The Pycnogonida are a group regularly recorded in deep-sea benthic samples, although normally in low numbers. Most analyses from such surveys record new species, and many of these remain known only from a few specimens, often only the types. However, the amount of deep sea-bed sampled is necessarily proportionately so small that it may be argued that any species taken are probably common, owing to their having been sampled at all. It is evident from the gaps in the (often world-wide) distribution of these known species and their limited occurrence that deeper water pycnogonid faunas are still at best poorly known (q.v. Child, 1982).

This study focuses on the dynamics of copepod abundances and species composition in the upper water column of a marine outfall area Tso-Ying (T-Y) in the boundary waters of the north-eastern South China Sea and the Taiwan Strait as an example. Zooplankton samples were collected in March, June and September 2002. Mean copepod abundance at all stations ranged from a minimum of 9.4 (individuals m−3) in March to a maximum of 1685 (individuals m−3) in June. A total of 66 copepod species belonging to 31 genera and 19 families were identified during three cruises. Copepod assemblages were dominated by Temora turbinata which occurred in >97% samples with a relative abundance of 75.46% combining all three sampling cruises. The ordination diagram derived from non-metric multidimensional scaling separated samples on the basis of season and revealed that different sampling stations clustered differently during each cruise. The second and third most dominant species were Acrocalanus gracilis and Acrocalanus gibber, representing 1.73% and 1.65% of the total copepod abundance respectively. The outfall area studied here correlates with lower copepod densities represented by a few species that show a higher relative abundance in comparison with non-affected areas. We provide here the first example where plankton assemblages indicate useful information about environmental changes in the course of sewage disposal at a stable outlet site.

The white-beaked dolphin Lagenorhynchus albirostris is the most numerous cetacean after the harbour porpoise Phocoena phocoena in the North Sea, including Dutch coastal waters. In this study, the diet of 45 white-beaked dolphins stranded on the Dutch coast between 1968 and 2005 was determined by analysis of stomach contents. Although 25 fish species were identified, the diet was dominated by Gadidae (98.0% by weight, 40.0% in numbers), found in all stomachs. All other prey species combined contributed little to the diet by weight (2.0%W). The two most important prey species were whiting Merlangius merlangus (91.1% frequency of occurrence (FO), 30.5%N, 37.6%W) and cod Gadus morhua (73.3%FO, 7.4%N, 55.9%W). In numbers, gobies were most common (54.6%N), but contributed little to the diet by weight (0.6%W). Three stomachs contained different prey compared to the others: one animal had taken 2250 gobies, accounting for 96.4% of all gobies found; one animal had fed on 29 small sepiolids; and one animal had solely taken haddock Melanogrammus aeglefinus. Squid and haddock were not found in any other stomach. The overall diet showed a lasting predominance of whiting and cod, without clear changes over time (35 years) or differences between sexes or size-classes of dolphins. This study adds to earlier published and unpublished data for Dutch coastal waters and agrees well with studies of white-beaked dolphins from other parts of the species’ range, in the North Sea and in Canadian waters, with Gadidae dominating the diet on both sides of the Atlantic.

Among the marine invertebrates whose settlement behaviour is well studied, the polychaete tubeworm, Spirorbis spirorbis L. ( = borealis Daudin), the barnacle, Balanus balanoides, and the oyster, Ostrea edulis, are different in form whether in the free-swimming or adult stage, yet the settlement behaviour patterns are basically similar (Crisp, 1973). The larvae have a sequence of movements during exploration of the substratum, with each activity initiated by a hierarchy of stimuli. Given a positive set of responses to a suitable habitat, the distances moved on the substratum are limited progressively so that finally the larva investigates a very restrictred area. When the exact site for settlement is determined the larva ceases to move, attaches permanently and immediately commences metamorphosis into the adult form. However, if certain stimuli are lacking or obnoxious to the searching larva, it recommences the initial free-swimming activity, in order to reach alternative substrata.

An analysis is made of the mysids which occurred in a series of bottom stramin net plankton hauls made at three stations in the Plymouth area in 1927–8.

There were two marked maxima in numbers of mysids, a summer one in July and August, and a winter one in December and January.

The summer maximum was due entirely to Leptomysis gracilis.

The winter maximum was due mainly to Schistomysis ornata and Anchialina agilis, but the two species of Gastrosaccus, and Neomysis longicornis also contributed to a lesser degree.

The summer maximum was composed mainly of adult males and breeding females of Leptomysis gracilis which appear to become markedly planktonic in habit at the breeding season though keeping to the deeper layers. Immature specimens were present but the majority were probably higher up in the water (mid-water).

There is a suggestion that a similar planktonic habit is to be found in Schistomysis ornata and Anchialina agilis during their breeding period in the winter, but it is not nearly so marked as in Leptomysis gracilis.

The winter maximum is mainly due to large numbers of immature forms and it is suggested that environmental factors, probably temperature, cause a concentration of immature stages in the bottom water during winter. At other times of the year these immature forms are distributed over a much greater depth range of water.

Idle swimming movements just over the bottom are a normal habit of bottom living mysids.

The collection provides evidence of three types of movements in mysids: (i) idle swimming just over the bottom, (ii) definite and marked movements into the plankton in the adult condition during the breeding season, and (iii) movements of the immature forms to greater or lesser depths according to environmental conditions, probably temperature.

Over the course of the moult cycle of Maja squinado, the spider crab changes in the hardness and colour of the carapace were assessed and used as methods to identify the intermoult stage in each individual. This intermoult staging was later verified by means of the microscopic observation of the maxilla. These staging techniques made it possible for the prompt identification of the principal intermoult stages—postmoult, intermoult and premoult. In 90% of the cases analysed, there was a correlation between the presence of an underlying carapace and a pink colour of the abdominal vein in crabs in advanced premoult stages.

The seasonality of the moult was studied based on the number of specimens in the postmoult stage. There were two main moulting periods—the first occurring in April, and the second, longer period was between July and November. A hypothetical growth model was established and growth rates were determined by length–frequency distribution analyses. Three groups of juveniles and one group of adults were identified. The adults were only found among the population between July and October. In both males and females, the moult increment rate was lower in terminal moults (mean=22%) than in juvenile or prepubertal moults (mean=27%).

The young clupeoid material which had been collected from 1913 onwards and sorted out with a view to future biological study, especially of the Pilchard, was handed over to me by Mr. R. S. Clark with the main object of differentiating the three species Pilchard, Herring and Sprat. A research was therefore undertaken to find out the best way of distinguishing them through all their life history until metamorphosis. This was practically finished when the thesis by Fage (1920) on young clupeoids of the “Thor” expedition was published, rendering a large part of my work unnecessary, as, thanks to him, it is now almost impossible to mistake them at any period of their development, and they are clearly differentiated at any time in their life history.

Thioploca are sulphur oxidizing-nitrate reducing gliding filamentous benthic bacteria belonging to the Beggiatoaceae. In this paper we report on the discovery of Thioploca resulting from a commercial fishery survey of Trachurus capensis (horse mackerel) and Merluccius capensis (hake) carried out off Namibia between 18°00·1′S and 25°00·8′S from 4–10 December 1996, on board the RV ‘Welwitschia’. The first positive finding of sheathed, presumably vacuolated, Thioploca in the Benguela Current ecosystem is now reported.

Enypniastes eximia (Echinodermata: Holothuroidea) is a prominent member of the benthic boundary layer community in deep Caribbean waters. Like most holothurians it feeds on benthic sediments. Feeding is episodic and after collecting food on the bottom it returns to the water column at altitudes within about 50 m of the sea floor. Direct observations from submersibles and laboratory studies of living specimens have shown how bioluminescence is produced. Light production in E. eximia is triggered mechanically, and is produced by hundreds of granular bodies within the gelatinous integument of the animal. Local stimulation yields a localized response which gradually spreads to the entire surface of the animal. Broad impact yields a whole-body luminescent response. The integument of E. eximia is quite fragile, and strong physical contact readily causes the skin to be sloughed off in a glowing cloud. The degree of luminous response is a function of the severity of contact. In the laboratory the skin of E. eximia, along with its luminescent capability, regenerated rapidly. The anti-predatory role of bioluminescence in this species is apparently a ‘burglar alarm’ strategy. In the dark, near-bottom habitat, physical contact by a predator elicits light production which reveals the presence of the attacker to its own visually-cued predators.

Sea turtles host a diverse array of epibionts, yet it is not well understood what factors influence epibiont community composition. To test whether epibiont communities of sea turtles are influenced by the hosts’ nesting or foraging habitats, we characterized the epibiota of leatherback, olive ridley and green turtles nesting at a single location on the Pacific coast of Costa Rica. We also compared the epibiota of these turtles to conspecific populations nesting elsewhere in the East Pacific. If epibiont communities are influenced by nesting habitats, we predicted that sympatrically nesting turtles would have comparable epibiont taxa. Alternatively, if epibiont communities are influenced by foraging habitats, we predicted the diversity of epibiont taxa should reflect the type and diversity of the hosts’ foraging habitats. We identified 18 epibiont taxa from 18 leatherback, 19 olive ridley and six green turtles. Epibiont diversity was low on leatherbacks (four taxa), but higher for olive ridley and green turtles (12 and nine epibiont taxa respectively). The epibiont communities of olive ridley and green turtles were not statistically different, but both were different from leatherbacks. In addition, conspecific sea turtles from other nesting locations hosted more similar epibiont communities than sympatrically nesting, non-conspecifics. We conclude that epibiont diversity of nesting sea turtles is partially linked to the diversity of their foraging habitats. We also conclude that the surface properties of the skin and carapace of these turtles may contribute to the uniqueness of leatherback turtle epibiont communities and the similarities between olive ridley and green turtle epibiont communities.

High plasticity in cephalopod populations shows dramatic changes in their biological traits. Commercial catches of Mayan octopus (Octopus maya) in six localities of the state of Campeche, Mexico, were sampled monthly for five consecutive fishing seasons (2005–2009) in order to describe variations in population structure and maturation. Octopus maya grows and matures during the fishing season, from August to December. Spent individuals predominate in January and February, revealing a year-long life cycle. However, the presence of a few spent females in all months sampled suggests that a small part of the population shows an extended spawning period. Overall sex ratios did not significantly shift from the expected 1:1 in most samples. Males are mostly mature while the majority of females are immature during the season. Use of illegal fishing gears (spear diving or pots) in central localities accounts for a larger share in mature females. Octopus size showed large interannual and geographic differences. Females mature at a larger size (1024 g body weight, BW; 124 mm mantle length, ML) than males (484 g BW; 91 mm ML). Size at maturity in both sexes varies more between seasons than between localities. Female ML at maturity is larger than the current minimum legal size and implications for current octopus fishing regulations are discussed.

The present study describes the embryonic development and early ontogeny of Amphiprion ocellaris from fertilization to post hatching. Anemonefish spontaneously spawned at 27–28°C. The newly laid eggs were orange in colour and elliptical in shape (1.8×0.8 mm). Melanin appeared as a black mass situated at the vegetal pole in mature eggs. This is rarely seen in eggs of other fish species. We documented developmental times at 27–28°C to egg activation (0.5 h), cleavage (4 h), blastula (11.5 h), gastrula (20 h), neurula (24.5 h), somite (28.5 h), turnover (72 h), blood formation (113 h) and internal ear and jaw formation (144 h). Hatching occurred 152 h after fertilization. On day 4, the eye buds were pigmented and melanophores formed on the ventral surface of the embryo. Internal ear and gill formation were completed on day 5 and coincided with movement of the opercula and pectoral fins. The mouth formed on day 6 and the digestive tract appeared on day 7. By day 10, the yolk was fully absorbed and a substantial amount of food was observed in the gut. Dark and orange pigments were dispersed and aggregated through muscle contractions by day 14, but red pigments did not appear until the fish were three months old. This study contributes to a further understanding of the embryology and the early ontogeny of damselfish and may help improve the culture of coral reef fish.

Doryteuthis gahi is a small squid species that has a wide distribution in South America. This species is characterized by coastal and benthic spawning, and its ontogenetic vertical migration is associated with upwelling zones, features that may restrict its dispersal potential. It has also been proposed that populations of these neritic squid are structured by the influence of local processes which act as barriers to gene flow. Based on this background, we evaluate the geographical structure of genetic diversity in D. gahi along its distribution in the south-eastern Pacific Ocean. We used 116 COI mtDNA sequences of squid collected from different sites in Peru and Chile and calculated genetic diversity, the population structure index Fst, and performed analysis of spatial molecular variance and exact tests to detect differences among localities. To infer demographic history we carried out tests of neutrality and Bayesian skyline analysis. Although there was little molecular divergence between Peru and Chile, we detected a significant genetic differentiation of D. gahi along its geographical distribution. Squid from Chile showed higher genetic diversity than those of Peru and the results of the demographic inference analysis suggest that the population of Peru is experiencing or experienced in the recent past demographic expansion, a pattern that was not found in Chile. We think that the current genetic patterns are consequences of northward migrations in the glaciation periods and posterior re-colonization of southern Chile in the deglacial period.

Laminariocolax tomentosoides is a common epi-endophyte on the I.O.M. Though probably pseudoperennial as an endophyte it produces fertile external filaments only from September to June with a March maximum in size and numbers. It reproduces vegetatively by growing through its host's tissues and asexually by means of zoospores from plurilocular sporangia. In culture, zoospores give rise to fertile plants in 7 days and several generations can be produced in 4 weeks. The offspring bear only plurilocular sporangia. The chromosome number is apparently 16 and the life-history probably a postponed series of diplonts.

Laminariocolax tomentosoides produces cysts which, in the past, have been mistakenly identified as unilocular sporangia and which are so similar to the ascocysts of Ascocyclus that this genus would seem to be based on a character of little value. Another description of unilocular sporangia in the species is tentatively attributed to infection by a fungus.

Removal of the eyestalks in Leander serratus does not result in an earlier moult, a shorter intermoult period, or a higher moult rate. There is no evidence of an eyestalk moult-inhibiting hormone in this species. The evidence points to the existence of an eyestalk moult-accelerating hormone. The possible correlation of the presence of the moult-inhibiting hormone and seasonal moulting is discussed.

Various aspects have been studied of the relationship between the entocommensal nemertean Malacobdella grossa [O.F. Müller, 1776] and its host on the Yorkshire coast, the lamellibranch Zirfaea crispata L. Larger host populations clearly show both a higher overall percentage infection and greater numbers of multiple infections. Larger hosts tend to harbour larger Malacobdella; allied with this fact is the conclusion that the older the host population the more restricted is the availability of potential hosts for future infections.

Preliminary observations have been made in the English Channel off Plymouth on the average obliquity of illumination under water, and on the relative intensity of light reflected upwards at various depths, the readings being made with a cubical photometer containing six “Electrocell” selenium rectifier cells mounted behind opal glasses and Jena VG 9 (green) filters. The cells measured the light of wave-lengths about 480–580 mμ falling on upward-and on downward-turned horizontal surfaces, and on four vertical surfaces i n rectangular azimuths.

The average angle with the vertical or of obliquity was from 36 to 40°, and no significant difference could be detected between that for smooth sea and overcast sky, and that for rough sea and either high or low sun. Figures for smooth sea and sunlight are more difficult to obtain, as in the absence of drift due to wind the photometer may rotate.

No decrease in average obliquity with depth was found, in some cases there was evidence of a slight increase. This is in accordance with our previous results, and accords well with the constancy of extinction coefficient so often found throughout a series. It is not, however, in agreement with the careful work of Johnson & Liljequist, so further determinations would seem to be desirable.

The percentage of the light which was scattered back so as to fall on a downward-turned surface varied from 5.5 for comparatively opaque water (extinction coefficient 0.20) inside Plymouth breakwater, to 2.1 for very clear water (extinction coefficient 0.076) some miles off at sea. The presence or absence of sunlight had little effect, values close to 3.0 being obtained with and without sun for water having a coefficient close to 0.110.

Gills are the typical respiratory organ of fish in their usual habitat of well-aerated water. The transition from water- to air-breathing required many modifications to the structural and physiological adaptations of the gas-exchange surfaces, i.e. gill, skin, swimbladder and other accessory organs of the alimentary canal. The skin is particularly important among air-breathing fish. This histological study showed varying degrees of adaptation of parts of the skin from different body regions, paying particular attention to the water/blood barrier. The results suggest a general importance in gas exchange in the following order: gill, inner operculum, nasal, body and outer opercular skin, as indicated by increasing thickness of the water/blood barrier.

Desma-bearing sponges, also known as lithistids or rock sponges, are a group typical of bathyal environments throughout tropical and warm-temperate regions. In this study the lithistids collected in the course of the Harbor Branch Oceanographic Institute eastern Atlantic 1991 campaign to Madeira, Selvagens and the Canary Islands were identified and assigned to eight species, representing eight genera and five families. Several constitute new records for these islands and one is a new species of Isabella, a genus thus far only known from the Norfolk Ridge in New Caledonia, that is here described and illustrated. Some considerations are made in regards to the diversity and biogeographical affinities of the Atlanto-Mediterranean lithistid sponges.

Breeding and development have been studied in a number of sipunculans, including Golfingia elongata (Keferstein), G. vulgaris (de Blainville), G. minuta (Keferstein), G. pugettensis Fisher, Phascolosoma agassizi Keferstein, Phascolopsis gouldi (Pourtalès), Themiste pyroides (Chamberlin), Phascolion strombi (Montagu) and Sipunculus nudus L. (see Åkesson, 1958, 1961; Gerould, 1903, 1904, 1906; Hatschek, 1884; Rice, 1967; Selenka, 1875). However, the annual cycle of gametogenesis has been investigated in very few sipunculans, notably G. vulgaris (Gonse, 1956 a, b, 1957a, b) and P. agassizi (Towle & Giese, 1966, 1967).