A study of the effects of salinity on the distribution and abundance of the amphipod Corophium volutator (Pallas) on the estuary of the River Ythan, Aberdeenshire, indicates that 2‰ is a critical minimum salinity controlling its distribution. In areas with salinities between 2 and 5‰ C. volutator was present, but in reduced numbers. Breeding occurred only in salinities greater than 7·5‰. In areas with salinity greater than 5‰, the distribution and abundance of C. volutator were controlled by the nature of the substrate; however, in areas with suitable substrates, but where the salinity was below 5‰, the effects of salinity override the effects of the substrate. The annual life-cycle is discussed. The results of this study are compared with those of a recent experimental study.

The respiration rates of five genera of benthic Foraminifera were determined by Cartesian diver microrespirometry. Across all genera studied, the rate averaged 11·3×10−3 μl O2 individual−1 h−1 at 10°C. Estimates of foraminiferal mean biovolumes ranged from 0·66 to 6·54×106μm3, giving an overall mean volume-specific respiration rate of 7·36 × 10−9 μl O2 h−1 μm−3. For non-symbiont-bearing Foraminifera, in general, volume-specific rates (log μl O2 h−1 μm3) are best described by the equation, −0·98 × (log cell biovolume, μm3)−2·01. The respiration results show that these benthic Foraminifera respire some ten times more rapidly than naked amoebae of equivalent size. The combination of high respiratory rates and the often large standing stocks of Foraminifera encountered, suggests that these organisms may contribute significantly to total microbial benthic respiration.

Chemostats were used to construct nutrient (vitamin B12) and energy budgets for the flagellate Monochrysis (Pavlova lutheri (Droop) Green) under varying conditions of nutrient and light limitation and luxury, the aim being to describe light limitation and luxury in terms analogous to those of the Cell Quota nutrient model. Measurements were made of steady-state dilution rate, biomass, cell quota, cell chlorophyll a, cell energy content, dark respiration and photosynthetic efficiency, under low irradiance (<13 W per m2).

Cell energy content was 0·54 joules per million cells and was not influenced by growth rate or nutrient/light status. Cell chlorophyll a was 25% less in the nutrient-limited cultures and did not show a clear trend with growth rate except in cultures receiving less than 4·3 W per m2. The effective specific extinction coefficient was 0·12 cm2 per μg chlorophyll. The photosynthesis/irradiance relation was linear. The mean slope (= efficiency) in samples from the light-limited chemostats was 0·225 and was independent of dilution rate. Samples from nutrient-limited chemostats showed a much lower slope, which decreased with decreasing dilution rate. These findings were confirmed by the chemostat kinetic data. Dark respiration varied with dilution rate in a hyperbolic manner and was greater in the nutrient- than the light-limited chemostat.

Light level had no effect on the subsistence quota when the nutrient was limiting, whereas under light-limiting conditions the subsistence quotas were enlarged in inverse proportion to the incident irradiance, thus showing a threshold rather than multiplicative interaction between light and the nutrient.

Energy absorption was very little reduced on nutrient limitation, the great reduction in overall efficiency being associated mainly with the reduction in photosynthetic efficiency.

The reciprocal of photosynthetic efficiency was shown to be analogous to a standardized nutrient cell quota, and an analogous coefficient of luxury could be defined as the ratio of the light-limited to nutrient-limited photosynthetic efficiency at the same growth rate. Thus, light limitation and luxury could be described in terms compatible with the nutrient model without having to introduce new concepts, and a practical criterion between light- and nutrient-limitation could be provided.

The order Isochrysidales was erected by Pascher in 1910 to accommodate chrysomonads with two equal flagella. It was based on the family Hymenomonadaceae (Senn, 1900) and included such genera as Synura Ehrenberg (later shown to be heterokont and therefore incorrectly placed here; Hovasse, 1949; Manton, 1955), Wyssotzkia Lemmermann and Hymenomonas Stein. Papenfuss (1955) used the name in a similar sense but encompassing also the coccolithophorids, while those genera with two equal flagella and a ‘short third flagellum’ ((Prymnesium Massart, Platychrysis N. Carter, Chrysochromulina Lackey) were placed in the order Prymnesiales. Subsequently it was demonstrated that members of the Isochrysidales and Prymnesiales differ from other chrysomonads in that the two true flag-ella are smooth with no coarse hairs (‘mastigonemes’) and that the third appendage found in genera of the latter order is a unique structure, termed the ‘haptonema’ by Parke, Manton & Clarke (1955). On the basis of these observations, Christensen (1962) erected a new class, the Haptophyceae (now referred to by the typified name Prymnesiophyceae; Hibberd, 1976 a), to contain the two orders although Bourrelly (1968) preferred to retain them within the Chrysophyceae whilst recognizing their unique status by the erection of a sub-class, the Isochrysophycidae.

Orbulina universa d'Orbigny is a spinose planktonic foraminifer which occurs throughout surface waters of the tropical, subtropical and transition zones of the world ocean (Bé & Tolderlund, 1971). This species is unique among planktonic Foraminifera in that its life cycle is composed of two growth stages. The juvenile stage is a trochospiral form which is enclosed within a terminal spherical chamber in the adult stage. O. universa is relatively omnivorous, and consumes a variety of prey that range in size and quality from phytoplankton to copepods (Bé et al. 1977; Anderson et al. 1979; Spindler et al. 1984). In addition, each individual harbors several thousand zooxanthellae which presumably are an additional source of nutrition for the foraminifer (Be et al. 1977; Hemleben & Spindler, 1983; Spero & Parker, 1985).

The concentrations of booster compounds were surveyed in the port of Osaka, Japan. The concentrations of Sea-Nine 211, Diuron and Irgarol 1051 in water samples from the port of Osaka were in the ranges <0·30–0·55 ng l−1, 13–350 ng l−1, 1·3–77 ng l−1, respectively. Pyrithiones were not detected in water samples. The levels of Diuron and Irgarol 1051 in the port of Osaka were high in the mooring area for small and medium-hull vessels with poor flushing.

Susceptibility of bacterial populations in estuarine water to antifouling biocides was studied. Sea-Nine 211, Diuron, Irgarol 1051 and Copper pyrithione dissolved in dimethyl sulfoxide (DMSO) were added to estuarine water and number of colony forming units (CFU) of bacteria in estuarine water was counted using R2A agar plate. The CFU was not decreased at the concentration less than 1·0 mg/l of Diuron, Irgarol 1051 and Copper pyrithione. However, CFU was decreased at 0·1 mg/l of Sea-Nine 211. Degradation of Sea-Nine 211, Diuron, Irgarol 1051 and Copper pyrithione by bacteria in estuarine water was studied using a die-away method. At an initial concentrations of 0·1 mg/l, observed half-lives of Sea-Nine 211 and Copper pyrithione were 10 and 20 days, respectively. In contrast, Diuron and Irgarol 1051 were degraded scarcely during 60 days of culture.

Photodegradation of these booster biocides by sunlight and UV light were studied. Under UV, all biocides were below detection limit after one day of irradiation. Under sunlight, Copper pyrithiones were also below detection limits after one day. Drastic decrease of Sea-Nine 211 concentration was observed after one day. Diuron and Irgarol 1051 scarcely decreased during 17 days of sunlight irradiation.

Fecundity and size at maturity of the European lobster Homarus gammarus (Crustacea: Decapoda) was estimated in four coastal regions of Ireland. Egg size increased with carapace length (CL) (egg size=0·9939×ln (CL)−3·0809). The size–fecundity relationship for all coasts combined was (fecundity=0·0044×CL3·1554).  Physiological maturity was assessed using ovary colour, ovary factor, ova size, abdomen width/CL ratio, cement gland activity and moult status as criteria. Size at 50% maturity varied from 92·5 to 96  mm depending on region. The size–maturity relationship for all coasts combined was (Maturity= 1/(1+exp(14·595−0·15598×CL))). Over 60% of lobsters in the commercial landings were under the size at 50% maturity.  Relative reproductive potential (RRP) of different size-classes was calculated from the size–fecundity and size–maturity models and the numbers by length in the landings. The modal RRP size-class was 98–100 mm. The commercial landings were dominated by the 86–92  mm size-classes.

Size-based analyses of marine animals are increasingly used to improve understanding of community structure and function. However, the resources required to record individual body weights for benthic animals, where the number of individuals can reach several thousand in a square metre, are often prohibitive. Here we present morphometric (length–weight) relationships for 216 benthic species from the North Sea to permit weight estimation from length measurements. These relationships were calculated using data collected over two years from 283 stations. For ten abundant and widely dispersed species we tested for significant spatial and temporal differences in morphometric relationships. Some were found, but the magnitude of differences was small in relation to the size-ranges of animals that are usually present and we recommend that the regression relationships given here, based on pooled data, are appropriate for most types of population and community analyses. Our hope is that the availability of these morphometric relationships will encourage the more frequent application of size-based analyses to benthic survey data, and so enhance understanding of the ecology of the benthic/demersal component of marine ecosystems and food webs.

The size distribution of benthic nematodes was investigated along different gradients of food availability in various regions of the north-eastern Atlantic: I, across the continental margin and II, with increasing distance from the continental rise. An overall trend for miniaturization with increasing distance from the food source was found. Moreover, our results indicate that seasonally varying food supply or a periodically pulsed input of organic matter to the sea floor affects nematode size spectra. The hypothesis is proposed that the life cycle of deep-sea nematode species and hence the size structure of their populations are related to seasonal energy availability. This dependence might result in one year life spans of deep-sea nematodes and probably other meiofauna.

Molecular analyses of 13 species of the marine bivalve family Thyasiridae, using sequences from 18S rRNA and 28S rRNA genes, showed that the family is monophyletic despite the anatomical disparity and inclusion of both chemosymbiotic and asymbiotic species. This new analysis also confirmed that the three families (Thyasiridae, Lucinidae and Ungulinidae), previously included in the Lucinoidea, were not closely related. Four species of Ungulinidae grouped within a clade containing Veneridae, Arcticidae and Mactridae. In relation to a range of other heterodont bivalves, Thyasiridae occupied a near basal position, apart from a clade comprising Carditidae/Astartidae/Crassatellidae. The earliest thyasirid recognized in the fossil record is a species from the Lower Cretaceous of England. Within the Thyasiridae, some groups can be identified but relations between these are weakly supported. Amongst the taxa analysed, those with symbiotic bacteria and two ctenidial demibranchs belong to at least three groups, while there is some support for a clade of asymbiotic taxa with single demibranchs. In recognition of the monophyletic status of the Thyasiridae, distinct from all other heterodont bivalves, we elevate the rank to superfamily Thyasiroidea.

Anchovy larvae, collected at 107 stations in the north-west Mediterranean were analysed, in relation to three possible variables, the diurnal or nocturnal time of sampling, the location of sampling stations in relation to the neritic and oceanic domain, and the assignation of anchovy samples to each of the two main anchovy spawning grounds in the region. Feeding activity appeared to be mainly diurnal, stomach contents consisting mostly of copepod eggs, nauplii and copepodites. The stomachs of larger larvae showed an increase in the size range of prey, together with a parallel increase in the incidence of copepodites in the diet.

In the deep water of the eastern North Atlantic below 2000 m. the variations with depth of salinity, temperature, density, oxygen, phosphorus compounds and nitrate are quite small. By contrast the silicate content is doubled in a descent from 2000 to 4000 m.

The distinctive behaviour of silicate is revealed by diagrams (Fig. I) relating it to salinity, temperature, density and total phosphorus at station 2659 worked by R.R.S. Discovery II on 12 May 1950 (Armstrong, 1951; Cooper 1952, Table IV). The temperature-salinity diagram (Cooper, 1952, fig. 15, to 1500 m. only) suggests that between 1200 and 2000 m. we have to deal with simple mixing of the mean Gulf of Gibraltar and North Atlantic Deep waters. If silicate concentration were subject only to mixing processes the curves in Fig. I between these depths would be straight lines. They are not—consequently it would seem that solution of either particulate silica or of aluminosilicates may be occurring. As yet, clear interpretation is not possible. At least five hypotheses may be erected to explain, in whole or in. part, the observed distribution: (i) solution of bottom deposits; (ii) solution of ‘clay’ and of silica in suspension; (iii) concentration by vertical partition; (iv) tundra drainage; (v) sinking of surface water. These are examined in turn.

Harbour porpoises (Phocoena phocoena) visit Ramsey Sound at specific states of tide to feed. The preferred foraging location is high-energy habitat in South Ramsey Sound where a tide race, overfalls and upwelling zones form during the ebb phase. Seabed topography and tidal currents combine to create a foraging resource exploited by harbour porpoises at regular and predictable intervals. Porpoises are observed surfacing repeatedly directly into the tidal stream above and adjacent to, a steep-sided trench on the seabed. Tidal currents and the steep walls of the trench are believed to concentrate prey which is funnelled towards the waiting porpoises. Schools with calves prefer areas on the periphery of the fastest flowing water, where current speeds are lower. The presence of harbour porpoises is restricted almost entirely to the ebb tidal phase, but porpoises regularly occupy this site for the entire ebb phase. Harbour porpoise foraging in a tide race habitat is widely reported from the geographical range of the harbour porpoise and raises issues regarding foraging strategy and the net energetic value of hunting prey in high-energy environments.

Experiments are described in which attempts were made to fertilize eggs of the lugworm taken from the coelom. These were unsuccessful except when the eggs were taken from spent or partially spent worms or from worms kept in the laboratory until they were about to spawn. It was concluded from this that maturation of the eggs precedes spawning but only by a matter of hours. That maturation begins in the body cavity was confirmed by histological examination of eggs from partially spent worms and criteria are given for the recognition of immature and mature eggs. Lack of success in previous attempts to fertilize coelomic eggs from non-spawning worms may be because females which are just about to spawn are not obtained by the normal methods of collection. It is suggested that this is due to a change in the behaviour of the worms associated with retention of eggs in the burrow after oviposition. With regard to the stimulation of spawning in female worms, it has been shown that maturation immediately precedes the onset of shedding. This, together with the fact that if eggs undergoing maturation are injected into a nonspawning worm they are shed automatically suggests that the primary stimulus for the onset of shedding is, simply, one which will induce maturation of the eggs.

Observations made during the above experiment together with the fact that worms can be induced to shed a few unripe eggs by injection of tissue extracts suggest, however, that spawning is not entirely passive and dependent on maturation. The lipid fraction of tissue extracts stimulates the active uptake of eggs from the coelom but it fails to induce maturation of the eggs and hence the free spawning produced in male worms. While the release of lipid into the body cavity may have some effect on the spawning of female worms (under natural conditions) similar to that previously suggested for males, it cannot provide the primary internal stimulus for spawning.

The ‘strength’ of the endogenous locomotor activity rhythm of four peracarid crustacean species, denned by the precision and persistence of the rhythm, was examined with particular reference to a ‘burrowing’ versus epifaunal supralittoral life-style. The ‘strength’ of the endogenous component of the activity rhythm was also illustrated using a modified periodogram analysis. In all species, the talitrid amphipods Talitrus saltator, Talorchestia deshayesi, Orchestra gammarella and the oniscoid isopod Ligia oceanica, the laboratory-monitored rhythm and the field emergence pattern displayed a nocturnal, circadian pattern with no clear evidence of any circa-tidal influence. The precision and particularly the persistence of the rhythm of the sand-shore burrowing species T. saltator and T. deshayesi are especially well developed, although a ‘strong’ endogenous component is present in the rhythm of all four species. The significance of the endogenous locomotor rhythms is considered with respect to the supralittoral ecology of the species.

Ashadze-1 (12° 58′N 44° 51′W, 4080 m) on the Mid-Atlantic Ridge (MAR) is the deepest known active hydrothermal vent field. The first observations on this site were numerous clear and black smokers and surprisingly few known symbiotic species dominant in other vent areas on the MAR. The species most abundant at Ashadze-1 are those usually found at the periphery of hydrothermal communities: sea-anemones Maractis rimicarivora and chaetopterid polychaetes Phyllochaetopterus sp. nov. This study comprised site mapping and faunal sampling and Ashadze-1 was completely mapped by using the remote operated vehicle ‘Victor 6000’ and a new high resolution tool available for deep-sea research. A photo-mapping survey was carried out with a long range optical black and white camera. Digitization of substrata and sea-anemones visible on the images was performed by GIS. Spatial distribution of Ma. rimicarivora was distinguished by high densities of 32 ind.m−2 on the western side of the main smoker area. Submersible sampling operations allowed taxonomic identification within a 200 × 110 m area. Carbon, nitrogen and sulphur isotopic ratios were measured in four dominant species to identify their trophic position. The present paper gives the complete maps and describes the faunal community of the Ashadze-1 vent field. The results obtained led us to consider this site as an ecosystem in its declining stage. Finally we compare the similarities of this community to other hydrothermal communities on the northern MAR.

An apparatus for sampling the fauna of the uppermost 10 cm of the sea is described. The net is designed to fish at speeds of 5–6 knots in undisturbed water to one side of a ship. A preliminary account is given of the catches made with the net in the Indian Ocean.

To reveal the annual patterns of planktonic ciliate communities, planktonic ciliate species composition, abundance and biomass, and responses to environmental conditions, were investigated during an annual cycle in Jiaozhou Bay, Qingdao, northern China. A total of 64 species belonging to five orders (Oligotrichida, Haptorida, Cyrtophorida, Hypotrichida and Tintinnida) were identified, 9 of which were dominant. Ciliate communities presented a clear seasonal pattern in terms of both abundance and biomass. A single peak of ciliate abundance and biomass occurred in late August, mainly due to the oligotrichids, tintinnids and haptorids. The 9 dominant species showed a distinct temporal distribution with seasonal successions of ciliate communities. Multivariate analyses revealed that ciliate abundance was significantly correlated with water temperature, dissolved oxygen and nutrients, especially nitrate nitrogen and soluble reactive phosphate (P < 0.05). These findings provided basic data on annual cycle of planktonic ciliate communities in a semi-enclosed bay of Yellow Sea, northern China.

Electric rays (Torpedinidae) are known to harbour on their gills certain monogenean parasites (Amphibdella spp. and Amphibdelloides spp.) whose taxonomy is in a very confused state. Muchof this confusion has centred around a single morphological feature: a ‘transverse bar’ has been variously held to be present or absent from the adhesive apparatus, or sometimes two such bars have been stated to be present. Among those who have regarded the trans-verse bar as having taxonomic importance, Price (1937) recognized two genera of amphibdellids distinguishable by the presence or absence of the bar, but Palombi (1949) and Bychowsky (1957) believe that the bar may be present in young specimens but absent or inconspicuous in older specimens. No-one has investigated the function of thistransverse bar, or, indeed, any functional aspect of the adhesive apparatus. Again little attention has been paid in taxonomy to the genitalia or host specificity, or, in spite of a record of an amphibdellid from the heart of its host, to micro-habitat.

The pelagic environment can be divided into five gross regions. These are the intertidal and estuarine, the neritic and the oceanic epipelagic, mesopelagic and bathypelagic regions. Each of these regions has an endemic crustacean fauna but many species inhabit more than one region. The ranges and rates of fluctuations of environmental characteristics vary from the extremes encountered in the intertidal and estuarine region to the relative constancy of those in the bathypelagic region.