Harmful algal blooms caused by raphidophyte species of the genus Chattonella (i.e. Chattonella antiqua, Chattonella marina and Chattonella ovata) have been documented in temperate coastal regions around the world. To understand the effects of physicochemical factors on bloom development of Chattonella spp., we investigated the variations of vegetative and resting cells (i.e. cysts) of Chattonella spp. and environmental variables in two coastal environments, Uranouchi Inlet (extremely closed) and Nomi Inlet (semi-closed), with contrasting enclosed natures. Although the vegetative cells and cysts of Chattonella spp. were distributed in both coastal regions, the densities were remarkably higher in Uranouchi Inlet than in Nomi Inlet. The mud content in the sediments of Uranouchi Inlet was also higher than that in the sediments of Nomi Inlet, meaning that fine particles such as cysts are likely to accumulate in the former region. Because of the extremely closed nature of Uranouchi Inlet, warm oceanic waters of the Kuroshio Current penetrate the inlet only infrequently. These results suggest that the closed nature of coastal regions is an important factor influencing either water exchange or the resultant accumulation of Chattonella cells in coastal environments.

Modiolus modiolus L. (horse mussel) reefs are a priority marine habitat of high conservation value that is currently listed as endangered and/or threatened across its European distribution. Population structure, density or shell morphology may influence the biodiversity of a reef, either directly or indirectly. Thus, such metrics are important considerations for successful conservation management of these biodiversity hotspots. Population structure, shell morphology and growth rates were examined in M. modiolus reefs across the UK range of the habitat to examine differences between key populations, including those near the Lleyn Peninsula in Wales (southern range), off Port Appin in Western Scotland (mid-range) and in Scapa Flow in the Orkney Isles, Scotland (northern range). Additionally, the influence of physical conditions (temperature and tidal flow) to growth rate and predicted maximum shell length for each population was examined. Growth rates were determined using acetate peels of sectioned shells. Lower juvenile abundance was observed in Scapa Flow. Small, narrow-shaped shells were found to be characteristic of North Lleyn mussels, and larger, globular-shaped shells were characteristic of mussels in Scapa Flow and off Port Appin. Mussels in Scapa Flow were slower growing, yet reached a longer asymptotic length (L∞) than mussels of Port Appin and North Lleyn. Growth curves from sites within this study were analysed with other published data. A trend of higher L∞ at higher latitudes and at lower flow rates was observed. Variations in growth and age are discussed in relation to flow regimes, connectivity to other reefs, density and latitude.

Argopecten purpuratus was exposed to two different diets which reflected short term variations in quantity and quality of the natural food supply typical in bays of southern Chile. No significant differences of clearance rate were observed over different time periods at either of two food concentrations. The scallop reduced its clearance rate significantly when it was exposed to the higher food concentration. Pseudofaeces production occurred only at this high diet and the time factor had no significant effect on this process. The organic content of pseudofaeces was significantly lower than the organic content of the food, suggesting a pre-ingestive selection mechanism. Based on this capacity for particle selection, A. purpuratus was able to compensate for the differences in food quality of the experimental diets and ingesting particulate material containing 38% organic matter as a result of the selection process when fed at the higher food concentration. Absorption efficiency was lower following exposure to the high food concentration, suggesting that the experimental time of 72 h was not sufficient to acclimate the digestive response to a food supply significantly different from that of its habitat of origin. Phytoplankton form the principal nutritional source for this epibenthic species, and resuspended detritus, although occurring in large quantities, may only be of importance once digestive processes become acclimated to processing them.

The morphology of the first zoea of Gnathophyllum elegans is described from laboratory-reared material for the first time and analysed in detail with light and scanning electron microscopy. For systematic reasons, morphological characteristics in G. elegans are compared with those in Gnathophyllum americanum, Periclimenes amethysteus, a representative of the subfamily Pontoniinae and the closely related Hymenocera picta (Decapoda: Caridea: Hymenoceridae). We observed differences in the morphology of both Gnathophyllum-larvae, such as the number and arrangement of certain setae. Thus, larvae of the two Gnathophyllum species can be readily distinguished from each other. Further differential diagnosis with P. amethysteus confirms a high similarity between Gnathophyllum-larvae and larvae in the subfamily Pontoniinae, as already mentioned in earlier publications. The systematic relationships of the Gnathophyllidae, Hymenoceridae and Pontoniinae are discussed based on zoeal characters.

Monitoring the spread of non-indigenous species is fundamental to study global warming effects on marine biodiversity. A valuable tool is represented by the continuous updating of the geographic range expansion of non-indigenous species. Lamprohaminoea ovalis is a Lessepsian mollusc initially recorded in the Mediterranean Sea in 2001. This paper reports its range expansion over the last 20 years related to water warming. The first record of Lamprohaminoea ovalis from the Ligurian Sea (NW Mediterranean) is also reported. Two individuals (about 10 mm length) were observed on a sub-vertical rocky bottom at 26 m depth displaying potential trailing behaviour. This recent finding extends the currently known distributional range of Lamprohaminoea ovalis, representing the northernmost occurrence of this non-indigenous species in the western Mediterranean Sea.

The reproductive biology of the commercial seabait polychaete species Perinereis nuntia brevicirris, Lumbrineris funchalensis and Halla parthenopeia was investigated from samples obtained from the Suez Canal, Egypt, to determine sex-ratio, reproductive maturity stages, spawning season, and fecundity. Samples were collected monthly from January 2002 to February 2003. The results of sex-ratio indicated that males of the three studied worms outnumbered females through the whole study period. Based upon histological features of the coelomic contents, four maturity stages were described in females of P. nuntia brevicirris, three stages were described for females of L. funchalensis and three stages for females of H. parthenopeia. The spawning season of P. nuntia brevicirris was found to take place during spring and L. funchalensis does not have a defined breeding season, while H. parthenopeia has two reproductive periods, one in May and the second in November and lasted to January. Fecundity was estimated by counting the number of oocytes per each female—it showed that P. nuntia brevicirris is more fecund (mean = 208.358 ±2080 oocyte/female) than L. fanchalensis and H. parthenopeia (mean = 2660 ±654 and 142,068 ±2005 oocyte/female respectively). This study is the first to document aspects of the reproductive biology of the highly commercial polychaetes in the Suez Canal and adds to our knowledge for understanding their reproductive patterns and strategies.

The slipper limpet Crepidula fornicata ranks among the main invasive species on French coasts and is known to cause ecological impacts on food web structure and nutrient cycling. This study investigated the effect of C. fornicata on different components of benthic megafauna diversity (species composition, α-, β- and γ-diversity). In Arcachon Bay (France), C. fornicata was present in 58% of the 221 sampling stations. Crepidula fornicata was particularly abundant in four of the main benthic megafauna assemblages, suggesting a non-random distribution of its population. The mean number of megafauna species per station (α-diversity) was 11 with C. fornicata vs six without. Conversely, community similarity among stations (β-diversity) was higher when C. fornicata biomass increased. Opposing α- and β-diversity trends in the presence of C. fornicata explained the similarity of the global number of species (γ-diversity) between both situations (with and without C. fornicata). These results highlighted how this exotic engineer species acted on different types of diversity: the presence of C. fornicata increased the number of species per sample (α-diversity) but homogenized the benthic community (decreasing β-diversity) in comparison with stations where C. fornicata was absent. Crepidula fornicata stock in Arcachon Bay was also monitored and compared with 1999. The spread of C. fornicata between 1999 and 2011 has been limited with a 318 t stock which was not statistically different than the previous estimate performed in 1999. However, the mean length of C. fornicata collected in 2011 was significantly smaller, mainly due to a higher proportion of small individuals.

A description is given of an underwater camera unit mounted inside a high-speed tow-net body. The method of using this apparatus for surveying the seabed is described. The illustrations show that good quality results can be obtained when the camera is towed at speeds around 5 knots. By keeping the camera within a fathom from the bottom, satisfactory photographs can be obtained even where turbidity prevents photography at greater ranges.

A dense population of Polybius henslowi Leach was recorded at the surface of the sea 15 miles off the north coast of Spain. The depth of water at this point was 1740 m. Visual observations of the swimming behaviour show that Polybius tends to swim with the body facing diagonally and backwards against the current. The space between individuals appears to be maintained deliberately and was never less than 6 ft. during daylight. Measurements show that there are at least two sizegroups present. Females represent 40% of the total of 251 animals collected, and these were at approximately the same reproductive state with the ova maturing. The males are on average 2·3 mm longer than the females. No food was found in the stomach of any of the animals taken.

The cellular features of mercury and selenium accumulation has been studied by transmission electron microscopy and x-ray microprobe analysis in the liver of striped dolphins. Mercury and selenium occurred as dense intracellular granules, located mainly within the liver macrophages (Kupffer cells). Granules were composed of 150 A spherical particles showing the same electron diffraction pattern and x-ray spectrum as mercuric selenide. The role of macrophages in mercuric selenide granule production and storage is discussed.

This study was conceived to evaluate seasonal changes in the lipid reserves of the digestive gland of the carnivorous intertidal caenogastropod Nucella lapillus, using a stereological approach. Volume density of lipid droplets in the digestive gland, digestive gland weight and volume were assessed in animals collected in March, June, September and December on the Portuguese coast. Gonad development was evaluated to detect any relationship between lipid content in the digestive gland and the reproductive cycle. The quantitative light microscopic analysis demonstrates that lipid droplets are a major component of the digestive gland. In males, the digestive gland and its lipid reserves were quite stable without significant variations throughout the year. In females, the percentage of digestive gland volume occupied by lipid droplets was higher in June and December, coinciding with the highest values of digestive gland volume. Due to the conjugation of these two factors, in June and December the total amount of lipids in the digestive gland was substantially increased in females. In both males and females a relationship between the development status of the gonad and the lipid reserves of the digestive gland was not evident. However, significant differences in the digestive gland lipid reserves were detected between males and females in June and December, pointing to a sex related effect on lipid reserves. To evaluate the use of lipid reserves as energy source in N. lapillus, the consumption of digestive gland lipids was followed during a starvation experiment.

A new species of Tetranchyroderma, T. garraffonii, is described from sublittoral sediments off the coast of Florida, USA. The new species possesses mixed scale types in the form of feathered biancres – a novel discovery for the genus – as well as feathered triancres and ordinary triancres. Biancres consist of a round scale base, a pair of ancre shafts that arise individually from a v-shaped cuticular ridge on the scale, and feathered ancres. Triancres are similar in appearance but have a different ridge pattern. Ordinary triancres occurred in two forms on the lateral sides of the body: a bowl-shaped ancre and a ‘pitchfork’ shaped ancre. Other distinguishing characteristics of the new species include the presence of cephalic tentacles, a papillated fringe to the oral hood, and a single pair of lateral and dorsolateral adhesive tubes at the posterior end. Confocal microscopy verified the presence of a muscular caudal organ and partly muscular vas deferens.

Two new species of chemosymbiotic bivalves are described from a poorly localized site in the Hatton–Rockall Basin at 1187–1200 m. The new species Isorropodon mackayi sp. nov. is compared with others of the genus from the North and South Atlantic. A novel anatomical structure, suggested to be a secondary gill, is described. The second bivalve Thyasira scotiae sp. nov. is compared with other species known to inhabit cold seeps in the Atlantic and most resembles Thyasira sarsi. Other than the minor morphological differences, the bathyal range and presence of commensal polychaetes, Antonbrunnia, never reported in T. sarsi support the erection of a new species. In the North Atlantic Isorropodon species and the larger thyasirids, with the exception of T. sarsi, are typically found at hydrocarbon seeps associated with pockmarks and mud volcanoes. If correct, then this is the first indication of active sulphidic seepage in the Hatton–Rockall Basin.

During a survey of the marine rotifers of the Northern Adriatic Sea, Italy, we found a total of 20 taxa, including a new species of Lecane. This novelty, Lecane insulaconae sp. nov., occurred in the interstitial area of sandy sediment in the outlet of the Isonzo River, at a salinity of 30‰ and is therefore the first exclusively marine representative of this diverse (~200 species) genus. It is characterized by unique sets of anterolateral projections on the ventral and dorsal lorica. Here, we present the description of the species, together with scanning electron microscopy pictures of trophi of this and some other species, and an account of the marine rotifers encountered during the survey.

The role of the ommastrephid squids Illex coindetii and Todaropsis eblanae (Mollusca: Cephalopoda) collected from two areas in the north-eastern Atlantic waters (north-west Spain) as hosts for larval ascaridoid nematodes was examined from November 1992 to November 1993. The morphology, morphometric growth, population dynamics and electrophoretic identification of the anisakid nematodes was described. The correspondence of Anisakis type I larvae recovered from both squid species within the sibling species Anisakis simplex B is confirmed by comparative data on morphology, morphometry, and genetic evidences. Almost all somatic structures showed progressive and continuous allometric growth corresponding with increase in worm length. Seasonal changes in parasite population levels were evident in both sampling areas.

The second recorded specimen of Stygiomedusafabulosa Russell was taken in June 1971 from 1200–1400 m in the Bay of Biscay, near the area in which the first was caught. The similarity of the two specimens of S.fabulosa suggests that Stygiomedusa stauchi Repelin, described from a single specimen taken near the Congo estuary, is a distinct species.

Survey work was carried out in the Greater Minch area on the west coast of Scotland in 1997. The survey covered an area of 17,000 km2, extending from Kinlochbervie in the north-east to the Stanton Banks in the south-west. Acoustic and ground-truth surveys were conducted using the seabed discrimination system RoxAnn© and underwater television cameras. This paper examines the macro infaunal component of the benthic community from 28 stations sampled throughout the region. From these, 198 taxa were identified, while species per station ranged from 11 to 69 with a maximum abundance of 2100 individuals per m2. Biomass ranged from 2·3 g m−2 to 103·1 g m−2, with a mean value of 21·0 g m−2. Multivariate statistical analysis of the infaunal data revealed the presence of three benthic assemblages, which were closely related to habitat type. An investigation into the dominant feeding guilds or isotrophic groups from each assemblage revealed that surface deposit feeding dominated the very fine sand habitats while both surface and subsurface deposit feeding were very common in the silt communities. A combination of feeding types (namely carnivorous, suspension and surface-deposit feeding) was associated with the sand habitats. The findings of this study are discussed in relation to those in similar habitat types.

Tetranchyroderma adeleae sp. nov. is described from North Stradbroke Island, eastern Australia, where it is present in low abundance in the clean, coarse sediments of Cylinder beach. The species is characterized by the presence of epidermal glands on the oral hood and three pairs of dorsolateral cirrata. This is also the first described species of Tetranchyroderma with mixed ancre types that consist of both ordinary triancres and feathered triancres. Ordinary triancres are present on the ventrolateral margins of the body while feathered triancres adorn the dorsal side. Details of the ultrastructure of the cuticle in T. adeleae sp. nov. and a species of Pseudostomella are compared to each other and the cuticle of additional species of Thaumastodermatidae. At the ultrastructural level, feathered triancres are composed of a thickened endocuticular base with three tines (shafts) that give rise to pointed, feather-shaped scales. The structure of the base, tines and scales reveals a finely granular construction without noticeable substructure. The ultrastructure of feathered triancres is similar to that of ordinary triancres and broadly similar to feathered triancres in other species. However, differences are noted in the contour of the feathered scales that are not detected with light microscopy. Future studies of the thaumastodermatid cuticle using scanning electron microscopy are warranted to provide enhanced three-dimensional resolution and insight into their evolution.

We analysed the morphological variations through geometric morphometric approaches of the dorsal and ventral views of growing male and female Callinectes danae Smith 1869, based on the hypothesis that swimming crabs present polymorphism during growth. Our research identified six instars for females, seven instars for males and one instar for unsexed individuals (young). The sixth instar of females and the seventh instar of males were composed of adults. We identified 20 landmarks from the dorsal view, and 16 landmarks from the ventral view. Based on canonical analysis and Procrustes distance, we observed the formation of clearly separated instars (both views), indicating a significant change during ontogeny, not only in the pubertal moult. The most prevalent changes occurred in the abdomen, with males thinning and females broadening the abdomen during growth. In the dorsal view, we observed a displacement of anterolateral spines to the posterior region throughout the growth period and that the anterolateral and frontal teeth of juveniles were more ornate than those of adults. The ontogenetic trajectories for males and females have similar origins and follow different directions over the instars, with maximum distance after the pubertal moult (P < 0.05).