Daily censuses of the hawksbill turtle Eretmochelys imbricata were taken during the nesting seasons 1995–2001 in three sandy beaches of the Yucatan Peninsula, Mexico (Celestun, El Cuyo and Isla Holbox), to evaluate aspects of its reproductive biology. A total of 9059 hawksbill turtle clutches was estimated for the study period. Nesting seasons began in mid-April and ended in early September, peaking in May–June. No significant differences were detected in the mean number of clutches per km among beaches. The largest number of clutches was observed in the supralittoral zone (6341: 70%), followed by the dune (2491: 27.5%) and the intertidal (227: 2.5%) zones. Variation in number of clutches showed a main peak in 1999, decreasing in 2000 and 2001. A significant decrease (3 cm) in body size of nesting females was detected between 1995 and 2001. Mean clutch size was 140 eggs/clutch, and a significant positive relationship between curved carapace length and mean clutch size was found at the three beaches. Incubation period, hatching success and emergence success varied between years (lowest values in 1998) and beaches (highest values at Isla Holbox), with no significant differences between the supralittoral and dune zones. Even though there was no evidence of a decreasing trend in nesting activity for the study period, the decrease in 2000–2001 suggests that additional beach monitoring is necessary to identify long-term trends, and to reduce potential losses of nests by human and natural causes in this globally important region for the hawksbill turtle.

Esperiopsis koltuni, a new species of the sponge family Esperiopsidae, is described from deep water of the Sea of Okhotsk. The new species has a unique growth form: there is a basal plate with radiating cylindrical branches, whose oval flat distal parts bear filament-like outgrowths. Megascleres are arranged differently in the main part of branches and in their distal flat parts. The dermal membrane contains isochelae with protruding alae and abundant sigmancistras. Microscleres are represented by large anchorate spatuliferous isochelae, small isochelae, sigmas and sigmancistras. Esperiopsis koltuni sp. nov. is hermaphroditic, with parenchymella larva. The larval skeleton consists only of sigmas and sigmancistras. Esperiopsis koltuni sp. nov. can be easily distinguished from other Esperiopsis species by dimensions and combination of spicule types. In particular, it is the only species in the genus with three different size categories of styles. The new species lacks the aquiferous system, has a characteristic body plan with symmetrical lateral expansions, an unusual arrangement of microscleres in the dermal membrane and true sigmancistras. Moreover, prey capture by a filament-like outgrowth of the flat distal part was observed. All of these characteristics indicate that Esperiopsis koltuni sp. nov. is a carnivorous sponge.

INTRODUCTION

Individuals of the Antarctic krill Euphausia superba Dana assemble in spring into dense formations (estimated 20,000 m3) which swim for long distances and at considerable speed (estimated 20 cm s−1) to search for patches of phytoplankton (Hamner, 1984). Recruitment to schools and maintenance of a defined position in a travelling formation, a remarkable social behaviour, requires some kind of communication system between individuals.

Vision, as a sophisticated image-processing system, habituating strongly with time, appears inappropriate for the task of continuously monitoring position in the formation. This is not in contradiction of the fact that the prominent eyes of Euphausia orient the shrimp with respect to the axis of light coming from above, and direct the photophores 180° away from light (Land, 1980). The function of the photophores is only partially explained (e.g. predator avoidance by counter-shading, Grinnell et al., 1988), their role in formation swimming being doubtful because they are reportedly active only during dawn and dusk. Of course the eyes help Euphausia to assemble in schools and to evade predators (Strand & Hamner, 1990) as well as fishing nets (Everson & Bone, 1986a,b), but a simple mechanical reflex seems more suitable to control individual position in the formation.

Specimens of the chemoautotrophic symbiont-bearing hydrothermal vent clam Calyptogena pacifica were collected from hydrothermal vents at the Endeavour segment of the Juan de Fuca Ridge. Total lipid was extracted from gill, foot and mantle tissues, and lipid class and fatty acid composition determined by thin layer chromatography with flame ionization detection (TLC–FID), gas chromatography (GC) and gas chromatography with mass spectrometry (GC–MS). An abundance of n–7 monounsaturated fatty acids (MUFA), especially in the gill, reflected the large contribution of chemoautotrophic symbiotic bacteria to the nutrition of this clam. The absence of n–8 MUFA suggests that C. pacifica does not contain methanotrophic symbiotic bacteria. Low levels of highly unsaturated fatty acids (HUFA) such as 20:5 n–3 and 22:6 n–3 were detected in C. pacifica and their presence is attributed to a source other than chemoautotrophic symbiotic bacteria. Significant levels of non-methylene interrupted dienoic fatty acids and eicosatrienoic acid (20:3) were also detected in C. pacifica and it is suggested that these fatty acids are synthesized from n–7 MUFA as alternatives to HUFA. In contrast to shallow water bivalves, elevated levels of triglyceride were detected in the gills compared to the mantle.

The harbour porpoise (Phocoena phocoena) is one of the common small cetaceans of European waters. This discreet and undemonstrative species is strongly represented throughout the cold waters of the northern hemisphere, and is the most abundant cetacean in the North Sea. In the last few years, some observations and studies indicate a shift of harbour porpoise distribution in European waters, from northern regions of the North Sea to the southern North Sea, English Channel and Celtic Sea. This shift may include a comeback around the coasts of France. Harbour porpoises inhabit shelf-waters and are often observed in shallow waters, conditions offered for instance by the coasts of Brittany in north-western France. We used opportunistic sightings, aerial survey and a ten-year strandings database to study the presence of harbour porpoises along the coasts of Brittany. Opportunistic sightings made by non-specialists did not confirm a strong presence of harbour porpoises along the Brittany coasts, most probably because of the undemonstrative behaviour of this cetacean. However, aerial survey and stranding analysis indicate that harbour porpoises have become natural inhabitants of the Brittany coasts once more: 68.6% of cetacean school sightings made during a 1578 km aerial survey of the Brittany coasts concerned harbour porpoises, with an encounter rate of 1.5 individuals per 100 km that peaked to 5.8 per 100 km to the top of the shallow waters of the south-western Western English Channel. The number of harbour porpoise strandings increased each year from 1997 to 2007, making a total of 135 along the coasts of Brittany. Other cetaceans did not show such an increase during the same period. Strandings of harbour porpoises were also characterized by an apparent increase as a proportion in relation to all the cetacean strandings during the months of September to January, by a marked impact of by-catch during winter, and by an almost total absence of stranded calves. The comeback of the harbour porpoise along Brittany coasts is clearly confirmed by our data, and a stable population seems to be established again along the coasts of Brittany. This tends to confirm the shift of the distribution of the species in certain European waters. Long term monitoring, diet and genetic studies are now planned for a better understanding of this shift, and for the effective implementation of a conservation plan.

The trophic behaviour, stomach contents, and morphology of the feeding appendages, with emphasis on setae, of a species of Laomediidae, Axianassa australis (Crustacea: Decapoda: Thalassinidea), were investigated. This species is a deposit feeder. The 32 described setal types were clustered in four main categories: plumed, serrate, plumodenticulate and simple. By examining the setae and spatial position of the segments of the appendages, it is possible to infer that the main function of the 1st and 2nd pereiopods, the 3rd pair of maxillipeds, as well as the dactylus, propodus, carpus and merus of the 2nd maxilliped, is to brush particles. The ischium, basis and coxa of the 2nd maxilliped appear to be specialized for particle retention. For the remaining mouthparts, brushing is generally the main function of the basal endites, while the coxal endites retain particles. Patterns of morphological adaptations to feeding habits are proposed for the Thalassinidea based on a review of the literature. Setal diversity, ratio of plumodenticulate to serrate setal types and mandible morphology are linked to ecological adaptations to trophic modes. Conversely, the presence and degree of development of the crista dentata appear to be related to phylogenetic heritage rather than to feeding mechanisms. Stomach contents are also indicative of trophic modes used by the species; while the predominance of small particles can indicate either filter or deposit feeding, stomach contents with high quantities of large particles suggest deposit feeding as the exclusive trophic mechanism.

Ptychodactiaria, currently recognized as an order equivalent to Actiniaria (sea anemones sensu stricto) and Scleractinia (‘true’ or hard corals) of cnidarian class Anthozoa, contains three monotypic genera, Dactylanthus, Ptychodactis, and Preactis, in two families, Ptychodactiidae and Preactiidae. Features that had been considered distinctive to the order among hexacorallian anthozoans were that gametes mature in protrusions from the mesenteries, as in octocorallian anthozoans, and that gametes do not mature embedded in mesogloea. However, we found that ptychodactiarian gametes develop in the mesenteries, surrounded by mesogloea, as in other sea anemones. We conclude that the three species constitute a clade, the most distinctive feature of which is medially fused mesenteries at the proximal end of the body. This clade merits subordinal status within order Actiniaria. We redefine Ptychodactiaria and its component taxa, moving Dactylanthus from family Ptychodactiidae to family Preactiidae.

During the course of a survey into the distribution and growth of the fan mussels Pinna nobilis and Pinna rudis from the coastal waters of the Spanish Mediterranean the presence within the mussels of Pontonia pinnophylax has been recorded. Pontonia pinnophylax typically occurred in adult pairs, but occasionally solitary male individuals were found. The width of the cephalothorax is greater in females than males, whereas the chelae of the second periopods, which are unequal, are larger in males. There is a general relationship between the size of P. pinnophylax and its pinnid host; the largest individuals were found in the largest Pinna and vice versa.

The morphology of burrows constructed by the eel goby Taenioides cirratus was studied using resin castings of burrows in situ as well as aquarium observations. Burrows had several openings, one of which was associated with a crateriform mound. The structure of the burrows consisted of the mound, gently sloping interconnected tunnels, and many short cul-de-sac side branches. The presence of the mound suggests that the fish actively process sediment.

Since 1912 extensive investigations have been carried on in the Laboratory of the Marine Biological Association at Plymouth on the genetics of Gammarus Chevreuxi Sexton, a brackish-water amphipod (Allen and Sexton '17 and '20, see also Sexton '13 and Sexton and Matthews '13).

During the course of the work, numerous individuals have appeared showing abnormalities in sexual behaviour or structure. In view of the interest attaching to such forms, especially after the work of Goldschmidt ('20), Banta ('16), Sturtevant ('20) and others, it was deemed advisable to collate and publish the available data in spite of their some what fragmentary character.

In normal circumstances, the males of Gammarus chevreuxi mate with the females some days (3 to 9 days) before fertilisation is due to take place. Unless the female is mated for the first time she will normally be carrying in her brood-pouch a brood of developing embryos. After hatching, the young are carried about 24 hours before extrusion, and during that time they come to the anterior end of the brood-pouch and feed on what the mother is eating. Finally they are extruded by a voluntary opening of the brood-pouch. Immediately afterwards the female moults, whereupon fertilisation occurs and a new batch of eggs is extruded into the pouch.

The pair have by now separated, and remain separated usually until the embryos have gone through about half their development in the pouch.

Cannibalism is of fairly frequent occurrence, the male eating the female immediately after she has moulted. It is extremely rare for the normal female to eat a male.

The predatory effects of Pachygrapsus marmoratus on populations of the intertidal limpet Patella depressa were analysed on rocky shores located on the central coast of Portugal. Nocturnal observations on crab feeding behaviour were conducted and experimental exclusion cages were set in the substratum to assess density effects on limpets. The results indicated that although crabs feed on adult limpets the predatory level was minimal. Crabs used consistent tactics to detach limpets from the substratum but the majority of the attacks were unsuccessful, possibly due to morphological and behavioural adaptations of limpets. An alternative recruitment hypothesis is advanced to explain non-significant differences between experimental treatments and a possible predatory role on shaping levels of recruitment on lower levels of the shore is considered.

Feeding and vertical distribution of pelagic chaetognaths were studied at coastal and open-sea stations in the northern part of the South Adriatic Pit during five cruises from April 1993 to February 1995. Chaetognaths were more numerous in the upper 100 m, decreased conspicuously with depth, and were captured only rarely between 600 and 1000 m. Copepods were the main food for the most abundant species in all layers. Cannibalism was evident in all species. Feeding on fertilized chaetognath eggs by Pseudosagitta lyra and Mesosagitta decipiens is reported for the first time. The food containing ratio (FCR) and number of prey items per chaetognath (NPC) of Flaccisagitta enflata were highest during the reproductive period. Higher FCRs and NPCs for M. decipiens and P. lyra were noted below 100 m, where the contribution of older specimens increased with depth and the abundance of copepods decreased.

This work is a continuation of my preliminary paper on the same subject, which was published in a former number of the Journal of the Association (vol. vi., p. 373, January, 1902).

This paper presents results of a study conducted on the trawling industrial fishery fleet of Merluccius gayi in south-central Chile, and the resulting interactions with the South American sea lion (Otaria flavescens). This study is based on observations made during September 2004, when incidental sea lion catch in the trawls was 6.3 sea lions/working day (1.2 sea lions/trawl−1). A total of 82 animals were incidentally caught, of which 12 were found dead, and the 70 remaining suffered from internal bleeding and/or fractures as a result of their capture. 83.3% of the fatalities occurred during nocturnal trawls, which comprise 30% of all observed trawls. Possible mechanisms of sea lion take are discussed. This note presents the first records of sea lions incidental by-catch by the trawler fleet along the south-east Pacific coast of Chile.

Populations of Caryophyllia smithii were studied at three sites of differing sedimentation regime in Lough Hyne, Ireland. The height, length, width and density of individuals were measured along with the depth of accumulated sediment on the rock substratum at each site. Calyx size was largest at the site of least sedimentation and smallest at the site of most sedimentation. In contrast, height of individuals was greatest at the site of most sedimentation and smallest at the site of least sedimentation. The height of individuals was correlated with the level of surrounding sediment (Pearson's correlation 0.836 P<0.05). The uppermost limit of C. smithii corresponded with the downward limit of the infralittoral zone at each site; 15, 13, and 12 m at the low, mid and highly sedimented site respectively. Density averaged over depth was greatest (70 ind m−2) at the site of moderate sedimentation and lowest (13 ind m−2) at the site of least sedimentation. Density was also found to increase with depth at the sites of moderate and high sedimentation.

The effect of sponge encrustation on swimming ability of Chlamys hastata was determined by investigating swimming behaviour, scallop morphometry, and energy expended during swimming with and without commensal epibionts. Scallops swam significantly longer after sponge encrustation was removed from their shells, but no significant differences were detected in swimming elevation or distance. Scallops with sponge encrustation showed no adductor muscle hypertrophy or changes in shell morphometry compared to scallops without encrustation. However, C. hastata did exhibit scaling relationships associated with maximizing swimming efficiency. Specifically, shell width and adductor muscle mass were positively allometric with shell height, while shell mass was negatively allometric with shell height. Scallops increased their energy expenditure (both aerobic and anaerobic) during valve-clapping, but no significant difference was detected between unencrusted (43·0 μmol adenosine triphosphate [ATP] consumed during a two min escape swim) and sponge-encrusted (40·0 μmol ATP) scallops. Scallops in both treatments derived 86% of the energy used for swimming from anaerobic sources. The lack of substantial differences between scallops with and without commensal sponges is partially explained by the observation that even heavy sponge encrustation increases the immersed weight of the scallop by only 5%. The presence of a sponge encrustation does not appear to inhibit swimming by this scallop species.

The feeding of the most important chaetognath species (Sagitta enflata, Sagitta minima, Sagitta setosa and Sagitta serratodentata) found in a grid of 35 stations in the north Aegean Sea (Strymonikos and Ierissos Gulfs) was investigated through gut content analysis during five sampling periods from June 1997 to May 1998. Sagitta enflata and S. minima were the most abundant species in summer–autumn 1997 and in spring 1998, respectively. Copepods were the main food for all chaetognath species in spring 1998, while cladocerans in summer–autumn 1997 dominated the diet, especially of S. enflata. In September 1997, the juvenile specimens of cladocerans were the most important prey of the immature Stage I specimens of S. enflata, which resulted from the major breeding period in late summer. The estimated impact of chaetognath predation on the copepod and cladoceran communities ranged between 0.02–2.76% and 0.01–1.29% of the copepod and cladoceran standing stock, respectively. Stage I specimens of S. enflata accounted for nearly 90% of the total copepod and cladoceran standing stock consumed per day by the total population of this species in September 1997.

The earliest detailed account of the nature of the sea bottom near Plymouth is that of Allen (1899), wherein analyses of the soils on the 30 fm. line are coupled with lists of the animals collected by trawl and dredge. Ford (1923) described a number of soils in shallower water, and gave a quantitative list of the bottom fauna, collected with a grab which covered an area of 0·1 sq. m. Smith (1932) described in great detail the soils of the area of shell-gravel which surrounds the Eddystone Lighthouse. By none of these workers, however, was special attention paid to the smaller burrowing Crustacea, which are often overlooked unless they are made the special object of collecting. Some species, e.g. of Bathyporeia and Ampelisca, may be very common, and certainly play an important part in the ecology of the sea-bottom. See Steven (1930) and Hunt (1925).

The pattern of habitat utilization by Elaphognathia discolor, a gnathiid isopod inhabiting terebellid polychaete tubes, was examined in bimonthly samples taken between June 2003 and April 2004 from Shizugawa Bay, north-eastern Japan. Nine species of terebellid polychaetes were obtained, and gnathiids were found in tubes of four terebellid species. Of the terebellids, Nicolea gracilibranchis was collected in each sample, while the other species were obtained only intermittently. Both larval and adult E. discolor inhabited the tubes of N. gracilibranchis throughout the year, with their prevalence in samples ranging from 57.1 to 80.0%. A large range of larval stages was found within N. gracilibranchis tubes, including the first larval stage and premature females, suggesting that this gnathiid species may use N. gracilibranchis tubes for resting and moulting throughout the larval period. The distribution of adult gnathiids within tubes significantly differed from random. Adult males rarely coexisted with other males in tubes, while several larvae and females often lived together. Groups of female gnathiids in polychaete tubes were usually attended by a single male, resembling the ‘harems’ observed in other gnathiids and suggesting that the mating system of E. discolor can be classified as semelparous harem polygynandry.

Laboratory experiments with whole water-columns from shallow, eutrophic lakes repeatedly showed collapse of the predominant filamentous cyanobacteria. The collapse could be due to viral activity, from the evidence of electron microscopy of infected cyanobacterial cells and observed dynamics of virus-like particles. Burst-size effects on single-host single-virus dynamics was modelled for nutrient-replete growth of the cyanobacteria and fixed viral decay rate in the water column. The model combined previously published equations for nutrient-replete cyanobacterial growth and virus–host relationship. According to the model results, burst sizes greater than 200 to 400 virions per cell would result in host extinction, whereas lower numbers would allow coexistence, and even stable population densities of host and virus. High-nutrient status of the host cells might accommodate a large burst size. The ecological implication could be that burst-size increase accompanying a transition from phosphorus to light-limited cyanobacterial growth might destabilize the virus–host interaction and result in the population collapse observed in the experiments.