Introduction

Despite the amount of literature published concerning the entocommensal rhynchocoelan, Malacobdella grossa (O. F. Müller), few references have been made about its ecology and life-history, and these for the most part consist of little more than isolated observations. The ecological knowledge available is composed almost exclusively of details pertaining to geographic distribution, hosts from which the worm has been recorded, and reports of the infection incidences found. Apart from suggestions by von Kennel (1878) and Gering (1911) that a relationship exists between host size and both worm incidence and size, the only detailed analysis of the host-commensal associations is that of Gibson (1967), who established a statistical correlation between host size and both incidence of infection and nemertean length, recorded the disposition frequency of the worm within its host, and examined both the occurrence of multiple infections and the Malacobdella population size composition.

Von Kennel (1878) further suggested that host-commensal size relationships would depand on the age (i.e. size) at which infection by the pelagic larvae occurred, and Ropes (1963) speculated on the role played by surface currents upon larval distribution.

The subumbrella of the hydrozoan medusa Obelia consists of three layers of cells. The innermost layer is the endodermal lamella whose broad polygonal cells are in close contact with the middle layer of polygonal myocytes which have striated myofibrils running in two layers at right angles to one another in the same cell. These myofibrils extend beyond the myocytes as plasma membrane-enclosed prongs to make contact with the prongs of neighbouring cells in such a way that whole mounts give the impression that the slender myofibrils are continuous over the subumbrella. Cross-layered myocytes can be seen to be another means of decreasing the surface area of the subumbrella, a condition necessary for medusoid locomotion. Helically banded radial myofibrils are found in the outer layer.

Sea urchins were collected in August 1999, at Salvador (Todos os Santos Bay, State of Bahia, Brazil). Twenty out of 20 Eucidaris tribuloides sea urchins studied had sponge remains in their guts, 12 of which, in large enough quantities to discard the hypothesis of sponge contamination on other food items. No other macroscopic evidence of alternative food sources has been encountered. Sponges found in large enough quantities were classified in seven genera, spread over seven families and five orders of the Demospongiae. Among the commonest sponges were Haliclona spp. and Iotrochota birotulata. The results show clearly the spongivorous habit of E. tribuloides at the studied site.

The goal of the present study was to assess the temporal and spatial distribution of L. schmitti in three bays of the northern coast of the State of São Paulo, Ubatumirim (UBM), Ubatuba (UBA) and Mar Virado (MV), over a period of two years (1998 and 1999). Abiotic factors were monitored to test their influence on the distribution of the species through redundancy analysis. The shrimp were captured using a commercial fishing boat equipped with double-rig trawling nets at six sampling points. A total of 5658 individuals were collected during the study (4437 and 1221 in the first and second years, respectively). The number of individuals differed between years, bays, seasons and sampling locations. The highest number of L. schmitti was collected in MV (N = 2747), followed by UBM (N = 1649) and UBA (N = 1262). Shrimp abundance correlated positively with organic matter content, salinity and temperature, with the highest number of individuals collected from sites with intermediate levels of organic content (4 and 6%) and increasing when the sediment had a higher proportion of fine and very fine sand + clay. Abundance was also associated negatively with rainfall, given that the analysed population showed a seasonal pattern, with an increase in capture rate in those months following the rainy season. Average rainfall was 222.47 ± 138.68 mm, with a maximum of 538 mm and a minimum of 22.4 mm. The results obtained in this study suggest that, in the region of Ubatuba, temperature, salinity, organic content and rainfall modulate the distribution of these animals.

The size–weight relationships, percentage water, ash-free dry weight and biochemical (protein, lipid and carbohydrate) contents of the coronate jellyfish species Periphylla periphylla have been analysed. A total of 48 medusae ranging in size from 13 to 80 mm bell diameter were collected from mesopelagic depths in the eastern Gulf of Mexico. The dry mass of whole medusae ranged from 1.12 to 10.53% of wet weight (mean 5.49%), while ash-free dry weight, a proxy for organic content, varied between 25.19 and 34.89% of dry weight (mean 30.14%). Preservation in 2% glutaraldehyde resulted in shrinkage in >75% of the medusae, with preserved bell diameters 2.9% to 28.6% smaller than the original fresh bell diameters. Preservation also produced a significant adjustment to the bell diameter to wet weight relationship. With regard to biochemical content, the typical gelatinous zooplankton trend of low carbohydrate (mean 8.99 mg gDW−1), intermediate lipid (mean 20.57 mg gDW−1) and high protein (mean 63.71 mg gDW−1) was observed. Although there was a high degree of variability in biochemistry, there was no apparent trend with size.

Five new species of sponges are described from the coast of Lebanon in the eastern Mediterranean, Levantine Basin. Euryspongia raouchensis (Dysideidae), Liosina blastifera (Dictyonellidae) and Niphates toxifera (Niphatidae) belong to genera that are new for the Mediterranean but widely distributed in the tropics. Cinachyrella levantinensis (Tetillidae) and Ciocalypta carballoi (Halichondriidae) are described in genera with a restricted distribution in the Mediterranean, which have affinities with species from the Atlantic West African coast. These species do not appear to be lessepsian migrants, but are interpreted as remnants of an ancient thermophilous fauna that survived in the easternmost part of the Mediterranean.

A decline in white-beaked dolphins Lagenorhynchus albirostris had been reported in the Minch (Scotland, UK) since the 1990s, coinciding with an increasing occurrence of short-beaked common dolphins Delphinus delphis. This has led to suggestions that rising seawater temperatures are causing D. delphis to out-compete and exclude L. albirostris in this region. A total of 793 km (66.3 hours) of survey data were collected in the Minch during August 2007, to examine fine-scale habitat selection by L. albirostris and D. delphis and investigate whether their ecological overlap is sufficient to result in interspecific competition and/or habitat partitioning. Ten sightings of L. albirostris (70 animals) were recorded in a relatively small spatial area in the northern Minch. In contrast, the eleven sightings of D. delphis (1486 animals) were more widely distributed. The relative abundance per 1/4 ICES rectangle ranged from 0.41 to 0.53 animals/km for L. albirostris and 0.13 to 6.68 animals/km for D. delphis. The mean group size and group body mass were higher for D. delphis than for L. albirostris indicating D. delphis as the dominant delphinid in the Minch during August. Lagenorhynchus albirostris occurred in waters significantly deeper and further from shore than D. delphis, suggesting interspecific differences in preferred habitat. Most dolphin schools were recorded as foraging/feeding. Behaviour and seabird associations indicated that the two species differed in diet and/or foraging strategy, with L. albirostris foraging sub-surface and D. delphis exhibiting surface-feeding with associated gannets Morus bassanus. This is consistent with published information on the stomach contents of Scottish animals. The results suggest that there are subtle differences in habitat selection and diet between these two species, which may enable L. albirostris and D. delphis to coexist in the Minch. Whether these differences result from niche partitioning arising from previous/ongoing interspecific competition or are the result of genuine differences in the habitat preferences of each species, remains unclear.

The ‘mucous’ tube of Platynereis dumerilii is made up of successive layers of fine threads held together by an adhesive secretion. Tube construction involves a regular sequence of behaviour which can be modified if algae or other objects are available for incorporation into the tube wall. Anterior parapodia are specialized for tube construction and gland cells producing tube components occupy most of the coelom in these segments. Several types of gland cell can be recognized histologically and those which form the threadsdischarge into a complex spiral organ below the cuticle.

The stomach contents of 344 four-spotted megrim, (Lepidorhombus boscii) and 159 megrim (Lepidorhombus whiffiagonis), off the eastern coast of the Gulf of Valencia (Spain), were analysed. The two species examined do not appear to have very similar diets, based on the species composition of prey. The vacuity coefficient is not high for any of the species, the main food being Crustacea (Decapoda and Mysidacea). Also Amphipoda and Teleostei are components of the diet. Variations in the food of both fish related to their length show few small crustaceans as prey of the major specimens. Finally, there was evidence for seasonal variation of the quality and quantity of the food consumed. There was no great dietary overlap between these two species.

Six benthic biotic indices (Shannon–Wiener H′log2, W-statistics, BOPA, BENTIX, AMBI and M-AMBI), based on different ecological principles, were applied to assess the health of variously disturbed tropical intertidal habitats of the Port Blair coastline. A total of 243 replicate samples were collected during the dry period (January, February and March) of 2014–2016. Temperature, salinity, dissolved oxygen, sediment pH, total organic matter content and texture were analysed. A high mean abundance of opportunistic species (Orbinia sp. 748, Capitella singularis 237 and Armandia sp. 114 ind. m−2) was observed at Phoenix Bay, a gradual decline in diversity at Junglighat and a comparatively high diversity and moderate biomass at Wandoor, reflecting a human pressure gradient. Results showed an annual decline of benthic quality from 2014 to 2016 (good to moderate). Overall BOPA failed to distinguish the magnitude of disturbances, while the rest of the indices classified the benthic quality from undisturbed/high (WD), slightly disturbed/good (JG), to moderately disturbed/moderate to poor (PB). The subjective analysis demonstrated that the urban centres corresponded to disturbed benthic communities of dominant first and second order opportunistic species, while sensitive (EGI) and indifferent (EGII) were associated with the least disturbed or undisturbed site. The study successfully demonstrated the performance of temperate indices in intertidal habitats against the mild organic enrichment. However, for an effective assessment, setting natural reference conditions and sampling in stable dry periods (strong seasonality in tropics) is desirable. In order to test the performance of biotic indices, a long-term monitoring approach of taking abiotic and biotic descriptors into account is recommended.

Miniature acoustic transponders wrapped in bait were deployed on the sea floor in the continental rise and slope regions of the Porcupine Seabight during August 1992. These were ingested by Centroscymnus coelolepis (Chondrichthyes, Selachii) at 1517–1650 m depth, Antimora rostrata (Osteichthyes, Moridae) at 2020–2501 m depth, and Coryphaenoides (Nematonurus) armatus (Osteichthyes, Macrouridae) at 2501–4050 m depth. Fish with baits in their stomachs were tracked using a scanning sonar deployed on the sea floor. All fish had moved out of range of the sonar (500 m) within 3–9 h of the bait reaching the sea floor, indicating no site fidelity. Swimming speed of C. (N.) armatus increased with depth from 0056 m s-1 at 2500 m to 0·109 m s-1 at 4000 m. This is partially explained by a bigger-deeper trend in fish size.

The observations which form the subject of the following notes deal with only part of the total material on which my studies of teleostean reproduction, pursued during the last two years, have been made; but as the other and larger part of the material consists of preserved specimens of the young (chiefly post-larval) stages of fishes collected during the four years 1906 to 1909 inclusive, it is more convenient to deal with the egg collections of the past year first and to treat the whole collection of young fry separately in a further paper.

A new flagellate alga is described which has the flagellar apparatus characteristic of the genus Pavlova, but not the external particles on the cell body. The minute particles on the long flagellum contain acid polysaccharide. Paramylon and polyphosphate occur as vacuolar inclusions. A peroxide resistant layer is present in the superficial cisterna. The opposite membranes of the superficial cisterna differ considerably in structure. A diagnosis is given and taxonomic relationships are discussed.

We report the information on loggerhead sea turtle (Caretta caretta) nesting events which occurred on the Spanish Mediterranean coast in 2006. Two clutches of 78 and 82 eggs were discovered in the provinces of Valencia (eastern Spain) and Barcelona (north-eastern Spain). We discuss the increasing number of reports of sea turtle nests in Spain within the context of the nesting range of this species in the Mediterranean Sea.

Water temperature is one of the most important factors greatly affecting the aquaculture of sea urchins. However, no information is available on how to improve commercial traits of sea urchins reared at high water temperature. Here, we investigated the effects of water temperature and feeding regime on food consumption, growth, gonad production, gametogenesis and gonad quality of the sea urchin Strongylocentrotus intermedius. We found that high water temperature (22°C) significantly decreased dried food consumption and gonad production of S. intermedius, but not the somatic growth. The feeding regime of formulated feed and kelp has direct application potential in S. intermedius aquaculture, especially at field temperature. Feeding kelp alone is not effective in supporting growth and gonad production for S. intermedius cultured at high water temperature. This finding greatly challenges the current commonly used feeding regime (feeding macroalgae only) for S. intermedius cultured at high water temperature. Based on the current results, we suggest the feeding regimes of formulated feed and kelp or formulated feed alone for S. intermedius aquaculture at high water temperature. The present study provides new information for aquaculture of S. intermedius at high temperature and for production out of season.

The present publication presents oxygen properties and pumping behaviour of Dysidea avara. Oxygen profiles were measured near and inside the atrial space of the osculum with a Clark-type micro-electrode. Pumping sponges had profiles with oxygen concentrations marginally lower than that of the aquarium water. In contrast, diffusive profiles, with a clear boundary layer above the sponge surface, and oxygen penetrating only 0.5 mm into the sponge tissue, were typically that of a sponge which was not pumping. Diffusive oxygen flux at the sponge surface was 4.2 μmol O2 cm2 d1 and the calculated volumetric filtration rate was 0.3 cm3 water cm3 sponge min1. The oxygen concentration in the osculum was temporally fluctuating between 95 and 59% saturation at a frequency of approximately once per minute. The combination of static oxygen micro-electrode measurements and particle tracking velocimetry (PTV) allowed us to simultaneously observe fine-scale oxygen fluxes and oscular flow patterns in active sponges, even at extremely low pumping rates. Oscular oxygen concentration and flow were correlated but not always synchronous to the second. Particle tracking velocimetry was used to visualize the flow field around the sponge and to distinguish sponge-generated flow from the unidirectional current in a flow-cell.

The distribution, abundance and recruitment of Chthamalus species were studied for one year at two rocky shores on the central coast of Portugal. Chthamalus montagui is the most abundant intertidal barnacle on the Portuguese mainland. Higher abundance of C. montagui was found on the lower levels of the more sheltered shore, which is closer to the influence of the Tagus estuary. Chthamalus stellatus was also present, in very low densities, and always confined to the lower level of the barnacle zone. Chthamalus stellatus was more common at the shore farther away from the estuary, in which exposure to wave action is higher. The metamorphs of C. stellatus settled at the studied shores are considered to be immigrants from other populations, where the density of adults is sufficient for cross-fertilization to occur. Chthamalus spp. recruited almost continuously throughout the year, with a peak between July and September and a gap during February and March. Variations in phytoplanktonic assemblages and temperature may be the main factors controlling the reproductive season of Chthamalus spp. Recruitment was usually stronger on the lower shore levels but extended for a longer period higher on the shore. Seasonalvariations of C. montagui abundance were greater on the lower levels of the more exposed shore. This is probably due to faster growth and higher mortality of barnacle populations occupying the lower shore levels at the more exposed habitats.

The diet of blue runner Caranx crysos (Carangidae) in the Gulf of Gabès (Tunisia, Mediterranean) is described from analysis of stomach contents (N = 1668 fish). The majority of samples were obtained from commercial purse seine and gill-net catches. The index of vacuity (%VI) was relatively high (58.7%) and differed significantly across months. Blue runner is an opportunistic predator that consumes mostly pelagic organisms, with benthic prey representing only a small proportion of the diet. The diet was quantified using the frequency of occurrence (%F), numerical abundance (%N), weight (%W) and the index of relative importance (IRI and %IRI) for each prey taxa.

The most important prey categories were teleosts (%IRI = 83.4) and crustaceans (%IRI = 16.6), with molluscs only observed occasionally (%IRI < 0.1). Fish were also the dominant food items in both terms of weight (89.60%) and frequency of occurrence (82.44%). In terms of numerical abundance, crustaceans were the most abundant prey (78.07%). Ontogenetic and seasonal differences in the diet were observed, although there was no difference between the diets of males and females.

Changes in phenotypic traits, such as mollusc shells, are indicative of variations in selective pressure along environmental gradients. Recently, increased sea surface temperature (SST) and ocean acidification (OA) due to increased levels of carbon dioxide in the seawater have been described as selective agents that may affect the biological processes underlying shell formation in calcifying marine organisms. The benthic snail Concholepas concholepas (Muricidae) is widely distributed along the Chilean coast, and so is naturally exposed to a strong physical–chemical latitudinal gradient. In this study, based on elliptical Fourier analysis, we assess changes in shell morphology (outlines analysis) in juvenile C. concholepas collected at northern (23°S), central (33°S) and southern (39°S) locations off the Chilean coast. Shell morphology of individuals collected in northern and central regions correspond to extreme morphotypes, which is in agreement with both the observed regional differences in the shell apex outlines, the high reclassification success of individuals (discriminant function analysis) collected in these regions, and the scaling relationship in shell weight variability among regions. However, these extreme morphotypes showed similar patterns of mineralization of calcium carbonate forms (calcite and aragonite). Geographical variability in shell shape of C. concholepas described by discriminant functions was partially explained by environmental variables (pCO2, SST). This suggests the influence of corrosive waters, such as upwelling and freshwaters penetrating into the coastal ocean, upon spatial variation in shell morphology. Changes in the proportion of calcium carbonate forms precipitated by C. concholepas across their shells and its susceptibility to corrosive coastal waters are discussed.

Although the harbour seal (Phoca vitulina vitulina) is relatively common in coastal waters of the Republic of Ireland, it remains largely unstudied. Issues including potential interactions with coastal fisheries and the occurrence of phocine distemper virus outbreaks in 1988 and 2002 have highlighted the need to increase our knowledge of the ecology of these animals. The diet of harbour seals was investigated using a combination of approaches: hard-part analysis of scat contents and fatty-acid analysis. A total of 102 scat and 13 blubber samples were collected from two locations in Ireland and were analysed following standard methodologies. Results from scat analysis indicate that the seals are opportunistic, generalist feeders, and probably consume prey in relation to its availability. Eighteen prey species were identified, with sandeels (Ammodytidae spp.) constituting 55% of the prey items by number. Biomass of prey was reconstructed using otolith-length regression equations, with and without the application of digestion correction factors and sole (Solea solea) (16.1%), sandeels (15.2%), and Trisopterus species (12.4%) were found to be the most important species by weight. Rarefraction curves were used to determine prey species diversity on a sample site basis and we used accumulation curves to ascertain whether sampling was sufficient on a site basis. Sixty-four fatty acids were isolated from the blubber and analysis of the fatty-acid profiles revealed the possible influence of season, seal weight and sex on the seals' long-term diet. Some of the prey species recorded in the diet overlap with commercially and recreationally caught fish species in Ireland; however, there was little overlap with marketed size-ranges.