Cerastoderma Edule Research Articles

Contrasting strategies to cope with storm‐induced erosion events: a flume study comparing a native vs. introduced bivalve

AbstractStorm‐induced erosion events may alter the diversity of tidal flat communities by selecting species that can better tolerate such disturbances. Introduced and invasive species are highly adaptable to a wide range of abiotic characteristics, and this adaptability may make them better able to withstand erosion events. With a novel flume method, we compared the ability of two bivalve species to resist storm‐induced erosion: Cerastoderma edule, a native species to the Scheldt estuary in the Netherlands, and Ruditapes philippinarum, an introduced species that is successful in the Netherlands and worldwide. We used three sediment erosion rates to simulate storms of increasing severity. At the 10.6 and 15.9 cm h−1 sediment erosion rates, all R. philippinarum were surfaced, whereas only half C. edule were surfaced. However, after being brought to the sediment surface, C. edule were more readily transported by currents and waves than R. philippinarum due to differences in their shell shape. We concluded that the two bivalve species had different strategies to avoid mortality by severe storm erosion: C. edule avoided being surfaced and R. philippinarum avoided being transported. In this case, it appears that extreme storms favor the specific adaptations of a native species over the broad adaptability of a non‐indigenous one. Indeed, C. edule may be more likely to survive moderately extreme storms than R. philippinarum, though the most extreme storms would be equally devastating to both species.

Does global warming threaten small-scale bivalve fisheries in NW Spain?

Shellfisheries of the intertidal and shallow subtidal infaunal bivalves Ruditapes decussatus, Ruditapes philippinarum, Venerupis corrugata and Cerastoderma edule are of great socio-economic importance (in terms of landings) in Europe, specifically in the Galician Rías Baixas (NW Spain). However, ocean warming may threaten these fisheries by modifying the geographic distribution of the species and thus affecting productive areas. The present study analysed the impact of rising ocean temperature on the geographical distribution of the thermal comfort areas of these bivalves throughout the 21st century. The Delft3D model was used to downscale climate data from CORDEX and CMIP5 and was run for July and August in three future periods (2025–2049, 2050–2074 and 2075–2099) under the RCP8.5 scenario. The areas with optimal temperature conditions for shellfish harvesting located in the middle and outer parts of the rias may increase in the near future for R. decussatus, V. corrugata and C. edule and decrease in the far future for R. philippinarum. Moreover, shellfish beds located in the shallower areas of the inner parts of the Rías Baixas could be affected by increased water temperature, reducing the productive areas of the four species by the end of the century. The projected changes in thermal condition will probably lead to changes in shellfish harvesting modality (on foot or aboard vessels) with further socio-economic consequences.

Marine trematode parasites as indicators of environmental changes

Coastal ecosystems are threatened by growing pressures related to global change. The evaluation of an ecosystem’s biodiversity and status is by consequence of increasing importance to assess potentially undergone changes and predict their future trajectory for management and conservancy purposes. Biotic indicators sensitive to ecosystem changes are thus continuously sought for. Trematode parasite communities were examined as potential indicators of environmental changes, considering that the achievement of their complex life cycle is modulated by several factors. Indeed, the rule for trematode is that each species complete their cycle by a succession of three different host species and two free-living stages, thus depending on several biotic and abiotic factors. To this end, we examined the trematode community infecting the common cockle in Banc d’Arguin, Arcachon Bay, France. Monthly data extending over 16 years and sampled at a single station were compared to field book notes describing the changes of the closely surrounding landscape. In 2021, we also sampled cockles at 15 stations presenting different substrate features along the bank. Over time, seven out of nine changes of the trematode community structure presented concordances with changes in landscape. We hypothesize this was related to the environment heterogeneous substrate (i.e., temporal succession of oyster parks, bare sands and seagrass) with cascading effects on host populations. However, some changes could not solely be explained by changes in landscape. Our spatial study showed that the trematode communities exhibited intricate infection patterns with a complex interaction between substrate heterogeneity and larval dispersal ability of parasites. Thus, trematode communities might be potential indicators of subtle changes in the environment. However, it remains unclear which scale of environmental changes trematodes are actually sensitive to.

Discovery of the parasite Marteilia cocosarum sp. nov. In common cockle (Cerastoderma edule) fisheries in Wales, UK and its comparison with Marteilia cochillia

Diseases of bivalve molluscs caused by paramyxid parasites of the genus Marteilia have been linked to mass mortalities and the collapse of commercially important shellfish populations. Until recently, no Marteilia spp. have been detected in common cockle (Cerastoderma edule) populations in the British Isles. Molecular screening of cockles from ten sites on the Welsh coast indicates that a Marteilia parasite is widespread in Welsh C. edule populations, including major fisheries. Phylogenetic analysis of ribosomal DNA (rDNA) gene sequences from this parasite indicates that it is a closely related but different species to Marteilia cochillia, a parasite linked to mass mortality of C. edule fisheries in Spain, and that both are related to Marteilia octospora, for which we provide new rDNA sequence data. Preliminary light and transmission electron microscope (TEM) observations support this conclusion, indicating that the parasite from Wales is located primarily within areas of inflammation in the gills and the connective tissue of the digestive gland, whereas M. cochillia is found mainly within the epithelium of the digestive gland. The impact of infection by the new species, here described as Marteilia cocosarum n. sp., upon Welsh fisheries is currently unknown.

Evolutionary and ecological insights from vital staining of bivalve oocytes: A Red Queen at the sweepstakes?

AbstractTo determine the proportion of inviable oocytes that are spawned along with normal oocytes in marine bivalves, we turned to a time‐honored technique not previously used on invertebrate oocytes: the neutral red vital stain. Despite the difficulty in obtaining induced spawns from field‐collected Cerastoderma edule (L), the results and insights from this simple procedure to answer a simple question were unexpected and far‐reaching. Mean proportions of inviable oocytes in the spawns of cockle C. edule ranged from 35% to 85%, with the vast majority represented by atresic (autolyzing) oocytes. These levels are in agreement with previous quantitative histological observations of prespawning atresia in both C. edule and the Manila clam Tapes philippinarum. Such elevated prefertilization inviability mirrors the known high level of postfertilization inviability in bivalves. Together, these high levels of inviability may account for much of the early mortality in the type III survivorship curves typical of marine bivalves. The combination of high fecundity and high oocyte inviability suggests a Red Queen‐type reproductive dilemma in these species. In addition, the great degree of interindividual variation observed in oocyte inviability suggests that cockles, and perhaps other intertidal bivalves, present a Sweepstakes Reproductive Strategy, in which highly variable individual fecundity confronts a highly variable environment. The neutral red technique promises to be a useful tool for investigating prespawning inviability in other marine taxa, as well as for aquaculture, conservation, restocking, ecophysiology, and environmental monitoring.

Analysis of the structural characteristics and spatial organization of macrobenthic fauna in Oualidia lagoon, Morocco

Morocco is a very rich country in terms of wetlands, including bays, estuaries, lagoons, lakes, and rivers, among others. However, many of them need to be well managed and better exploited, thus requiring baseline descriptive studies to assess faunal patterns and trends. Oualidia lagoon is not an exception. In fact, the studies conducted to date in the lagoon mainly focused on its oceanographic features and aquaculture capacities. The present paper presents the first study on the whole macrofaunal assemblages of Oualidia lagoon, having as main objectives analyze the composition and structure of the assemblages, as well as their relationships with the main environmental variables explaining their spatial distribution variability in the enclosed ecosystem of the Oualidia coastal lagoon. The benthic macroinvertebrates of Oualidia lagoon were studied in summer 2013 based on 43 stations spread over the whole lagoon by using a Van Veen grab. Two replicate samples were collected for macrobenthos and one additional replicate for sediment analyses at each station. Also, single water salinity and temperature measurements were recorded at each station. Fifty-one species from seven different taxa were recorded, among which mollusks (37%), polychaetes (25%) and crustaceans (25%) dominated in terms of species number. Peringia ulvae, Abra alba, Sphaeroma serratum, Cerastoderma edule and Corophium sp. accounted for 88% of total abundance. The benthos was structured along a downstream–upstream gradient, showing three assemblages, named according to the IndVal index: (1) Diopatra cf. marocensis, (2) Peringia ulvae, and (3) Cerastoderma edule, while the main factors driving their distribution were granulometry and salinity. The Biotic and Environmental analysis showed that the combination of granulometry and salinity was the major factors controlling the spatial distribution of the macrozoobenthos in the Oualidia Lagoon.

50 years of estuarine cockles (Cerastoderma edule L.): Shifting cohorts, dwindling sizes and the impact of improved wastewater treatment

Bivalve populations are prone to change due to sudden or gradual alteration in the natural environment and anthropogenic interference. Fisheries and environmental managers are therefore interested in long-term trends and disentangling natural and human influences, assisting them in conservation efforts and the management of bivalve stocks. Here, 64 monitoring reports covering a 50-year period from 1958 to 2009 of cockles Cerastoderma edule (Linnaeus, 1758) in South Wales, UK, were scrutinised for data on recruitment, growth and mortality. Changes in these population parameters were related to the modernisation of wastewater treatment in 1997, weather and climate variables (temperature, sun hours, air frost days, NAO) and numbers of cockles in the estuary. Recruitment as well as mortalities were high during the first and last decade of the study, and variation was significantly linked to the total number of cockles in the population. Cockle sizes of all cohorts as well as overall biomass declined in the late 1990s. Modernisation of wastewater treatment was significantly related with the downward trend, suggesting that the changed nutrient regime in the estuary may have resulted in reduced food provision for cockles. The average size of newly settled cockles was related to their mortality: the smaller the recruits the higher their mortality. The study indicated a link between the change in wastewater treatment in 1997 and diminishing sizes of cockle recruits that shortened their life span. Survey methods were profoundly changed after 2009, and it is recommended to develop conversion factors between the pre- and post-2009 survey methods. This would allow an extension of the timeline and deeper insight into the long-term impact of the change in wastewater treatment and the recovery of the cockle population.

Spatial and Temporal Variations of Cockle (Cerastoderma spp.) Populations in Two Portuguese Estuarine Systems With Low Directed Fishing Pressure

Cockles are amongst the most exploited bivalve species in Portugal, playing an important ecological and socioeconomic role in coastal ecosystems. Two sympatric species of cockles, Cerastoderma edule (Linnaeus, 1758) and Cerastoderma glaucum (Bruguière, 1789–1792) may co-occur in estuaries and coastal lagoons in mixed populations along the European Atlantic coast, namely in Portugal, France and the United Kingdom. The increasing importance of shellfish harvesting in Portugal requires a good knowledge of cockle stocks and temporal variability in stock levels to better inform sustainable management practices. Therefore, this study aimed at assessing spatial and temporal variations in cockle populations in two Portuguese estuarine systems where the species are exploited at low levels. Sampling was carried out using a clam dredge, covering the entire potential area of occurrence of cockles in the Tagus and Sado estuaries at around the same time of the year in each of the three sampling years (2015, 2018, and 2019). The abundance, spatial distribution and population structure of cockles were examined at each system. Moreover, several water and sediment parameters were measured to understand the influence of environmental conditions on the spatial distribution and abundance of cockles. The results obtained showed that cockles occur mostly in the intermediate areas of both estuarine systems and are more abundant in the Tagus estuary. Depth, average sediment grain size and the species Ruditapes philippinarum were the factors that better explained the probability of species occurrence. The population structure analysis indicated that natural mortality is constraining the cockle communities given the low abundance of adult individuals with marketable size in both estuaries. This study highlights the need for appropriate management measures to ensure the sustainability of these bivalve population stocks that have significant socioeconomic importance for local populations.

Himasthla spp. (Trematoda) In The Edible Cockle Cerastoderma edule: Review, Long-Term Monitoring And New Molecular Insights.

AbstractTrematodes are the main macroparasites in coastal waters. The most abundant and widespread form of these parasites is metacercaria. Their impact on their host fitness is considered relatively low but metacercarial larvae of some species can have deleterious effects on individuals and/or populations. This review focused on the cockle Cerastoderma edule and four species of the genus Himasthla; a common host–parasite system in marine coastal environments. Our aims were (1) to review literature concerning Himasthla continua, Himasthla elongata, Himasthla interrupta and Himasthla quissetensis in cockles; (2) to provide molecular signatures of these parasites and (3) to analyse infection patterns using a 20-year monthly database of cockle monitoring from Banc d'Arguin (France). Due to identification uncertainties, the analysis of the database was restricted to H. interrupta and H. quissetensis, and it was revealed that these parasites infect cockles of the same size range. The intensity of parasites increased with cockle size/age. During the colder months, the mean parasite intensity of a cockle cohort decreased, while infection occurred in the warmest season. No inter-specific competition between trematode parasites was detected. Furthermore, even if the intensity of H. interrupta or H. quissetensis infection fluctuated in different years, this did not modify the trematode community structure in the cockles. The intensity of infection of both species was also positively correlated with trematode species richness and metacercarial abundance. This study highlighted the possible detrimental role of Himasthla spp. in cockle population dynamics. It also revealed the risks of misidentification, which should be resolved by further molecular approaches.

Okadaic Acid Depuration from the Cockle Cerastoderma edule.

The cockle Cerastoderma edule is a commercially important species in many European Countries. It can accumulate okadaic acid (OA) and other toxins in its group, which makes it unsuitable for human consumption, producing harvesting bans to avoid intoxications. The duration of those bans depends in part on the depuration kinetics of the toxin in this species. In this work, this kinetics was studied by means of fitting different models to depuration data experimentally obtained, using naturally contaminated cockles. Cockles depurated OA faster than most other bivalve species studied. Models that include Michaelis-Menten kinetics describe the depuration better than those using a first order exponential decrease to describe the first (or the only) compartment. One-compartment models were not able to describe the final part of the depuration curve, in which OA was depurated very slowly. Therefore, two-compartment models were needed. Esters were depurated at a much faster rate than the free form of the toxin; however, no significant esterification was detected during the process. The slow depuration rate suggests that other bivalve species could be used as sentinels to monitor cockle populations, but caution should be taken when toxin concentrations are very high.

A case study of local ecological knowledge of shellfishers about edible cockle (Cerastoderma edule) in the Ria de Aveiro lagoon, Western Iberia

BackgroundThe cockle is available to numerous fishing villages in Europe, especially Portugal. In the Ria de Aveiro, there is a lack of a fisheries management program and the need for new ecological studies on cockle biology, ecology, and conservation. We shared local ecological knowledge (LEK) highlights about the cockle—Cerastoderma edule (Linnaeus 1758) in the Ria de Aveiro in favor of adaptive management of this bioresource.MethodsSemi-structured interviews with sixty shellfishers in this coastal lagoon were carried out during April and May 2021. LEK data on the biology and ecology of the cockle were analyzed using an ethical-emic approach and the model of integration of different individual skills. These informal data were compared with previously published data for the species, the Fish Base, and GBIF databases.Results and discussionThe average minimum size of the cockle for capture was 23.4 mm, and the average capture per tide was 137.12 kg. The areas with the highest productivity and the most shellfish were RIAV1 and RIAV2. Cockles inhabit areas of sand and mud at an average depth of 2.71 cm. Feeds are mainly small particles, plankton, mud, and algae. The main predators were crabs, European plaice, and bird species. Cockles spawn primarily in late spring and summer. As of 2010, there was a slight decrease in cockle stocks in the Ria de Aveiro due to overfishing, increased rainfall, and changes in the sediment. Considering and analyzing this knowledge is essential for a better understanding of the environmental context the cockles thrive in the view of users of the natural resource.ConclusionInformal data shared by shellfishers in the Ria de Aveiro were typical of filter-feeding bivalves. LEK may assist in planning future management plans for cockles, and unrefuted data may serve as untestable hypotheses. Ethnobiological studies in the Ria de Aveiro lagoon with other species may improve the management of this system since multiple fisheries are carried out in this coastal area.

Thermal stress affects bioturbators' burrowing behavior: A mesocosm experiment on common cockles (Cerastoderma edule)

The intensity of marine heatwaves is increasing due to climate change. Heatwaves may affect macroinvertebrates' bioturbating behavior in intertidal areas, thereby altering the deposition-erosion balance at tidal flats. Moreover, small-scale topographic features on tidal flats can create tidal pools during the low tide, thus changing the heat capacity of tidal flats. These pools could then potentially operate as refuge environments during marine heatwaves. We studied behavior responses to heat waves using the well-known bioturbating cockle Cerastoderma edule as a model species. Different temperature regimes (i.e., fluctuating between 20 and 40 °C) and micro-topographies (i.e., presence vs. absence of tidal water pools) were mimicked in a mesocosm experiment with regular tidal regimes. Our results demonstrate that behavioral responses to heat stress strongly depend on the site-specific morphological features. Cockles covered by shallow water pools moved up when exposed to thermal stress, while burrowing deeper into the sediment in the absence of water pools. But in both cases, their migratory behavior increased under heat stress compared to regular ambient treatments. Moreover, long-term cumulative heat stress increased cockles' respiration rates and decreased their health conditions, causing mass mortality after four weeks of gradually increasing heat exposure. Overall, the present findings provide the first insights into how bioturbating behavior on tidal flats may change in response to global warming.

Assessment of the environmental distribution of the protozoan parasite Perkinsus olseni by next-generation sequencing, qPCR and histopathology allows the identification of alternative bivalve hosts

Perkinsus olseni is a protozoan parasite that infects a wide variety of molluscs worldwide, causing economic losses in the aquaculture sector. Consequently, Perkinsosis has been catalogued by the World Organization for Animal Health (O.I.E.) as a notifiable disease, and international measures have been established to control it (O.I.E., 2019). In the present study, we analysed the spatial and temporal distribution of transmissible stages of Perkinsus olseni in an endemic area of the parasite from 2016 to 2018. The pathogen was detected using high-throughput sequencing of the 18S rRNA gene and a specific real-time PCR assay (qPCR) in samples of water, sediment and several bivalve species. Histopathological assays were also conducted on bivalve samples.P. olseni was not detected in environmental samples by qPCR; however, eDNA sequencing revealed its presence in both the water and sediment at all sampled points, showing a seasonal pathogen prevalence. As expected, the parasite was detected in clams, but a few cases were also found in mussels and cockles. The presence of the parasite was confirmed in Cerastoderma edule by histology and qPCR using RNA to evaluate the presence of proliferative life stages of the parasite. Therefore, this is the first time that P. olseni has been found in C. edule but with low abundance and infection intensity levels.

Coastal ecosystem engineers and their impact on sediment dynamics: Eelgrass–bivalve interactions under wave exposure

AbstractHabitat forming ecosystem engineers play critical roles in structuring coastal seascapes. Many ecosystem engineers, such as seagrasses and epifaunal bivalves, are known to have positive effects on sediment stability and increase coastal protection and ecosystem resilience. Others, such as bioturbating infaunal bivalves, may instead destabilize sediment. However, despite the common co‐occurrence of seagrasses and bivalves in coastal seascapes, little is known of their combined effects on sediment dynamics. Here, we used wave flumes to compare sediment dynamics in monospecific and multispecific treatments of eelgrass, Zostera marina, and associated bivalves (infaunal Limecola balthica, infaunal Cerastoderma edule, epifaunal Magellana gigas) under a range of wave exposures. Eelgrass reduced bedload erosion rates by 25–50%, with digital elevation models indicating that eelgrass affected the sediment micro‐bathymetry by decreasing surface roughness and ripple sizes. Effects of bivalves on sediment mobilization were species‐specific; L. balthica reduced erosion by 25%, C. edule increased erosion by 40%, while M. gigas had little effect. Importantly, eelgrass modified the impacts of bivalves: the destabilizing effects of C. edule vanished in the presence of eelgrass, while we found positive additive effects of eelgrass and L. balthica on sediment stabilization and potential for mutual anchoring. Such interspecific interactions are likely relevant for habitat patch emergence and resilience to extreme wave conditions. In light of future climate scenarios where increasing storm frequency and wave exposure threaten coastal ecosystems, our results add a mechanistic understanding of sediment dynamics and interactions between ecosystem engineers, with relevance for management and conservation.

Genomic survey of edible cockle (Cerastoderma edule) in the Northeast Atlantic: A baseline for sustainable management of its wild resources.

Knowledge on correlations between environmental factors and genome divergence between populations of marine species is crucial for sustainable management of fisheries and wild populations. The edible cockle (Cerastoderma edule) is a marine bivalve distributed along the Northeast Atlantic coast of Europe and is an important resource from both commercial and ecological perspectives. We performed a population genomics screening using 2b‐RAD genotyping on 9309 SNPs localized in the cockle's genome on a sample of 536 specimens pertaining to 14 beds in the Northeast Atlantic Ocean to analyse the genetic structure with regard to environmental variables. Larval dispersal modelling considering species behaviour and interannual/interseasonal variation in ocean conditions was carried out as an essential background to which compare genetic information. Cockle populations in the Northeast Atlantic displayed low but significant geographical differentiation between populations (F ST = 0.0240; p < 0.001), albeit not across generations. We identified 742 and 36 outlier SNPs related to divergent and balancing selection in all the geographical scenarios inspected, and sea temperature and salinity were the main environmental correlates suggested. Highly significant linkage disequilibrium was detected at specific genomic regions against the very low values observed across the whole genome. Two main genetic groups were identified, northwards and southwards of French Brittany. Larval dispersal modelling suggested a barrier for larval dispersal linked to the Ushant front that could explain these two genetic clusters. Further genetic subdivision was observed using outlier loci and considering larval advection. The northern group was divided into the Irish/Celtic Seas and the English Channel/North Sea, while the southern group was divided into three subgroups. This information represents the baseline for the management of cockles, designing conservation strategies, founding broodstock for depleted beds and producing suitable seed for aquaculture production.

Species composition and abundance of seashells in the intertidal zone of Tubalan cove, municipality of Malita, Davao occidental province, Philippines

The study determined the seashells’ species composition, relative abundance, population density, species diversity, substrate types and the gleaners’ socio economic-profiles in the intertidal zone of Brgy. Tubalan, Municipality of Malita, Davao Occidental Province, The Philippines. Eight seashell species were identified in the study area namely: Anodontia edentula, Anadara antiquata, Cerastoderma edule, Lutraria australis, Nerita undata, Paphia amabilis, Strombus urceus and Terebralia sulcata. Among the stations, Cerastoderma edule had the highest number of relative abundance with 35.42 in Station 2, while the Anodontia edentula with 5.21 is exhibited lowest value (Station 1). For population density, the highest value was with Cerastoderma edule accounted 55 individuals/m2, while the lowest is Anodontia edentula with 5 individuals’ species/m2. In terms of species diversity, Station 2 had the highest number with 3.737, and the lowest was in Station 1 with 2.376. The result on the substrate type characterization revealed that fine sand to medium sand substrates were observed in all stations. Collected seashells by the local gleaners will usually sell it in their public market, others are in their neighbours. To most gleaners, gleaning activity is considered as their main source of income to sustain daily needs. Statistically, the T-test results revealed no significant differences for abundance with the value 0.795 and for population density with the value of 0.379 among the two stations; this implies that tabulated value of 0.05 is lesser than the calculated value. For the number of species in relation to abundance with 0.03 and population density with 0.023, tabulated value of 0.05 was greater than the calculated value which implies that the null hypothesis on the number of species in terms of abundance and population density among two stations was rejected. It is recommended to conduct further study in other barangays, highlighting the inclusion of physico-chemical parameters factors affecting species composition and abundance of seashells.

Assessment of carbamazepine acute toxicity in the cockle Cerastoderma edule through chemical, physiological and biochemical tools.

The cockle Cerastoderma edule was exposed to four concentrations (5, 10, 20 and 70 μg L-1) of carbamazepine (CBZ). This anticonvulsant was found to alter the mussel behavior of by reducing its clearance rate (CR). Analysis of CBZ accumulation in tissues of C. edule was carried out using HPLC-UV after 48 or 96 hours of exposure. In addition, an overproduction of H2O2 by the bivalves was detected following exposure to CBZ but nitrite levels remained unchanged. Moreover, superoxide dismutase and catalase activities showed a significant increase in relation to their contact with CBZ. The activity of the biotransformation enzyme gluthatione-S-transferase did not change during exposure. Malondialdehyde (MDA) levels indicating cellular damage, increased when bivalves were exposed to 20 and 70 μg l-1 of carbamazepine for 96 h CBZ. The results also indicate that acetylcholinesterase activity (AChE) was inhibited in all CBZ concentrations during the 48 h exposure period. However, during the 96 h exposure period, AChE was only inhibited at the highest concentration. Further studies are needed now for more exploration of the toxicity of CBZ since it could be bioaccumulable throughout the food web and may affect non-target organisms.

State‐dependent environmental sensitivity of reproductive success and survival in a shorebird

To understand the consequences of anthropogenic and environmental changes for wildlife populations, it is important to study how individuals differ in their sensitivity to environmental change and whether this depends on individual characteristics. An individual's reproductive performance may provide an integrative, unidimensional proxy of an individual's characteristics. In this study, we define an individual's characteristics by three such reproductive states, namely successful, failed and non‐breeders in the previous year. We used a 16‐year dataset of individually marked breeding Eurasian OystercatchersHaematopus ostralegusto examine the interannual fluctuations in reproductive success and survival among breeding states, and their state‐dependent sensitivity to environmental conditions. Environmental conditions included available biomass of the main prey species of breeding Oystercatchers (Ragworm, Baltic Tellin and Lugworm), tidal height, which reflects one of the main causes of nest loss (flooding), and conditions that may impact the energetic requirements during incubation, such as temperature. We also included environmental variables measured in winter, including available biomass of the main winter prey species (Blue Mussel and Common Cockle) along with factors that may affect food availability and energetic requirements for homeostasis, namely bivalve weight loss, windchill, winter severity and precipitation. Breeding birds that were successful the previous year had higher survival and were more likely to remain successful, in comparison with failed or non‐breeders. The effects of environmental conditions acted in the same direction on reproductive success but had opposite effects on survival among the three breeding states, especially for windchill and Blue Mussel biomass. The contrasting state‐dependent effects of the environment on survival thus averaged out when examining consequences for lifetime reproductive nest success (LRnS); instead, LRnS was largely influenced by environmental conditions acting upon reproduction. Our study indicates that an individual's previous breeding state provides an integrative measure of heterogeneity in individuals' sensitivity of reproduction and survival to environmental change. Incorporating previous breeding state as a source of individual heterogeneity in population modelling may improve predictions of future population dynamics in a rapidly changing world.

Assessing the elemental fingerprints of cockle shells (Cerastoderma edule) to confirm their geographic origin from regional to international spatial scales

Geographic origin is directly linked to the quality and commercial value of bivalves. The globalization of the seafood trade and the increasing number of fraudulent practices in the bivalves industry has prompted consumers to become increasingly aware on the geographic origin of the seafood they consume. To enhance consumers' confidence and allow authorities to effectively enforce regulations and contain risks that threaten public health, fast and accurate tools must be made available to confirm claims along the trade chain on the geographic origin of bivalves. In the present study the efficiency of using the elemental fingerprints of a small-homogenized subsample of the shell of common cockles (Cerastoderma edule) to confirm their harvesting location is evaluated at different spatial scales: i) regional (along the Galician coast (Spain) - Espasante, Barallobre, Rio Anllóns, Camariñas, Muros, Noia, Carril, Grove, Combarro, Placeres, Moaña, and Baiona), ii) national (along the Portuguese coast - Ria de Aveiro, Óbidos lagoon, Tagus estuary, Sado estuary and Ria Formosa), and iii) international (along the Northeast Atlantic coast - Hejeltefjorden (Norway), Nykobing Mors (Denmark), Sylt (Germany), Slikken van Viane (Netherlands), Roscoff (France), Plymouth (England), Swansea (Wales), Ria de Aveiro (Portugal) and Oualidia (Morocco). Results confirm that elemental fingerprints of bivalve shells are significantly different among locations and that they can be successfully used with high accuracy to discriminate the geographic origin of cockles at all spatial scales surveyed (97.2% at regional scale, 99.3% at national scale and 100% at international scale). Overall, elemental fingerprints of a small-homogenized subsample of the shell showed to be a replicable, low cost and fast tool to reliably trace the place of origin of cockles sampled at different spatial scales, with success rate of discrimination directly increasing with distance between collection sites.

Biopolymer-based polycaprolactone-hydroxyapatite scaffolds for bone tissue engineering

This work synthesized Hydroxyapatite (HA) from common cockle shells using a precipitation method and fabricated nanofiber scaffolds of polycaprolactone (PCL)-HA composites with combinations of several polymers (i.e., gelatin, chitosan, and collagen) using electrospinning. The synthesized HA had a small agglomerate shape, solid structure, and few interconnected micropores. Energy Dispersive X-Ray Spectroscopy (EDS) analysis revealed that the synthesized HA exhibited a Ca/P molar ratio of 1.68. All nanofiber samples were nontoxic with cell viability values of 70.46–91.78%. The PCL-HA-Gelatin nanofiber was the best mechanical properties of the scaffold with the high values of tensile strength, modulus of elasticity, and breaking-point elongation at (9.80 ± 1.36) MPa, (0.81 ± 0.09) MPa, and (61.5 ± 7.75) %, respectively. There was no significant difference in the average cell viability of the samples. Nanofiber scaffolds of PCL-HA polymer have the potential for bone tissue engineering applications by satisfying their mechanical property and cytotoxicity assay criteria.