The diet breadth and diet overlap of two co-existing species of flatfish, plaice (Pleuronectes platessa) and dab (Limanda limanda) inhabiting a shallow bay in south-west Ireland are compared. They were shown to vary with the resource matrix, the gut region and the sample size. Diet breadth was calculated using Levin's index and diet overlap calculated using Horn's index. Values of diet breadth were considerably less for numerical abundance data when compared to percentage occurrence data. Similarly, diet overlap values were less for numerically derived data. In dab, diet breadths were significantly lower for stomach-only contents than for intestine-only or whole gut contents. In plaice, there were no significant differences in diet breadths between gut regions. Significantly lower diet overlaps for stomach-only data were also found. Reducing the size of sample to N=30 and N=10 resulted in increases in the calculated value of diet breadth, by as much as 0·13 and 0·34 respectively, these increases were frequently significant. The same reductions in sample size for diet overlap decreased overlap values by 0·02 and 0·13 respectively, significant only when sample reduced to N=10.

To study zooplankton–phytoplankton relationships in the diatom-dominated plankton communities of the northern Adriatic we performed feeding experiments with diatoms and zoea I larvae of the brachyuran Xantho poressa. We found that zoea I of X. poressa feed on diatoms of different forms (centric, pennate, colony forming, single celled, with or without setae) and size classes. In a laboratory setup, we presented the zoeas with a mix of diatom species similar to communities observed during blooms regularly found in the northern Adriatic. We report that the grazing activity resulted in a decrease of the relative abundance of the toxic diatom Pseudo-nitzschia calliantha. For the colonial, bloom-forming diatom Skeletonema marinoi our results show a chain length reduction in the presence of zoea I. Of particular interest is the observation that the presence of larvae also resulted in an increased growth rate and abundance of S. marinoi, which resembles bloom induction by grazer presence.

Malmgrenia louiseae sp. nov. is described from both the western Mediterranean in the Gulf of Lions, and the north-east Atlantic from off Portugal and the Bay of Biscay. The species was found in muddy sediments in shallow water and is possibly associated with echiurids or synaptid holothurians. Malmgrenia louiseae sp. nov. can be clearly distinguished from all other known Malmgrenia species by the presence of an infra-acicular process in addition to the supra-acicular process on the acicular lobe of the neuropodia, the lack of microtubercules on the elytra, two kinds of notochaetae (stout with blunt tip and slender with fine pointed tip), and exclusively unidentate neurochaetae. An identification key to the north-east Atlantic and Mediterranean Malmgrenia species is provided.

The mole crab Emerita brasiliensis inhabits exposed sandy beaches, both reflective and dissipative, along the Atlantic coast of South America, where it usually attains high biomass and production. We assessed the effects of physical characteristics of beaches (mean grain size, beach width and slope) on production and turnover rate (P/B ratio) of E. brasiliensis. Six production and P/B ratio datasets, estimated with cohort-based and size-based methods, were gathered from studies carried out on subtropical (~25°S) and temperate beaches (~32°S). Based on the estimates available, general trends were identified. Production was positively related to the intermediate/dissipative conditions of wider beaches with finer sand grains and gentler slopes. P/B ratio was negatively related to grain size (mm) and positively related to beach width. These results suggest that P/B ratios also increase towards intermediate/dissipative features due to higher growth rate, as indicated by higher values of the curvature parameter of the von Bertalanffy growth function (K) in more benign conditions (wider beaches with finer grains). In addition, the recurrent pattern of size structure on intermediate/dissipative beaches, with high frequency of recruits, leads to higher P/B ratio estimates on these beaches than on reflective beaches. The relationship of production and P/B ratio with physical features, such as mean grain size, beach width and slope indicates that a ‘short-cut’ approach to estimate Emerita brasiliensis production is a promising prospect and, therefore, more data on the production of this species should be provided.

An opportunistic sighting of an Indo-Pacific humpback dolphin (Sousa chinensis) was reported in the nearshore waters off the east Liaodong Peninsula, China. This is the first at-sea sighting in this area, and the northern-most sighting record of this species with a distance >3000 km away from the nearest described conspecific population located in the mid-China. The present sighting occurred in close proximity to the location at which another Indo-Pacific humpback dolphin was found by-caught in 2003. The sighted individual could not be identified through the existing photo-identification catalogues of this species in China (>3500 individuals). Therefore, we suggest that a population of Indo-Pacific humpback dolphins that was never reported might exist in the north of the Yellow Sea.

The known distribution of the Northern Rockling, Ciliata septentrionalis (Collett, 1875) is discussed and several additional occurrences reported. These greatly extend the range of the species. Notes on the biological background of the fish are provided, as are synoptic descriptions of it and its relative C. mustela.

INTRODUCTION

Venus striatula (da Costa) (= Venus gallina L.) occurs in high densities in shallow water on a bottom of clean fine sand in the Bay of Douarnenez. The environmental conditions are characterized by an obvious sediment instability due to a high exposure to westerly swells (Guillou & Le Moal, 1978). This species is preferentially distributed in the fine sands (Petersen, 1913; Thorson, 1957), but is relatively tolerant towards certain ecological factors and so is sometimes found in very muddy sediments. It also shows an extended latitudinal range, since it is recorded from the Lofoten Islands to the Canaries, in the Mediterranean and the Black Sea (Tebble, 1966).

A recent review of polychaete diets (Fauchald & Jumars, 1979) considered aphroditids to be slow-moving carnivores, taking microscopic prey if nothing else is available but specializing in slow-moving or sessile prey. This opinion was based on remarks by Day (1967) and on two documented gut analyses of Aphrodita aculeata (Blegvad, 1914; Hunt, 1925). Other reports in the literature were either derived from these few original statements or else gave unsubstantiated accounts of the type of food taken.

In 1964 the late Gunnar Thorson told me that he had seen a specimen of A. aculeata swallowing a large Nereis virens and likened it to a hedgehog eating a snake. This vivid analogy puts Aphrodita in a rather different light, as an active predator capable of dealing with relatively large, powerful prey. In fact Hunt (1925) had recorded remains of ‘Pectinaria, Lumbriconereis, Polynoidae and Nereidae’ in 24 out of 26 specimens containing food. Very young crabs and hermit crabs were recorded in five guts and a nemertean in one. Blegvad (1914) recorded the chief food to be other worms, especially sabellids and terebellids, besides nemerteans, from examination of 50 specimens, 35 of which were empty.

I have kept A. aculeata, obtained from Millport and from Plymouth, in bowls containing several centimetres depth of beach sand in a closed-circuit sea-water system. Worms without sand took no interest in items offered as food, neither did worms which had emerged from the sand and were wandering over the surface, but buried worms fed readily. A variety of living animals was given as potential food including Macoma balthica, Corophium volutator, Nephtys hombergi and Nereis diversicolor.

We report the occurrence of a high diversity of minute (∼1 μm diameter) organic and siliceous protistan scales in small samples (total volume ∼35 μl) of superficial sediment from the Porcupine Abyssal Plain (PAP), north-east Atlantic (4850 m water depth). Many exhibit characters by which they can be identified to species. The organic scales belong to the haptophyte genera Chrysochromulina (8–9 species), Chrysocampanula and Dolichomastix (1 species each). The siliceous scales belong to the chrysophytes Paraphysomonas vestita and Meringosphaera sp. and to the heterotrophic flagellate genus Thaumatomastix (T. dybsoeana, T. formosa, Thaumatomastix sp.). As far as we are aware, this is the first time that non-calcareous protistan scales have been observed in deep-sea sediments (although siliceous skeletal plates and cysts are reported). All scales probably originated from the upper water column and were delivered to the deep-sea floor on rapidly sinking detrital aggregates. However, naked heterotrophic flagellates are known to thrive in abyssal sediment habitats and so the possibility that some scale-bearing protists also live in benthic deep-sea environments cannot be eliminated. Many species identified at the PAP site are common in coastal marine waters around Europe; some occur as far afield as Tasmania and New Zealand. Five Chrysochromulina species are known from central oceanic areas, including parts of the North Atlantic, while another species, C. pringsheimii, is reported from a British freshwater lake. We retrieved ∼15% of the 55 named Chrysochromulina species (∼8% of the estimated total number of species in this diverse group) in the ∼35 μl of abyssal sediment. Because the scales can persist and be identified after cell death, they may provide useful time- and space-averaged information about the distribution of protist species in marine habitats. The long-term fate of the scales on the sea-floor is unknown. It is possible that at least some of the organic scales are preserved as microfossils in deep-sea sediments.

A new species of Ophiomisidium is described and regards about reproduction are presented. It is the first species in the genus to posses, apparently, a brooding development. Very few specimens of species of Ophiomisidium have previously been collected, but over 3000 specimens of the new species were collected on the continental shelf and slope (60–810 m depth) off southern Brazil. They were obtained during the REVIZEE Programme, the first extensive surveys to examine Brazilian ophiuroids from depths greater than 200 m.

The Norway lobster, Nephrops norvegicus is a target fishery species in European waters. The stock assessment of N. norvegicus is complicated because it is caught in commercial gear only when it emerges from its burrow. Landings are lower in winter, and feeding limitations have been hypothesized as the cause. Wild large-sized male lobsters were sampled each season (winter, spring, summer and autumn), and two groups of animals were kept in captivity for 90 d (fed and food-deprived). The hepatopancreas and muscle were dissected, weighted, frozen for biochemical analyses (proximal analyses and DNA/RNA) and fixed in Bouin solution for microscopic observations. The oxygen consumption rates in the wild individuals caught in the spring and in the captive animals after the treatments were measured. Significant differences among the experimental groups were observed in the lipid concentration of the hepatopancreas and muscle, the water content in the hepatopancreas, and the numbers of vacuoles and pyknotic nuclei in the cells of the tubules of the hepatopancreas. The results showed that the wild Norway lobsters generally presented intermediate values between those observed in the food-deprived and the fed lobsters kept in captivity, but the values were closer to those obtained for the fed animals. This finding indicates that the wild animals exhibit a good nutritional condition throughout the year. Therefore, the wild males of N. norvegicus do not face food deprivation during winter as is suggested by the pattern of commercial catches, the flow of organic matter, and the moulting period/reproductive behaviour of the species.

Measurements of pH, oxygen content, O2-combining capacity, and haemoglobin concentration were made for the vascular blood of the burrowing polychaete Neoamphitrite figulus in order to assess the role of its two respiratory pigments in respiration. The oxygen equilibrium curve of the erythrocruorin (extracellular haemoglobin) in the vessels was sigmoidal, having an n50 value of 1·5 and a low affinity for oxygen as determined by the P50 which was 26 mmHg at pH 7·31 and 18 °C. O2-binding by the erythrocruorin is sensitive to changes in pH (Δ log P50/Δ log pH = –0·24 to –0·29). The coelomic cell haemoglobin has a hyperbolic equilibrium curve (n50 = 1·0) and a high affinity for oxygen (P50 = 4·5 mmHg) independent of pH, suggesting an oxygen transfer system from the erythrocruorin to the coelomic cells.

The LS5096 h of prawn, Palaemon elegans, was determined at various salinities (0–45 ppt) with the Caspian Sea salt proportion. In addition, growth indices, survival and moulting at salinities 8, 13 and 18 ppt were also studied during four weeks. All the experiments were carried out in the laboratory (24±1°C). The results showed that more than 50% of the prawns survived at 1 to 30 ppt salinity range, while above and below this range, less than 50% survived within 24 hours. No significant differences (*P > 0.05) in growth parameters such as carapace length (CL) increase, specific growth rate (SGR) and also in survival and moulting rates were observed in prawns reared in salinities 8, 13 and 18 ppt. Mean intermoult period in each salinity was 8.12 ± 3.07, 8.61 ± 2.96 and 8.92 ± 3.47 days, respectively. Salinity 8–18 ppt was found to be the optimum range for P. elegans in the studied length range (CL, 6–9 mm).

A new species of the genus Celleporella (Celleporella galaica sp. nov.) is described from material collected in Galicia (north-west Spain).

A new species of Australonuphis Paxton, 1979 from the Ecuadorian coast, eastern Pacific, is described. The new species is characterized by seven modified parapodia, cirriform ventral cirri on the anterior 16 to 19 chaetigers, subacicular hooks beginning from chaetigers 43 to 57, and cirriform interramal processes on chaetigers 7–10 to 16–18 transformed back in a rounded lobe. This species belongs to the species group with unidentate pseudocompound hooks. Other species of this group are A. beltrani de León-González & Góngora-Garza, 1993, A. hartmanae (Friedrich, 1956), A. parateres Paxton, 1979 and A. teres (Ehlers, 1868).

A total of 75 specimens belonging to four species of thalassinoids were collected in the intertidal and estuarine zones of two localities along the Pacific coast of Mexico. Callianassa tabogensis is recorded for the first time in Mexico, and is transferred to the genus Neotrypaea. Material of Callichirus is assigned to Callichirus seilacheri with some doubts due to taxonomic problems related to this genus in the eastern Pacific. Neocallichirus cf. grandimana, an amphi-American species described for the western Atlantic and previously reported in Ecuador and along the Pacific coast of Panama and Colombia, is reported for the first time in Mexico. Upogebia dawsoni is recorded for the second time from the coast of Jalisco. An updated list of Axiidea and Gebiidea known from the Mexican Pacific is provided, including 35 species.

An area in the English Channel of 20 × 40 nautical miles, centred on the Plymouth routine stations L, L and E, was sampled at almost monthly intervals from August 1969 to November 1970, using an improved version of the 1 m net towed at 4 knots on an oblique path. The area includes an inshore region where depths are about 20 fm (37 m) and salinities 35·0‰ or less, and an offshore region with depths over 40 fm (74 m), where salinities can exceed 35·3·. During the first year the offshore region was characterized by water of south-western origin, and temperatures were higher than in the following year when north-western plankton was more in evidence.

In order to determine the changes in the relative importance of different kinds of preys as larval anchoveta Engralis ringens grows, the present study reports information about feeding incidence, type, size, and carbon content estimates of preys, at the beginning of the main spawning season in mid-winter off central Chile. Our results show a mixed diet initially dominated by phytoplankton and later switching to zooplankton in older larvae. While larval anchoveta grows, they feed on preys whose widths do not vary much compared to their body length and volume. These preys might be different taxa or a single species whose body widths vary little among life stages (i.e. nauplii and copepodites). Differences in estimated carbon content were observed among food items and a marked increase in carbon consumption was observed in the larger larval sizes (>9 mm standard length). These ontogenetic changes in feeding are coincident with the increased proportion of larger preys and also with the number of preys consumed by larger larvae.

Three species of leptostracan malacostracous Crustacea occur in the Rockall Trough. The epibenthic Nebalia typhlops, previously recorded at depths of 200–500 m in the north Atlantic but to 1100 m in the Mediterranean, was found at depths of 1990–2925 m. The epibenthic Nebaliella caboti, previously recorded in the northwestern Atlantic at depths of 378 and 2085 m, was caught in the Rockall Trough at 1390–29000 m. The pelagic Nebaliopsis typica only occurred in samples from depths greater than 1500 m. A comparative study of the previously recognized species within the Nebaliacea is required.

An analysis has been made of plaice fecundity at four localities in Norway. The fish tended to be larger than those used in other fecundity investigations, and the comparison between localities has been made by considering the average egg number expected in a 50 cm fish. In general the plaice off Norway had more eggs than in the North Sea or round the British Isles. At Arendal in the Skagerrak the fecundity was 355 thousand for 50 cm, which is lower than has been found in the Kattegat, but a little higher than I found at Bergen (317 thousand eggs). At Arendal and Bergen the fecundity was higher than has been found in the North Sea but lower than in localities farther north in Norway. In Trondheim Fjord the plaice fecundity was very high indeed. Among the eleven fish examined it varied from 673 thousand to nearly ½ million eggs, and for an average 50 cm plaice would be 819 thousand. The female fish on the coast outside the fjord were quite different and contained about half the number of eggs (407 thousand for 50 cm). These coast plaice were very similar to those caught in the vicinity of Tromso where a 50 cm fish would have about 400 thousand eggs.