The secondary production of Nereis diversicolor and Scoloplos armiger (Annelida, Polychaeta) was studied at Stiffkey saltmarshes (north Norfolk coast). Production estimation on the basis of monthly sampling (August 1992–July 1993) gives 17.91 g C m−2 y−1 for N. diversicolor, 3.37 g C m−2 y−1 for S. armiger. Oxygen consumption of individuals was studied using a respirometer at four temperatures (5, 10, 15 and 20°C). At 15 °C, the relationships between O2 consumption (mg h−1) and body dry weight (mg) is Y=0.003X0.695 for S. armiger and Y=0.003X0.498 for N. diversicolor. Ammonia excretion of S. armiger tends to increase with decreasing temperature whereas it increases from 5 to 15 °C for N. diversicolor. Carbon loss through respiration for the sampling period is estimated at 32 g C m−2 y−1 for S. armiger, and 31.7 g C m−2 y−1 for N. diversicolor. About 20% of the potential supply of phytobenthic carbon in the marsh would be converted by the populations of both species. Estimations of carbon and nitrogen budgets of S. armiger are discussed.

Supralittoral rockpools form an extreme environment due to severe fluctuations in salinity, temperature and oxygen concentration. The only seaweed species in supralittoral rockpools around Great Cumbrae, Firth of Clyde was the green alga Enteromorpha intestinalis. Only two animal species were recorded permanently over a three year period in this environment; the orange harpacticoid copepod, Tigriopus brevicornis, and the chironomid larva, Halocladius fucicola. The present study demonstrates the role of the hollow thallus of E. intestinalis in the lifestyles of T. brevicornis (adults and nauplii) and H. fucicola. The thallus provides a moist refuge reducing desiccation when the rockpools completely dry out. Several hundred individuals of T. brevicornis have been observed in a single E. intestinalis thallus. This observation may explain how the species can successfully recolonize completely evaporated supralittoral rockpools after several weeks. The study also raises questions about the reliability of previous population estimates of Tigriopus spp. in light of this constantly overlooked refuge.

The experiments during the 1953 season were arranged to investigate certain criticisms and suggestions made to us after publication of the earlier work (Wilson, 1951; Wilson & Armstrong, 1952), and there were included tests of our own devising intended to narrow the field within which must be made any search for an explanation of the observed biological differences between sea waters from different localities. We were again unable to obtain water from the Celtic Sea and once more, by kind co-operation of the Millport Marine Station, used water from the Firth of Clyde instead. Both the E1 and Clyde waters were collected on the same day and the fertilizations of Echinus esculentus were made and the experiments started 4 days later, which was the minimum time possible after collection of the Clyde water. Every experiment included a control comparison of the two waters.

Vertical hauls were made with a very fine silk net having a meter attached, which measured the volume of water filtered, at positions off Plymouth throughout the year 1933.

The quantity of phytoplankton was assessed from its content of yellowgreen colouring matter, and expressed in terms of “units of plant pigments” per cubic metre of water filtered.

The diatom population per cubic metre at Station L4 on March 28th was estimated to contain phosphorus amounting to 2 mg. P2O5, whereas dissolved phosphate amounting to some 15 mg. P2O5 had been used from each cubic metre of water by the diatoms during the previous six weeks.

It is concluded that the production of phytoplankton during this period greatly exceeded the quantity found at the height of the spring outburst, and that the excess had been eaten by the herbivorous zooplankton.

The feeding habits of John Dory (Zeus faber) were studied, based on the analysis of stomach contents from fish sampled in five groundfish surveys. These surveys were carried out off the Portuguese coast during different seasons between 1990 and 1992. The main aspects of feeding biology analysed in this paper are: ontogenetic diet changes, temporal variations in food composition and feeding intensity. Multivariate methods were used to investigate ontogenetic diet shifts. Two main length groups were identified: 8.0–24.9 cm fish, feeding mainly on dragonets and silvery pout, and 25.0–55.9 cm fish whose diet was mainly composed of blue whiting and snipefish. A transitional phase (24.0–30.9 cm fish) with a mixed food composition was observed. This ontogenetic diet shift does not seem to correspond to any important change in body morphology but it does coincide with the onset of sexual maturity in the species.

John Dory switched from a diet of small prey species with more pronounced benthic behaviour to a diet of larger schooling pelagic species. This suggests parallel evolution to more pelagic foraging behaviour. However, John Dory feeding habits appear to be largely controlled by the availability and accessibility of prey species: (i) the diet of adult John Dory is dominated by very abundant species; (ii) shifts in the main prey items between different times of the year and between different areas seem to be related both with their absolute and relative abundance in the environment and with the overlap between the depth distribution of predator and prey.

A cohort of newly settled Mytilus edulis (L.) (Mollusca: Bivalvia) spat (mean shell length 530 µm) was collected from red filamentous algae at a site on the North Wales coast. After a period of growth in the laboratory, cellulose acetate and starch gel electrophoresis were used to investigate genotype frequencies at the Gpi, Odh, Lap, Pgm, Idh and Mpi loci. Individual testing of each locus, using the X2 test revealed significant deficiencies of heterozygotes at the Pgm, Mpi and Idh loci. However, further testing using a sequential Bonf erroni test, designed to assess the probability of observing at least one significant result from a number of tests by chance alone, revealed that only the deficiency of heterozygotes at Pgm and Mpi loci was significant at the table-wide 95% level. Since post-collection mortality was <3%, these heterozygote deficits must have existed at the time of collection. The conclusion drawn is that heterozygote deficiencies in mussels are generated during the larval stage or at early settlement.

Fish assemblages associated with shallow rocky bottoms along the coast of Cape Milazzo were investigated within three selected habitats, each represented by a different degree of complexity and namely vermetid reef (VR), rocky-algal reef (RR) and boulder and pebbles (BP). The area, located along the northern coast of Sicily (southern Tyrrhenian Sea) was studied by using a non-destructive diver visual census methodology evaluating species composition and abundance. A total of 39 fish taxa belonging to 15 families were recorded over the three habitats investigated. Multivariate and univariate approaches detected significant differences among the three habitats. These differences were either in fish assemblage structure, in the assemblage parameters or in the abundances of some common species. A multidimensional scaling performed on the entire fish density data set showed distinct groupings for the three habitats. The highest values of mean species richness (S), diversity (H′), evenness (J) and density (N) occurred over the more complex habitat, represented by VR, than over rocky-algal reef habitat or BP. Different habitat preferences were evidenced for several fish species. Diplodus sargus, Serranus scriba, Tripterygion tripteronotus, T. delaisi and T. melanurus were significantly more abundant over VR whereas Thalassoma pavo and Symphodus tinca were more abundant both over VR and BP habitats. Statistical comparison did not detect habitat preferences in Symphodus roissali, Oblada melanura, Diplodus vulgaris and Sarpa salpa. As far as the size is concerned, small, medium and large-sized specimens of D. sargus and only large-sized individuals of D. vulgaris were significantly more abundant over the VR habitat side than over the other two. These results suggest that differences in assemblage parameters are related to habitat structure. Greater habitat complexity means greater surface available, thus providing additional resources for adults and juveniles of many species: food, cavities, caves and then new niches, refuges from predation, from artisan fishery nets, as well as resting or mating sites, boosting the total number of individuals and species. The results of this study highlight the importance of VR in sustaining the biodiversity of fish assemblages and emphasize the need for their careful management in an area already proposed as a Site of Community Interest.

In the course of a study by Gibbs (1984) of the reproductive biology and the population dynamics of the bivalve Abra tenuis (Montagu) collected from the Fleet, a brackish water lagoon in Dorset, and from the Plym Estuary, Plymouth, a number of species of apparently pathogenic larval digeneans was found. These could not be satisfactorily identified from their larval characters alone, and following collaboration with Professor J. Llewellyn (personal communication) it was decided that they should be made the subject of a further study.

Two morphotypes of the venerid bivalve Chamelea gallina (L.), viz. C. gallina s.s. and C. striatula, were electrophoretically compared at seven polymorphic enzyme loci. In three populations from the Ría Formosa (southern Portugal), both morphotypes occurred sympatrically. Analyses of genotype frequencies in these mixed populations revealed departures from Hardy-Weinberg expectations at nearly all loci. These deviations were mainly attributable to a Wahlund effect, caused by mixing the two morphotypes. Nei's mean unbiased genetic distance between the two forms was D=1·138, while the mean genetic distances between populations within morphotypes were D=0·083 in C. gallina s.s. and D=0·229 in C. striatula. It is therefore concluded that C. gallina and C. striatula are reproductively isolated (biological) species, the geographical distribution of which is outlined.

The distribution and ecology of scleractinian corals on reef ecosystems along the coast of the State of Alagoas, north-east Brazil, were characterized. The scleractinians comprised 13 species in nine families, with five endemic corals, on the Alagoas coast. All of these species were found on reef ecosystems of two distinct geological origins. Coral reefs are predominant on the northern and central coast with banks near the beach line and distributed along the coast line, with many platform surfaces emerging during low tide. Sandstone reefs are more common along the south coast of Maceió city and the southern coast of Alagoas. These reefs were formed by old sand banks solidified through sedimentation starting from chemical reactions with calcium carbonate or iron oxide from the Quaternary period, and are generally in rows parallel to the coastline and near the outlets of rivers and estuaries. A few species including Favia gravida and Siderastrea stellata were found in the intertidal zone on top of the reef platform of both types of reefs. The other scleractinian species were observed on the reef borders where there were some inlets and channels. A larger number of coral species occur on the northern coast where the seawater is clearer throughout the year.

The 37 sq. miles of intertidal banks in the Mersey Estuary have been surveyed and classified according to their nature and fauna.

Half the banks occur in the Outer and half in the Upper Estuary. Four-fifths of the total area is composed of sand and most of the remaining one-fifth of mud occurs in the Upper Estuary.

The burrowing fauna of the Outer Estuary is abundant and varied; that of the Upper Estuary is abundant but not varied.

The distribution of species in the Mersey Estuary is similar to that in the estuaries of the River Tees and Tay, except that in the Mersey Estuary a sudden drop in the numbers of species occurs at Rock Light. This is attributed o t the strong tidal streams in the Narrows.

The densely inhabited banks of the Upper Estuary are mainly composed of mud and are situated high in the shore zone. In the Outer Estuary the densely inhabited banks are of muddy sand with some banks of mud and are situated near the low-water mark in sheltered positions.

The burrowing species of the Upper Estuary also occur, with many others, in the Outer Estuary.

The observations described in this paper were made during an investigation of the estuary of the River Mersey by the Water Pollution Board of the Department of Scientific and Industrial Research and the results are published by permission of the Department.

Assessing the sensitivity of ectotherms to variability in their environment is a key challenge, especially in the face of rapid warming of the Earth's surface. Comparing the upper temperature limits of species from different regions, at different rates of warming, has recently been developed as a method to estimate the long term sensitivity of shallow marine fauna. This paper presents the first preliminary data from four tropical Ascension Island, five temperate New Zealand and six Antarctic McMurdo Sound species. The slopes and intercepts of these three assemblages fitted within the overall pattern for previously measured assemblages from high temperature tolerance in tropical fauna and a shallow slope, to low temperature tolerance and a steep slope in Antarctic fauna. Despite the tropical oceanic Ascension Island being subject to upwelling events, the fit of the intercept and slope within the overall assemblage pattern suggests that the upwelling is sufficiently predictable for the fauna to have evolved the plasticity to respond. This contrasts with previously analysed species from the Peruvian upwelling region, which had a steeper slope than other temperate fauna. The speed and capacity of faunal assemblages to acclimatize their physiology is likely to determine the shape of the rates of warming relationship, and will be a key mechanism underpinning vulnerability to climate warming.

Spatial variation in the structure of macrobenthic assemblages on intertidal flats is known to be related to different environmental variables. Most of the studies have observed that along the estuarine gradient, salinity is the most important variable driving the patterns of the macrobenthic assemblages. However, the great majority of studies have been done on single estuarine systems in temperate regions. We investigated the relationship between the macrobenthic assemblages in intertidal habitats and the environmental variables along three tropical estuaries. From lower to upper estuarine regions we sampled benthic macrofauna, salinity and sediments. The structure of the benthic assemblages was primarily related to salinity. There was a decrease in the number of taxa from the upper to the lower estuarine regions, indicating important deviation from Remane's model of estuarine diversity. There were important similarities of taxa abundance along different estuarine salinity gradients which can be properly tested in other tropical and temperate regions. We advocate that in order to adopt general and robust management practices it is essential to identify broad patterns and general rules governing estuarine systems.

The development and growth of a feather star Decametra tigrina from Notojima Island, Japan, is reported. This is the first record describing the complete development, from early embryos to juveniles, in the family Colobometridae. Their larval development was observed to progress independently from the adults, and was similar to other feather star species. Embryos hatched as uniformly ciliated gastrulae, which turned into doliolaria larvae when four narrow circumferential ciliated bands were formed. Skeletal ossicles began to form inside the doliolaria larvae, which subsequently settled to the substrate, proceeding to the cystidean stage. The protrusion of the arms from the oral opening marked the beginning of the pentacrinoid stage. About 45 days after hatching, they autotomized their stalks and became juvenile comatulids with arms about 6 mm long. These early juveniles apparently differ from the adults in morphological characters, such as having no pairs of tubercles or spines on the dorsal of their cirrals, and no proximal pinnules except for the first pinnule (P1). Both features are prominent in adults and are used for the classification of D. tigrina. Morphological differences between juveniles and the adults may also occur in other feather star species. A revision of the classification of comatulids, which considers morphological changes with growth, is required.

The present study describes the reproductive cycle and population structure of the intertidal crab Petrolisthes laevigatus, an abundant inhabitant of the upper rocky intertidal zone, as well as the relationship between seasonal patterns in the release of its planktonic larvae and recruiting. A total of 22900 individuals was collected along the coast of southern Chile between May 2001 and March 2003.The structure and density of the adult population (males and females) was relatively constant throughout the study period, although seasonal variations were observed in these two parameters of the benthic population (males, females, juveniles and megalopae), principally due to the incorporation of new individuals (recruitment) into the intertidal zone. Petrolisthes laevigatus presented a prolonged reproductive period. Females with initial eggs were present from the end of summer through to the middle of the following summer (11 months) and the breeding season lasted seven months (from August to February), as reflected in the six months of intertidal settlement (October–March).The interannual patterns and variations observed in the settlement along the southern Chilean coastline were related to the patterns in the abundance of potential released planktonic larvae. Petrolisthes laevigatus, unlike most temperate species, has a broad reproductive and settlement period in the south of Chile, which allows a highly stable structure and population abundance in this intertidal zone.

The bryozoan benthos of the European continental slope is attracting attention after a long period of neglect. Expedition reports, such as those of the ‘Challenger’ (Busk, 1881, 1884, 1886; Waters, 1889), ‘Travailleur’ and ‘Talisman’ (Jullien, 1882; Calvet, 1906), and ‘Hirondelle’ (Jullien & Calvet, 1903) made important contributions to our knowledge. Such monographs have been supplemented by shorter papers dealing with the Bryozoa of offshore banks and island groups (Guérin-Ganivet, 1911; Norman, 1909) or of limited areas within the European region (Duerden, 1893; Nichols, 1911). Following the recent increase of interest in offshore benthos generally, the papers of d'Hondt (1970, 1973a, b, 1974, 1975) provide much new information on the slope and outer shelf bryozoan fauna. However, many of the often enigmatic species of earlier authors have yet to be redis-covered, and d'Hondt has shown that a high proportion of the Bryozoa collected comprises species new to the area or new to science. Clearly, the study of many more collections will be necessary before any comprehensive account can be given.

For the first time, saccular otolith shape and size were analysed in 254 samples of the bogue Boops boops collected from the marine stations of Bizerte and Kelibia situated in north-east Tunisia. The objectives were (1) to examine the inter- and intra-population variation in the otolith shape and size, including length (Lo), width (Wo) and area (Ao) measurements, and (2) to assess the relationship between otolith mass asymmetry (OMA) and total fish length (TL). In addition, the impact of pollution present in these two stations on the shape and size of the otolith in relation to the TL was discussed. Analyses of the otolith shape and biometric data showed a statistically significant asymmetry in the otolith shape (P < 0.0001) between the right and left sides within the population of Bizerte, as well as between the otoliths from the same right-right and left-left sides between the populations of Bizerte and Kelibia. Similarly, a significant Wo asymmetry (P < 0.05) was recorded within the population of Kelibia. Conversely, a significant symmetry was detected in Lo and Ao (P > 0.05) between the right and left sides within the populations of Bizerte and Kelibia. Moreover, the level of asymmetry of Ao was higher than that of Lo and Wo in both populations. Nevertheless, Student's t-test showed no statistically significant differences (P > 0.05) for Lo, Wo and Ao in relation to the means of TL between the three groups of the populations of Bizerte and Kelibia, although significant differences (P < 0.05) were found by using box plots. Furthermore, no statistically significant relationship (P > 0.05) was detected between OMA and TL within and between the populations of Bizerte and Kelibia. The possible cause of fluctuating asymmetry (FA) in the otolith shape and size both within and/or between populations of the two stations has been discussed in relation to the instability of development induced by environmental stress associated with the variation in water temperature, salinity, depth, feeding conditions and pollutants present in these stations.

Environmental cues such as photoperiod and water temperature are often used by fish as a sign to begin reproduction. However, even after the reproductive cycle has started there are other signs, such as the moon phase that may affect the number of eggs laid by some fish species. The existence of a moon effect has never been investigated in any fish of the sparid family.

In the present study, the effect of moon phase was observed on eggs laid by two Sparus aurata in indoor tanks over a four month period, from January to May, 2003. During this period a peak in eggs laid was observed around the Full Moon. A total of 8644 g and 5653 g of eggs were collected, 4535 g corresponding to the Full Moon and 2882 g to the New Moon.

The common dogfish (Scyliorhinus canicula L.) is caught regularly at Plymouth and is parasitized by two monogeneans, the gill-parasitic polyopisthocotylean Hexabothrium appendiculatum (Kuhn, 1829) Nordmann, 1832 and the skin-parasitic microbothriid Leptocotyle minor (Monticelli, 1888) Gallien, 1937. Unsuccessful attempts have been made to hatch the larvae of both of these parasites, e.g. Euzet (1957) and Wiskin (1970) for H. appendiculatum, and Llewellyn (1963) and Kearn (1965) for L. minor. Euzet (1957) and Kearn (1965) found that larvae developed within the eggs of H. appendiculatum and L. minor respectively but that these larvae failed to hatch.

Evidence is presented that eggs and sperm of Spirorbis borealis are shed through the nephridioducts, and that fertilization occurs externally to the body but inside the tube.

The eggs fail to develop in vitro unless sperm is present. In individuals collected in winter and maintained at 15 or 19° C, the male and female gonads mature more or less simultaneously. Among groups of individuals sperm is usually shed first and soon afterwards a large proportion may be observed to have extruded ova.