The Pacific sleeper shark Somniosus pacificus is one of the largest predators in deep Suruga Bay, Japan. A single individual of the sleeper shark (female, ~300 cm in total length) was observed with two baited camera systems deployed simultaneously on the deep seafloor in the bay. The first arrival was recorded 43 min after the deployment of camera #1 on 21 July 2016 at a depth of 609 m. The shark had several remarkable features, including the snout tangled in a broken fishing line, two torn anteriormost left-gill septums, and a parasitic copepod attached to each eye. The same individual appeared at camera #2, which was deployed at a depth of 603 m, ~37 min after it disappeared from camera #1 view. Finally, the same shark returned to camera #1 ~31 min after leaving camera #2. The distance between the two cameras was 436 m, and the average groundspeed and waterspeed of the shark were 0.21 and 0.25 m s−1, respectively, which were comparable with those of the Greenland shark Somniosus microcephalus (0.22–0.34 m s−1) exhibiting the slowest comparative swimming speed among fish species adjusted for size. The ambient water temperature of the Pacific sleeper shark was 5.3 °C, which is considerably higher than that of the Greenland shark (~2 °C). Such a low swimming speed might be explained by the ‘visual interactions hypothesis’, but it is not a consequence of the negative effects of cold water on their locomotor organs.

Stable isotope compositions were studied in particulate organic matter (POM), zooplankton and different trophic groups of teleosts to compare food chains based on plankton at two sites (lagoon and outer slope) in a New Caledonian coral reef. For each trophic compartment, δ13C values were always lower in the outer slope than in the lagoon. This result may be explained by potential differences in POM composition between the two environments, suggesting that the two food chains are based on different primary sources of carbon. In contrast, δ15N values did not vary between the lagoon and the outer slope, indicating that these two food chains presented similar length and trophic levels, despite being distinguishable.

Consideration has been given to the cell diameters of twenty-four samples of Rhizosolenia styliformis var.oceanica from a wide range of latitude together with material from eleven other collections already briefly recorded in Part II of this paper.

It was found that the cells of the smallest diameter occurred in high latitudesand that the average values were greater at lower latitudes.

More auxospore generations were present simultaneously in higher latitudes. An interpretation of these observations is that the prevalence of smaller cell diameters and the simultaneous presence of more auxospore generations in high latitudes could be due to relatively lighter grazing by herbivorous zooplankton in these regions.

Measurements of a few samples of a form of Rhizosolenia styliformis (Bright-well) which I called var. oceanica have been published earlier (Wimpenny, 1946), and auxospore formation was recorded from the Faroe-Shetland area. Since that time, owing to the kindness of the late Dr Vedel Taning, I have been able to see sixteen samples taken in the North Atlantic by the Danish research ship 'Dana' in1948. Mr J. Corlett of the Fisheries Laboratory, Lowestoft, has also been good enough to have made available to me three collections containing this variety from the Weather Ships 'Jig' and 'Item' in 1950 and two from the west ofBear Island in 1952. Finally, I have to add two samples of 33 and 50 specimens fromthe northern North Sea area made available to me many years ago by the late Miss Ogilvie and another sample from which I have been able to measure 100 specimens givenme by Dr James Fraser (E 34, 1934).

The lengths of chthamalid cyprids collected during August 1996 on six rocky shores in County Cork, Ireland are reported. The lengths showed a bimodal distribution. The smaller length mode corresponded well with the length range of laboratory-reared cyprids of Chthamalus montagui (Crustacea: Cirripedia), whilst the larger length mode was greater than the length range reported for laboratory-reared C. stellatus. Size may be a useful means to identify Chthamalus cyprids in field investigations.

Tubiclavoides striatum, a new species of an athecate hydroid, was found on mud volcanoes, inactive carbonate chimneys, and cold-water coral stands in the Gulf of Cadiz (south-western Iberian Peninsula, Atlantic Ocean). The new family Tubiclavoididae and the new genus Tubiclavoides are proposed to accommodate the new species. The new hydroid is characterized by scattered filiform tentacles, sporosacs developing among the tentacles and hydrocauli covered with striated perisarc, often subdivided into imbricating cones. A full description and illustrations are provided, as well as some notes on the ecology and distribution of the new species.

The bivalves Mytilus chilensis, Venus antiqua, Mulinia edulis and Tagelus dombeii inhabit different levels of the tidal flats in Yaldad Bay, southern Chile. Mytilus chilensis is an epifaunal bivalve, which, at this location, is also farmed in culture rafts; whereas the other species belong to the infauna. The objective of this study was to compare filtering capacity of these species; in order to do this, measurements of food consumption were taken by quantifying clearance rates, as well as taking morphological measurements of their feeding systems (gills and labial palps), and endoscopic observations to determine the velocity of particle transport within the gills. All of these parameters were related to the sediments present in environments occupied by these species. In Mytilus chilensis, both wild and farmed, gill area was significantly higher than in the three infaunal species. Mulinia edulis and Venus antiqua did not show any significant differences in gill area. As far as Tagelus dombeii is concerned, the species presented the lowest values among all species studied. Weight of labial palps was significantly higher in Mulinia edulis compared to the other species. There were no significant differences between labial palps of either wild or farmed Mytilus chilensis or in those of Venus antiqua and Tagelus dombeii. A positive, significant relationship was identified between labial palps size and mud sediment content. Both culture-rafts and intertidal Mytilus chilensis displayed a clearance rate that was significantly higher than the infaunal species, concurring with a significant relationship between clearance rate and gill area in the different species studied. Clearance rates displayed by Venus antiqua, Mulinia edulis and Tagelus dombeii did not show significantly different results among them. Mytilus chilensis from both culture-rafts and intertidal zone displayed higher values of particle transport velocity than the infaunal species. Particle transport was not observed in the dorsal canal of any of the species studied. The conclusion is that in these species filtering capacity is determined mostly by gill size and that labial palp size displays a strong relationship with sediment content in the mud of Yaldad tidal flats.

During 1996–1997 a systematic sampling programme was carried out in brackish coastal lakes and lagoons and in the delta of the River Po. In six of the nine collecting locations, 12 species of Gastrotricha were identified. One species, Chaetonotus ichthydioides, is new to science; another three species, the chaetonotidans Heterolepidoderma foliatum and the macrodasyidans Dendrodasys ponticus and Turbanella cf. pontica, and one macrodasyidan genus, Paradasys (P. subterraneus), were found in Italy for the first time. The unusual morphology of some of the species identified shows that Gastrotricha colonized brackish waters from both marine and freshwater habitats.

Shells inhabited by hermit crabs are unique microhabitats with an abundant epi- and endofauna. Using polychaetes as an example, communities associated with the whelk Stramonita haemastoma, the hermit crabs Clibanarius erythropus and Calcinus tubularis, as well as empty, damaged shells were investigated. No polychaete community was associated with live S. haemastoma: only 30% of the investigated gastropods harboured polychaetes. Hermit crab-occupied shells supported polychaete communities dominated by Spirorbidae in the case of Clibanarius erythropus and by small Sabellidae, Spirobranchus polytrema and Dipolydora armata in Calcinus tubularis. The polychaete fauna associated with empty shells was similar to that on shells previously inhabited by one of the hermit crab species but different from those of the surrounding hard bottom. The reproductive strategy of the some polychaetes species is adapted to life on this small-sized habitat.

Four species of Pisionidae (Polychaeta) are reported from Coiba National Park (Pacific, Panamá), one is a well known species of the area Pisionidens indica, one is a new species of Pisione and there are two new reports: Pisione galapagoensis and Pisione cf. papuensis. Pisione longispinulata sp. nov. possesses buccal aciculae distally elongated with a conspicuous notch, three compound chaetae per parapodium, with dense and long spines on margins, and a single pair of copulatory organs, each with modified ventral cirrus, distal spherical enlargement and distal papillae. The closest species is Pisione garciavaldecasasi, also from the Coiba National Park, although it lives in freshwater streams in the northern part of Coiba Island.

The feeding biology of bahia sprat (Rhinosardinia bahiensis) was studied in two habitats of a tropical semi-arid estuary, on the north-eastern Brazilian coast. Samplings were collected on a monthly basis (January 2010–February 2011), and fish were caught during the day using an 8 m beach seine. Habitat use was size-dependent, with tidal mudflat occupied by higher size-classes than tidal creeks, which were occupied by smaller conspecifics. The diet analysis of different size-classes revealed that all sizes of fish consumed similar taxa (Calanoida, Cyclopoida and Decapoda larvae), and that the relative proportion of taxa consumed reflected fish size. Dietary differences between the two nursery areas mainly reflected prey availability. Although high diet overlap was only found between some size-classes in tidal mudflat, these results seem to demonstrate a strategy for efficient use of space potential; intraspecific competition was probably minimized by a differential habitat use patterns.

The marine amphipod fauna of Tunisian shallow water was studied during 2003 to 2009. In this paper, we report—for the first time—the presence of two lessepsian amphipod species Elasmopus pectenicrus and Stenothoe gallensis from the south-east Tunisian coast.

This study was carried out in order to provide basic information on the population ecology of the crab Sesarma rectum in the Ariquindá River mangrove, Tamandaré, State of Pernambuco, Brazil. The population was analysed with regard to the following aspects, in particular: the size-class frequency distribution of carapace width (CW), mean body size (CW) of males and females, morphological sexual maturity, sex-ratio, reproductive period, and recruitment. Samples were collected monthly from April 2008 through to March 2009; the crabs were collected manually, with a capture effort by one person for 30 minutes, during low tide. The specimens obtained were measured for CW, length of the propodus of males, and abdomen width of females; and the sex and ovigerous condition were noted. Altogether, we obtained 511 specimens (132 juvenile and 137 adult males, and 171 juvenile and 71 adult females, of which 32 were ovigerous). The median CW of males (16.15 mm) was significantly larger than that of females (13.82 mm) (P < 0.05). The size at morphological sexual maturity was 15.73 mm in males and 16.71 mm in females. The sex-ratio for the total of specimens analysed was 1.11:1 (male:female) (P > 0.05). The sex-ratio by size-class showed an anomalous pattern, with a greater abundance of males in the larger size-classes. The reproductive period was continuous and the highest frequency of ovigerous females was recorded in the spring and summer. The major pulse of recruitment occurred during autumn and winter, which is related to greater reproductive activity during the warmer months of the year.

The ectoparasite community of the blackspot seabream, Pagellus bogaraveo, was studied in different locations in Portuguese waters of the north-east Atlantic Ocean. This is the first study to focus on the ectoparasites of this commercially important sparid fish. Nine ectoparasite species were detected. Gnathia sp., Aega deshaysiana, A. antillensis, Rocinela danmoniensis and Argulus sp. are reported for the first time on this host. Significant differences were detected among the sampling locations, with monogeneans being more prevalent in mainland waters, and crustaceans being more prevalent in the Atlantic islands of Madeira and Azores. Fish from Madeira showed significantly higher infection levels of all ectoparasites, especially crustaceans, and particularly high prevalence of Hatschekia pagellibogneravei. The potential impact of the species detected on captive fish is also discussed, since the blackspot seabream is a promising new species for marine aquaculture.

Specimens and nests of Pomatoschistus pictus adriaticus have been caught for the first time along the French Mediterranean shore (Gulf of Lions). Six types of nests are found on sandy-gravelly bottom at 10 m depth and 25.3 to 27.5 g 1−1 salinity, using in 84.7% of cases, a valve of Cardium edule (3.3≤weight g≤40.6; 507≤surface mm2≤2490). Nest size, egg patch, surface area and nesting fecundity are positively correlated. Nesting fecundity varies between 669 and 4690 eggs. For a similar egg diameter, the egg height is less than that of P. minutus which spawns on the same bottom and localities. Larval length at hatching varies from 1.70 to 2.67 mm.

Growth increments in statoliths of Idiosepius paradoxus were observed for aging analysis. The rate of increment formation was examined by staining the statoliths with tetracycline at 5–14 d intervals. In 6 of 16 specimens, increments formed daily, but in the other specimens, increments formed less than one per day. The maximum number of increments observed in males and females were more than 150 and 140, respectively, suggesting a life span of ≥150 and ≥140 d. During the cool season (from November to April), the dorsal mantle length (DML) and the number of increments gradually increased. Specimens collected in June showed bi-modal patterns in DML and the number of increments. Only small specimens were collected from August to October. These results suggest that two generations alternately occurred in the cool season and in the warm season.

Recent studies have improved our understanding of nearshore marine ecosystems surrounding Ascension Island (central Atlantic Ocean), but little is known about Ascension's benthic environment beyond its shallow coastal waters. Here, we report the first detailed physical and biological examination of the seabed surrounding Ascension Island at 100–1000 m depth. Multibeam swath data were used to map fine scale bathymetry and derive seabed slope and rugosity indices for the entire area. Water temperature and salinity profiles were obtained from five Conductivity, Temperature, Depth (CTD) deployments, revealing a spatially consistent thermocline at 80 m depth. A camera lander (Shelf Underwater Camera System; SUCS) provided nearly 400 images from 21 sites (100 m transects) at depths of 110–1020 m, showing high variability in the structure of benthic habitats and biological communities. These surveys revealed a total of 95 faunal morphotypes (mean richness >14 per site), complemented by 213 voucher specimens constituting 60 morphotypes collected from seven targeted Agassiz trawl (AGT) deployments. While total faunal density (maximum >300 m−2 at 480 m depth) increased with rugosity, characteristic shifts in multivariate assemblage structure were driven by depth and substratum type. Shallow assemblages (~100 m) were dominated by black coral (Antipatharia sp.) on rocky substrata, cup corals (Caryophyllia sp.) and sea urchins (Cidaris sp.) were abundant on fine sediment at intermediate depths (250–500 m), and shrimps (Nematocarcinus spp.) were common at greater depths (>500 m). Other ubiquitous taxa included serpulid and sabellid polychaetes and brittle stars (Ophiocantha sp.). Cold-water corals (Lophelia cf. pertusa), indicative of Vulnerable Marine Ecosystems (VMEs) and representing substantial benthic carbon accumulation, occurred in particularly dense aggregations at <350 m but were encountered as deep as 1020 m. In addition to enhancing marine biodiversity records at this locality, this study provides critical baseline data to support the future management of Ascension's marine environment.

In summer 1997, the stomach contents of 235 red pandora collected by bottom trawl from Hisarönü Bay in the southern Aegean coast of Turkey, were analysed. It was observed that red pandora is predominantly a diurnal feeder. More intensive feeding started in the afternoon, reaching its maximum value in the evening and continued until dusk. The minimum feeding intensity occurred during the night. The diet was found to consist primarily of polychaetes, especially Glyceridae, and crustaceans, mainly Natantia. No significant diel variation was observed in the diet composition of red pandora.

INTRODUCTION

In the deep oceans where the water depths are in excess of 4000 m the benthic environment is widely separated from the productive euphotic zone and there is an exponential decline in pelagic biomass with increasing depth (Vinogradov, 1968; Wishner, 1980; Angel & Baker, 1982). The sea-bed acts as a sediment trap stopping the downward drift of particulates. Here resuspension and biological and geochemical processes in the benthic boundary layer cause enrichment of the waters above the sediments. Wishner (1980) has noted some of the evidence for near-bottom increases in phosphorus, nitrogen, ATP and sediment resuspension in the deep sea. In parallel with this enrichment and probably related to it, the pelagic macroplankton biomass is increased, at least to distances up to 100 m off bottom (Wishner, 1980; Angel & Baker, 1982). This suprabenthic zone seems to be inhabited by a distinct community of nektonic and planktonic species quite different to that inhabiting comparable depths in the abyssopelagic zone. Marshall & Merrett (1977) reviewed what was known of this community, with special reference to the fishes. Grice & Hulsemann (1970) and Grice (1972) have described new suprabenthic copepod species and Angel & Baker (1982) recorded an entirely novel pelagic ostracod fauna of 25 new species in a 5–20 m off bottom haul at 20°N, 21°W in 4005 m of water.

Despite the increase in the number of deep-sea studies, little is known about the hadal molluscs. For Brazil, only a few studies have treated the Septibranchia. This contribution is part of an effort to increase the knowledge of this group off the Brazilian coast, although it is focused only on the Campos Basin (22°S), State of Rio de Janeiro. Four species of the family Verticordiidae are recognized here. For Spinosipella tinga Simone & Cunha, 2008, the known depth distribution is extended to 1050 m. For Verticordia woodii Smith, 1885, previously reported from Brazil, the known distribution is extended southwards to the Campos Basin. Verticordia quadrata Smith, 1885, is reported from Brazil for the first time. A previously unknown species, Verticordia ouricuri sp. nov., is described. The presence of small spines, typically with a hexagonal column and a stellate structure at their distal end emerges as an additional taxonomic character for the verticordiids.