The filter feeding bivalves Mulinia edulis and Mytilus chilensis, were exposed to a broad spectrum of concentrations and qualities of seston in order to compare the results of filtration rates measured volumetrically and gravimetrically, by both the traditional clearance method of Coughlan (1969) and the biodeposits method. Filtration rates, measured gravimetrically by both methods, tended to give similar results for both species, increasing with increase in seston and with decrease in seston organic content. With volumetric measurements, the filtration rates for both species also increased with the concentration of seston, however, in Mulinia edulis, the effect of the organic content of the food was less than that observed using gravimetric units, which is seen in the smaller slope of the regression equation (TFRv=−0·49). In the case of Mytilus chilensis there was no verifiable effect of the quality of the food on the filtration rate when expressed on a volume basis. The filtration rates of Mulinia and Mytilus measured by two methods and two units showed a similar behaviour with increase in the concentration of seston.

The species diversity and distribution of demosponges dwelling in the coral reefs, at Had Khanom—Mo Ko Thale Tai National Park on the southern coast of the Gulf of Thailand, was investigated, with field surveys undertaken at 12 sites in November 2006 using SCUBA diving and random observation. Forty-five species of demosponges from 10 orders, 24 families and 34 genera were recorded. The most abundant and common sponges in this area are: Oceanapia sagittaria; Neopetrosia sp. blue; Xestospongia testudinaria; and Haliclona (Gellius) cymaeformis. Most species are common representatives of the Indo-Pacific fauna found throughout the Gulf of Thailand.

The capacity for oxygen uptake of a respiratory organ can be estimated using morpho-metric techniques, the two essential measurements being respiratory surface-area and thickness of the tissue barrier across which oxygen diffuses. In cephalopods, the gills are the main site of respiratory exchange and this study was designed to estimate oxygen uptake capacity of the gills of four different genera of cephalopods. A preliminary study was required to determine the form and structure of the gills. Light microscopy showed the surface of the gills to be highly folded, particularly in Octopus. A level of microscopy was chosen at which the outline of the smallest folds of the epithelium and the blood vessels of the gills could be easily resolved. Stereological techniques were then employed to obtain values for the respiratory surface-area related to body weight (cm2 g-1), tissue barrier thickness (μm) and oxygen-diffusing capacity (ml O2 min1 Torr·1 kg1). Values for these three variables obtained for the different species were as follows: Octopus vulgaris 2·9 cm2 g-1, 10 μm, 0·05 ml O2 min-1 Torr-1 kg1; Alloteuthis subulata 10·6 cm2 g1,6 μm, 0·27 ml O2 min-1 Torr-1 kg-1; Nautilus sp. 4·9 cm2 g-1,15 μm, 0·05 ml O2 min-1 Torr1 kg-1; Sepia hatchlings 13·3 cm2 g-1, 4 μm, 0·52 ml O2 min-1 Torr-1 kg-1.

The Guiana dolphin, Sotalia guianensis, is a small delphinid found in coastal areas from northern Honduras to southern Brazil. Little is known about the ecology of this species in several areas of its geographical distribution. In this paper, we present new data about the residency of Guiana dolphins in Ilha Grande Bay, south-eastern Brazil. Boat surveys were conducted at the study area from May 2007 to March 2008. Applying the photo-identification technique, we took pictures of dolphins' dorsal fins, looking for natural markings on them. A total of 17,969 photographs were taken, from which was created a databank of 462 distinct dolphins. Individuals showed different degrees of residency in the bay. More than 50% of the catalogued dolphins were considered non-residents and/or showed a low degree of residence. The average interval between resightings was 35 ± 27.4 days. Animals without markings (calves and juveniles) accounted for 45% (N = 2917) of photographs taken. These results indicate that this population has a fluid structure including different individuals over time. We suggest a possible relationship between the presence of some individuals and local resource availability, such as prey and protected areas.

Grey seals (Halichoerus grypus) of the North-east Atlantic are protected at designated European Marine Sites (Special Areas of Conservation, SACs) typically during their reproductive periods and in the UK at Sites of Special Scientific Interest (SSSI). As a mobile marine species, grey seals spend other parts of their annual life cycle in non-designated habitat. There is limited information on individual grey seal movements in south-west England. Citizen science photo identification (PID) revealed the movements of 477 grey seals at a regional scale (54 haul-outs up to 230 km apart) for over a decade. Reconstructed movements showed considerable individual variability. Four SACs were linked to up to 18 non-designated sites and two SSSIs in Cornwall were linked to a maximum of 41 non-designated sites. Observations support the value of existing SSSIs at both the well-connected West and North Cornwall sites. Thirteen Marine Protected Areas (MPAs) were visited by grey seals from four SACs and two SSSIs in Cornwall. As a mobile species, grey seals could be included in English MPA management plans. The application of functional linkage from SACs and SSSIs, informed by the movements evidenced in this research, could aid management efforts. This analysis reveals grey seal movements occur across a complex network of interconnected designated and non-designated sites that need to be managed holistically for this species for which the UK has a special responsibility.

From 1994–2007 Ceredigion County Council and a network of shore-based, volunteer observers monitored levels of boat traffic and the occurrence of bottlenose dolphins Tursiops truncatus at seven sites on the coast of Cardigan Bay, Wales. We report high rates of site use and site occupancy by this species during the summer: at Mwnt for example, dolphins were recorded in >80% of 2 hours' observation periods; and at New Quay Harbour dolphins were present in >30% of all 15-minute intervals. At Mwnt and Aberporth there was a significant annual trend for increasing sighting rates; at Ynys Lochtyn a positive trend was only marginally non-significant; at New Quay Bird's Rock the trend was ambiguous but appeared stable over the seven most recent years. Although trends in site use may not reflect population trends in the wider region, these data were consistent with recent abundance estimates that indicate that the number of bottlenose dolphins using Cardigan Bay is stable or slightly increasing. Average group size at our study sites was small (<3 animals), which contrasts with observations of larger schools of the same population elsewhere in their range. The predominant behaviour in coastal Cardigan Bay is demersal foraging, often by solitary animals in shallow near-shore habitats. There was evidence that boat traffic suppressed site use by dolphins at New Quay Harbour, the busiest monitoring site: sighting rates fell when high numbers of boats were present and sighting rates were higher in 2007 than in previous years, when boat use was reduced due to poor weather during the main tourist season. This study demonstrates that networks of volunteer observers can provide a cost-effective, non-invasive means of gathering data on marine mammals for the purposes of coastal zone management.

Seven hundred and six specimens of Scolelepis cf. chilensis and 551 specimens of Scolelepis goodbodyi were analysed. Individuals of each species were classified according to sex (male, female, and immature individuals). Width (w) and height (h) of setigers 3 and 5, the position of the first and the last gametogenic setigers, the total number of setigers, and the total length of each worm were measured. The area and volume of the setigers were estimated. Discriminant analysis was used to determine whether there were sexually dimorphic features, apart from the presence of gametes. Linear regression analysis was used to evaluate the relationship between each parameter and the number of setigers. Scolelepis cf. chilensis was found to be significantly larger than S.goodbodyi (t=21·71 and t=36·44, P<0·05 for length and number of setigers, respectively). These species also differed in the position of the first gametogenic setiger, which averaged 27 (SD=3) in S. cf. chilensis and 22 (SD=1) in S.goodbodyi (t= 29·18, P<0·05). There were no sexually dimorphic features in either sex of S. cf. chilensis (Wilks' lambda=0·9675, P>0·05, eigenvalue=0·034) or S.goodbodyi (Wilks' lambda=0·8429, P>0·05, eigenvalue=0·186). The total length showed the strongest correlation with the number of setigers in both species (r2=0·887 and 0·850 for S. cf. chilensis and S.goodbodyi, respectively), followed by the width and the volume of setigers.

Serpulid polychaetes are often important components of marine communities, yet current knowledge of serpulid reproduction, development and settlement is largely based on the study of only a few species. This study examined whether spawning and sexual development of the mid-intertidal serpulid Spirobranchus cariniferus are typical of patterns observed in other serpulids, and also examined the effect of diet on larval development and identified cues that induce metamorphosis. Populations of S. cariniferus on the east and west coasts of New Zealand's North Island had an extended spawning season with a high proportion (75–100%) of individuals carrying ripe gametes at any given time from the late spring to early autumn, consistent with other serpulid species. However, contrary to proposed patterns of sexual development in serpulids, sex-ratios and average male and female body masses suggest S. cariniferus are not protandric hermaphrodites. A diet experiment revealed that larval growth was fastest when provided with a mixed diet of three algal species. Solutions of 3-isobutyl-1-methylxanthine at a concentration of 10−4 M were potent inducers of metamorphosis in S. cariniferus larvae, revealing that competence is reached by 13–15 days after fertilization. When exposed to surfaces coated with conspecific tube or tissue homogenates, 6% of competent larvae settled and metamorphosed on surfaces coated with tube homogenate whereas none settled on tissue homogenate or in the controls, suggesting specific cues are required for settlement and the likely presence of a settlement cue in the tubes of adult worms, consistent with the highly gregarious distribution of the species.

Topshells play a pivotal role in intertidal rocky ecosystems and are adapted to harsh thermal and hydric stress. Phorcus sauciatus, a common grazer in the Macaronesian region (Madeira and the Canaries), has rarely been studied due to its restricted geographic distribution compared with Phorcus lineatus. Monthly samples were taken throughout 2017 to analyse biological parameters and evaluate the harvesting effect on the stocks of this species in Madeira. Individuals of the first age classes (<4 years) were dominant (~89%), while immature individuals were more abundant during the summer season. The spawning season occurs between March and August, especially from March to June. The size at first maturity was 12.95 mm long (1.68 years), with a continuous recruitment pattern throughout the year. Yield-per-recruit analysis (Y/R) showed that maximum production is achieved at a fishing mortality of 1.7 year−1, corresponding to a Y/R of 0.023 g. Currently, Phorcus sauciatus seems to be moderately exploited in Madeira, but urgent conservation measures, such as a landing obligation, the establishment of a minimum catch size of 15 mm length, and a closed season (February–May), are warranted to preserve stocks of this species in the medium to long term.

The mesozooplankton of the south-western Caspian Sea, off Anzali, sampled from 1996–2010, had undergone severe changes, especially after the year 2001, when the invasive ctenophore Mnemiopsis leidyi bloomed for the first time. Native species vanished or decreased, while invasive species such as Pleopis polyphemoides, Acartia tonsa, M. leidyi and the larvae of Balanus sp., plus Hediste diversicolor dominated the zooplankton. It could be stated that the increasing amount of nutrients since the early 1980s led to a decrease of endemic species and smoothed the way for opportunistic invader species, which outcompeted and depleted the endemic species in their turn. However, the major changes in the zooplankton community and possibly the blooming of M. leidyi during 2001–2002 were triggered by changing weather patterns, when a period with heavy rain at the end of the 1990s was followed by a prolonged drought (2001–2002). It is not clear to what extent M. leidyi was responsible for the disappearance of endemic Copepoda and Cladocera species such as Eurytemora grimmi, Limnocalanus grimaldii, Cercopagis pengoi, and Polyphemus exiguous, because the mesozooplantic invader species seemed to be more successful competitors than the endemic Caspian Sea fauna. Compared with other areas of the Caspian Sea, the development of the M. leidyi stock was moderate in the area under investigation. Mnemiopsis leidyi numbers and biomass increased from the beginning of sampling in 2001 to about 600 n.m−3 and 40–60 g wet weight m−3 until 2003. Since then the stock oscillated in this range until 2010.

A number of different factors have been shown to affect the vertical migration of the zooplankton, among them changes in light intensity, temperature, salinity and the presence of food (see Russell, 1927; Hardy & Paton, 1947; Cushing, 1951; Bainbridge, 1953; Harris, 1953; Moore, 1958; Banse, 1959). The object of the present study was to find out whether in female Calanus there was any relation between vertical migration and the degree of ripeness.

When Calanus were taken by tow-nettings near the laboratory it was noticed that the percentage of adult females in the ripe condition was generally greater in hauls made close to the surface than in those from deep water. For example in the spring of 1953 a series of hauls was made near the surface in Fairlie Channel where the maximum depth is about 40 m, and at 60–80 m off Garroch Head a few miles away where the depth is 115 m. Throughout the period of examination there was a much higher percentage of ripe females in the shallow than in the deep hauls (Table 1, Fig. 1). The deep hauls show the progressive ripening of the females during the spring reaching a peak in percentage ripe which coincides with the spring diatom increase in the middle of March. It also coincides with the maximum number of eggs produced by laying females. In shallow water the sequence is not so obvious because of the high percentage of ripe females at the surface most of the time.

The spatial distribution of the subtidal crustacean assemblages of the Guadiana Riverestuary was studied previous to the building of the Alqueva Dam (the biggest dam inEurope). The differences between an estuarine and marine environment seem to be the mainreason responsible for the composition and distribution of the crustaceans along the studyzone. The Guadiana estuary has shown high number of species in comparison with othernearby estuaries and this richness seems justified by the scarce influence of pollutants(most of them have shown low or moderate values) and their hydrodynamic and granulometriccharacteristics (76 species were found, 39 in the estuarine area). A gradient ofenrichment and structuring of the assemblages was shown from the upstream to the marinezones and a spatial segregation of species was found along this estuarine environmentalgradient, e.g. the amphipod Corophium multisetosum and the isopodCyathura carinata in the upper estuary; the amphipodBathyporeia cf. pilosa and the isopodsLekanesphera levii and Saduriella losadoi in themiddle estuary; the amphipod Melita hergensis in the mouth; and a highnumber of species in the marine area. Since the Alqueva Dam will reduce the riverdischarges and may cause changes in the abiotic characteristics such as granulometry ofsediments or salinity, this study establishes a baseline against which a monitoringprogramme or follow-up studies could measure any significant effects of the dam or relatedimpacts.

The franciscana dolphin (Pontoporia blainvillei) is a coastal dolphin endemic to the western South Atlantic Ocean. The dolphin is listed as vulnerable in the IUCN Red List, with incidental catches in gillnet fisheries the greatest conservation concern for this species. Insights into the feeding habits of this dolphin are essential to understand its distribution, movements and use of habitat, which are fundamental for effective management of the species. The feeding habits of franciscana dolphins were investigated from analyses of stomach contents of animals incidentally caught by two fishing operations from southern and northern regions of the southern Brazilian coast. In this study we investigate the existence of intrapopulation (sexual maturity and sex-related) variation in the diet of the franciscana dolphin, evaluating the spatial (northern and southern geographic areas) and seasonal influences. The analyses were based on Linear and Generalized Linear Models (LM and GLM). The majority of identified prey species were bottom-dwelling teleosts and the squid Doryteuthis sanpaulensis. The most important prey differed spatially and seasonally between northern and southern regions of the study area, and our results revealed significant differences between sexes and sexual maturity stages, mainly related to prey species sizes. This variation might indicate differences in prey selection, availability or habitat use patterns among these groups. In any case, these dietary differences are likely to minimize intraspecific competition for food resources, and/or indicate spatio-temporal variation in prey availability.

During a study on the parasite assemblages of two endemic catshark species, the dark shyshark (Haploblepharus pictus) and the puffadder shyshark (Haploblepharus edwardsii), from the west and south coasts of South Africa, a trypanosome new to science was observed in the blood of all sharks examined. This trypanosome species, Trypanosoma haploblephari sp. nov., is characterized by its large size, particularly its width, the shape and orientation of the cell nucleus, and its geographical location. Trypanosoma haploblephari is the first species of elasmobranch trypanosome to be described from southern Africa and represents the first description of a blood parasite from South African sharks.

Spatio-temporal variability in the population structure of long-spined black sea urchin, Diadema antillarum, was investigated at two islands (Gran Canaria and Tenerife) in the Canarian Archipelago over a year. The mean abundance of D. antillarum across all counts was 2.70±0.07 ind m−2 (mean±SE, N=1440), while the mean biomass was 105.76±3.75 g m−2 (mean±SE, N=1440). Abundances and biomasses of D. antillarum differed consistently between vegetated and unvegetated bottoms; however, locations within each habitat at each island fluctuated following different trends. For the overall study, mean densities and biomasses in the barren locations varied between 3.36–6.97 ind m−2 and 93.76–405.13 g m−2, respectively; while mean densities and biomasses in the algal stand locations varied between 0–0.33 ind m−2 and 0 – 7.34 g m−2, respectively. Striking differences existed in the size-structure among locations; however, larger size-classes (test diameter >3.5 cm) were present at all locations, and usually dominated in terms of abundance. The majority of individuals in the algal stands were large-sized, probably as a result of the high abundance of the most palatable food. In contrast, small-sized individuals (test diameter <1.5 cm) only occurred in the barren habitat, suggesting that recruitment of D. antillarum could be favoured by the presence of high densities of congeners, as a way to decrease the risk of predation.

The Hydroids experimented on were Antennularia ramosa, and A. antennina.

These were cut in pieces and pressed through bolting silk, with the result that isolated cells and small cell aggregates were obtained, which soon aggregated together to form compact masses.

These restitution masses secreted a perisarc within from 12 to 18 hours.

Various changes in shape, and general retraction of the mass away from the perisarc occurred later, but even up to 60 days there was no sign of the regeneration of the hydranths.

The restitution masses consisted of ectoderm and endoderm cells, and in addition such structures as nematocysts, ova, and brokendown cells, all of which were subsequently absorbed and played no part in the future development. The ectoderm cells were relatively little damaged, and were embedded in a plasmodial mass formed by the endoderm cells.

A definite layer of ectoderm cells is formed on the surface, and thesecells secrete the perisarc.

Gradual aggregation and segregation of the endoderm cells from the plasmodial mass takes place ; and they form very definite tubules similar in structure to the coenosarcal tubules continuous with the enteric cavities of the normal hydranths. These tubules are embedded in a mass of ectoderm cells, they are convoluted and ramify in all directions. Many granules develop in the cytoplasm of these cells, and after about a month many of them have degenerated.

The ectodermal cells show no signs of degeneration, and the masses containing them have been kept alive for 60 days at the time of writing.

In none of the experiments was there any sign of the occurrence ofcell division

Population characteristics can be influenced by specific factors of the habitat and the natural variability of populations can confuse the effect related to protected environments. This study compares the demographic characteristics of Octopus tehuelchus in three coastal environments: two Marine Protected Areas (San Antonio Bay (SAB) and Islote Lobos (IL)) and a traditional fishing zone (El Fuerte (EF)). Weight–frequency distributions, sex-ratio and recruitment were monthly compared between the three intertidal zones. Octopus tehuelchus was smaller in IL, where fishing intensity is lower or null, and reached the largest sizes in the main fishing area of EF and within SAB (where there is no regulation and a mid–high fishing intensity). The sex proportion in SAB and EF was 1:1 all along the year. Although the proportion of mature females in IL was higher, the highest recruitment was observed in EF (the traditional fishing ground). These new data suggest that previous studies, which reported that Marine Protected Areas have positive effects for O. tehuelchus populations, can no longer be supported, and highlight the importance of understanding and quantifying the magnitude and range of natural variability in each environment when assessing the effectiveness of Marine Protected Areas.

The investigation of the food contents in the stomachs of young fishes was included in the scheme of scientific investigations drawn up and initiated by Professor Herdman for the Lancashire Sea Fisheries Committee nearly thirty years ago. The lengthy series of Annual Reports contain here and there accounts of the observations made on the stomach contents of various Pleuronectidæ captured close inshore, and the pelagic stages of other fishes caught from time to time in the plankton tow-nets. No systematic attempt has, however, been made, in connection with the investigation of the Irish Sea, to determine the food of any particular species of fish during the early part of its life history.

Other observers working in other areas, notably Dr. Marie Lebour at Plymouth, have added very much to our knowledge of the early food of young fishes. Dr. Lebour's reports, published in the Journal of the Marine Biological Association, Vols. XI and XII, deal with a very large number of larval and post-larval stages of the more important food fishes caught in the tow-nets and young fish-trawl in Plymouth Sound and beyond.

The present report gives an account of the food contained in the stomachs of young plaice (Pleuronectes platessa, Linn.) from a few days after hatching to about five months old. The samples examined in April and May were taken from the spawning pond at Port Erin, Isle of Man, where they had hatched from the pelagic eggs spawned by the adult plaice early in 1921. The later stages examined during May to August represented young plaice hatched in the open sea about the same time as those in the pond, and which had made their way close inshore.

The closure response to low external salinity of three species of intertidal and estuarine barnacle (Balanus balanoides, B. crenatus and Elminius modestus) when exposed to various rates of salinity change were investigated. Comparisons were made between the responses of specimens collected from estuarine and coastal sites. In addition the responses of the brackish water barnacle Balanus improvisus were measured.

We report here an investigation on intertidal mangrove pneumatophores, examining the relationships between arthropod abundance (for ten taxa, mostly belonging to the meiofaunal size-class), algal biomass and sediment cover. There was a strong correlation between the mass of sediment and the mass of macroalgae, supporting the assumption that pneumatophore sediment cover depends on algal growth. These two components of pneumatophore cover were negatively related to elevation, an effect probably relating to desiccation-limited algal growth towards the pneumatophore tips. Total arthropod abundance and that of some taxa (particularly, Uropodidae (Acari), Metidae (Crustacea), Ceratopogonidae (Insecta) and Empidoidea (Insecta)), was negatively correlated with elevation and positively correlated with sediment and algal cover, suggesting a good relationship between abundance and habitat availability. Other arthropod taxa (particularly, Halacaridae (Acari)) however, showed the opposite pattern of relationships. When the pneumatophore cover was physically removed, in an experiment to assess assemblage recovery rates, some arthropod taxa (Halacaridae (Acari), Harpacticoidea (Crustacea) and Ceratopogonidae (Insecta)) had completely recovered by 25 weeks, while others (Tanaididae (Crustacea) and Empidoidea (Insecta)) only partially recovered.