A luminous organ of a hitherto undescribed type has been found in a Macrurid fish. This organ is described in the present paper. It consists essentially of an epithelium for the secretion of luminous substance, which has been thrown into long folds and wholly invaginated to form a gland. This gland is bound in connective tissue and has a compact appearance, and is furnished with supporting tissue internally. The duct is a flat and wide passage, continuous with the gland, which opens to the exterior about the anus in such a way as to surround the lower part of the rectum. The gland lies in the thickness of the body-wall forward of the rectum and between and behind the pelvic fins.

The nature of the secretion is discussed and some experiments described. The luminescence appears to be due not to bacteria living as guests within the tissues of the fish, as has been shown for other species, but is essentially due to the well-known reaction wherein a substance luciferin is burnt to oxyluciferin in presence of the ferment luciferase, with emission of cold light.

The north-eastern Atlantic sacoglossan gastropod Elysia viridis was studied on littoral and sublittoral shores of the British Isles from 2001 to 2007 to evaluate its potential role in the known decline of the invasive green alga Codium fragile ssp. fragile. Across its European range, this sacoglossan associates with eight genera of algal hosts within three algal orders and two divisions; these hosts include native and introduced macroalgae. The ‘specialist’ herbivore was investigated primarily within the rocky shore community at Lough Hyne Marine Reserve, County Cork, south-west Ireland, with comparative information from surveys of 95 other sites in the British Isles. In Lough Hyne, E. viridis associated with the green algae Codium, Cladophora and Chaetomorpha as well as the red alga Griffithsia. The sacoglossan associated with Codium, Cladophora and Chaetomorpha as well as the red alga Halurus in Devon, Isle of Wight and the Channel Islands. Recruitment of E. viridis to Codium spp. in the lough was substantially higher than in most areas of the British Isles with 100% of the Codium hosts attacked during annual September surveys. The strong autumn pulse of sacoglossan recruitment, coupled with the asynchronous population dynamics compared to other shores, indicates retention of planktotrophic larvae within the lough. The previously reported decline in sacoglossan density with tidal level was hypothesized to be caused by sublittoral predators. Although our experiments failed to demonstrate an effect by large predators, the foraging of the abundant fingerling fish and small crabs could not be tested conclusively. Field experiments were consistent with the interpretation of intense sacoglossan herbivory in certain areas of the lough. However, even if the sacoglossans contribute to the local decline of C. fragile in the lough, they cannot account for the regional decline of the alga on the north-eastern Atlantic shores.

The present paper is the first annotated account listing all species of Cirripedia: Thoracica recorded from the Canary Islands (eastern Atlantic Ocean) together with notes on their distribution and ecology. Voucher specimens have been deposited as reference material in the collection of the Instituto Canario de Ciencias Marinas. Seventeen species are listed and seven of them are recorded for the first time for the Canaries: Lepas hilli, Conchoderma virgatum, Xenobalanus globicipitis, Chthamalus sp. (cf. C. proteus), Acasta cyathus, Balanus trigonus and Perforatus perforatus.

This paper is the first attempt to study the recruitment of Serpuloideans in a Mediterranean marine cave through the use of artificial substrates placed in three different positions, from the entrance to the interior of the cave. This study provides qualitative and quantitative data concerning Serpuloidea recruitment on panels removed successively after one, three, six and 12 months of permanence in the cave. A homogeneous distribution of juveniles Spirorbidae throughout the cave axis had already been detected after one month of panel immersion. Spirorbids were recorded also on panels removed after three months as well as serpulids, which began to be detected during this sampling time, even though represented by just one species. A significantly different pattern of distribution throughout the cave axis was observed after only six months, while other serpulids were detected for the first time. The pattern of species distribution seemed to reflect the biotic and environmental conditions of the cave. The highest serpuloidean species abundance and diversity was found on panels placed in the intermediate position within the cave. After only one year of panel immersion, a total of 20 taxa (11 Serpulidae and 9 Spirorbidae) was recorded, including five species listed for the first time in the marine caves of the Salento Peninsula.

Age and growth of Todarodes sagittatus were estimated based on statolith analysis from individuals (N=352; 81–418 mm mantle length) caught by bottom trawlers during a year of sampling in the western Mediterranean. The daily nature of statolith increments was indirectly validated comparing the mean age of consecutive monthly modes (identified on the monthly length–frequency distributions) with the corresponding increase of 30 days. In agreement with other ommastrephids, results confirmed the following points: (1) lifespan lasts nearly a year; (2) growth rates decrease with age; (3) when adult, females have higher growth rates than males; and (4) females mature about a month later than males. Significant correlation was found between hatching (which occurred throughout the year but with a peak in November) and temperature at 50 m depth (where it is thought that hatchlings inhabit). Age and growth results were compared with those obtained in a similar work carried out in north-west Africa (Arkhipkin et al., 1999). Comparisons suggested that due to higher growth rates in juveniles, southern populations reach maturity and consequently decrease somatic growth at younger ages and smaller sizes than northern squid, which attain larger sizes as a result of maintaining fast growth and delaying maturation. Greater growth rates in juveniles from west Sahara could be explained by higher temperatures in this area than in the Mediterranean.

Parapenaeopsis coromandelica shrimp populations along the western coast of Sri Lanka have supported coastal trawling for the last hundreds of years. Two non-overlapping adjacent fishing grounds (Hendala and Negombo) sustain different fishing intensities. In order to obtain information on the population structure and genetic diversity of P. coromandelica in these two regions, differences in length–weight relationships, growth, spawning seasons, sex-ratios, gonadosomatic index, length at 50% maturity (L50) and sequence variation of the mitochondrial cytochrome oxidase subunit I were examined. Significant differences in population biology and genetic diversity were revealed from the two fishing grounds. Samples of Hendala showed lower L50 and genetic diversity which are considered as potential effects and symptoms of extensive selective harvesting. Further, the shrimps' behaviour seems to be triggering the separation through low mixing of individuals at the two fishing grounds resulting in significant divergence based on haplotype frequencies. Management of P. coromandelica should consider the revealed biological and genetic evidences on existence of two sub-populations/stocks together with a routine monitoring of genetic effects due to harvesting.

The cirratulid species Chaetozone corona is reported for the first time from the North-east Atlantic waters. Several specimens were collected during oceanographic surveys between 1996 and 2015 from soft bottom habitats along the coasts of Brittany (Western France). This species, originally described from the coast of California, was recently recorded for the first time from the Mediterranean Sea. We hypothesize that this species could have been recently introduced to the Atlantic coasts of Europe and colonized the northern coast of Bay of Biscay from the Loire estuary to the Iroise Sea. We discuss the potential vectors of introduction and the main environmental factors that could explain its current distribution. An identification key to all the known North-east Atlantic species of Chaetozone is given.

The hypothesis investigated in this paper is that the interstitial polychaete Saccocirrus sonomacus is excluded from beaches impacted by tailing disposal as a result of the blocking of the interstitial space and not by a response to the toxicity of elevated copper concentrations. Field evidence suggested that abundances of S. sonomacus on beaches where they would be expected to occur under natural conditions are lower when a beach has received a significant amount of tailings. In choice experiments, S. sonomacus always preferred an open coarse sand matrix to one where the interstitial spaces had been blocked by fine sand (a tailings substitute). Using invitro bioassays, we found that the LC50 for S. sonomacus with copper was 44 μg Cu l−1, this being higher than the values of interstitial labile copper measured on the beaches investigated in this study. We therefore accept the hypothesis of a physically mediated exclusion rather than a toxically mediated one.

Fatty acid profiles were used to investigate aspects of bottlenose dolphin populations around the Azores archipelago. Biopsy samples were obtained from 70 dolphins during the period 2002–2004. No statistically significant differences in profiles were found between different island groups, between sexes or between year of sampling. Thus no evidence was seen for island group fidelity, in contrast to bottlenose dolphins found around similar island groups such as the Hawaiian archipelago or the Bahamas. The findings are consistent with concurrent genetic and photo-identification studies on dolphins in the Azores.

Population structure of the important commercial brown shrimp, Crangon crangon, was investigated in samples from five UK sites using a multidisciplinary approach based on morphometrics, allozyme electrophoresis and amplified fragment length polymorphism (AFLP). Multivariate analysis of the morphometric data revealed variation in the tail shape of C. crangon from Wansbeck (north-east England), which was found to have longer inner uropod and telson lengths in comparison with all other sites. Linear discriminant analysis was also able to place 86% of the Wansbeck individuals in the correct group. Crangon crangon were screened at two allozyme loci (Gpi and Pgm) revealing higher levels of polymorphism at both loci than previously reported. Allozyme allele frequencies showed evidence of population subdivision between east and west coast UK sites (FST=0.011). Data from three AFLP loci (Cra47, Cra56 and Cra70) confirmed population differentiation (FST=0.083) and combined allozyme and AFLP genetic data identified C. crangon from Wansbeck as different from all other sites. Random genetic drift and selection in populations with restricted gene flow are likely to be the main causes of the differentiation observed. The results do not support an earlier report of six distinct populations based solely on morphometric analysis.

Epifaunal invertebrates are sensitive to changes in the identity of the dominant host plant, so assessing differences in the structure of epifaunal assemblages is particularly pertinent in areas where seagrasses have been replaced by alternative vegetation (e.g. green seaweeds). In this study, we aimed to compare the diversity, abundance and structure of epifaunal assemblages, particularly amphipods, between meadows dominated by the seagrass Cymodocea nodosa and the green rhizophytic algae Caulerpa prolifera on shallow soft bottoms of Gran Canaria Island, determining whether patterns were temporally consistent between two times. The epifaunal assemblage structure (abundance and composition) consistently differed between both plants, those assemblages associated with C. prolifera-dominated beds being more diverse and abundant relative to C. nodosa meadows. Amphipods constituted ~70% of total crustaceans for the overall study, including 37 species belonging to 16 families. The amphipod abundance was ~3 times larger in C. prolifera-dominated beds than in C. nodosa meadows. We detected species-specific affinities; for example, Microdeutopus stationis, Dexamine spinosa, Aora spinicornis, Ischyrocerus inexpectatus and Apherusa bispinosa were more abundant in C. prolifera-dominated beds; while the caprellid Mantacaprella macaronensis dominated in C. nodosa meadows. However, some species, such as Pseudoprotella phasma and Ampithoe ramondi, were found in both habitats with varying abundances between times.

The pollack, Pollachius pollachius, is an important commercial species for the Spanish artisanal fleet in Atlantic Iberian waters. This study provides information on the reproductive biology of the species, including length at maturity, reproductive cycle and gamete development pattern based on histological methods. A collection of 622 individuals were sampled from fish markets along the western coast of Galicia (NW Spain), between November 2009 and October 2010. Histological examination of the gonads revealed an asynchronous development of secondary growth follicles. Testicular tissue was of lobular type. The reproductive season extended from January to April for females and from January to May for males, with a peak of reproductive activity in February for both sexes. The hepatosomatic index was related to the reproductive cycle, with a mean maximum value during the developing reproductive phase. Length at 50% maturity was significantly different between females (47.1 cm) and males (36.1 cm).

Preliminary feeding experiments (Morris, Ferguson & Raymont, 1973) showed that Neomysis integer was capable of incorporating dietary labelled [1-14C]fatty acids (16:04 18:1,18:2,18:3) into its lipid. Radioactivity was observed in all the major fatty acids of Neomysis, including the polyunsaturated fatty acids. Neomysis could also convert dietary 14C-labelled starch into lipid, producing a range of fatty acids, including long-chain polyunsaturated acids, incorporated in both triglycerides and phospholipids. During these metabolic conversions, the mysid was observed to incorporate more radioactive14C into the phospholipid fraction with increase in the experimental feeding period.

Growth of the echinoid Sphaerechinus granularis from the Gleiian Islands (Brittany, France) was studied by analysis of growth zones in longitudinal cross-sections of interambulacral oral plates. The diameter-at-age data pairs were increased using a back-calculation technique, which allows for a more efficient estimation of von Bertalanffy growth curve parameters. The annual value of the skeletal growth marks agreed with the analysis of the population's size-frequency distributions taken from a previous study. Significant differences in growth and morphological parameters were observed between two populations of the archipelago in close geographical proximity and inhabiting the same type of substratum. These differences, which appear as population phenotypic responses to different hydrodynamic conditions, confirms growth plasticity in S. granularis.

A new species, Endeolophus skeneae sp. nov., epibiotically associated with the gastropod Skenea profunda, is described from light microscope and scanning electron microscope observations. The new species is characterized by homogeneous ornamentation of the cuticle with annules with very fine and numerous longitudinal ridges, equally distributed around the body, subcuticular discontinuity in cuticle pattern along the lateral sectors of the body, relatively long body (1.1–1.6 mm) and relatively long tail (141–188 μm, c' = 7.5–11.4), short (19–22 μm) L-shaped spicules with ventrally bent blade and simple plate-like gubernaculum without apophysis. Symbiotic associations between aquatic nematodes and molluscs are discussed, with special emphasis on Dreissena polymorpha, zebra mussels. It is suggested that nematodes find food and shelter in the mantle cavity of the bivalve molluscs, and in the umbilicus and aperture of the gastropods, but to reveal the exact mechanisms of symbiotic associations of nematodes with aquatic molluscs requires further research.

Since the incursions of the introduced green macroalgae Codium fragile ssp. tomentosoides and ssp. atlanticum on European shores, the abundance and distribution of the native congeners C. tomentosum and C. vermilara have come under closer scrutiny. Hypotheses regarding the reported declines in the native(s) are largely speculative due to the paucity of quantitative information on the natives, the cryptic nature of the invaders and the unknown processes regulating Codium assemblages. As part of a field-based Codium study on north-eastern Atlantic shores, our surveys on Guernsey shores, Channel Islands, in September 2002 have revealed two unexpected and noteworthy results: (1) thriving populations of C. tomentosum are quite abundant on mid to low littoral shores; and (2) in marked contrast, sparse populations of C. fragile ssp. tomentosoides are restricted primarily to upper mid-littoral rock pools. Native Codium has not been displaced or eliminated from the southern end of the British Isles.

Data on life history aspects of two species of Squalus genus were collated from five different studies carried out in the Eastern Ionian Sea from 1995 to 2014. Data were collected from 948 longnose spurdogs Squalus blainville (Risso, 1827) and 65 spiny dogfish Squalus acanthias Linnaeus, 1758 caught by trawl and longlines. The mean length of both species increased with depth. Sexual segregation was observed for S. blainville, whereas a segregation of immature and mature individuals was detected for S. acanthias. The length–weight relationship for S. blainville indicated positive allometry (b > 3) for both sexes, whereas a negative allometry (b < 3) was found for S. acanthias for the combined sexes. The sex ratio of both species was in favour of males. For S. blainville, the gonadosomatic and hepatosomatic indices differed significantly between sexes but not between seasons with the maturity data supporting the hypothesis of continuous reproduction throughout the year. Length at first maturity (L50) for female and male S. blainville was 603 and 413 mm respectively. For S. acanthias, males collected in autumn had finished their spawning activity; the single specimen caught in summer was reproductively active. Females, caught only in summer, were all gravid. Prey identified in the stomachs of S. blainville belonged to three major groups: fish, cephalopods and shrimps. Other groups such as echinoderms and ascidians were also found. Identified prey in the stomachs of S. acanthias belonged to two main groups, fish and cephalopods, although other groups (including echinoderms and polychaetes) were also present.

The small volcanic island of Ascension is situated in the middle of the South Atlantic Ocean, more than 1500 km from the coast of Africa, its nearest continental area. To date, eight ‘opisthobranch’ species were reported from the island. As a result of a recent survey, 10 species were found. Seven species are new records from Ascension: Platydoris angustipes (Mörch, 1863), Diaulula sp., Dolabrifera dolabrifera (Rang, 1828), Aplysia parvula Guilding in Mörch, 1863 and Caliphylla mediterranea A. Costa, 1867, and two new species: Phidiana mimica sp. nov.; and Felimida atlantica sp. nov. Half of the species found have a wide geographical distribution, being not restricted to the Atlantic Ocean. However, traditional taxonomy based on few characters is probably masking complexes of species.

The nematode Halenchus fucicola (de Man), causing galls on the thallus of the sea weed yAscophyllum nodosum, has been found in the Plymouth area (Wembury Bay) and at Croyde Bay on the north Devon coast, and a redescription of the worm is given. A new species of Halenchus (H. dumnonicus) causing similar growths on the sea weeds Fucus vesiculosus and F. serratus is described. This latter form is also found at Wembury Bay; at Looe, Cornwall, and at Lyme Regis, Dorset.

The original descriptions of these two species are discussed and the material mentioned in Smith's description is examined. Discrepancies between Smith's description of Coscinodiscus concinnus and the present interpretation of this species are pointed out. Ways of typifying the two species so as to preserve current usage and still fulfil the requirement of the International Code of Botanical Nomenclature are given. Lectotypes for the two species are designated. Diagnostic characters distinguishing the two species in the living state as well as the cleaned valves are given.