This study presents a comparison of distribution and abundance of dominant megafaunal species at the TAG hydrothermal mound on the Mid-Atlantic Ridge from 1994 to 2004. A geographical information system (GIS) database was compiled from georeferenced observations of faunal abundances at 534 locations on the TAG hydrothermal mound, determined by image analysis of ROV dive footage from November 2004. These data are compared with observations from submersible dives in 1994 to assess changes in the extent and population density of aggregations of the shrimp Rimicaris exoculata at the central black smokers of TAG. The GIS database was also used to assess changes in abundance and distribution of the anemone Maractis rimicarivora by simulating the path of a biotransect conducted in 1994 and 1995. There was no evidence of a decline in the extent of shrimp aggregations at the central black smokers of TAG between 1994 and 2004. This result indicates that occasional exposure to high-intensity submersible lighting, which took place during several scientific expeditions in the intervening period, does not pose an immediate conservation threat to populations of R. exoculata. Similarly, there were no significant differences in the distribution and abundance of anemones between 1994 and 2004. These results indicate a constancy in the identity, distribution and abundance of dominant species at TAG that contrasts with other vent sites where quantitative time-series have been established. The reproductive pattern of R. exoculata was also examined by dissection and direct measurement of oocytes from females collected in September 1994 and November 2004, providing the first comparison of reproductive development in samples from different months for this species. There was no significant difference in oocyte size–frequency distributions of females collected in these samples, indicating a lack of seasonal reproduction in R. exoculata.

The primary productivity of an area of inshore sea in the South Orkney Islands was measured using in situ techniques in two consecutive seasons. Liberation of extracellular products of photosynthesis occurred, accounting for about 1 % of the total carbon fixed at the depth of maximum photosynthesis but rising to 38 % or more when photosynthesis was inhibited at high light intensities.

The winter of 1989/1990 was a year of marked warm water inflow along the Iberian, Spanish and French continental slopes and three anticyclonic eddies developed in the southern Bay of Biscay. Winter temperatures along the northern Spanish slope were examined in the belief that warm water inflow is related to the production of anticyclonic eddies in the southern Bay of Biscay. The annual cycle of temperature (at ~200 m depth) is most unusual in that the warmest temperatures occur in January, the coldest in the summer. Year-to-year variations are evident with the suggestion of a periodicity, though variable, of about five years.

In April 1992, an opportunity presented itself for a late winter eddy survey in the south-eastern corner of the Bay of Biscay from RRS ‘Charles Darwin’. Two Argos buoys were deployed in what was thought to be, or would develop into, an anticyclonic eddy, and one of the buoys was caught in the eddy. This buoy was drogued at a depth of 320 m in a relatively well-mixed part of the water column thought to contain the eddy core. This buoy made ~60 clockwise orbits in the eddy and remained within 15 km of the eddy centre over the 200-d observation period. The normalized relative central vorticity of the eddy had a minimum value of -0·6 and the eddy rotation period experienced by the buoy ranged from 2·5 to 6·5 d. The decay scale for the eddy was estimated at 250 ±100 d. The mean variance of the east-west velocity component was significantly larger than the north-south value, and the buoy's orbit was significantly elliptical towards the end of the period of the observations.

The present study considered the influence of the tide on shallow water fish assemblages within the Wakatobi Marine National Park, Indonesia. Timed underwater visual observations were made across a gradient of intertidal to subtidal habitats from near-shore to reef crest at different tidal heights. Transient fish were found to dominate shallow water fish assemblages and the assemblage composition varied with tidal state. Fish assemblages were more diverse and abundant at higher tides in both coral and sea grass habitats, however, this was more pronounced within sea grass habitats. A tidal reduction from ≈2.0m to ≈0.8m (above chart datum) corresponded to a 30% reduction in fish abundance, while species richness also significantly decreased from 13.5 to 10.8 species per standardized timed observation. Fifty fish groups were reported from sea grass habitats with the most abundant being from the Engraulidae family and Lethrinus harak, which form important local subsistence fisheries. This research confirms the importance of tidal changes in structuring the fish fauna of Indonesian sea grass habitats and underlines the connectivity that exists between these habitats and nearby coral reefs.

The distributions of Corophium insidiosum and C. bonnellii on the shores of Northumberland and Tyne and Wear suggest the former species to be common in areas of high turbidity, and the latter species in relatively clean conditions. In C. insidiosum breeding takes place throughout the year except during the months of November and December when mature females enter a ‘resting’ stage and immature females delay the onset of maturity. There are two main generations per year. Egg production is linked to a semi-lunar rhythm with peaks around the times of spring tides. Fecundity, brood mortality and feeding activity each vary seasonally.

This paper will discuss the buoyancy of the sperm whale throughout its range and show that the whale probably has some control over its own buoyancy. Evidence will then be presented in support of the hypothesis that the whale can attain neutral buoyancy at depths greater than 200 m by control of the temperature of the spermaceti oil in its head. As a basis for this, papers describing the detailed structure and proportions of the whale (Clarke, 1978a) and some physical properties of spermaceti oil (Clarke, 1978b) have already been published.

Biological invasions can alter the biodiversity of native communities generating an ecological impact that in many cases is irreversible. In 2001, Undaria pinnatifida invaded Macrocystis pyrifera kelp in Cracker Bay (42°56′S, 64°27′W; Northern Patagonia, Argentina). The possible impact of that invasion was evaluated in March 2004 with a study of population and morphological parameters of both kelp species and their associated holdfast biodiversity. Three nearby areas of spatial distribution of the kelps were differentiated, one dominated by M. pyrifera (M), an intermediate area characterized by M. pyrifera and U. pinnatifida (M+U), and another dominated by U. pinnatifida (U). In each area, sporophytes in nine quadrats of 1 m2 were collected. The density and biomass m−2, the height of the sporophytes and the size of the holdfast of  M. pyrifera did not diminish in the presence of  U. pinnatifida. The richness, abundance and diversity of the flora associated with the holdfast of both kelps were similar, whereas these parameters were higher in the case of the fauna associated to M. pyrifera than U. pinnatifida Results obtained in this work suggest that, at this invasion stage, there is no evidence of interspecific competition. Nevertheless, since density and diversity of the fauna associated with the holdfast is different, we expect community changes if the U. pinnatifida invasion continues to expand.

The cosmopolitan genus Orchestia is divisible into two ecological groups: littoral and terrestrial, as denned by Hurley (1959). Only littoral species are known from Britain and three which occur in the Medway estuary have been studied. O. gammarella (Pallas) and O. mediterranea A. Costa are marine or estuarine, the former being found above the recent high water mark under wrack or stones and the latter below this level under stones. O. cavimana Heller is a freshwater species, extending into the oligohalinicum of estuaries (Den Hartog, 1963), which is found near the wrack line. During a study of the biology of these species possible mechanisms which control the tidal levels occupied on the shore were investigated, including the temporal characteristics of locomotory activity.

Cadmium, and its compounds, has been placed on the blacklists of most international pollution conventions by virtue of its toxicity, potential for bioaccumulation and persistence (Taylor, 1983).

The ability of many marine molluscs, and in particular gastropods, to accumulate Cd to a high degree in apparently unregulated fashion has led to their frequent use in monitoring programmes. Thus Cd levels in the winkle, Littorina littorea (L.) closely reflect gradients in environmental contamination (Bryan et al. 1983), demonstrating the excellent ‘indicator’ properties of this group.

1. Sabellaria alveolata Linnæus has been reared for the first time from the egg through the pelagic stages and metamorphosis to early bottom stages. The chief features in the development of the external characters are described and special attention is drawn to the existence of peculiar grasping-cilia on the telotroch. The manner in which the young worm builds its first tube of sand grains is also described.

2. Sabellaria spinulosa Leuckart has similarly been reared for the first time from the egg to early bottom stages. Its development is very similar to that of the preceding species, but during the later pelagic life the two can easily be separated, as the primary palese of the crown, which appear among the long provisional bristles of the first pair of parapodia, show a marked specific difference. The early stages cannot be distinguished.

3. A larva which is probably that of the rare Pallasia murata Allen is described.

4. A tentative key to the British Sabellarian Larvaæ is drawn up.

5. The observations of previous workers are discussed. It is shown that Sabellarian larvaæ have frequently been described as the larvaæ of Spio or of Polydora, in spite of the fact that the early stages of Sabellaria had been obtained more than once from artificial fertilisations. Caullery was the first to point out the error, and he is fully confirmed in this paper.

6. It is shown that the caudal appendage of a full-grown Sabellaria alveolata possesses internally a series of fifty or sixty transverse septa.

Extensive field observations were made in the Mingan Islands, northern Gulf of St Lawrence, to evaluate spatial and temporal variations in the use of habitat and prey resources by two major subtidal predators, the seastars Leptasterias polaris and Asterias vulgaris. Although both seastars have similar size structures and generally overlapped in their spatial and temporal distribution, the degree of overlap varied in different sites and appeared to be related to prey abundance, substratum type and slope. Three general patterns were observed: (1) both species aggregating in shallow water and decreasing in numbers with depth; (2) the two species showing inverse depth distributions; and (3) both seastars occurring in low numbers across the subtidal zone. Temporal changes in availability of the preferred prey of the two seastars, the mussel Mytilus edulis, appeared to be a major factor affecting their abundance and distribution. The two seastars occurred together in dense aggregations on mussel beds in shallow water. They consume similar-sized mussels until the number of mussels becomes reduced when A. vulgaris, but not L. polaris, begins to select larger mussels. Once a mussel bed is decimated, the seastars appear to move away, possibly in search of other beds. Intensive seastar foraging limits the distribution of mussels to a few metres in depth. Below the mussel zone, the two seastars are spatially segregated at a small spatial scale (1 m2 quadrat) and select different alternative prey, L. polaris feeding mainly on the crevice-dwelling clam Hiatella arctica and A. vulgaris on the ophiuroid Ophiopholis aculeata. The size partitioning of the preferred prey in shallow water, and spatial segregation and selection of different alternative prey at greater depths may reflect mechanisms permitting the two seastars to coexist.

Knowledge of the distribution of molybdenum in sea water is needed for an understanding of the behaviour of the element in the geochemical cycle of weathering and sedimentation and for the assessment, in relation to environmental levels, of its possible utilization by marine organisms. The principal measurements of molybdenum in sea water are summarized in Table 1; the results of earlier investigations (Ernst & Hoermann, 1936; Bardet, Tchakirian & Lagrange, 1938; Noddack & Noddack, 1940) are excluded from this summary as later work suggests that they were inaccurate. The summary indicates that molybdenum is a comparatively uniformly distributed trace element in sea water with a concentration usually in the range of 9–13 µg/l. Except for waters directly affected by continental drainage or other localized influences, the only values appreciably below this range appear to be those reported by the early workers cited above, by Zhavoronkina (1960) for a single sample from the Atlantic, and by Brooks (1965) for waters off New Zealand.

Two earlier papers (Wilson, 1968 a, b) have described the rearing of Sabellaria alveolata (L.) and the settlement behaviour of the larvae. It was thought that some of the questions remaining unanswered might be resolved for the cost of one more rearing to obtain the crawling stages needed. With this end in view adult worms were collected at Duckpool on 12 July 1968 during the lowest day-time spring tide of that month. The worms were found to be spawning and had already shed about half of their genital products. On returning to the laboratory a fertilization was made immediately, using a mixture of ova from many females and a mixture of sperms from several males. This fertilization, made at 8 p.m. a few hours after leaving the shore, is the basis of most of the work described in this paper.

The aspidochirote Holothuria forskali is a large common species found in the Atlantic and the Mediterranean. Its reproductive cycle has been determined in a population from Brittany using histological observations of the different classes of gonadal tubules, oocyte size frequencies and evolution of gonad indices. The cycle is annual and synchronous in both sexes. The different phases are well marked and are characterized by a long maturation during summer and autumn followed by a pre-spawning period during winter. Spawning is probably related to the increase in temperature. Most of the mature gametes are released. The resorption of the relict and spent tubules continues during the onset of the next vitellogenesis in the secondary tubules, without a rest period. The reproductive effort, documented from the gonad indices, is very high in this population which is composed of adult individuals.

There have been several reports in recent years of the mass occurrence or blooms of the dinoflagellate Gyrodinium aureolum Hulburt in northern European Waters (Ballantine & Smith, 1973; Helm et al. 1974; Pingree et al. 1975; Pingree, Holligan & Head, 1977; Tangen, 1977). Gyrodinium aureolum is probably one of the most common ‘red-tide’ dinoflagellate species in these waters and some of the blooms of G. aureolum (ranging from 100 to 20000 cells ml-1) have been followed by the mass mortality of various fish and invertebrate species (Tangen, 1977). It has been suggested that the adverse effects of G. aureolum on marine organisms are caused by (a) the production of toxins and/or (b) the oxygen depletion during darkness due to dinoflagellate respiration and decomposition of cells.

Activity patterns of the first maxillae of Calanus helgolandicus and Temora longicornis, restrained in a flow-through system, were investigated using a micro-impedance electrode technique. Copepods were exposed to four dinoflagellate species of similar cell size with filtered sea water and the diatom Thalassiosira weissfloggi as controls. In short-term transition experiments the beat frequency of the maxilla changed rapidly with the introduction and removal of cells from the surrounding medium. Similarly the introduction of cell-free algal homogenate, filtered through a 0·2 µm membrane, produced elevated beat frequencies, evidence consistent with chemosensory food detection. During 24 h exposure experiments frequencies for Calanus on all dinoflagellate diets were lower than for the diatom, and in the case of Scrippsiella trochoidea did not differ significantly from the seawater controls. In Temora, frequencies when feeding on dinoflagellates, except Prorocentrum micans, were lower than on the diatom. With Scrippsiella trochoidea and Gonyaulax tamarensis beat frequencies were the same as those for the sea-water controls. Significant depression of frequency below that observed in filtered sea water was shown for both copepods when presented with the bloom-forming, Gyrodinium aureolum. Differences in beat frequency in response to dinoflagellate diets are mirrored by other aspects of feeding activity, gut contents, egg production and mortality.

The presence of antibacterial activity in the haemocytes of the shore crab, Carcinus maenas (L.) (Crustacea: Decapoda), was investigated using a selection of Gram-positive and Gram-negative bacteria from geographically diverse waters. Preliminary investigations into the relationship between this activity and the prophenoloxidase activating system (proPO) were also carried out. Antibacterial activity against both Gram-positive and Gram-negative organisms were found to reside exclusively in the granular haemocytes and eight of the twelve bacteria tested were susceptible to this effect. Additional studies, using Psychrobacter immobilis (= Moraxella sp.), revealed that the factor (or factors) responsible was 90% effective within 60 min and was also heat stable, independent of divalent cations, and non-lytic in character. Although antibacterial activity resides in the same cell population that carries the proPO system, there appears to be no relationship between antibacterial activity and phenoloxidase itself. Other components of the proPO system, however, may be involved.

The ecological significance of heterotrophic micro-flagellates in marine plankton has recently drawn considerable interest among biological oceanographers (Anderson & Fenchel, 1985; Haas & Webb, 1979; Fenchel, 1985 and references therein). Such organisms have been shown to be numerous, occurring in densities of 5 x 102 to 2 x 103 per ml in surface coastal and oceanic waters. Their grazing activities are believed to account for virtually all of the turnover of populations of suspended bacteria.

Fifteen experiments on the foraminiferid Elphidium crispum (L.) are described. They deal with feeding, movement, the substratum, and salinity, and their bearing on ecology.

The daily production of feeding cysts was used as a measure of the metabolic rate and healthiness of the foraminiferids. Phaeodactylum tricornutum, both living and dead, was used as food; a distinct preference was shown for living food. However, kaolin and graphite having a similar size to the Phaeodactylum were also accepted as food. It is suggested that E. crispum selects its food on the basis of size. The colour of the protoplasm is shown to be closely related to the pigments of the food

Movement in the horizontal plane is normally random. However, this species prefers a clean, hard substratum to one of clay; once a specimen has escaped from a clay substratum, it is loathe to return to it and therefore movement in this instance must be directed and not random.

Movement in the horizontal plane is normally random. However, this species prefers a clean, hard substratum to one of clay; once a specimen has escaped from a clay substratum, it is loathe to return to it and therefore movement in this instance must be directed and not random.

The rate of feeding is shown to be closely related to the salinity of the water, the feeding rate decreasing with the salinity. The amount of calcium present in sea water or in subsaline waters does not appear to affect the rate of feeding. However, lowered temperatures help E. crispum to survive for longer periods in subsaline water. At temperatures of 8° and 16° C , cultures survived subsaline water of 20%0 salinity for 38 days, but at a salinity of i5%03 only the culture kept at 8 C survived (for 15 days).

It is well known that intertidal animals exhibit temporal patterning of behaviour in which locomotor activity occurs at particular times of day and state of tide. Naylor & Atkinson (1976) postulate that such behavioural rhythms are partially controlled by endogenous timing processes which determine the approximate periodicity of a rhythm, as expressed in constant conditions in the laboratory, and that these circadian and circatidal rhythms are entrained by environmental variables which in nature synchronize the expression of behavioural rhythmicity at adaptively appropriate times. Several tidal variables, such as temperature, pressure, light and wave action, have been shown to synchronize and entrain endogenous rhythms (Palmer, 1974; Naylor & Atkinson, 1976) but so far there appears to be little evidence of entrainment of tidal rhythmicity in coastal animals by variations in salinity. A tidal rhythm of responsiveness to water of reduced salinity has been demonstrated by Arnold (1970) in the cirral activity of Balanus balanoides (L.), but entrainment by this response in Balanus has not been tested. In any event the tidal rhythm of cirral activity in Balanus balanoides on the shore is not expressed in barnacles kept in constant conditions in the laboratory (Southward & Crisp, 1965) and therefore appears to be largely controlled by exogenous factors. It therefore seemed worthwhile to investigate the effects of salinity changes upon the locomotor rhythm of Carcinus maenas (L.), the control of which by internal factors (Arechiga, Huberman & Naylor, 1974) and some external factors (Naylor & Atkinson, 1972) is well documented.