The temporal distribution of autotrophic and heterotrophic components of the planktonic community was studied from samples collected weekly at station L4, located to the south of Plymouth, UK, from October 1992 to January 1994. Phytoplankton succession followed the typical pattern of temperate waters, the development of a summer Gyrodinium aureolumbloom being the most prominent feature. Bacterial numbers were significantly correlated with temperature during autumn and winter, whereas resource availability and predation, including viruses, appear to be the most important controlling factors in spring and summer. High mesozooplankton densities, mainly copepods, were observed throughout most of the study associated with a series of diatom blooms, and also during autumn when low phytoplankton biomass was measured. This data set was analysed in order to build up conceptual trophodynamic models whereby the role of biological communities on the cycling of organic matter could be inferred. The results obtained in this study provide empirical evidence supporting the existence of a sucession of trophic organization patterns in a coastal temperate environment. Classical models (herbivorous or microbial webs) appeared episodically whereas transition models (multivorous web) dominated throughout most of the seasonal cycle.

The macrobenthos of the subtidal, mesohaline zone of the Schelde Estuary (Belgium) was sampled in October 1996 and 1997 at 54 and 73 sampling locations respectively. Sediments ranged from silty to very coarse, with the dominant sediment type being silt (33% of all locations). Of the 35 macrobenthic species observed, only seven species occurred in more than 20% of the samples. The polychaete Heteromastus filiformis and Oligochaeta were most common. Multivariate techniques revealed three distinct communities, linked mainly with sedimentological factors: (1) a species-poor (nine species) community with a dominance of the amphipod Bathyporeia pilosa, a low mean abundance and biomass (86 ind m−2, 0.0189 g ash-free dry weight (AFDW) m−2), and a mean median grain size of 215±19 μm (fine sand); (2) a species-rich (22) community, with the small polychaete Polydora ligerica as indicator species, a relatively high mean abundance and biomass (2298 ind m−2, 1.395 g AFDW m−2, oysters excluded), a mean median grain size of 133±41 μm, and also the occurrence of sediments with hard substrates being characteristic for this community; (3) a community with an intermediate species richness (12), abundance and biomass (248 ind m−2, 0.249 g AFDW m−2), with H. filiformis and Oligochaeta as indicator species, and a median grain size of 76±9 μm. In the study area several typical brackish water species were observed (e.g. Polydora ligerica, Corophium lacustre, Gammarus salinus).

Mean total abundance and biomass were very low, and the benthic communities appeared to be under stress, with a dominance of mainly small, subsurface deposit and surface deposit feeding opportunistic species. This is probably a combined effect of both natural physical and human-induced disturbance. Only sediments with hard substrates (e.g. rocks) seems to favour species richness, providing a shelter against physical disturbance.

A new species of Gastrophanella, G. cavernicola sp. nov. (Demospongiae: Siphonidiidae), is described from submarine caves in Fernando de Noronha Island (north-east Brazil), Carrie Bow Cay and Columbus Cay, Belize (central Western Atlantic), at depths of 5-30 m. It differs from all other species of the genus by its lobate shape with thin superficial canals and centrotylote tylostrongyles. Gastrophanella cavernicola sp. nov. is the second record of the genus Gastrophanella from both Brazil and the Caribbean. It is the sixth ‘lithistid’ sponge reported from the Brazilian coast, whereas at least 32 other desma-bearing sponges are known from the Caribbean. The genus now includes five valid species, G. implexa Schmidt from the West Indies (type species), G. mammilliformis Burton from South Africa, G. primore Gómez from the Pacific Coast of Mexico, G. stylifera Mothes & Silva from south Brazil, and G. cavernicola sp. nov. from north-east Brazil and Belize. Aciculites oxytylota Lévi & Lévi from New Caledonia is transferred to Siphonidium Schmidt. The family Siphonidiidae Lendenfeld, which is probably related to order Hadromerida, is redefined to contain only Siphonidium and Gastrophanella, both with fused rhizoclone desmas associated to microspined exotyles.

The reproductive cycle of the Australasian barnacle Elminius modestus (Crustacea: Cirripedia) was studied at three sites within Whitegate Bay, Cork, Ireland over 15 months. At all three sites, there were seasonal trends in development of the male and female reproductive organs with, for example, the ovaries regenerating whilst eggs were being brooded. Throughout the year, significantly lower percentages of animals were brooding embryos at the site of a warm-water outfall than at another site nearby. The factors which may affect the reproductive cycle of E. modestus are discussed.

Substratum heterogeneity on rocky shores can affect the distribution pattern of sessile epibenthic organisms. The rocky shore at Usujiri, southern Hokkaido, Japan, is composed of well-developed, columnar jointed dolerites. In this area, landscape is characterized by a mosaic of barnacle and mussels, where species composition in patches differs among typical topographic-classes, i.e. barnacles dominate on horizontal planes and vertical planes while mussels only inhabit in grooves. To determine the factors maintaining those distribution patterns, the recruitment of dominant sessile species in the typical topographic-classes with and without adults of barnacles and mussels were examined by field experiment. The results showed that the distribution pattern was determined by recruitment, and the recruitment pattern was strongly affected by rock-surface topography. Moreover, the presence of conspecific adults contributed to the maintenance of this topography-related mosaic by facilitating recruitment. These results show: (1) the presence of resource division for rocky topography among barnacles and mussels; and (2) that intraspecific positive interaction rather than interspecific competition may play important role in maintaining the topography-related mosaic of barnacle and mussels at Usujiri.

Postmarsupial development and growth of Natatolana borealis were studied from Skogsvåg and Raknesvåg on the western coast of Norway. Growth was determined from size and instar stage distributions. Growth was also examined in laboratory kept isopods that were collected from Skogsvåg. The postmarsupial instar stages were identified using the number of articles and the position of setae on the flagellum of the first antenna and other morphological features. The mean size of isopods in instar stages 1—3 did not show any significant seasonal variation in Raknesvåg. The estimated growth and mortality rates of males and females were not significantly different. Nine and 11 postmarsupial instar stages were found in material from Skogsvåg and Raknesvåg, respectively. The life span from instar stage 1 to 9 of male and female N. borealis from western Norway was estimated to be 3—4 y. Mortality rate increased significantly from instar stage 9 to 10 of both sexes. Isopods that attained instar stage 10 and instar stage 11 in Raknesvåg, may have lived 4—5 y. The mean size of instar stages 8 and 9 and the size-to-weight relationships were significantly higher in material from Raknesvåg relative to that from Skogsvåg and may have been caused by differences in food access and predation pressure at the two study sites. Specimens sampled from the Bay of Monaco attained smaller adult size than the isopods from the Norwegian population.

This study examined the use of replica limpets made from modelling wax to provide an index of encounter frequency between crabs and their limpet prey. Video observations at Port Erin Marine Laboratory, showed that the intertidal crabs, Carcinus maenas (L.), Necora puber (L.) and to a lesser extent Cancer pagarus L., regularly examined and tried to remove both real and replica limpets with their chelae. Replica limpets became scratched or gouged as a result of these encounters. The frequency of attack was similar for both real and replica limpets. Hence marks on the limpet models provided a reliable index of attacks on real limpets. The frequency, timing and spatial distribution of encounters between limpets and crabs were recorded by scoring the marks made on model limpets deployed amongst real limpets on the shore. During a 28-day period at Port St Mary on the Isle of Man, limpet models were marked more frequently and with longer scratches on the lower shore than on the upper shore, suggesting that larger crabs were present on the lower shore. Models, deployed at Prawle Point, Devon, showed that encounters between crabs and limpets occurred during both day and night-time high tides. The models were durable and provided an inexpensive method for recording encounters between crabs and limpets. Some replicas were also marked by the teeth of small fish and rodents. Model prey such as these could also be used to study other predator–prey encounters, particularly in conditions which preclude direct observation or video recording, or for use with animals that might be disturbed by observers or cameras.

The porcellanid crab Liopetrolisthes mitra is a common associate of the black sea urchin, Tetrapygus niger in north central Chile. The host-use pattern, population dynamics and reproductive pattern of L. mitra on sea urchins were examined between January 1996 and February 1997. Each month, between 60 and 95 per cent of all collected urchins hosted crabs, with the highest frequency of cohabitation occurring during the austral summer (January to March). Group sizes of crabs on individual urchins ranged from 1 to 25 crabs per host. The average density of crabs on the urchins ranged from 2 to 5.5 crabs per host. Large urchins were inhabited by crabs more frequently than small urchins but urchin size had no effect on the number or size of crabs. The sex ratio of adult crabs was ˜1:1 during most months. Reproduction occurred throughout the year but was most intense during the austral spring and summer (October to March), when the highest percentage of ovigerous females were found. Similarly, recruitment of L. mitra occurred throughout the year but reached a peak during austral summer and early autumn (January to May). All life stages of L. mitra including recently settled megalopae and reproductive adults were found on urchins. Size–frequency analysis indicated that many crabs live >1.5 years. The results of this study confirm that the association between L. mitra and T. niger is strong and persists throughout the benthic life of the commensal crab.

The combined effects of cadmium (Cd) and temperature on the physiology (oxygen consumption rate (MO2)) and biochemistry (glycogen, metallothionein (MT) and Cd concentrations) of fasted dogwhelks Nucella lapillus were investigated using two Cd concentrations (<0.01 or 500 μg l−1) and two water temperatures (5 or 10°C). After 20 days of exposure, the MO2 of dogwhelks of various sizes (12—32 mm in shell length) were measured individually. Dogwhelks exposed to Cd exhibited significantly lower MO2 at 10°C but not at 5°C when compared with controls at the same temperature. Inhibition of MO2 by Cd increased with increasing water temperature and decreasing animal size. Cadmium exposure caused significant reductions in glycogen concentrations in foot muscle and digestive gland at both temperatures. Cadmium-exposed dogwhelks showed significantly higher MT concentrations in the Leiblein gland at 10°C but not at 5°C, indicating that MT synthesis is temperature dependent and temperature is an important factor affecting toxicity of Cd in N. lapillus. Activity of dogwhelks and oxygen carrying capacity of the haemolymph, were significantly reduced as a result of Cd-exposure at 10°C. In addition, mucus secretion and necrotic cells were observed on the gill surface of Cd-exposed individuals. Therefore, reduction in MO2 may be directly linked to Cd-induced mucus production, structural damage to gills and reduction in oxygen carrying capacity of haemocyanin. However, metabolic depression, including low MO2 and activity, in Cd-exposed N. lapillus may be a strategy to: (i) minimize the uptake and toxicity of Cd; and (ii) minimize energy expenditure to spare energy reserves for detoxification (e.g. MT synthesis) and maintenance (e.g. repair of cellular damage). The results are discussed with reference to the use of MT and glycogen as biomarkers for metal exposure and toxicity in marine molluscs.

Annual gametogenic cycle in ocean quahog, Arctica islandica, was investigated using specimens collected regularly from a near shore population in north-western Iceland from December 1997 to November 1998. Gonads from 450 adult quahogs with shell length ranging from 65 to 106 mm were examined after being prepared by standard histological techniques. Observed gametogenic progression was categorized by five phases: (EA) early active; (LA) late active; (R) ripe; (PS) partially spent; (S) spent. All phases of the gametogenic cycle were present in the samples all the year around except in May and June when no spent individuals were seen, and in June and July when no individuals in the early active phase were observed. Morphologically ripe specimens predominated in the samples from May until August when partially spawned individuals dominated the population and did so until February. Spawning activity as inferred from the histological examination appears to be all the year around but most intense from June until August.

The aim of this study was to characterize the daily shell growth of Pecten maximus from early 1998 to late spring 1999 in the Bay of Brest with a careful qualitative and quantitative description of the pelagic primary production. Our results, in accordance with previous studies, demonstrate that there are episodic declines in the growth rate. Concurrent events of low growth rate and large bottom-concentrations of algae following diatom blooms (Cerataulina pelagica or Rhizosolenia delicatula), suggests that this high concentration of phytoplankton on the bottom layer may affect food intake or respiratory activity of the scallops by gill clogging or oxygen depletion. In this study, silicic acid or phosphorus are inferred to be limiting factors responsible for the collapse of the spring bloom. Further, we suggest that, in an N-enriched ecosystem, Si or P-limitation and the changing sinking velocities of phytoplankton, could affect the biology of benthic suspension-feeders.

The magnitude of geographical variations of stable isotope ratios of carbon and nitrogen was examined in ten squid species captured in seven areas of the world's oceans. The average of all 139 squid was −17.4±1.4‰ for δ13C and 11.6±1.6‰ for δ15N. The δ13C of squid showed a clear-cut negative correlation with the latitude of the sampling locations, reflecting the well-known latitudinal characteristics of phytoplankton δ13C, while squid δ,15N did not correlate with the latitude significantly. The δ15N reflected the regional characteristics of nitrogen metabolism such as denitrification and N2 fixation, and it was conspicuous in the intraspecific variation in Sthenoteuthis oualaniensis ranging from 10.0±1.5‰ off Japan to 16.3±0.6‰ off Peru in the Pacific Ocean. Significant isotopic variations were also found in the local area among the five species off Japan in the Pacific Ocean and among the three species in the Japan Sea. Attention must be paid to the isotopic variations of primary producers as well as those of squid in examining the trophic positions of squid.

The cirrate octopod family Stauroteuthidae is revised on the basis of new material collected from the North and South Atlantic and a thorough examination of relevant type material. The family is characterized by the presence of a secondary web, U-shaped shell vestige, reduced mantle aperture and with long cirri, not reaching the arm tips. The radula is absent. The family contains a single genus with two valid species, Stauroteuthis syrtensis and S. gilchristi, which are redescribed based on the holotypes and new material. Chunioteuthis ebersbachii is a junior synonym of S. syrtensis and C. gilchristi is placed in the genus Stauroteuthis. The genus Chunioteuthis is no longer valid. The form and arrangement of suckers distinguish the two species of Stauroteuthis. Stauroteuthis syrtensis is broadly distributed in the North Atlantic at depths of 700—4000 m with peak abundance at 1500—2500 m. Stauroteuthis gilchristi is known only from the type locality off Cape Town (2604 m) and from new material captured off South Georgia (1000 m).

The growth of Octopus vulgaris (Mollusca: Cephalopoda) in tanks and the sea was modelled and calculated following tagging studies in Senegal. Octopus exhibits a large individual variability in growth and the exponential growth curve is the best fitting theoretical model among other usual models tested. Globally, the growth rates were comparable in the sea and in tanks. Growth rates for the hot season were lower than those for the cold season. Applied to in situ data, the statistical tests showed that females grow more quickly than males. Life expectancy was estimated at between 12 and 14 months. These results question the previous growth curves for the region, all of which were obtained from modal analysis using size or weight–frequencies and were used during stock assessments of this important resource off the north-west African coast.

Sponge communities were sampled at 3 m depth intervals at six sites experiencing different flow regimes at Lough Hyne, Ireland. Sponges were identified and classified within the following morphological groups: encrusting, massive, globular, pedunculate, tubular, flabellate, arborescent, repent and papillate morphological types on both vertical (≈90°) and inclined (≈45°) surfaces.

Differences in the proportional abundance of the sponge body forms and density (sponge m−2) were observed between sites and depths. The density of sponges increased with depth at sites of slight to moderate current flow, but not at the site where current flow was turbulent. Morphological diversity of sponge communities decreased with increasing current flow due to the removal of delicate forms such as pedunculate and arborescent shaped sponges. Massive and encrusting morphologies dominated at the high-energy sites (fast and turbulent flow regimes) due to a high basal area to volume ratio, which prevents removal from cliff surfaces. However, pedunculate, papillate and arborescent types dominated at the low current sites as these shapes may help to prevent the settlement of sediment on sponge surfaces. Bray–Curtis Similarity analysis and Correspondence Analysis were used to distinguish between five different morphological communities.

Numerous studies of their population genetics have reported incipient reproductive isolation among sympatric populations of the common intertidal beadlet anemone Actinia equina. This has lead to certain morphs being raised to specific status. A study of the nematocysts of the green sea anemone Actinia prasina and three genetically isolated morphs of A. equina was undertaken to establish that mean nematocyst length could act as diagnostic phenotypic characters within a morphologically variable group. The results support genetic and ecological evidence for the specific status of the three red/brown coloured morphs of A. equina. The data are discussed with respect to the ecology of Actinia and concepts of species, but more work is required before the specific status of A. prasina can be confirmed.

The effects of polychaete (Lysidice ninetta, L. collaris, Nematonereis unicornis (Annelida: Polychaeta)) and limnoriid isopod (Limnoria tuberculata (Crustacea: Isopoda)) borers in the Mediterranean sea grass Posidonia oceanica (Potamogetonaceae) were assessed in the meadows of Olbia and Genoa (western Mediterranean Sea). Borer invertebrates were mainly found into the old leaf sheaths of the sea grass. At Olbia, a mean density of borers (202.6±34.8 ind m−2) significantly higher than at Genoa (23.2±7.3 ind m−2) was observed. In 3.3% of samples from Olbia, large polychaetes and isopods were also observed boring into living plant tissues. Only fractions from 0.8—3.9% of the sheath production was actually removed by borers at the two studied meadows. The fact that sheath weight loss with time was higher at Genoa than at Olbia regardless of the presence of borers suggests that other factors than the activity of such organisms are important in the sheath decay process.

Numbers of naked amoebae (Gymnamoebae) inhabiting the lower intertidal zone of two sandy beaches were estimated using a novel enrichment cultivation method. Samples were collected between June and September, 1999. Beach sand at Kames Bay, Isle of Cumbrae, Scotland contained on average 2604 amoebae cm−3 while at Dania Beach, Florida, USA, sand harboured 4236 amoebae cm−3. This is the first study to focus on the abundance of naked amoebae inhabiting a sandy beach. These numbers are higher than densities generally reported for shallow subtidal sands and show that amoebae must be considered in future studies on the dynamics of sandy beach communities.

Hediste diversicolor from several populations on the Basque coast shows great intraspecific variation in the number of paragnaths (chitinous teeth) in its proboscis. Interpopulation variation in the number of paragnaths was observed in groups I and III. Most group numbers are strongly correlated; only group VI seems to behave independently. In general, the number of paragnaths is higher than those from earlier studies on other populations at locations along the whole latitudinal gradient of the species distribution; groups II and VI are the most stable. A significant relationship was observed between the paragnath number and the granulometry of sediment: in general the number is higher in coarse sandy sediments and decreases with the fine grain fraction.

Paragnath variation was examined in two populations of the epitokous form of the polychaete Perinereis cultrifera from the English Channel and the Algerian Mediterranean coast. Populations differ from each other in the mean number of paragnaths in groups I, II, III, V and VII–VIII, in the number of teeth per half jaw and in the morphology of paragnaths in the posterior belt. Individuals of the two populations studied share no common alleles at five loci involved in electrophoretic comparison. The general protein band patterns reveal 13 markers that discriminate between the Perinereis individuals. Congruence of all the reported results agree with the assignment that P. cultrifera is a complex of species, probably more than two.