Search

There is an important small-scale fishery using mechanized dredges and targeting clams (mainly wedge clam Donax trunculus and striped venus clam Chamelea gallina) along the Catalan coast (NW Mediterranean Sea). This study evaluated for the first time the discards and impact of mechanized clam dredging on the Catalan coast. To this end, three surveys were performed on board standard clam vessels (September and November 2016 and January 2017). Surveys were conducted in the three main clam fishing areas (Rosas Bay, South Barcelona and Ebro Delta). The composition of discards and the impact caused to discarded species was assessed using a three-level scale (undamaged; minor or partial damage; and lethal damage). Our study revealed that a large proportion of the catch (between 67–82% weight) is discarded. Even though about 63% of the discarded species were undamaged, 11% showed minor or partial damage and 26% lethal damage. Infaunal and epifaunal species with soft-body or fragile shells were the most impacted by the fishing activity (e.g. the sea urchin Echinocardium mediterraneum (~89%) and the bivalve Ensis minor (~74%)). Our results showed different levels of impact by target species and fishing area.

Metabolic activities such as breathing and digestion, resulting from natural functions of the body through oxidation, lead to the formation of free radicals that cause cancer, premature cardiac aging and some chronic diseases. Antioxidants are substances that remove free radicals and prevent cell damage. Seafood significantly contributes to the elimination of free radicals, especially owing to its high quality nutrient content. In this context, the objective of the study was to determine the radical antioxidant capacity and the total amount of carotenes in razor clams. The IC50 (mg g−1) value of the DPPH radical sweeping effect varied over the months (p < 0.05), showing the highest value in June, gradually decreasing from September and reaching the lowest level in February. The total amount of carotenoids also varied, with the highest value in September (p < 0.05). The total amount of chlorophyll ranged from 6.15 μg g−1 in August to 66.71 μg g−1 in December.

Invasions of marine species are changing coastal food webs worldwide, impacting on trophic interactions between native species (e.g. predator-prey relationships). Here, the impact of 3 macrozoobenthic invasive species on food web structure and functioning at Balgzand (western Wadden Sea) is quantified by using ecological network analysis (ENA). The bivalves Ensis leei and Magallana gigas were observed for the first time in 1984 and 2001, respectively, and the polychaete Marenzelleria viridis appeared in 1989. Although E. leei and M. viridis reached similar peak biomasses in the 2000s (ca. 1700 and 2000 mg C m-2, respectively), the bivalve consumption was higher (>45% of total consumption) than that of the polychaete (M. gigas remained relatively low. E. leei occupied an ecological niche that was relatively unoccupied, which led to competitive advantage with respect to other suspension feeders. Increasing biomass of E. leei coincided with a 70% increase of trophic carbon transfer from primary to secondary producers and an 80% increase from secondary producers to detritus. Carbon flows from secondary producers to higher trophic levels were reduced by more than 60%. These shifts in trophic transfer were stronger than those observed during the invasion of M. gigas in the NE Wadden Sea. At Balgzand, biomass of M. gigas and M. viridis rapidly declined to low values in the 2010s, implying a temporally limited impact. In the 2010s, E. leei was still responsible for 30% of the total consumption in the 2010s, indicating a longer-term impact.

Chitin can be found in animal source especially arthropods such as crustacean, mollusk and insect, as well as in plant source such as fungi. Chitosan is obtained from chitin after the acetyl group is removed from chitin structure through deacetylation step and has wide application in various fields (food, cosmetics and pharmaceutical). In this study, chitosan was extracted from razor clam shells, where the extraction conditions were optimized. Two- factors of randomized D-optimal design was used to determine the optimum condition for the extraction of chitosan from razor clam (Ensis arcuatus) by using response surface methodology (RSM). The chemical extraction was optimized using five levels with two factors which were the deacetylation time (2,4,6,8,10 hrs) and deacetylation temperature (50, 60, 70, 80 and 90ºC). A randomized design suggested by Design Expert software was implemented with four responses evaluated: yield (%); degree of deacetylation (%); molecular weight (kDA); and ash content (%). Time (h) and temperature (ºC) of the deacetylation significantly (p

International audience; Ashdown Brickworks, near Bexhill, East Sussex, has produced a large number of vertebrate fossils from the Wadhurst Clay Formation, part of the Wealden Supergroup (Hastings Group; Valanginian; Lower Cretaceous). Here we describe the microvertebrate fauna of the ‘conglomerate bed’, representing a rich sample of taxa. While most of the recovered teeth and bones are abraded, some heavily, most can be identified to species level. The taxa include four species of hybodont sharks (Egertonodus basanus, Planohybodus ensis, Polyacrodus parvidens, P. brevicostatus), three taxa of bony fishes (an unidentified Lepidotes-like semionotiform, the pycnodontiform Ocloedus, and an albuliform), three taxa of crocodyliforms (the goniopholid Hulkepholis, a bernissartiid, and the atoposaurid Theriosuchus), and the theropod dinosaurs Baryonyx and an allosauroid. Sediments of the Wadhurst Clay Formation as a whole indicate freshwater to very slightly brackish-water environments of deposition, and the mainly aquatic time-averaged mixture of fishes and tetrapods recovered from the ‘conglomerate bed’, together with isolated terrestrial species, confirms this interpretation.

Instructive taphonomic principles are demonstrated by the skeletons of dead invertebrates. Bivalves have resistant skeletons and are common fossils. The thin-valved razor shells, Ensis spp., have a good fossil record despite being fragile. This may be due, in part, to rapid post-mortem encrustation of valves by mineralized invertebrates. Two Recent specimens of Ensis siliqua (Linnaeus), encrusted post-mortem, are described from the Irish Sea coast of Southport, Merseyside. An articulated shell with an intact ligament is encrusted posteriorly on all surfaces by the balanid Balanus crenatus Brugiere. Barnacles inside the shell are smaller than those externally, yet may represent the same spatfall; those inside were constrained by growing in an enclosed space. To a palaeontologist, a mollusc valve encrusted inside and out by cementing organisms would be interpreted as having had a long residence time on the seafloor. This specimen demonstrates the disjunction between loss of soft tissues (days?) and loss of the ligament (weeks, perhaps months), between which encrusters may settle inside the shell, early in its post-mortem history. Similar patterns of encrustation by balanids are now known two species of Ensis and the cockle Cerastoderma edule (Linnaeus). A fragment of a single valve is encrusted only on the internal surface by serpulids and bryozoans. This is balanulith-like, but is only encrusted on the inner surface and not by balanids. Ensis valves can be reinforced by a range of calcareous encrusting organisms; an Ensis fragment encrusted both inside and out by serpulids would be worthy of being named a serpulith.

Genus Ensis Schumacher, 1817 Ensis Schumacher, 1817: 143 Ensatella Swainson, 1840: 365, objective synonym, type species: Ensatella europea Swainson, 1840 (= Ensis ensis, (Linnaeus, 1758)). Hypogaea Poli, 1791: 29 (partim) (see remarks). Type species: Ensis magnus Schumacher, 1817: 143, pl. 14, fig. 1 [= Solen ensis Linnaeus, 1758], by monotypy. Diagnosis: Shell length up to 250 mm, elongate, equivalve, with sharp and smooth edges; umbo anterior, terminal; hinge plate with two cardinal teeth in the right valve, anterior one vertical to hinge plate (rvt) aand posterior one horizontally oriented (rht), elongate; four cardinal teeth in the left valve, two anterior ones, small, vertically placed (lvt1, lvt2) and two somewhat larger and horizontally oriented (lht1, lht2). Remarks: The genus Ensis currently includes 14 species (Coan & Valentich-Scott 2012; Cosel 2009; Huber 2010). Ensatella Swainson, 1840 and Hypogea Poli, 1791, are synonyms (Coan & Valentich-Scott 2012). The former genus — type species E. europea Swainson, 1840, = Ensis ensis (Linnaeus, 1758) —was introduced to distinguish more curved species from the genus Solen. Hypogea included species belonging to Solenidae, Pharidae, Pholadidae and Tellinidae. According to the genetic study by Vierna Fernández (2014), eight valid species of Ensis are recognized from the Atlantic Ocean. Distribution: Europe, Atlantic coast of America, western Africa, Pacific coast of America from USA to Chile (Coan & Valentich-Scott 2012; Cosel 1993, 2009; Guerra et al. 2011; Huber 2010)., Published as part of Giacomino, Sebastián & Signorelli, Javier H., 2021, Systematic redescription of Solen (Ensisolen) tehuelchus and Ensis macha (Bivalvia: Solenoidea) from Argentina, southwestern Atlantic Ocean, pp. 541-558 in Zootaxa 4964 (3) on pages 547-548, DOI: 10.11646/zootaxa.4964.3.6, http://zenodo.org/record/4742425, {"references":["Schumacher, C. F. (1817) Essai d'un nouveau systeme des habitations des vers testaces: avec XXII planches. L'Imprimerie de Ma. le directeur Schultz, Copenhagen, 348 pp. https: // doi. org / 10.5962 / bhl. title. 35863","Swainson, W. (1840) Treatise on malacology, or shells and shell fish. Longman, Orme, Brown & Longmans, London, i - viii + 419 pp.","Linnaeus, C. A. (1758) Caroli Linnaei, Equitis de Stella Polari, Archiatri Regii, Med. and Botan. Profess. Upsal.; Acad. Upsal. Holmens. Petropol. Berol. Imper. Lond. Monspel. Tolos. Florent. Soc. Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, Locis. Editio Decima, reformata, 2 vols. paged continuously. Impensis Laurentii Salvii, Holmiae [Lipsiae, Stockholm], 824 pp. https: // doi. org / 10.5962 / bhl. title. 542","Poli, G. S. (1791 - 1795) Testacea Utriusque Siciliae Eorumque Historia et Anatome. Tomus primus & Tomus secundus. Bodoni ed., Parma, 257 pp. https: // doi. org / 10.5962 / bhl. title. 79042","Coan, E. V. & Valentich-Scott, P. (2012) Bivalve seashells of tropical west America (Part 1 & 2). Santa Barbara, CA, Santa Barbara Museum of Natural History, 1258 pp.","Cosel, R. v. (2009) The razor shells of the eastern Atlantic, part 2. Pharidae II: the genus Ensis Schumacher, 1817 (Bivalvia, Solenoidea). Basteria, 73 (1), 9 - 56.","Huber, M. (2010) Compendium of bivalves. A full-color guide to 3,300 of the World's Marine Bivalves. A status on Bivalvia after 250 years of research. ConchBooks, Hackenheim, 901 pp.","Vierna Fernandez, J. (2014) Genetic analyses in various razor shell species of family Pharidae, with a focus on Atlantic Ensis. Ph D dissertation. Universidad de La Coruna, 231 pp.","Cosel, R. v. (1993) The razor shells of the eastern Atlantic. Part 1: Solenidae and Pharidae I (Bivalvia: Solenacea). Archiv fur Molluskenkunde, 122, 207 - 321. https: // doi. org / 10.1127 / arch. moll / 122 / 1993 / 207","Guerra, A., Lodeiros, C., Gaspar, M. & Da Costa, F. (2011) Razor clams: Biology, aquaculture and fisheries. Conselleia do Mar, Xunta de Galicia, 428 pp."]}

[Objective]: As shellfish preservation is still nowadays a challenge for the food industry, in this paper, the effectiveness of hyperbaric storage in preserving Atlantic razor clams (Ensis directus) was evaluated both at low (HS-LT) and at room temperature (HS-RT)., [Methods]: The study was carried out in two phases. In the first phase, razor clams were stored at different pressure levels, both at 5 °C and 20 °C, for 7 days to identify the most efficient storage pressure at both temperatures. Then, in the second phase of the study, HS-LT and HS-RT experiments were performed at these conditions for 14 days to compare the effectiveness of both methods., [Results]: Microbial analysis after storage showed that, at 5 °C, a minimum pressure of 50 MPa was needed to prevent microbial growth in the samples, while 75 MPa were required at 20 °C. In the second phase of the study, results revealed that both HS-LT (50 MPa/5 °C) and HS-RT (75 MPa/20 °C) extended the microbial shelf-life of the razor clams to, at least, twice that achieved in conventional refrigeration, but quality decline was larger in the samples stored at 75 MPa and 20 °C., [Conclusions]: HS-LT resulted more effective than HS-RT for the preservation of razor clams., This work was partially supported by the State Programme for Knowledge Generation and Scientific and Technologic Strengthening of the R&D&i system of the Spanish Ministry of Science, Innovation, and Universities through the MALTA CONSOLIDER TEAM Research Network (RED2018-102612-T).

Coastal bivalve populations are characterized by large temporal fluctuations, driven by recruitment success dependent on environmental conditions. The present study evaluated the relationship of rainfall, chlorophyll-α, sea surface temperature (SST) and wind, with the biomass of four commercial bivalve species (Spisula solida, Donax trunculus, Chamelea gallina and Ensis siliqua) that occur both along the Barlavento (western region), and the Sotavento (eastern region), along the South coast of Portugal, between 1999 and 2011. Multiple regression models were used to test two hypotheses: a) the association between environmental conditions three months prior to the spawning period and the biomass in the following year (response variable) and b) the association between environmental conditions during the spawning season plus one month and the biomass in the following year. Wind was not included in the model to test a). The environmental variables considered were not important for E. siliqua. In the period prior to spawning, temperature was significant for S. solida (both study areas), rain for D. trunculus and C. gallina (western area) and chlorophyll-α for C. gallina (western area). All the correlations were positive. During the spawning period, rain was significant for all three species but with different trends. The correlation with rain in months early in the spawning season was positive for S. solida (both areas) and D. trunculus (western area). The correlation with the rain in months towards the end of the spawning period was negative for D. trunculus, and C. gallina (western area). Chlorophyll-α in months at later stages of spawning was significant and positive for D. trunculus (both areas) and C. gallina (western area). The wind, expressed as an index developed to indicate the overall occurrence of winds blowing parallel to the coast (assumes to favour the retention of larvae in appropriate environments), was negatively correlated with biomass for mid to late spawning season for S. solida (eastern area) and D. trunculus (western area). For C. gallina there was a positive correlation with wind early in the spawning season. The SST was not an important variable during the spawning period with the exception of D. trunculus where the temperature at mid spawning season was significant with a negative correlation in the western coast and positive in the eastern coast. This study highlighted the annual spatial distribution of four commercially important bivalves and how environmental factors are likely to play an important role on both biomass and location of the fishing beds. Monitoring of the environmental variables could provide information to predict biomasses of bivalve species, an important tool for its management, as well as predict trends and plan strategies in response to global environmental changes. info:eu-repo/semantics/publishedVersion

The Sand Motor is a very large (20 million m3) nourishment constructed along the coast in The Netherlands. The huge volume of sand is redistributed along the coast by natural forces stemming from tidal currents and waves. For environmental evaluation of this large construction, the benthic subtidal fauna has been sampled prior to the construction of the Sand Motor, and at 1, 2, 4, and 6 years after construction. Although some significant differences between years were detected, overall the total density, total biomass and average number of species per sample were surprisingly constant over this time period. However, large differences were found in the species accumulation curves over samples, and in the rank-biomass and rank-abundance plots. These were related to two important trends in the communities. First, the invasive mollusk Ensis leei, the biomass dominant in the years before construction of the Sand Motor, dwindled in importance in later years. Recruitment of the species failed, but it is unclear whether, and how, this is related to the construction of the Sand Motor. Second, the correlation structure between depth, grain size, bottom shear stress due to waves and currents, which is very tight along a linear coast, was disrupted by the Sand Motor. The community composition was shown to depend strongly on these physical factors. The nature of the dependencies did not change, but the range of different combinations of factors after construction of the Sand Motor was widely larger than before. Although samples had similar number of species per sample before and after construction, the average difference between samples after construction was much larger than before. The Sand Motor is a very large construction, leading to loss of a substantial area (order 100 ha) of submarine area, which recovers at a long time scale. Total disturbance of benthos by burial, expressed as area∗(time before full recovery) was shown to be similar for the Sand Motor and for other coastal nourishment schemes when expressed per unit volume of sediment applied. However, in contrast to beach and shoreface nourishments, the Sand Motor led to a habitat diversification in the coastal zone.

One hundred and ninety-two samples from six species of mollusks classified into the following taxonomic classes: Gastropoda (Patella aspera, Patella candei crenata), Bivalvia (Mytilus galloprovincialis, Ensis directus), and Cephalopoda (Abraliposis morisii, Pyroteuthis margatifera) were investigated. Samples were collected in the Atlantic Ocean (Canary Islands and Galicia). The concentrations of Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Sr, V, and Zn were determined by ICP-OES. Statistical analysis verified that the classes of benthic organisms had the highest concentration of elements. However, the Cephalopoda class had the highest Cd (1.685 ± 0.929 mg/kg) and Pb (0.826 ± 1.104 mg/kg) content. On the other hand, the values obtained in this study were compared with studies conducted in other parts of the world to verify the environmental state of the Atlantic Ocean using the organisms studied as bioindicators.

Length–weight relationships of bivalve species collected during razor clam (Ensis minor) surveys along Italian coastal waters (Northern Adriatic and Tyrrhenian Sea) in the 3-year period 2016–2018 are reported. A total of 13,588 individuals, belonging to 12 bivalve species and 20 populations between the Adriatic and Tyrrhenian Seas, were sampled for this study. Analyzing growth parameters for each population, we found 11 allometries and nine isometries. About half of the species investigated showed different growth characteristics between the two areas.

We observe that the Atlantic razor clam (Ensis directus) burrows out of sand rapidly by simply extending and contracting its muscular foot. This is notably different from its well-known downward burrowing strategy or the dual-anchor mechanism, where closing/opening of the shell and dilation of the foot are also involved. Inspired by this burrowing-out strategy, we design a simple self-burrowing-out robot (SBOR) consisting of a single segment of fiber-reinforced silicone tube actuator and an external control board. The reinforcing fibers limit the motion of the actuator to axial extension/contraction under inflation/deflation. For an actuator that is vertically buried in the sand, cyclic inflation and deflation naturally drives it out of the sand, mimicking the motion of a razor clam. We characterize the burrowing-out behavior of the actuator by varying the actuation period and the relative density (packing) of the sand. Each burrowing cycle features an initial upward advancement during inflation, followed by a downward slip during deflation, resulting in a net upward stride. During the burrowing-out process, the stride length first increases due to a drop in the overburden pressure, the end pull-out resistance, and the side frictional resistance; the stride length then decreases after the top of the actuator moves out of the sand layer, due to a reduction in the effective length of the actuator. The results also indicate that the average burrowing-out speed decreases with the relative density of the sand and changes with the actuation pressure. We developed a simplified model based on soil mechanics to predict the burrowing-out processes in relatively loose dry sands, and the modeling results match well with the experiment results. From this model, the burrowing-out behavior is readily explained by the asymmetric nature of the resistant forces on the two ends of the actuator and the flowing nature of sand upon yielding. Our findings imply that razor clams leverage the natural stress gradient of sand deposits to burrow upward. Another insight is that in order to burrow downward into the sand, additional symmetry-breaking features such as asymmetric geometry, friction, stress state or external load are needed to increase the resistant force (anchorage) in the upward direction and to reduce the resistant force (drag) in the downward direction.

International audience; A few data are related to the anthropophily of Malagasy Phlebotomine sandflies. Prior studies focussed mainly to inventories and description of new species. Our goal was to emphasize the anthropophily of Malagasy Phlebotomine sandflies. We worked in the Makira region, using two simultaneous methods: human landing catches (HLC) and CDC light traps. We collected sandflies in three rural communities adjacent to the Makira Natural Park. In each community, three different biotopes were sampled: within community settlements; at the edge of forest, typically in agricultural land; and within the forest. We collected 61 sandflies belonging to two new species presently described: Phlebotomus artemievi sp. nov. and Sergentomyia maroantsetraensis sp. nov. These sandflies were caught exclusively in the forest edge biotope. None were captured within communities or within forests. HLC provided 97% of the collected sandflies, corresponding to a human-biting rate of 15 females per human per night. CDC provided only two females. Ph. artemievi sp. nov. was predominantly captured by HLC and appears to be highly anthropophilic. Here, we update the behavioural ecology of sandflies and describe two new species. Further research is required to understand their vector competence and their ability to transmit arboviruses and other pathogens such as Leishmania.

Herring gulls (Larus argentatus) are opportunistic predators that prefer to forage in the intertidal zone, but an increasing degree of terrestrial foraging has recently been observed. We therefore aimed to analyze the factors influencing foraging behavior and diet composition in the German Wadden Sea. Gulls from three breeding colonies on islands at different distances from the mainland were equipped with GPS data loggers during the incubation seasons in 2012–2015. Logger data were analyzed for 37 individuals, including 1,115 foraging trips. Herring gulls breeding on the island furthest from the mainland had shorter trips (mean total distance = 12.3 km; mean maximum distance = 4.2 km) and preferred to feed on the tidal flats close to the colony, mainly feeding on common cockles (Cerastoderma edule) and shore crabs (Carcinus maenas). In contrast, herring gulls breeding close to the mainland carried out trips with a mean total distance of 26.7 km (mean maximum distance = 9.2 km). These gulls fed on the neobiotic razor clams (Ensis leei) in the intertidal zone, and a larger proportion of time was spent in distant terrestrial habitats on the mainland, feeding on earthworms. δ 13C and δ 15N values were higher at the colony furthest from the mainland and confirmed a geographical gradient in foraging strategy. Analyses of logger data, pellets, and stable isotopes revealed that herring gulls preferred to forage in intertidal habitats close to the breeding colony, but shifted to terrestrial habitats on the mainland as the tide rose and during the daytime. Reduced prey availability in the vicinity of the breeding colony might force herring gulls to switch to feed on razor clams in the intertidal zone or to use distant terrestrial habitats. Herring gulls may thus act as an indicator for the state of the intertidal system close to their breeding colony.

Germany is an EU member state and is thus obliged to monitor and protect its marine and coastal areas in the context of international treaties (e.g. EU Marine Strategy Framework Directive, EU Natura2000 directives, Trilateral Monitoring and Assessment Programme, OSPAR) to achieve the good environmental status (GES). Suitable indicators thus need to be developed to assess the status of relevant ecosystems. Intertidal bivalve beds belong to the most productive habitats in the shallow coastal waters of the Wadden Sea but are highly dynamic and difficult to monitor. Extensive benthos and sediment sampling are required to study their development and distribution. We therefore evaluated the suitability of herring gulls (Larus argentatus) as a bioindicator species for monitoring these habitats. As flexible and opportunistic top-predators, herring gulls prefer to forage on intertidal flats and feed on bivalves (Cerastoderma edule, Mytilus edulis, Ensis leei) and crustaceans, with intertidal habitats near the breeding colony preferred during the incubation period. We used state of the art tracking devices to analyse habitat selection by herring gulls, and assessed how this was driven by biotic and abiotic factors. We then designed a habitat model to predict the occurrence of intertidal bivalve beds for directed monitoring, based on GPS logger data from herring gulls and hydrodynamic data. Both methods showed high correlations of herring gull foraging patterns with bivalve biomass and inundation time, depending on the distance from the breeding colony. The movement patterns of herring gulls clearly mirrored intertidal bivalve distributions. These results showed that combining GPS-logger data for top-predators, such as birds, with environmental data has great potential for monitoring and assessing the GES. We propose that herring gulls may be used as an indicator to locate bivalve beds in the Wadden Sea and to detect changes in the food web.

Tirtadanu, Suprapto. 2017. Trawling ban impact on the stock density of shrimps in the Java Sea, Indonesia. Ocean Life 1: 49- 54. The level of over-exploitation of shrimps and the use of destructive fishing gear in the Java Sea caused the goverment of Indonesia to ban the trawl operation since 2015. Information on the stock density of shrimps in the Java Sea is needed for evaluation of the management regime. The aims of this research was to study the impact of the trawling ban on the density of shrimps in the Java Sea. The research was conducted in October-November 2015 and October-November 2017 using a swept area trawl method. The results showed that the biomass of demersal fish and rays has increased but the biomass of shrimps in the Java Sea has decreased that might be due to the predator-prey relationship.The biomass of some smaller-size shrimps such as Metapenaeopsis palmensis, Trachypenaeus malaiana and Metapenaeopsis stridulans decreased, while the biomass of larger shrimps such as Metapenaeus ensis, Penaeus merguiensis and Penaeus monodon increased. This condition caused the changes of dominant shrimps in Java Sea where the dominant shrimps before the trawling ban were M. palmensis, while the dominant shrimps after two years trawling ban were M. ensis. From the results, there is an assumption that the ecosystem is more stable after two years of the trawling ban. Most of the density of larger-sized shrimp increased only in the middle of Java Sea, while the density in the coastal zone still decreased. We suggest regulations to control the quota of fishing vessels in the coastal waters to ensure the sustainability of shrimp resources.

This paper describes the distribution of the razor clam Ensis directus in the Dutch coastal zone with emphasis on its relation to sediment grainsize, in particular silt. The study includes a spatial survey along the coast of North Holland (Netherlands) and an in-situ experiment for the burial of silt. Densities of E. directus appeared highest close to the coast in the siltiest sediment, where also the highest body mass index values (BMI) were found suggesting the best conditions for growth. The largest specimens with the lowest BMI were found at the less silty, outermost off-shore stations. In the shallow (10 m) zone a “lander” frame was deployed at the seabed containing ~ 100 pvc tubes filled with silt free sand that each hosted either a living E. directus , an empty shell, or bare sand. After three 3-weeks periods the silt content in the different tubes was determined and compared. The silt content around a living E. directus appeared 34% (spring) and 12% (autumn) higher than around an empty vertical shell, and 56% (spring) higher than in bare sand. We discuss the different pathways along which silt is brought into subsurface sediment layers and speculate about the potential role of E. directus in the coastal sediment and silt dynamics. It is estimated that E. directus facilitates the (temporal) burial of up to 6 Mton of fine particles in the coastal zone annually. This equals up to 27% of the annual SPM transport along the Dutch coast and is between 45 and 85% of the annual influx into the western Wadden Sea. The results show that the coastal E. directus population has a large impact on mass balance and behaviour of SPM, and on the ecological functioning of Dutch coastal and estuarine ecosystems.

A foraging group of Clangula hyemalis (Long-tailed Duck) was observed on 10 February 2010 diving behind a commercial boat that was clamming near Monomoy Island, Nantucket Sound, MA. We used a shotgun to collect 9 of the ducks, and our analyses of gizzard and gullet (esophagus and proventriculus) revealed 37 food items in the gizzard and 16 in the gullet. Mollusca were the dominant food in the gizzard (49%), whereas Crustacea were dominant in the gullet (57%). Crustacea were the second most important food in the gizzard (38%), whereas Mollusca were the second most important food in the gullet (31%). Relatively high volumes of the Amphipoda Caprella sp. (skeleton shrimp) and the Decopoda Crangon septemspinosa (Sand Shrimp) were recorded in the gullet and gizzard. Ensis directus (Atlantic Jackknife Clam) formed the greatest volume of Mollusca in the gizzard (15%) and in the gullet (15%). Long-tailed Ducks had fed on this Bivalvia and several other species of Mollusca that had no shell or broken shel...

Bivalve specimens from legacy frozen tissue collections, and others freshly obtained, were surveyed for the presence of the Steamer long terminal repeat (LTR)-retrotransposon associated with disseminated hemic neoplasia of the soft-shelled clam Mya areneria. Of 22 species investigated using primers for the pol region, only Atlantic M. arenaria, Atlantic and North Sea razor clams Ensis directus, and Baltic clams Macoma balthica from the North Sea were found to possess copies of Steamer in their genomes. Notably, close relatives like Mya truncata and Siliqua patula did not exhibit evidence of Steamer. Amplified Steamer sequences were uniformly identical in all M. areneria specimens, and were highly variable across specimens of E. directus. Variation in the latter included nucleotide polymorphisms among and within individuals as well as length variation in 2 specimens corresponding to the deletion of a predicted stable hairpin structure. Results implicate Atlantic razor clams as the proximal source for horizontal transmission of Steamer among ecologically similar yet markedly distantly related bivalves. The consequences of cross-species transmission of the Steamer retrotransposon are unknown, and the finding of Steamer in 3 bivalve species suggests that further spread is possible.

Bivalve molluscs fishery is of great importance along the Italian coasts, both in economic and landing terms, and different edible bivalve species are harvested both in Adriatic and Tyrrhenian Seas. A medium-term assessment of the impact of the hydraulic dredges targeting razor clam Ensis minor on macro-benthic community was made during two surveys carried out in winter 2017 and late spring – summer 2018 in central Tyrrhenian Sea, which represents the main fishing ground for this species. The study area was located between 1 and 4 m depth, within 0.3 nautical miles from the coast. A net sampler (40 cm width, 18 cm height, and 14 mm mesh size) was mounted on a commercial dredge (3 m width) and enabled to collect specimens of the smallest sizes for the entire community present in the areas. A control area was identified where fishing does not occur, in order to compare exploited and not exploited sea bottoms. The results show that benthic assemblages found in dredged areas are characterized by species living in high-energy habitat, due to the closeness to the shore, and thus showing a high resilience at medium-term disturbs. Differences in species richness were not clearly evident both for the entire community and for the mollusc assemblages evaluated over the two surveys, among the control and the impacted areas, with few exceptions mainly depending on local conditions and anthropic pressure. Thus, even if the benthic community is typical of a moderately disturbed environment, the effects of fishing on the community structure are still discernible over and above the natural variation.

The Common Scoter (Melanitta nigra) is a common sea duck, which predominantly feeds on sedentary benthic bivalve prey and occurs in large late-summer moulting concentrations in the German North Sea in areas which differ from those used by later wintering concentrations. Assuming scoters distribute in response to prey accessibility, abundance and profitability, we hypothesis that their contrasting distribution during moult compared to winter potentially reflects differences in prey type and distribution. We compared benthic bivalve community composition, abundance, ash-free dry mass and flesh-to-shell ratios between both areas to investigate factors influencing the seasonal difference in areas used by scoters. The American Razor Clam (Ensis leei) was the most common bivalve in the moulting area (mean abundance 1004 ± 1681 ind. m−2, mean ± SD) with the highest flesh-to-shell ratio (0.341 g m−2 ± 0.729 g m−2), whereas the American Piddock (Petricolaria pholadiformis) showed the highest ash-free dry mass (0.635 g m−2 ± 0.392 g m−2). In the wintering area, the most common bivalve was the Bean-like Tellin (Fabulina fabula, 13 ± 17 ind. m−2), Spisula solida had the highest ash-free dry mass (1.639 g m−2 ± 1.262 g m−2) and F. fabula and Abra alba had the highest flesh-to-shell ratios. Overall benthic species community composition differed considerably between moulting and wintering areas, with fewer species and lower abundances in the wintering area. The high abundance and food quality (flesh-to-shell ratio) of E. leei (an invasive alien to the German North Sea since the 1980s) in the moulting area suggests its relative importance and potentially explains the seasonal differences of Common Scoter distributions.

espanolEl estudio de los habitos alimentarios de la barracuda mexicana, "Sphyraena ensis" Jordan y Gilbert, 1882, es importante para conocer los aspectos relevantes de su ecologia trofica (presas consumidas, amplitud de dieta, nivel trofico y flujos de energia), ya que brindan informacion valiosa sobre la dinamica de las comunidades marinas. En este contexto, el objetivo del presente trabajo fue determinar los habitos alimentarios de la barracuda mexicana, S. ensis, asi como las variaciones troficas con respecto a sexo (machos, hembras), tallas (individuos pequenos, medianos y grandes) y estacionalidad (lluvias y secas). Se obtuvieron muestras mensuales durante el periodo de febrero de 2014 a enero de 2015 en la region de San Blas, Nayarit, Mexico. En total se capturaron 308 organismos, con tallas de entre 30.6 y 58.7 cm de longitud total y pesos de entre 405 y 836 g. De los estomagos analizados, 264 (86%) contenian alimentos y 44 (14%) estaban vacios. El espectro trofico de la barracuda mexicana se conformo de 13 tipos de presa, agrupadas en 11 familias, 12 generos y 9 especies. De acuerdo con el indice de importancia relativa, las presas mas importantes fueron los peces, particularmente Sardinops spp. (40.36%), Hemiramphus saltator (40.24%), Opisthopterus dovii (10.83%), Anchoa spp. (4.17%) y Mugil cephalus (3.05%). Con base en los resultados obtenidos, la barracuda mexicana puede categorizarse como un depredador ictiofago oportunista de la zona epipelagica costera que se alimenta, principalmente, de especies de peces que forman densos cardumenes. Su espectro trofico no presento variaciones significativas por sexo y talla, pero el consumo de las presas mas importantes vario significativamente por estacion. EnglishUnderstanding the feeding habits of the Mexican barracuda, "Sphyraena ensis" Jordan and Gilbert, 1882, is important to elucidate relevant aspects of its trophic ecology (prey intake, diet breadth, trophic level, and energy flows), which in general provide valuable information on the dynamics of marine communities. Therefore, the purpose of this work was to assess the dietary habits of the Mexican barracuda, S. ensis, and to determine dietary variations by sex (males, females), size (small, medium, and large individuals), and season (rainy and dry). Monthly samples were obtained from February 2014 to January 2015 in the San Blas region, Nayarit, Mexico. A total of 308 specimens were captured. Individuals measured between 30.6 and 58.7 cm total length and weighed between 405 and 836 g. Of the analyzed stomachs, 264 (86%) contained food and 44 (14%) were empty. The diet of the Mexican barracuda comprised 13 prey items from 11 families, 12 genera, and 9 species. According to the index of relative importance, the most important prey were fishes, particularly Sardinops spp. (40.36%), Hemiramphus saltator (40.24%), Opisthopterus dovii (10.83%), Anchoa spp. (4.17%), and Mugil cephalus (3.05%). We conclude that the Mexican barracuda can be categorized as an opportunistic ichthyophagous predator in coastal epipelagic zones that feeds mainly on schooling fish species. The trophic spectrum did not vary significantly by sex or size, but the consumption of preferred prey varied significantly by season.

Electricity can be used to facilitate fish and invertebrate capture in both marine and freshwater environments. In freshwaters, electrofishing is largely used for research or management purposes. In marine environments electrofishing is principally used in the form of electrotrawling for the commercial capture of fishes and benthic invertebrates, in particular common sole (Solea solea L.), brown shrimp (Crangon crangon L.), and razor clams (Ensis spp.). The terminology and definitions used to describe the electrical stimulus characteristics and experimental set-ups have, so far, been diverse and incomplete, hampering constructive discussion and comparison of electrofishing studies. This paper aims to (i) harmonize existing terminology, abbreviations, and symbols, (ii) offer best practice recommendations for publishing results, and (iii) provide a concise and comprehensible reference work for people unfamiliar with this topic. By incorporating common practice in marine electric pulse trawling terminology and related freshwater electrofishing studies, based on existing terms where possible, we provide a framework for future studies. The suggested guideline is recommended by the ICES Working Group on Electrical Trawling as a constructive approach to improved communication standards in electrofishing and electrical pulse stimulation research and publications.

In this study, we valorize the use of Ensis siliqua shell powder (ESSP) as a biosorbent to remove Cu(II), Zn(II) and Ni(II) ion from aqueous solutions. A batch scale experiment for different mass d...

Razor clam species are commercially important worldwide. In Tunisia, studies on razor clams aim to promote harvesting and ensure a rational and durable exploitation. In Tunisia, Solen marginatus (Pulteney, 1799) is the most abundant razor clam species although Ensis species, particularly Ensis minor, are also found. The aim of this study is to understand the allocation strategies of S. marginatus in terms of growth and reproduction. For that, condition indices and histological analysis were performed and related to temperature and chlorophyll a. Clams were collected monthly in the southern Mediterranean Sea (Gulf of Gabes, Tunisia). Body and somatic mass increased in summer and autumn. Body condition was highest in September 2007 and the highest somatic condition index was measured in August 2008. Body and somatic mass loss occurred in winter and late spring-early summer with lowest values found, respectively, in February and May 2008. Gametogenesis rate was slow and held in a synchronous way dur...

Hatcheries providing seed for bivalve mollusc aquaculture can suffer from disease outbreaks resulting in high losses of larvae. Previous research demonstrated the effectiveness of candidate probiotics Phaeobacter inhibens S4 (S4) and Bacillus pumilus RI06-95 (RI) in protecting the larvae of eastern oysters Crassostrea virginica, against bacterial challenge. In this study, the ability of this probionts in protecting larvae of other bivalve species, including northern quahog Mercenaria mercenaria, bay scallops Argopecten irradians, blue mussels Mytilus edulis, and razor clams Ensis directus, was investigated. Pretreatment of larvae with 106 colony forming units /ml probiotic S4 and a mixture of S4 and RI protected bay scallop larvae [relative percent survival (RPS): 69% ± 4%]. In pilot-scale hatchery trials, daily additions of candidate probiotics to the water of static tanks containing northern quahog or bay scallop larvae had no significant impact on larval growth and survival. Daily treatment of...

RoboClam is a biomimetic burrowing robot that imitates the valve expansion/contraction digging pattern of the Atlantic razor clam, Ensis directus , to dig into submerged soil using an order of magnitude less energy than would be required to push into the soil with brute force. This paper examines whether it would theoretically be possible to use the same method to dig into dry soil. The stress state of the soil around the contracting robot was analyzed, and a target zero-stress state for dry soil digging was found. Then, the two possible modes of soil collapse were investigated and used to determine how quickly the robot would have to contract to achieve the target zero-stress state. It was found that for most dry soils, a RoboClam-like device would have to contract in 0.02 s, a speed slightly faster than the current robot is capable of, but still within the realm of possibility for a similar machine. These results suggest that the biomimetic approach successfully used by RoboClam to dig into submerged soil could feasibly be used to dig into dry soil as well.

Since its introduction from North America in the 1970s, the American razor clam Ensis leei (M. Huber, 2015) has successfully spread throughout North Sea coasts from Spain to Norway and the United Kingdom to the western Baltic. We investigated the distribution and abundance of this non-indigenous bivalve species as a potential novel food resource for common scoter Melanitta nigra (Linnaeus, 1758) along the eastern German North Sea coast. Highest densities of flightless moulting and wintering common scoters coincided with areas of high E. leei abundance. Other European studies showed common scoters extensively feed on E. leei. Even with these findings, it remains difficult to demonstrate convincingly that E. leei constitutes a major food source for common scoter in the German North Sea during their non-breeding season. However, our study suggests that E. leei has become an important prey item for internationally important concentrations of common scoters at large spatial scales.

Shrimp is a wealth of fishery resources are abundant and has a high economic value in Laguna Segara lagoon. So the existence and habitat of life from larvae to adult need attention to maintain the survival of shrimp. Therefore, the purpose of this research is to know the distribution of abundance and characteristics of shrimp juvenile habitat in Segara Anakan lagoon. Sampling is done 3 times (June, August and October 2013), with 9 stations Observation station. The results showed that the abundance of shrimp based on the amount in Segara Anakan lagoon was dominated by Metapenaeus elegans (205-8723 ind./1000 m2), whereas the abundance of M. ensis, F merguensis, P. semisulcatus and P. monodon relatively low had the same habitat , ie waters with high fertility and relatively low salinity, relatively high pH. Found in Motean observation station, Muara Dua, Kleces and Majingklak. Harpiosquilla annandalei (0-330 ind/1000 m 2 ), P. monodon (0-238 ind/1000 m 2 ), and Acetes sp (0.1-5.196 ind/1000 m 2 ) sounded a lot of water habitat that contain BOT and high zooplankton abundance. Thus the shrimp Harpiosquilla annandalei, P. monodon , and Acetes sp are found in Tritih observation stations, and are quite commonly found in Kleces observation stations. Keywords : abundance, habitat preferences, juvenile shrimp, Segara Anakan Lagoon

The European seas are known to be the recipient of several hundreds of Non-Native Species (NNS) due two main origins: shipping and aquaculture. More than 160 NNS had been recorded along the Normandy coast, which remains low in comparison with the number of marine invertebrate species known in the English Channel (> 3,000). The main sites of introduction are the harbours, especially Le Havre and the oyster cultivation zones. Among these NNS, 56 are present in Normandy and considered invasive along the European coasts, but only ten (one macro-algae and nine invertebrates) are invasive in Normandy. Six examples are illustrate, the molluscs Magallana gigas, Crepidula fornicata, Ensis leei, and Ruditapes philippinarum, the polychaete Ficopomatus enigmaticus and the crab Hemigrapsus sanguineus. The two first species have changed the dynamics and functioning of the coastal ecosystems, while the others have lower impact. In fact, the oyster and the manila clam are now key species for the French economy, while the rapid expansion of the other species change biodiversity in the more colonised sites. The ALEX (ALien Biotic IndEX) proposed by Cinar and Bakir in 2014 for the Mediterranean Sea is used for the first time in Atlantic waters.

The availability of Indian specimens of Plesionika persica (Kemp, 1925) and P. reflexa Chace, 1985 provided more information on the taxonomy around these two species. Moreover, it is the first record of P. persica to India. Although P. taiwanica Chan and Yu, 2000 is superficially rather similar to P. persica , there are many differences between them and probably it is inappropriate to establish a species group for these two species. It is likely that all previous records of P. ensis (A. Milne-Edwards, 1881) from India actually represent P. reflexa Chace, 1985. Nevertheless, the present Indian specimens of P. reflexa have more than 10% COI sequence divergence from the topotypic materials of both P. ensis and P. reflexa , and the epipods at the pereiopods III and IV reduced or absent. This data further highlights the confusing taxonomy in the “ P. ensis ” group.

Benthic oxygen and nitrogen fluxes were quantified within the years 2012 to 2014 at different time series sites in the southern North Sea with the benthic lander NuSObs (Nutrient and Suspension Observatory). In situ incubations of sediments, in situ bromide tracer studies, sampling of macrofauna and pore water investigations revealed considerable seasonal and spatial variations of oxygen and nitrogen fluxes. Seasonal and spatial variations of oxygen fluxes were observed between two different time series sites, covering different sediment types and/or different benthic macrofaunal communities. On a sediment type with a high content of fine grained particles (o63 mm) oxygen fluxes of �15.5 to �25.1 mmol m�2 d�1 (June 2012), �2.0 to �8.2 mmol m�2 d�1 (March 2013), �16.8 to �21.5 mmol m�2 d�1 (November 2013) and �6.1 mmol m�2 d�1 (March 2014) were measured. At the same site a highly diverse community of small species of benthic macrofauna was observed. On a sediment type with a low content of fine grained particles (o63 mm) high oxygen fluxes (�33.2mmol m�2 d�1 August 2012; �47.2 to �55.1 mmolm�2 d�1 November 2013; �16.6 mmol m�2 d�1 March 2014) were observed. On this sediment type a less diverse benthic macrofaunal community, which was dominated by the large bodied suspension feeder Ensis directus, was observed. Average annual rain rates of organic carbon and organic nitrogen to the seafloor of 7.44 mol Cm�2 y�1 and 1.34 mol N m�2 y�1 were estimated. On average 79% of the organic bound carbon and 95% of the organic bound nitrogen reaching the seafloor are recycled at the sediment–water interface. & 2015 Elsevier Ltd. All rights reserved

Statutory monitoring of the fauna of the ‘mudflats and sandflats not covered by seawater at low tide’ biotope complex on St Martin's Flats, a part of the Isles of Scilly Complex Special Area of Conservation, was undertaken in 2000, 2004 and 2009. The targets set by Natural England for “characteristic biotopes” were that “composite species, abundance and diversity should not deviate significantly from an established baseline, subject to natural change”. The three specified biotopes could not be distinguished, and instead three assemblages were subjectively defined based on sediment surface features. There were statistically significant natural changes in diversity and species composition between years, especially in the association initially characterised by the razor-clam Ensis , and possible reasons for this are discussed. It is suggested that setting fixed local limits on natural variability is almost always impractical. Two possible approaches to distinguishing between natural and anthropogenic changes are suggested; a change in ecological condition as indicated by AMBI scores, and a significant change in average taxonomic distinctness (Δ + ) compared with expectation. The determination of species biomasses as well as abundances might also open more possibilities for assessment. The practice of setting objectives for a marine Special Area of Conservation (SAC) feature that include the range and number of biotopes cannot be supported, in view of the difficulty in ascribing assemblages to recognised biotopes. A more realistic definition of species assemblages might best be gained from examination of the species that consistently make a substantial contribution to the Bray–Curtis similarity among samples collected from specific sites.

Ovalipes guadulpensis (Saussure) is a portunid commonly trawled from the sand bottoms along the northwestern Florida Gulf Coast. A sister species, 0. ocellatus (Herbst) , is reported to bury itself in the sand bottoms off North Carolina. When buried the respiratory currents are reversed and the crab emerges from the sand and actively “?�hunts” for food during rising or falling tides ( Pearse, Humm, and Wharton, 1942) . The habitats of the two species are similar, except adult 0. guadul/,ensis are usually not found near-shore (Williams, 1965). As no other information was available on the habits of 0. guadulpensis, a study was undertaken to determine the food and feeding mechanisms of this crab and to assess the morphological adaptations to a burrowing existence. MATERIALS AND METHODS Specimens of 0. guadulpensis were trawled from sand bottoms in the Gulf of Mexico along northwestern Florida in waters from three to eight meters in depth. Some individuals were preserved upon collection in 70% ethanol and then re frigerated. These crabs were used in stomach content analyses and morphological investigations. Other crabs were kept alive and returned to the laboratory and placed in running seawater aquaria. These were the subjects of observations on feeding, burrowing, and respiratory currents. Stomach contents and the gastric mill were investigated following the methods of Caine (1974). Motion pictures were made of both feeding and burrowing activity and the film was analyzed frame by frame. Analysis of the film was correlated with the morphology of the appendages and visually verified by repeated observations. Respiratory currents were tested using carmine to follow external currents and small quantities of methylene blue in a seawater solution to trace the internal water pathways.