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.

This study presents two years of characterization of a warm temperate rhodolith bed in order to analyse how certain environmental changes influence the community ecology. The biomass of rhodoliths and associated species were analysed during this period and in situ experiments were conducted to evaluate the primary production, calcification and respiration of the dominant species of rhodoliths and epiphytes. The highest total biomass of rhodoliths occurred during austral winter. Lithothamnion crispatum was the most abundant rhodolith species in austral summer. Epiphytic macroalgae occurred only in January 2015, with Padina gymnospora being the most abundant. Considering associated fauna, the biomass of Mollusca increased from February 2015 to February 2016. Population densities of key reef fish species inside and around the rhodolith beds showed significant variations in time. The densities of grouper (carnivores/piscivores) increased in time, especially from 2015 to 2016. On the other hand, grunts (macroinvertebrate feeders) had a modest decrease over time (from 2014 to 2016). Other parameters such as primary production and calcification of L. crispatum were higher under enhanced irradiance, yet decreased in the presence of P. gymnospora. Community structure and physiological responses can be explained by the interaction of abiotic and biotic factors, which are driven by environmental changes over time. Biomass changes can indicate that herbivores play a role in limiting the growth of epiphytes, and this is beneficial to the rhodoliths because it decreases competition for environmental resources with fleshy algae.

Many marine annelids are active tube builders. Several polychaete families make agglutinated tubes by fixing sediment particles with specific secretions from their epithelial glands. The fine structure of the tubes of six species of Maldanidae from five genera (Nicomache minor, N. lumbricalis, Maldane sarsi, Praxillella praetermissa, Axiothella catenata, Rhodine gracilior) was examined by scanning electron microscopy. These species exhibit different lifestyles. Nicomache minor and N. lumbricalis inhabit massive hard tubes attached to stones. Other species live in the sediment, Rhodine in rigid organic tubes, Praxillella, Axiothella and Maldane in sand or mud tubes. All the examined maldanid tubes have a similar basic structure. The inner sheath of the tubes is made of a hardened organic lining secreted by the worm. Fibres from the inner sheath fasten sediment particles of the agglutinated layer. In Nicomache the tube surface is covered with a fibrous outer layer. All tube layers contain variously arranged organic fibres, which form a 3D network in the agglutinated layer and fabric-like linings in the inner sheath and outer layer. The tubes of Maldanidae may be important for taxonomy, and useful for identification of fossils.

Intertidal organisms have long been considered an ideal system to quantify how physical variations determine differential energy allocations in specimens inhabiting environmental gradients such as exposure to wave action. In habitats with differential intertidal wave exposure (sheltered, Sh; and exposed, E) seasonal gonadal and foot weight variations and their associations with exposure and food availability (algae abundance) were determined in the keyhole limpet Fissurella crassa. Gonadal weight is used as a measure of reproduction allocation whereas foot weight is an indirect indicator of energy allocation to survival. RNA:DNA ratio in limpets obtained from Sh and E habitats during the two different seasons was used as an indicator of biosynthetic capability. Our results indicate that algae abundance in E sites was higher in summer and lower in winter compared to Sh sites. In E sites the muscular foot weight of limpet was higher in summer in contrast to Sh sites where F. crassa muscular foot weight of limpet was higher in winter. Gonadal weight in Sh sites was higher in summer and remained constant in winter; whereas in E sites gonadal weight was lower in summer and higher in winter. RNA:DNA ratios indicate that regardless of intertidal wave exposure, F. crassa showed higher biosynthetic capability in summer. Energetic allocation in animals that inhabit sheltered intertidal habitats would support constant allocation towards reproduction. In contrast, animals that inhabit exposed habitats may favour seasonally reproduction allocation at expense of survival.

A new species of cirrate octopod, Opisthoteuthis borealis sp. nov. is described from specimens caught at depths of 957–1321 m off the coast of Greenland. Opisthoteuthis borealis sp. nov. is the most northerly of the Atlantic species of the genus and can be distinguished from the other species by the form of the digestive gland and the arrangement of enlarged suckers on the arms of mature males.

Nebalia kocatasi sp. nov. (Crustacea: Leptostraca) is described from specimens collected off the coast of Turkey (Aegean Sea). The new species differs from the other known species of the genus in having a rostrum about 2.4 times as long as wide, the antennular scale is twice as long as wide, the third article of the antennule has up to four short distal spines, the third article of the antenna has three robust spines on the external lateral face, the two distalmost being the longest, the endopod of the second maxila is composed of two sub-equal articles, the exopod of the second maxilla is as long as the first article of the endopod, pleonites 6–7 have pointed denticles along the posterior dorsal borders, the protopod of pleopod 4 has 2–3 serrations along the posterior border and the terminal seta of the caudal furca is about twice the length of rami. This is the second leptostracan species reported to date from the eastern Mediterranean.

A new species of Platidia (Brachiopoda, Platidiidae) was dredged by R.V. ‘Sarsia’ in November 1956 in the La Chapelle Bank region, attached to the dead part of the coral Anisopsammia rostrata (Pourtales). Eight entire specimens and two smashed were dredged at position 47° 30′ N., 7° 20′ W. at a depth of 870 to 970 fathoms, and one at position 47° 38′ N., 7° 28′ W. at 710 to 750 fathoms. All, except the two smallest, were a reddish brown, the coloration being due to a deposit of manganese oxide: the natural colour is a yellowish white. The dead coral was almost black with the same deposit (see Southward, 1958, p. 644).

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.

In order to investigate social structure, 11 years of individual photo-identification data of bottlenose dolphin were analysed. We examined the type of association indices between pairs of identified individuals; the patterns of affiliation between individual dolphins and the probabilities of association between individuals over time. Between 2001 and 2012, there were 272 encounters which resulted in the identification of 501 individuals. The discovery curve resulting from the photo-identification analysis indicated an open population with regular recruitment of new individuals. All individuals were found to be associated at an association index of <0.05. A total of 291 individuals recorded from 2004 to 2012 were used to assess the temporal pattern of the social structure. The model fit to the Standardized Lagged Association Rate (SLAR) that best described the studied bottlenose dolphin population was ‘casual acquaintances’, and the analysis of associations over time showed a decreasing SLAR curve that falls until reaching the null rate, confirming random associations. The decline of the SLAR curve after ~500 days (1.4 years) suggests disassociation over that time period which can be explained by demographic events such as mortality or emigration. In an open ocean habitat like Madeira this is not unexpected, as there are neither geographic boundaries nor enclosed environments. This population presented a dynamic and fluctuating social structure, where groups change in size and composition. In future conservation efforts this population should be considered as one large community, where individuals associate, disassociate and reassociate with each other over time.

In this work we describe Actinia ebhayiensis sp. nov. from South Africa. The species is externally similar to the type species of the genus, Actinia equina, from which it can be distinguished by nematocyst and allozyme data. Actinia ebhayiensis has a smooth, red column, with well-delimited parapet leading to a deep fosse where conspicuous blue acrorhagi can be found. Tentacles and oral disc are crimson red, and the pedal disc has a lighter pink colour. The microbasic p-mastigophores and b-mastigophores of the mesenterial filaments of the new species are significantly smaller than those of A. equina. Actinia ebhayiensis can also be clearly distinguished from other species of the genus in nematocyst measurements, genetic data and muscle morphology.

We examined the population dynamics and life history characters of the boreal larvacean Oikopleura vanhoeffeni in Conception Bay over two years and determined its role in secondary production. Based on the analysis of age structure inferred from statolith diameter, the generation time was approximately one year. Recruitment of new cohorts and maximum population growth rate occurred in the spring. Somatic growth rate was 0.017 d−1 from the year 2001 to 2002 and 0.043 d−1 from 2002 to 2003, with an acceleration in growth rate during April in response to the spring diatom bloom despite the coldest water temperatures. The annual production rate (i.e. somatic + house production) of 8.7 g C m−2 y−1 in 2001/2, and 3.8 g C m−2 y−1 in 2002/3, represented 2.9–6.7% of primary production and 37–87% of estimated mesozooplankton production, suggesting that O. vanhoeffeni is a major secondary producer in Conception Bay. Individuals matured at seasonally variable body size throughout the year and potential fecundity peaked as the individuals matured at their largest body size during the spring bloom, most likely resulting in maximum egg production and population growth rates at that time of year. Thus, a seasonal pulse of food is a major driving force that regulates the variation in life history characters and population dynamics of the boreal O. vanhoeffeni.

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.

For the first time, an otolith shape analysis was used to investigate the stocks of saddled bream (Oblada melanura, Linnaeus, 1758) in three fishing zones along the Tunisian coast (Bizerte, Kélibia and Sayada). Otolith shape analysis was used on 30 otoliths for each site, sampled during the spawning period. Using elliptic Fourier descriptors (EFD) the quantization of the shape otolith was investigated by SHAPE and multivariate statistical procedures. Considering the environmental and the genotypic aspects, the preliminary results of the otolith shape analysis showed dissimilarity in silhouette of otoliths of saddled bream stocks collected from the north (Bizerte), the north-east (Kélibia) and the east (Sayada) of the Tunisian coast. Therefore, these three groups could be considered as three sub-units of the Tunisian stock, which should be managed separately.

Ice algae have successfully adapted to the extreme environmental conditions in the Antarctic, however the underlying mechanisms involved in the regulation and response of thylakoid membranes and chloroplast to low-temperature stress are still not well understood. In this study, changes in pigment concentrations, lipids, fatty acids and pigment protein complexes in thylakoid membranes and chloroplast after exposure to low temperature conditions were investigated using the Antarctic ice algae Chlamydomonas sp. ICE-L. Results showed that the chloroplasts of Chlamydomonas sp. ICE-L are distributed throughout the cell except in the nuclear region in the form of thylakoid lamellas which exists in the gap between organelles and the starch granules. Also, the structure of mitochondria has no obvious change after cold stress. Concentrations of Chl a, Chl b, monogalactosyl diacylglycerol, digalactosyl diacylglycerol and fatty acids were also observed to exhibit changes with temperature, suggesting possible adaptations to cold environments. The light harvesting complex, lutein and β-carotene played an important role for adaptation of ICE-L, and increasing of monogalactosyl diacylglycerol and digalactosyl diacylglycerol improved the overall degree of unsaturation of thylakoid membranes, thereby maintaining liquidity of thylakoid membranes. The pigments, lipids, fatty acids and pigment-protein complexes maintained the stability of the thylakoid membranes and the normal physiological function of Chlamydomonas sp. ICE-L.

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.

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.

Studies on differences in external morphology and pigmentation patterns were historically carried out using stranded individuals or opportunistic sightings; few studies have involved sampling systematically free-ranging individuals. In order to investigate and describe main pigmentation characteristics, outlining ‘typical’ regional pigmentations, this work analysed systematic photographic information taken on free-ranging striped dolphins, Stenella coeruleoalba. Photographs of dolphins in the Ligurian Sea were collected between May 2004 and December 2006. All individuals were described by the presence/absence of pigmentation variables and by differences in colour shades. The frequency of all the pigmentation variables analysed is stable in the population (10 ‘gene’ variables, 19 ‘allele’ variables), and remains similar between each different group of dolphins. But population presents widespread pigmentation variability between specimens, allowing identification even at single individual level. Cluster analysis also found that the majority of the pigmentations derive from two main colour patterns, called ‘mat’ and ‘pale’ patterns (fmat = 0.68; fpale = 0.12). The Bray–Curtis index showed a high variability of the intra-group pigmentation distance between groups. This resulted in a positive correlation between group size and ‘intra-group’ pigmentation distance: the distance increases rapidly up to a group size of 40 individuals. According to the results obtained, the striped dolphins seem to be concentrated in small groups in which there is a large phenotypic similarity among individuals. These small units could be associated between them to form temporary large groups observed only in pelagic waters.

The observation in natural conditions of headless chaetognaths with healed scars and ripe gonads led us to reproduce this condition experimentally. Histological sections were made on specimens of Sagitta and Spadella at different times after beheading. The muscles contract and the gut closes the wound, so that by the end of the first two hours, the body wall and gut ‘basement membranes’ are in continuity, so restoring the integrity of the body. After two hours, the muscular layer of the body wall is reshaped and closes up the wound; the gut seals off, and a ‘clot’ is evident in the wound area. The benthic Spadella cephaloptera survives some 30 d or more after decapitation. Specimens carrying ripe ova were able to lay them, to mature and fill their seminal vesicles once or twice and to mate with normal mature specimens. Headless chaetognaths must take up nutrients through the integument. It appears that chaetognaths cannot really regenerate head or tail tip.

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.

The analysis of remotely sensed altimeter data and in situ measurements shows that ERS 2 radar can monitor the ocean permanent thermocline from space. The remotely sensed sea level anomaly data account for ∼2/3 of the temperature variance or vertical displacement of isotherms at a depth of ∼550 m in the Subtropical North Atlantic Ocean near 32·5°N. This depth corresponds closely to the region of maximum temperature gradient in the permanent thermocline where near semi-annual internal vertical displacements reach 200 to 300 m. The gradient of the altimeter sea level anomaly data correlates well with measured ocean currents to a depth of 750 m. It is shown that observations from space can account for ∼3/4 of the variance of ocean currents measured in situ in the permanent thermocline over a 2-y period. The magnification of the permanent thermocline displacement with respect to the displacement of the sea surface was determined as −×650 and gives a measure of the ratio of barotropic to baroclinic decay scale of geostrophic current with depth. The overall results are used to interpret an eight year altimeter data time series in the Subtropical North Atlantic at 32·5°N which shows a dominant wave or eddy period near 200 days, rather than semi-annual and increases in energy propagating westward in 1995 (west of 25°W). The effects of rapid North Atlantic Oscillation climate change on ocean circulation are discussed. The altimeter data for the Atlantic were Fourier analysed. It is shown how the annual and semi-annual components relate to the seasonal maximum cholorophyll-a SeaWiFS signal in tropical and equatorial regions due to the lifting of the thermocline caused by seasonally varying ocean currents forced by wind stress.