Measurements on cultivated larvae and data from the literature demonstrate that length and width of pelagic sea lice larvae, Lepeophtheirus salmonis and Caligus elongatus, are overlapping. Therefore measurements on planktonic developmental stages are of little practical value in specific identification. A standard WP-2 net with 200-μm mesh size will, in practice, collect free living sea lice larvae satisfactorily. The naupliar and copepodid stages of sea lice are illustrated and pigment distribution described. Larvae of L. salmonis are characterized by black and brown pigment, those of C. elongatus by red. The distributions of pigment are distinctive in the species mentioned, and in pelagic larvae of Lepeophtheirus pollachius and L. pectoralis which also are measured, described and illustrated for comparison. The copepodid stages of larvae are different in shape of pro- and urosome, morphology and armature of the maxilliped, distribution of pigment and its colour. The black and brown pigmented copepodid of L. salmonis is slender and oval in outline, somewhat pointed anteriorly, broadest in the middle of prosome and more narrow posteriorly. The proximal segment of the maxilliped is robust without seta, but the subchela has a slender branching barb with three to five ‘fingers’. The red pigmented prosome of C. elongatus is elongate, broad anteriorly with two lateral notches. The extreme breadth of the copepodid is clearly before the middle of the prosome. The corpus of the maxilliped is elongate and equipped with a seta. In addition the appendage has a medial 2-divided process.

In constant conditions, freshly-collected Lipophrys pholis show an endogenous circatidal activity rhythm, the initial activity peaks of which are phased to the expected time of high tide. The rhythm usually damps out over a few days but it may re-appear spontaneously or as a result of disturbance caused by handling and transfer to the experimental apparatus. The free-running period is more variable in fish kept in non-tidal conditions for prolonged periods than in those recorded shortly after capture. The non-circatidal periodicity shown by some fish may be the result of stable coupling in antiphase of desynchronised oscillators. There is no semilunar variation of the circatidal rhythm and no influence of the slight diurnal inequality in tidal period upon the rhythm's periodicity, at least at the site studied. The activity rhythm of Lipophrys varies seasonally.

Benthic polychaetes in the largest intertidal mudflat of Hong Kong were analysed for potentially stressed environmental conditions from pollution. Over a two-year period, a total of 14 species were recorded with the species diversity (H′(log2)) ranged from 0.54 to 2.4. The community was dominated by two large polychaetes (Neanthes glandicincta and Potamilla acuminata) and a number of small pollution tolerant species (Tharyx, Capitella capitata and Prionospio cirrifera). It was also characterized by both temporal and spatial variations in terms of abundance and species composition with the lowest species number observed at onshore Station B in August and the highest at offshore Station D in February. Two distinct polychaete communities were formed along the intertidal towards subtidal mudflat, particularly the assemblage at onshore Station B showing a significant difference from those at the other three stations (P < 0.05, N = 32). Results of the abundance–biomass comparison (ABC) indicated a typical impacted community at the whole study area, especially at Station B which was close to the Shenzhen River mouth and mangrove forest. The total organic carbon had a significant positive effect on the abundance of Capitella capitata (P = 0.037, N = 8) while sedimentary compositions were statistically related to the abundance of Potamilla acuminata, Tharyx and total abundance of polychaetes (P < 0.05, N = 8). In conclusion, both the polluted Shenzhen River and nearby mangrove may be responsible for the decline in species richness and diversity as well as changes in community structure. Polychaetes can be used as the appropriate indicators in habitat ecological condition assessment instead of the whole benthic community.

Thirty-six boat surveys were conducted in Guanabara Bay, south-eastern Brazil, from October 2002 to June 2004 in order to investigate marine tucuxi group characteristics. The average and the range of tucuxis group size in the Guanabara Bay are similar with areas where small group sizes have been recorded. Group size ranged between one and 40 individuals (13·0±9·5; median=10·0). Groups of two to ten dolphins were the most common (53·9% of observations). Group size and the maximum number of dolphins sighted in each survey day did not vary between seasons (Kruskal–Wallis test, H3,36=3·249; P=0·355). Spatial geometry varied with group size and mixed groups were the largest (Kruskal–Wallis test, H3,218=57·149; P<0·001). The presence of calves had a great effect on group size, and nursery groups (mean =14·3±9·1; median=13·0) were twice as large than non-calf groups (mean=7·1±5·2; median=6·0). It is suggested that larger groups may aid in the calves development and learning. Group size changed frequently, resulting in 82·2% of observations with no constant size. Group size of marine tucuxi was not affected by the dolphins' behaviour (Kruskal–Wallis test, H2,215=5·626, P=0·06) neither by water depth (R2=0·012; F1,219=2·82; P=0·094).

This is the first report of egg release by the oviparous excavating sponge Cliona viridis. Adult specimens of excavating (α) and massive (β) sponge forms for the presence of oocytes were monitored from 11 May to 12 July 2000, in a shallow-rocky coast of the north-west Mediterranean. The immediate environment around the sponge was sampled for the presence of eggs. Spawning occurred synchronously in the study area at temperatures above 19°C. Oocytes were released in clusters enclosed in adhesive maternal tissue. They contained symbiotic zooxanthellae. Free, adhesive egg-masses drifted in the water or adhered to erect algae in the vicinity of the sponge. Morula stages and larval release are described.

Nest temperatures for green turtles (Chelonia mydas) nesting on Ascension Island, South Atlantic (7°57'S 14°22'W), were examined. Temperature probes were placed into nests on two beaches, Long Beach (26 nests) and North East Bay (8 nests). Within these beaches there was relatively little thermal variation (SD of nest temperature was 0.32°C for Long Beach and 0.30°C for North East Bay). To examine inter-beach thermal variation temperature probes were buried at 55 cm on 12 beaches. Inter-beach thermal variation was large and was related to the beach albedo with the darkest beach (albedo, 016) being 4.2°C warmer than the lightest coloured beach (albedo, 0.73).

The larval development of the parasitic barnacle, Sacculina carcini, has been closely followed. Size and volume measurements have been made for the four naupliar stages and cyprids of both male and female broods. Volume increases between naupliar stages are minimal (x 1.03–1.09) and in line with other barnacle species with lecithotrophic larvae. However, the large volume reduction between stage IV and cyprid for S. carcini, which is more acute for the female larvae, is a unique characteristic. The reduced setation formulae of the larval appendages of S. carcini and another rhizocephalan are compared to those of larvae, both lecithotrophic and planktotrophic, of a range of barnacles. Sex ratios and carapace length data for 184 S. carcini cypris populations are presented which reinforce the seasonal changes in sex ratios.

During a routine North Sea demersal fish survey, very low fish catches were recorded at two primary stations off the Danish coast in September 1981. The catch of benthos at thesestations was much greater than the previous year, and underwater photographs from a headline camera revealed that this was a result of most infaunal species having emerged from beneath the sand. The phenomenon was assumed to be caused by low oxygen concentrations in bottom water following the collapse of a bloom of the dinoflagellate Ceratium furca.

P. platycheles was proved to be an osmoconformer, as expected. It is assumed that the other three species are conformers.

Littoral specimens of E. bernhardus have a similar salinity tolerance to P. platycheles, surviving from between 17 and 20·4‰ salinity to between 40·8 and 51‰ salinity if a median lethal time of above 500 h is taken to indicate survival.

The stenohaline species G. squamifera andP. longicornis swell rapidly and die in 60‰ s.w. (20·4‰ salinity). Their locomotion is rapidly impaired by swelling and the integument distorted.

P. platycheles, a moderately euryhaline species, is capable of resisting swelling in 60‰ s.w., and eventually regains its original weight.

Littoral E. bernhardus showed an unusual pattern of volume change in 60‰ xs.w. Initial swelling of 15·4‰ in the first hour was great compared with decapods like C. maenas or P. platycheles, yet did not cause much interference with movement, and was substantially reversed in a few hours.

Increased urine production prevents swelling in P. platycheles. It is thought that increased antennary artery pressure and or a shift to a diuretic hormone balance cause increased nitration by the antennal gland.

Increased urine production is delayed until substantial swelling has occurred in E. bernhardus.

The abdomen of E. bernhardus makes up significantly more of the total animal weight in dilute media than in full sea water, confirming the idea that the abdomen is a ‘swelling reservoir’ protecting the rest of the animal from the mechanical effects of water inflow.

Salt loss in the urine is more important than integumental loss in both E. bernhardus and P. platycheles when they are placed in 60 % s.w.

An account is given of the populations of P. montagui occurring off the Northumberland coast at depths ranging from 20 to 50 fm. Sampling, which extended from 1954 to 1961, shows that the population in 20–30 fm is composed predominantly of o-group males and females and smaller numbers of 1-group females while that in 50 fm is composed predominantly of 1 and 2 group males and females. This difference can be explained in terms of sex change and migration.

Eggs laid in the period from the last week in November to the first week in January hatch by the end of April. Growth of the new year-group is so rapid that they mature in time for the next breeding season. Egg numbers vary from 200 to 3000.

It can be calculated that the number of larvae hatched out inshore exceeds that offshore by 15 times, but many of the larvae produced by the deep-water.

Large-scale blooms of dinoflagellates, such as Prorocentrum donghaiense and Karenia mikimotoi, have occurred frequently in the East China Sea (ECS) in recent decades. However, little is known about their effects on the entire life history of copepods. Under laboratory conditions, we investigated the effects of these two common dinoflagellates on the survival of Calanus sinicus individuals at different stages and on reproduction of this copepod. Compared with the control treatment (Skeletonema costatum), the presence of P. donghaiense and K. mikimotoi decreased the survival rates of adults and nauplii during the 16 days of the experiment. Survival of nauplii decreased to 49% and 48%, respectively, relative to the nearly 80% survival of adults. Among the six stages of nauplii, individuals at NII and NIII were more susceptible to P. donghaiense and K. mikimotoi. Lower egg production rates were also observed when copepods were exposed to P. donghaiense and K. mikimotoi, and hatching success decreased only with exposure to P. donghaiense. These results suggest that blooms of the two common dinoflagellates may have detrimental effects on the survival of nauplii and the reproduction of C. sinicus, which may pose a major threat to the recruitment of C. sinicus.

In 1801 Vaucher discovered the oogonia of Vaucheria—or Ectosperma as he called it—but he described the antheridia in a very incomplete way without seeing the spermatozoids (Vaucher, 1801, 1803). These were first observed some fifty years later by Pringsheim (1855), who also saw fertilization, one of the first observations on fertilization to be made in the lower plants.

Changes in the composition of the diet, foregut fullness, and the degree of digestion of ingested food were taken into account in determining diel feeding activity of the numerically dominant species of decapod crustaceans dwelling on the Catalan Sea Slope (western Mediterranean). Two 24-h periods were sampled at two different stations on the upper middle slope (between 400 and 710 m) using bottom trawls. Additional foregut fullness data for Aristeus antennatus and Acanthephyra eximia were recorded below 1000 m. The influence of the relatively shallow-living mesopelagic fauna (Pasiphaeidae, Sergestes arcticus, euphausiids, and fishes) over the 24-h cycle apparently had a large effect on the feeding activity rhythms in the deep-sea decapods studied. Species can be classified into two different groups according to their feeding patterns. Thus, species whose diet was based on pelagic prey (Plesionika edwardsi, Plesionika martia, and A. eximia) exhibited a feeding pattern conditioned to the availability of this type of prey. In contrast, in those species in which pelagic prey contributed only a small portion of the diet (A. antennatus, Plesionika acanthonotus, Polycheles typhlops, and Geryon longipes) no variations in the foregut fullness or in the percentage of undigested prey in foreguts during the diel feeding cycles were recorded. The decrease in the influence of the abundance of mesopelagic fauna with depth, with a commonly accepted boundary at around 1000 m would be responsible for the progressive flattening out of activity rhythms among the species dwelling on the lower slope. Foregut fullness values for certain species with broad depth distributions in the Catalan Sea (A. antennatus, A. eximia), would support this hypothesis.

The reproductive biology of the tarwhine Rhabdosargus sarba has been studied in three very different environments in Western Australia, namely the lower reaches of the Swan River Estuary and marine waters at the same latitude, i.e. ≈32°S, and a large subtropical marine embayment (Shark Bay) approximately 800 km further north. A macroscopic and histological examination of the gonads demonstrated that R. sarba is typically a rudimentary hermaphrodite in Western Australian waters, i.e. the juveniles develop into either a male or female in which the ovarian and testicular zones of the gonads, respectively, are macroscopically undetectable. This contrasts with the situation in the waters off Hong Kong and South Africa where R. sarba is reported to be a protandrous hermaphrodite. Although R. sarba spawns between mid-late winter and late spring in each water body, the onset of spawning in the estuary is delayed until salinities have risen well above their winter minima. Although males and females attain sexual maturity at very similar lengths in the Swan River Estuary and Shark Bay, i.e. each L50 for first maturity lies between 170 and 177 mm total length (TL), they typically reach maturity at an earlier age in the former environment, i.e. 2 vs 3 years old. During the spawning period, only 25 and 12% of the males and females, respectively, that were caught between 180 and 260 mm TL in nearshore marine waters were mature, whereas 94 and 92% of the males and females, respectively, that were collected in this length-range over reefs, were mature. This indicates that R. sarba tends to move offshore when it has become ‘physiologically’ ready to mature. The L50s at first maturity indicate that the minimum legal length in Western Australia (230 mm TL) is appropriate for managing this species.

A survey by Yonge (1962) of the byssal apparatus in the Bivalvia indicates that the formation of byssus is a larval characteristic which may or may not be retained in the adult. Some species such as the mussel, Mytilus edulis, retain the byssal attachment but have the ability to break the byssus and move over a limited area. Others, such as the scallop, Pecten maximus, lose the byssus entirely, become unattached and move by swimming. Yet others, such as the oyster, Ostrea edulis, relinquish all mobility at metamorphosis by cementing the shell to the substratum, and after metamorphosis lose all trace of the foot. Ostrea, Mytilus and Pecten therefore encompass a wide variety of life styles in the adult and are chosen as examples for detailed comparison of the byssus forming glands and other foot glands in the pediveligers.

In a previous paper (Harris, 1972) the meiofauna of an exposed sand beach at Whitsand Bay, Cornwall, was described in relation to the physical environment. During this study special emphasis was placed on the harpacticoid copepods, of which 13 species were recorded on the beach. In the present paper the horizontal and vertical zonation of the copepod species on the beach is described. An account of seasonal changes in the copepod population will be given in a subsequent paper.

Fish assemblages associated with wave exposed and sheltered sides of breakwaters, and with adjacent sandy habitats were studied in western Calabria (Mediterranean Sea, south-western Italy). Overall, 26 fish taxa were recorded (21 associated with exposed breakwater sides, 21 with sheltered sides, and four with sand). Fish assemblages significantly differed between breakwaters (both sides) and sand, and, to a lesser extent, between exposed and sheltered sides of breakwaters in terms of whole assemblage structure, densities of species, and juvenile stages.

The present work aims to determine and analyse the distribution of individuals of different size-classes of the southern stingray, Dasyatis americana, in distinct habitats at Fernando de Noronha Archipelago. The stingrays were visually sampled, quantified and described according to a standard protocol through intensive search method during direct observations. The relationships among individuals of various disc length (DL) classes and their habitat features were described by the correspondence analysis. A total of 356 individuals were sampled. Individuals between 15 and 35 cm DL were observed mostly at the beaches while the greater DLs were strongly related to reef environments. This distribution reflects a tendency of the younger stingrays to occupy the shallow beach areas, while larger individuals move to deeper waters with reef characteristics during the ontogeny.

This study constitutes a first contribution to the knowledge of the ecology of the decapod crustaceans in waters off Guinea-Bissau. Samples were collected during a survey undertaken between October and November 2008. A total of 122 species of decapod crustaceans were identified. Results showed an increase of decapod biomass and abundance with depth, reaching maxima values in the 200–500 m depth stratum but decreasing at depths over 500 m. Average diversity by strata increased with depth, with maximum over the deep slope. Seven main assemblages were identified: five primarily associated with depth—coastal shelf (<60 m), shelf (60–200 m), upper slope (200–300 m), middle slope (300–500 m), deep slope (500–1000 m)—and two other northern shelf assemblages affected by sediment type—coastal shelf-north (<50 m) and shelf-north (50–100 m). Species of each assemblage are typified. This study provides new information about composition, distribution, abundance and assemblage structure of decapod crustaceans in Guinea-Bissau that may be useful for future assessment of the effect of trawling pressure in the area.

In both protected and fished rocky reefs in the southern Adriatic Sea, the behaviour of the sea breams Diplodus sargus and D. vulgaris (both targeted by spear-fishing) in the presence of divers was found to be mostly negative (i.e. escape response). However, at protected reefs sea breams frequently swam into the closest shelters, whereas in fished reefs they mostly escaped in open water. This study suggests that spear-fishing may alter the escape response of fish from natural predators and that marine reserves may re-establish natural behaviour patterns.