Uruguay river) by using maximum classification-likelihood models (MLE and MCL) and quadratic discriminant analysis (QDA). Considering the three models used, the Uruguay River was the most important contributor for both young and adult populations. The young population (2011) was highly mixed with contributions between 31.7 to 68.3%, while the degree of mixing was found to decrease in 2017 (adult fish) from 97.1 to 100% contributions. The three employed methods showed comparable estimates, however, the QDA showed a high similarity with the MCL model, suggesting sensitivity to evaluate small contributions, unlike the MLE method. Our results show the potential application of maximum likelihood mixture models and QDA for determining the relative importance of recruitment sources of fish in estuarine waters of the La Plata Basin.

Two new species of hydroid, Sarsia pinforma and Sarsia striata, Family Corynidae, have been found near Oban, west coast of Scotland. Their life-histories have been worked out and their medusae have been reared to maturity in the laboratory. Medusae of striata have also been found in the sea and hydroids have been reared from them. The hydroids and the stages of development of the medusae are fully described and figured, with observations on habits and comparisons with other species of Sarsia. Observations on the development of the gonophores of Sarsia occulta and comments on Sarsia densa are added.