The harbour porpoise (Phocoena phocoena) is the most frequently sighted cetacean in the UK, yet there is a conservation need to assess both abundance and distribution for this species. During May–August, 2002–2004 a boat-based visual survey, employing effort-related line transect methodology was conducted for specified areas of the west coast of the UK. Estimates of relative abundance were made, with full DISTANCE analysis being carried out during 2004 for each of the areas surveyed. A generalized additive model (GAM) was constructed examining porpoise presence in relation to month, position (latitude and longitude), depth and sea surface temperature for all years and for each year of the study individually. Harbour porpoise density showed a significant decrease in the South West, with an increase for West Scotland over the study period, whilst the highest numbers for both Northern Ireland and the Firth of Clyde were recorded in 2003. The porpoise population in the south-west of England was estimated at 163 (67LCI–400UCI) individuals during the months of May and June, 387 (170LCI–877UCI) individuals were present off Northern Ireland during July, 1645 (823LCI–3289UCI) individuals around the Firth of Clyde in July and 3105 (2032LCI–4745UCI) off West Scotland during August and September. The GAM demonstrated that porpoise presence increased around the 100 m depth contour. Whilst further research is required in each of the areas throughout the year, this study provides important information on the distribution and habitat use of the harbour porpoise within UK waters.

The loss of external tags is one of the biggest problems in mark-recapture research. An evaluation of tag loss is therefore required to improve tagging methodology, select appropriate tag types, and accurately estimate population status and dynamics. We estimated tag loss probability of double-tagged green turtles (Chelonia mydas) nesting at Redang Island, Malaysia (05°49′ N 103°00′ E), from 1993–2014. For both titanium and Inconel tags, we found a tag loss pattern with a high initial tag loss rate that decreased to an asymptote near a constant value above zero. The initial tag loss probability for titanium tags was higher than for Inconel tags, and titanium tags were lost earlier than Inconel tags in more individuals when both types of tags were attached. In addition, comparison of the tag loss probability of Inconel tags attached during the period when tagging staff changed every year to that when senior tagging staff were not changed, indicated that lack of consistency in tagging staff affected the application of at least one of two Inconel tags. Estimated tag loss probability was incorporated into a recapture model, and annual survival probability was estimated to be 0.893 (95% confidence interval: 0.857–0.921).

Octopus mimus is the main octopus targeted by the small-scale fishery in the Eastern Pacific. Commercial catches of octopus from the Reserva de Producción Faunística Marino-Costera Puntilla de Santa Elena (REMACOPSE) Marine Protected Area in Ecuador were sampled from July to December 2013 in order to describe the reproduction and population structure of this octopus. The 4171 sampled octopuses ranged from 56 to 250 mm in mantle length (ML) and 45 to 3178 g in body weight (BW). Mean octopus weight did not change monthly. Males were mostly mature while the majority of females were immature. Presence of some mature and a few spent females in all months sampled suggests that the population shows an extended spawning period. No spawning peak could be properly defined. Sex ratios did not significantly shift from the expected 1:1 in most samples. Females mature at a larger size (1234 g, BW; 165 mm, ML) than males (487 g BW; 114 mm ML). We recommend considering a minimum legal size of 1200 g BW. A year-long sampling programme for O. mimus should also be completed in order to detect any spawning peak.

This study investigated the emission of subaquatic noise from recreational tourism motorboats, schooners and a sea-bottom mounted water pump. Analyses demonstrated alterations in several whistle (IF: t = 2.42, P = 0.015; FF: t = −2.22, P = 0.025) and calls patterns (MIF: t = −3.13, P = 0.001; MAF: t = −3.49, P = 0.0005; FD: t = −2.21, P = 0.027; D: t = 2.89, P = 0.004), caused primarily by motorboats. Duration of clicks was also modified (D: t = −3.85, P = 0.0001), mainly by the water pump. The frequency range of all noises (0.43–35.8 kHz) overlaps that used by dolphins (1–48 kHz), causing sound emissions changes, with a considerable increase in number of whistles and a reduction in clicks trains. These changes may be a strategy developed by these dolphins to overcome the noise band. Mitigation measures, such as boating regulations and environmental education for the local community, boaters and tourists are needed to conserve the species. The Guiana dolphin population is apparently already suffering, evidenced by diminished residence time and reduced number of individuals entering the inlet during the presence of pleasure craft.

This study intends to reliably estimate the general status of the benthic and the epiphytic foraminifera community related to each studied seagrass ecosystem (Posidonia oceanica, Cymodocea nodosa and Halophila stipulacea) distributed in different shallow sites in the coastal archipelago of Kerkennah (Gulf of Gabes, Tunisia) during winter. We were able to first sort and subsequently identify some characteristics conditioning their behaviour. Twenty-four species of foraminifera were encountered. Among them, three epiphytic species identified on these seagrass leaves had a much lower abundance than those in the sediment. We were interested in highlighting the foraminiferal community related to Halophila stipulacea, since this seagrass species is newly introduced into the Mediterranean sea. Thanks to the statistical study, we were able to identify the favourable habitat for epiphytic and benthic foraminifera among the three seagrass ecosystems. A correlation between the identified foraminifera species and some environmental parameters was addressed using a variety of software.

We investigated the influence of the Changjiang diluted waters (CDW) on the distribution of nanophytoplankton (<20 µm) abundance and biomass in the northern East China Sea (ECS) during two research cruises conducted in the summers of 2010 and 2012, using flow cytometry. Each group of nanophytoplankton responded differently to the distribution of the CDW. In the surface layer, Synechococcus 1 which has low orange fluorescence, a major component of summer nanophytoplankton, were more abundant under the large extension of CDW to the northern ECS in August 2010, whereas the abundance of other groups including Synechococcus 2 which has high orange fluorescence, and pico- and nano-eukaryotes (0.2–2 and 2–20 µm in diameter, respectively), dramatically increased under the small extension of CDW in August 2012. The subsurface chl-a maximum layer became more developed under the small extension of CDW, and was dominated by nano-eukaryotes. During two study periods, environmental characteristics in the CDW also showed annual variations, with higher seawater temperature, lower salinity, and higher nitrate concentration in the surface layer of the CDW in August 2010. The summer distributions of Synechococcus and nano-eukaryotes were likely to be limited by low salinity and high temperature, respectively, indicating that phytoplankton distribution could be influenced not only by the extension level of the CDW but also by the change of the environmental characters of the CDW.

Chub mackerel, Scomber colias, is widely distributed in the warm waters of the Atlantic Ocean including the Mediterranean and Adriatic Seas. This medium-sized pelagic fish species occurs in deeper waters during the colder part of the year and schools are found in coastal waters during the warmer parts of the year, where they spawn and feed. Atlantic chub mackerel is one of the most important commercial fish throughout its habitat and as a consequence of its wide distribution and broad commercial exploitation, biological information on the growth and mortality is required for stock assessment and management. Despite the abundance and economic importance of S. colias in the Adriatic Sea, knowledge about its biology and population dynamics is still limited. Studies of the age, growth, mortality and exploitation rates of S. colias have not been undertaken previously in the Adriatic Sea. Therefore, the exploitation status of this species' stock in the Adriatic Sea is unknown. The purpose of this study was to provide information on the age, growth and length–weight relationship as well as estimates of mortality and exploitation rate in order to define the present state of the population in the Adriatic Sea.

Four microsatellite loci in the razor clam Solen marginatus are described. Loci were isolated from the sequences of intersimple sequence repeat (ISSR) markers and an enriched library. Detailed analysis of these sequences led to the design of eight primer pairs. Allelic variation was assessed in 20 individuals from Redondela, Spain. The genetic variation observed in the markers presented here will be useful for future studies on the population structure of Solen marginatus in the wild and for aquaculture of this species.

A behavioural assay based on a ‘homosexual’ response in males has revealed that female Harmothoe imbricata release a substance that induces pair formation. Extracts from unfertilized spawned oocytes (diameter approximately 120 μm), but not sub-mature oocytes (90 μm diameter) removed directly from the coelomic cavity, have significant pair formation-inducing activity in comparison to the control. Preliminary results indicate that the substance is stable under standard purification techniques and larger than 10 kDa, as well as being heat and trypsin insensitive.

Surface fluorescence measurements in June in the Bay of Biscay showed little correlation with chlorophyll a measurements due to the presence of a marked diurnal fluorescence rhythm although satisfactory correlations have been obtained at other times of year in the same region (see Fig. 10 of Pingree et al. 1982). By contrast, the beam attenuation coefficient values showed a good correlation with the chlorophyll a measurements and can be used to map the sea surface distribution of chlorophyll a when the diurnal rhythm is present, particularly when the phytoplankton is dominated by a single species. This conclusion may be of considerable practical significance when contemplating synoptic surveys in such situations. As Prezlin & Ley (1980) have observed there is growing awareness that fluorescence per unit chlorophyll a is not a constant that can be used reliably in mixed phytoplankton biomass estimates based on in vivo chlorophyll a fluorescence, and the problem is clearly compounded if some species exhibit a marked diurnal fluorescence rhythm. Furthermore, the present observations support the caveats of Falkowski & Kiefer (1985), that in situ moored fluorometers, the use of air-borne laser-induced fluorescence, or satellite-received passive, solar-induced fluorescence, only measure fluorescence, not chlorophyll per se.

The fluorescence response near the shelf-break over a 24 h period following a drogued dahn buoy showed a variation of about a factor of 5 between the day and night fluorescence levels. Beam attenuation coefficient measurements and Coulter Counter analyses showed that these results could not be attributed to the migration of the phytoplankton.

Potential fecundity, number of oocytes in the mature ovary, and realized fecundity, number of eggs extruded and attached to the pleopods of female Nephrops, caught at the start of the incubation period were estimated for females from the eastern and western Irish Sea grounds. Potential fecundity was found to differ significantly between eastern and western Irish Sea stocks, while realized fecundity did not differ between areas. Inter-year comparison of realized fecundity, and effective fecundity (the number of mature eggs on the pleopods of females at the end of the incubation period) in the western Irish Sea stocks revealed no significant variation over time. Egg loss during the transition from oocytes in the ovary to mature eggs increased with female size, ranging from 40% at 25 mm carapace length (CL) to 65% at 40 mm CL. No relationship was found between egg diameter or volume and female size.

Presently, there is no information about the functionality of the immune system in the franciscana dolphin (Pontoporia blainvillei), a small dolphin from southern Brazil. As in the case of the franciscana, the population of southern right whale (Eubalaena australis) which inhabits Brazilian waters has not yet been surveyed in what concerns MHC expression. For the first time it was possible to observe the DQB gene expression in skin of these two species of cetacean using RT-PCR. Skin pieces of the animals were collected to RNA extraction. The fragment corresponding to DQB exon 2 was amplified, cloned and sequenced. A total of five alleles were found, one to franciscana and four to southern right whale. The observed dN/dS ratio of 2.77 (P = 0.03) suggests that this gene is under balancing selection pressure (positive Darwinian selection). The sequences indicate that, in both species analysed, the DQB gene is functional.

The pilchard, Clupea pilchardus Walbaum, is known to spawn in summer in the southern North Sea in the neighbourhood of the Sandettié Bank (Buchanan-Wollaston, 1911; Furnestin, 1939a, 1945) and in the eastern English Channel off Beachy Head (Furnestin, 1939a, 1945). Furnestin (1939b, 1945) concludes from these records that spawning is in all probability continuous throughout the Channel from the southern North Sea to the Celtic Sea. There appear, however, to be no previous references to pilchard spawning in the central part of the English Channel. The following records from the area are of interest therefore, and provide confirmation of Furnestin’s conclusion.

Despite the current global decline in seagrass, sessile epifaunal invertebrates inhabiting seagrass ecosystems, particularly sponges and ascidians, have been poorly studied due to their taxonomic complexity. Understanding patterns of distribution of sessile epifaunal communities in seagrass meadows is an important precursor to determining the processes driving their distribution and species interactions. This study (1) identified the sponge and ascidian assemblage associated with Posidonia australis meadows and (2) determined distributional patterns of these invertebrates at a hierarchy of spatial scales in Jervis Bay, Australia. We used a fully nested design with transects distributed in the seagrass (10s m apart), two sites (100s m apart), and six locations (km apart). Within these transects, we recorded the abundance, volume, diversity and substratum used for attachment by sponges and ascidians. We encountered 20 sponge species and eight ascidian species; they were sporadically distributed in the seagrass meadows with high variability among the transects, sites and locations. A few sponge and ascidian species dominated the assemblage and were widespread across the largest spatial scale sampled. The remaining species were mostly rare and sparsely distributed. Sponges attached to a variety of substrata but most notably shells, P. australis and polychaete tubes. No obligate seagrass species were recorded although three species predominantly used P. australis as a substratum. These sponge species relying heavily on seagrass for their attachment are likely prone to disturbances impacting their host habitat. Examining the response of sessile epifauna to the degradation of their seagrass habitat remains a key challenge for the future.

Abundance and structure of phytoplankton and zooplankton, along with their relationship to hydrographic conditions were determined in the highly stratified estuary of the karstic Ombla River, south-eastern Adriatic. Sampling was carried out during 17 cruises within a one year period. River discharge lowered surface salinity and enriched the estuary with NO3 and SiO4. Nutrient ratios suggested that PO4 was the most likely limiting nutrient for phytoplankton growth in the estuary. Diatoms were present in low numbers and dominated the winter–early spring period. Dinoflagellates dominated from the end of May to August. Phytoplankton and zooplankton were composed mostly of marine species and their abundance decreased in seaward direction. Planktonic populations are controlled by the river runoff, temperature, salinity, nutrient concentrations and grazing. The results were consistent with the hypothesis that no algal blooms have been recorded due to short renewal time.

The Magharees fishery (Brandon and Tralee Bays in south-west Ireland) is 495 km2 in extent, the majority of this area ≤20 m in depth. Since 1981 it has been occupied by a directed spider crab fishery yielding in some years all of the national catch of Maja brachydactyla. Maximum recorded landings were 336 t in 1999 and effort has numbered up to 10,000 pots annually. Increasing fishing capacity and declining opportunities have accentuated fishing effort on spider crab. This paper describes a catch census undertaken in the fishing season of March to August inclusive, 2000–2007 and a mark–recapture experiment, 2005–2007. A method of ageing the adult moult by attributing a chronology to the rate of erosion of the claw on the dactyl is introduced. Males migrated longer distances, moved into the fishery on a wider trajectory and demonstrated greater wear on the claw than females. Recapture rate of males was twice that of females. The conduct of the fishery changed in its 26 years in existence. Landings became more concentrated in the earlier months of the year and the recent summer fishery was characterized by fewer male captures. Larger males were quickly removed and none >140 mm carapace length survived in the fishery longer than one year.

Many observers have noted that the sea is full of loud sounds, both ongoing and episodic. Among the many sources of natural ambient noise are wave action, physical processes such as undersea earthquakes, and biological activities of shrimps, fish, dolphins and whales. Despite interest by acoustics experts, sound production by cephalopods has been reported only twice, both involving squid. The ‘faint poppings’ produced were thought to result from fluttering of the thin external lips of the squid's funnel while water is being expelled through it. Otherwise, no information is available on cephalopod sounds. Here we present a noise produced by a stressed common octopus. The event was filmed and recorded in the wild. The hypothesis we offer to explain how this sound was produced is cavitation, which has been documented in several biological systems. In our case, the water expelled through the funnel may have created a jet with a velocity so high that the turbulent pressure dropped locally below the vapour pressure of the water. Seawater contains gas microbubbles, which will grow in size when they are entrained in the region of low pressure. Subsequently, the bubbles collapse violently when pressure rises again. The sound produced by the octopus is like a gunshot, and distinct lights observed at the same time contradict the existence of a simple pressure wave and point to the possible presence of gas-bubbles, which would change the light intensity by reflection and refraction of the sunlight. This behaviour seems to be a defensive strategy to escape from vibration-sensitive predators.

Population dynamics of the planktonic diatom Pseudo-nitzschia pungens was investigated at the Zhelin Bay, China, between May 2000 and December 2004. Monthly or seasonal plankton samples were collected from nine stations along the inner to outer bay gradient. Among the 1045 samples collected, P. pungens on average accounted for 2.9% of the total phytoplankton cells, with densities ranging from 0 to 50.94 × 104 cells l−1 and a grand mean of 1.43 × 104 cells l−1. Two hundred and fourteen samples (20.5%) had densities of P. pungens above 104 cells l−1 and 40 samples (3.8%) had densities that were above 105 cells l−1. Results of the grey incidence–regression analysis show that water temperature, zooplankton and salinity were the most important among the 13 environmental factors influencing population density of P. pungens. Water temperature has a highly significant linear relationship with the population density, with 23.8°C or higher being an essential condition for the algal bloom. Grazing by zooplankton was probably the most important factor controlling the algal bloom. With continued decreasing of richness and organism size of the zooplankton community at the Zhelin Bay, P. pungens blooms may become more frequent. The bay has a large-scale mariculture operation, therefore it is important to carefully examine and monitor the potential impacts of toxin-producing P. pungens on human health as well as ecosystem health of the bay.

In the current study, commercially valuable penaeid shrimp, Melicertus kerathurus, were attained approximately monthly in the Izmir Bay, southern Aegean Sea from May 2004 to April 2005. For each specimen, we measured body length, body weight and ovarian weight, and calculated gonadosomatic indices (GSI). GSI values results pointed out that the GSI in Melicertus kerathurus increased during vitellogenesis (2.03 ± 0.24%) but sharply decreased after spawning (0.53 ± 0.35%) to reach levels similar to those in immature females. We also examined oogenesis in Melicertus kerathurus by histological observation of the ovary to determine reproductive cycle for future domestication. The observation on the gonads leads us to conclude that there are five stages of development for the females: (I) previtellogenic; (II) early vitellogenic; (III) late vitellogenic; (IV) mature; and (V) spent. Histological characteristics showed that the best time to capture adult shrimps for breeding purposes was between the months of April and June. The numbers of each oocyte type that were present were also counted, measured, and used to evaluate the following traits: total oocyte number; mean oocytes diameter; and maximum oocyte diameter. Oocyte diameter was significantly different at all stages (P < 0.05) and the largest diameter was observed as 163.92 ± 4.51µm at stage IV.

Several types of relationships link organisms to each other, including competition, predation and various types of associations. This paper presents the first case of association/interaction between dugongs, Dugong dugon, the only strictly marine herbivorous mammal, and three species of tropical dolphins in and around the lagoon of Mayotte (45°10'E 12°50'S), in the western tropical Indian ocean. Data were collected opportunistically from 1999 to 2005 in the surrounding waters of Mayotte from boat (N=2 observations) and ULM (ultra-light motorized vessel, N=2). The dolphin species involved in associations with dugongs were Indo-Pacific bottlenose dolphin, Tursips aduncus, Indo-Pacific humpback dolphin, Sousa chinensis, and spinner dolphin, Stenella longirostris. In one case, dugongs were associated with both bottlenose and humpback dolphins. Associations were observed in the protected waters of the lagoon and outside, along the external slope of the barrier reef. Group size, activity and group structure of each species were recorded. Behavioural observations suggest that dugongs and dolphins were engaged in similar activities, such as travelling, on several occasions and were clearly associated when group formation was tight. If dolphins and dugongs may not associate for feeding purposes, then these interactions may occur: (1) for predation avoidance toward sharks; or (2) without any ecological reasons due to dolphin and dugong habitat overlap around the island.