Edulis Populations Research Articles

Will climate change constrain the altitudinal range of threatened species? Experimental evidence from a biodiversity hotspot

Abstract A fundamental goal in ecology and evolution is to explain the factors that shape species' abundance and range limits. Evaluating the performance of early life‐stages across an altitudinal gradient can be valuable for understanding what factors shape range limits and for predicting how plant species may respond to climate change. To experimentally evaluate the presence of local adaptation in a threatened palm (Euterpe edulis) at early life‐stages, we reciprocally sowed seeds at two contrasting elevations. In addition, to evaluate the effect of seed predation on E. edulis seed germination and seedling establishment, seed addition experiments were conducted at three different elevations. Our results showed no evidence of local adaptation in the early life‐stages for the two E. edulis populations. We observed lower germination and seedling performance of both E. edulis populations at the low‐elevation site. The exclusion of seed predation increased seedling establishment across all elevations. Seed predation and dry soil conditions were the main factors that constrained seedling establishment at the upper altitudinal limit and at the lower elevation, respectively. Climate change in the study area will result in warmer and drier environmental conditions. The lack of local adaptation and the lower performance of both E. edulis populations in warm and dry conditions, combined with a higher seed predation at the upper altitudinal limit, might cause an altitudinal range contraction, increasing the vulnerability of this threatened species to climate change.

Population connectivity of the swordtip squid Uroteuthis edulis between southern Japan and northern Taiwan using statolith trace elemental analysis

Uroteuthis edulis (Hoyle, 1885) is an Indo-Pacific squid species widely distributing in the western Pacific, and commercially important especially in Japan and Taiwan. It has been suggested that some individuals are possibly transported from the spawning ground in north Taiwan to the coasts of Japan, however, the strength of population connectivity between those areas and its influence on U. edulis population dynamics were unveiled. To understand the U. edulis population connectivity in this area, the correlations between statolith trace elements and abiotic/biotic factors were examined first, and then squid experienced environments were postulated throughout their entire life cycle. Sr/Ca ratio showed a strongly negative correlation with ambient water temperature but no correlation with individual growth rate, suggesting that Sr/Ca ratio can be used to reflect squid experienced temperatures. Most squid caught in the Sea of Japan hatched in the areas having similar water temperature with where Taiwanese squid hatched, that would be off the north Taiwan or even warmer area. Statolith trace elements successfully distinguished the catch locations but not the hatching grounds, implying that hatching grounds of Japan and Taiwan squid were largely overlapped. Thus, we suggest that there is strong population connectivity of U. edulis population between southern Japan and northern Taiwan. As there was no clear evidence for existence of local population hatched in the Sea of Japan in this study, U. edulis population might display a source-sink population dynamics, that is, population in Taiwanese waters and/or further south as the source, and the one in the Sea of Japan as a sink population. As U. edulis should be considered as a metapopulation, collaboration among countries in the northwestern Pacific is required for sustainable fishery management of this species.

Regenerative strategies of Euterpe edulis (Arecaceae) at its altitudinal limits in the Atlantic Forest

AbstractPopulations occurring at the limit of a species' altitudinal distribution undergo strong environmental filtering. Rapid climate change intensifies this process, impacting ecological responses of populations. Understanding the effects of climate change, especially in the early stages of plant development, has become essential to predict vulnerability to extinction. However, few studies have explored initial establishment strategies of plant populations at the limit of their distribution in the face of global warming. We tested the effects of increasing temperatures on germination performance and on initial seedling establishment on two populations of Euterpe edulis, a palm tree widely distributed in the Atlantic Forest between 0 and 1400 m altitude. The tests were conducted in a laboratory, where the seeds were exposed to three conditions for 90 days: control at 25°C, and two treatments at higher temperatures (35 and 40°C). Germination percentage was not affected by population, seed size class or treatments. Average time for germination only increased in the Montane Forest population in the most extreme treatment, while in the sea level Restinga population, time for germination was affected by a small temperature increase. Mortality percentage in the Restinga population was similar in the post‐germination phase and in the temperature treatments. We concluded that E. edulis populations located at their lower altitudinal limit are closer to the species thermal limit, thus being more vulnerable to temperature increase than populations at the upper limit of the species' altitudinal distribution.

The Fecundity Characteristics and Spawning Strategy of Uroteuthis edulis in the East China Sea.

The fecundity characteristics and spawning strategy of Uroteuthis edulis in the East China Sea were investigated by observing the potential fecundity (PF), relative fecundity by dorsal mantle length (PFML) and relative fecundity by body weight (PFBW). The relationship between fecundity and a single biological indicator was measured, and generalized additive models (GAMs) were fit by adding environmental variables to help better understand this comprehensive relationship. The long diameter and short diameter of the ovarian oocytes ranged from 0.72 mm to 4.74 mm and from 0.46 mm to 3.67 mm, respectively. The long and short diameters of oviducal eggs ranged from 0.61 mm to 5.12 mm and from 0.39 mm to 3.81 mm, respectively. The egg diameter had a unimodal distribution. The PF, PFML and PFBW ranged from 540 to 13,743 cells, 5 to 86 cells/mm and 6 to 53 cells/g, respectively. Three fecundity indicators were unimodally distributed, and the PFBW was more stable than the PFML (δ2PFBW < δ2PFML). The fecundity and single biological indicators were fitted, and it was found that the PF and PFML were positively correlated with dorsal mantle length (ML) and body weight (BW). The generalized additive model (GAM) fitting showed that when considering the interaction between dorsal mantle length and sea surface height (M13), the deviation explanation rate of the PF and PFML was the highest. Studies have shown that the ovary oocytes of U. edulis mature in batches, and then the eggs are laid in batches. The dorsal mantle length (ML), water temperature at 25 m depth (T25) and sea surface height (SSH) are important indicators to measure the fecundity of U. edulis. These findings allow for a deeper understanding of the U. edulis population dynamics for the future management of this economically and ecologically important species.

Assessing the demographic connectivity of common cockles in a shallow estuary as a basis for fisheries management and stock protection efforts

Common cockle Cerastoderma edule populations in the Danish Limfjorden constitute an important ecosystem component and a valuable resource for fishermen and industries, providing a large proportion of cockle landings in both Denmark and the European Union. However, processes driving cockle recruitment and mortality are not well understood, and prevent sustainable fisheries management and species protection efforts. We report a thorough study of processes that are the main drivers of population recruitment, namely larval dispersal and settlement. Outputs from biophysical modelling of cockle larval dispersal, connectivity analysis and derived graph theory metrics were used to analyse potential demographic connectivity or isolation between known cockle populations and other parts of Limfjorden. The results show that the most productive and commercially important cockle beds are almost exclusively dependent on larval imports from unexploited spawning biomass elsewhere rather than on self-recruitment, allowing for exploitation levels that would be unsustainable otherwise. Other parts of Limfjorden are relatively isolated, relying mostly on self-recruitment. The results also show that in some areas where predicted larval settlement potentials are highest, the absence of a cockle population indicates that other factors, likely environmental, are more important. This study provides an example of contrasting population dynamics and connectivity, suggesting that the vulnerability of cockle populations to exploitation or natural mortality may be highly variable and interlinked. Ignoring processes affecting larval dispersal may jeopardise cockle populations and fisheries in Limfjorden. This study highlights the importance of understanding processes of marine connectivity for the protection of bivalve populations and sustainable fisheries management.

Toxicity of tributyltin to the European flat oyster Ostrea edulis: Metabolomic responses indicate impacts to energy metabolism, biochemical composition and reproductive maturation.

Tri-Butyl Tin (TBT) remains as a legacy pollutant in the benthic environments. Although the toxic impacts and endocrine disruption caused by TBT to gastropod molluscs have been established, the changes in energy reserves allocated to maintenance, growth, reproduction and survival of European oysters Ostrea edulis, a target species of concerted benthic habitat restoration projects, have not been explored. This study was designed to evaluate the effect of TBT chloride (TBTCl) on potential ions and relevant metabolomic pathways and its association with changes in physiological, biochemical and reproductive parameters in O. edulis exposed to environmental relevant concentrations of TBTCl. Oysters were exposed to TBTCl 20 ng/L (n = 30), 200 ng/L (n = 30) and 2000 ng/L (n = 30) for nine weeks. At the end of the exposure, gametogenic stage, sex, energy reserve content and metabolomic profiling analysis were conducted to elucidate the metabolic alterations that occur in individuals exposed to those compounds. Metabolite analysis showed significant changes in the digestive gland biochemistry in oysters exposed to TBTCl, decreasing tissue ATP concentrations through a combination of the disruption of the TCA cycle and other important molecular pathways involved in homeostasis, mitochondrial metabolism and antioxidant response. TBTCl exposure increased mortality and caused changes in the gametogenesis with cycle arrest in stages G0 and G1. Sex determination was affected by TBTCl exposure, increasing the proportion of oysters identified as males in O. edulis treated at 20ng/l TBTCl, and with an increased proportion of inactive stages in oysters treated with 2000 ng/l TBTCl. The presence and persistence of environmental pollutants, such as TBT, could represent an additional threat to the declining O. edulis populations and related taxa around the world, by increasing mortality, changing reproductive maturation, and disrupting metabolism. Our findings identify the need to consider additional factors (e.g. legacy pollution) when identifying coastal locations for shellfish restoration.

Population dynamics of the European native oyster in a Marine Conservation Zone exposed to unregulated harvesting

The implementation of closed zones as fishery management tools have been shown to be successful in the augmentation of habitat restricted species. A concerted restoration effort is currently being focused on the European native oyster throughout its natural range. This has been accompanied by an increase in oyster prices. In 2018 a native oyster for restoration purposes cost 80 pence sterling by 2021 the price had increased to £3.50. It is likely that these price increases have led to harvesting pressure on established wild populations. A number of recovering Ostrea edulis assemblages in Strangford Lough Northern Ireland are located within a closed zone which has been in operation since 2008. This research investigated the effectiveness of this restricted area in regards to protecting O. edulis assemblages. The study revealed that within policed regions of the restricted area the population increased from an estimated 1000 oysters in 2004 to &gt;88,000 in 2021. Furthermore, the age structure and population dynamics differed considerably from non-policed areas which still experienced harvesting. The research supports the use of closed zone legislation as a conservation tool with developing O. edulis populations. As newly restored populations become established, rising market prices will place these under increased harvesting pressure. The use of closed zones may offer a means of protecting these emergent populations.

Features of the spatial structure of the macro- and meiobenthos community of the lagoon ecosystem of Kislaya Bay head (Gulf of Kandalaksha, White sea)

The spatial and species structure of meio- and macrobenthos communities of the Kislaya Bay (Gulf of Kandalaksha, White Sea) lagoon ecosystem was analysed. A total of 32 species of benthic organisms (including 11 species of invertebrate larvae) and 9 species of seagrasses and algae were found. Eumeiobenthos groups were identified to the level of large taxa (nematodes, harpacticoids, ostracods, turbellaria). The highest total biomass of macrobenthos organisms was mainly observed in the lower horizon of the littoral zone and at the exit from the lagoon (high biomass of Mytilus edulis populations). For meiobenthos biomass was the highest in the middle and upper littoral horizons and in the bayhead. This may indicate a complementary distribution of meio- and macrobenthos: the role of meiofauna grew where macrobenthos development was somewhat inhibited. An analysis of the similarity of meio- and macrobenthos of different habitats revealed differences in the species structure of communities between the three littoral horizons – upper, middle, and lower. Communities of the lower and middle horizons of the littoral zone exhibited a greater similarity of the species structure than communities of the upper horizon. The differences in the structural characteristics of the community lengthwise – with increasing water salinity, are less pronounced (especially when compared with the corresponding structural changes in meio- and macrobenthos in the Chyornaya River estuary). This is probably due to the milder salinity conditions in the lagoon versus the Chyornaya River estuary, lower impact of this factor on the distribution of aquatic organisms and, accordingly, smaller change in the species structure of the community lengthwise – from the bayhead towards the sea.

Chromosome-level genome assembly of the European flat oyster (Ostrea edulis) provides insights into its evolution and adaptation

The European flat oyster (Ostrea edulis) is an endangered and economically important marine bivalve species that plays a critical role in the coastal ecosystem. Here, we report a high-quality chromosome-level genome assembly of O. edulis, generated using PacBio HiFi-CCS long reads and annotated with Nanopore full-length transcriptome. The O. edulis genome covers 946.06 Mb (scaffold N50 94.82 Mb) containing 34,495 protein-coding genes and a high proportion of repeat sequences (58.49 %). The reconstructed demographic histories show that O. edulis population might be shaped by breeding habit (embryo brooding) and historical climatic change. Comparative genomic analysis indicates that transposable elements may drive lineage-specific evolution in oysters. Notably, the O. edulis genome has a Hox gene cluster rearrangement that has never been reported in bivalves, making this species valuable for evolutionary studies of molluscan diversification. Moreover, genome expansion of O. edulis is probably central to its adaptation to filter-feeding and sessile lifestyles, as well as embryo brooding and pathogen resistance, in coastal ecosystems. This chromosome-level genome assembly provides new insights into the genome feature of oysters, and presents an important resource for genetic research, evolutionary studies, and biological conservation of O. edulis.

Impacts of landscape-scale forest loss and a dry event on the demographic structure of the endangered palm Euterpe edulis Mart. in the Atlantic Forest

Forest loss is one of the most serious threats to biodiversity in the tropics and mainly occurs due to the conversion of native forests by the expansion of human activities. In addition, regional climate change is likely to adversely affect the remaining biota. These disturbances may have direct or indirect consequences on the demographic structure of plant species in human-modified landscapes. To test this hypothesis, and thus look for management practices aimed at enhancing the population viability, we used the palm species Euterpe edulis Mart. (Arecaceae) to assess the demographic structure of five ontogenetic stages prior (2014) and after (2017) a prolonged drought event (2015) that occurred in the northeastern Atlantic Forest of Brazil. We also investigated the influence of landscape forest cover on the ontogenetic demographic structure, given that forest remnants were embedded within landscapes ranging from 6 to 97% of forest amount. We revealed that forest cover was a key predictor explaining the abundance patterns of E. edulis, with all ontogenetic stages (except seedlings, immature, and adults) exhibiting lower abundance in forest remnants surrounded by lower amount of native forests. Conversely, the regional drought event unaffected the demographic structure of this palm species, which may suggest that populations of E. edulis were able to cope with an isolated, though severe, drought event. The impacts of forest loss on E. edulis demographic structure, particularly on juveniles, raises a concern about the future persistence of E. edulis populations, since the early stages represent the adult generation in the near future. Management measures, including species reintroduction, forest restoration, environmental education programmes and the enforcement of environmental laws must be encouraged to safeguard E. edulis populations in the Atlantic Forest.

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.

Linking Plant Functional Traits to Demography in a Fragmented Landscape

Habitat loss in highly deforested landscapes such as the Brazilian Atlantic Forest has been severely affecting the diversity and survival of palm species. As some species are more sensitive than others, trait responses to the environment, as well as environmental effects on fecundity, growth, and mortality rates, may affect species demography. Considering this context, we studied functional and demographic responses of three palm species (Astrocaryum aculeatissimum, Euterpe edulis, and Geonoma schottiana) to habitat loss in the Atlantic Forest in southeastern Brazil by measuring morpho-physiological traits related to plant growth and light acquisition for photosynthesis. We also tested the response of population fitness to fragment size. Plant survival and growth was subsequently monitored in 2006 and 2007, and population dynamics were summarized in pool matrices for large and small forest fragments in the monitoring periods comprehending one full year between 2005–2006 and 2006–2007. The asymptotic growth rate of populations (defined here as population fitness, λ) in five forest fragments was then calculated. Diameter of individuals of the demography plots (from year 2005 to 2007) was used to calculate the relative diameter growth rate. Later, in 2015, we measured a set of morpho-physiological functional traits in palms in the same plots used in the demographic studies. While A. aculeatissimum populations were stable in both monitoring periods in small and large fragments, E. edulis populations were predicted to decline due to intense predation by monkeys in the large fragment, but were stable in the smaller fragments, and G. schottiana populations were stable in the large fragments in both monitoring periods, but populations in the smaller fragments were predicted to decline in the second period, i.e., with lower fitness in these fragments. In addition, the functional traits analyzed showed that G. schottiana is a forest interior species associated with the shade/understory environment response. E. edulis was also affected by the size of the fragment, but due to a disruptive interaction with a predator and showed intermediate functional traits values. On the other hand, A. aculeatissimum thrived in areas with higher and lower incidence of light and was not demographically affected by forest remnant size. This suggests that E. edulis and A. aculeatissimum are habitat generalists. We concluded that differences in the ecophysiological performance of palms due to distinct morpho-physiological functional traits related to leaf economic spectrum, such as LDMC or specific leaf area (SLA) and to photosynthetic responses to light environment as electron transport rate (ETR) and saturation irradiance (Ik) were linked to the demographic variation observed in forest remnants of different size.

Genomic Insights into the Historical Population Dynamics and Spatial Differentiation of an Endangered Island Endemic Palm,Brahea edulis

Premise of research. Brahea edulis is an endangered palm endemic to the oceanic island of Guadalupe, Mexico, with a small population of just about 4000 individuals; it was chronically grazed by goats for about two centuries. The evolutionary specificities of insular biotas provide unique scenarios for studying the roles of geography, demography, and climate in driving population divergence. A comprehensive comparison between insular and mainland sister species contributes to a much better understanding of the species-specific responses to the ecological drivers of diversity, divergence, and speciation.Methodology. Here we used a comparative approach coupled with genomic (genotyping by sequencing; single-nucleotide polymorphisms) data to analyze samples from island and mainland Brahea palm species and elucidate their diversity, population divergence, and demographic history.Pivotal results. Genetic diversity analyses revealed higher diversity in insular palms compared with their mainland sister species. Genetic relationships among palm individuals on Guadalupe Island resulted in two strongly diverged clusters that reflected their geographic distributions. Divergence among B. edulis populations was mostly driven by the joint effect of low migration and the climatic heterogeneity of the island’s conditions. Using approximate Bayesian analysis, we further evaluated the demographic history of B. edulis. We found the genetic signatures of demographic fluctuations, inferring an effective population size (Ne) reduction that occurred in the late Quaternary and relatively low current Ne.Conclusions. These findings contribute to the ever-growing body of evidence that low genetic diversity in island populations cannot always be generalized. Besides, genetic diversity and differentiation on islands are more likely to be species specific and are strongly influenced by population size and historical factors such as the time since the population was established, ecological characteristics of the island, and anthropogenic impact. Our results also represent groundwork for future conservation and restoration programs for this endangered insular palm species.

Co-occurrence of pathogen assemblages in a keystone species the common cockle Cerastoderma edule on the Irish coast.

Despite coinfections being recognized as the rule in animal populations, most studies focus on single pathogen systems. Pathogen interaction networks and the drivers of such associations are lacking in disease ecology studies. Common cockle Cerastoderma edule populations are exposed to a great diversity of pathogens, thus making them a good model system to investigate. This study examined the diversity and prevalence of pathogens from different taxonomic levels in wild and fished C. edule on the Irish coast. Potential interactions were tested focussing on abiotic (seawater temperature and salinity) and biotic (cockle size and age, and epiflora on shells) factors. No Microsporidia nor OsHV-1μVar were detected. Single infections with Haplosporidia (37.7%) or Vibrio (25.3%) were more common than two-pathogen coinfected individuals (9.5%), which may more easily succumb to infection. Fished C. edule populations with high cockle densities were more exposed to infections. Higher temperature and presence of epiflora on cockle shells promoted coinfection in warmer months. Low seawater salinity, host condition and proximity to other infected host species influenced coinfection distribution. A positive association between two Minchinia spp. was observed, most likely due to their different pathogenic effect. Findings highlight the major influence that ecological factors have on pathogen interactions and host–pathogen interplay.

Modelling spatial and temporal patterns in bioturbator effects on sediment resuspension: A biophysical metabolic approach

Tidal flats are biogeomorphic landscapes, shaped by physical forces and interaction with benthic biota. We used a metabolic approach to assess the overarching effect of bioturbators on tidal landscapes. The benthic bivalve common cockle (Cerastoderma edule) was used as model organism. The effect of C. edule on sediment resuspension was approximated as a function of the overall population metabolic rate per unit of area. We combined i) laboratory observations on how C. edule affect sediment resuspension along gradients of bioturbation activity, sediment cohesiveness and hydrodynamic force with ii) spatial data on the natural distribution of intertidal C. edule populations. This allowed us to build an integrated model of the C. edule effect on sediment resuspension along the tidal gradient. Owing to the temperature dependence of metabolic rate, the model also accounted for seasonal variation in bioturbators activity.Laboratory experiments indicated that sediment resuspension is positively related to the metabolic rate of the C. edule population especially in cohesive sediments. Based on this observation, we predicted a clear spatial and seasonal pattern in the relative importance of C. edule contribution to sediment resuspension along a tidal transect. At lower elevations, our model indicates that hydrodynamics overrules biotic effects; at higher elevations, inter-tidal hydrodynamics should be too low to suspend bioturbated sediments. The influence of C. edule on sediment resuspension is expected to be maximal at the intermediate elevation of a mudflat, owing to the combination of moderate hydrodynamic stress and high bioturbator activity. Also, bio-mediated sediment resuspension is predicted to be particularly high in the warm season.Research into metabolic dependency of bio-mediated sediment resuspension may help to place phenomenological observations in the broader framework of metabolic theories in ecology and to formulate general expectations on the coastal ecosystem functioning.

Phylogeography in an \u201coyster\u201d shell provides first insights into the genetic structure of an extinct Ostrea edulis population

The historical phylogeography of Ostrea edulis was successfully depicted in its native range for the first time using ancient DNA methods on dry shells from museum collections. This research reconstructed the historical population structure of the European flat oyster across Europe in the 1870s—including the now extinct population in the Wadden Sea. In total, four haplogroups were identified with one haplogroup having a patchy distribution from the North Sea to the Atlantic coast of France. This irregular distribution could be the result of translocations. The other three haplogroups are restricted to narrow geographic ranges, which may indicate adaptation to local environmental conditions or geographical barriers to gene flow. The phylogenetic reconstruction of the four haplogroups suggests the signatures of glacial refugia and postglacial expansion. The comparison with present-day O. edulis populations revealed a temporally stable population genetic pattern over the past 150 years despite large-scale translocations. This historical phylogeographic reconstruction was able to discover an autochthonous population in the German and Danish Wadden Sea in the late nineteenth century, where O. edulis is extinct today. The genetic distinctiveness of a now-extinct population hints at a connection between the genetic background of O. edulis in the Wadden Sea and for its absence until today.

Resilient protected area network enables species adaptation that mitigates the impact of a crash in food supply

With coastal wader populations exhibiting long-term declines globally, understanding how they respond to changes in their preferred prey is important for future predictions, especially given the potential for warming seas to affect invertebrate populations. The cockleCerastoderma edulepopulation in the Burry Inlet Special Protection Area (SPA) in south Wales, UK, declined from 1997-2004 before an abrupt ‘crash’ in stocks between 2004 and 2010. While there has been some recovery since, stocks of larger cockles are still very low. Using survey data from the UK Wetland Bird Survey and analyses of apparent survival and biometrics from ringing, we investigated how the Burry Inlet SPA’s wintering Eurasian oystercatcherHaematopus ostraleguspopulation responded to this crash. Our analysis showed that both body condition and apparent survival of wintering adult oystercatchers were reduced in the years following the cockle crash but both recovered. The number of birds using the Burry Inlet SPA decreased through the course of the cockle stock decline whilst numbers of birds in the adjacent Carmarthen Bay increased, indicating the importance of adjacent sites for buffering the effects of such changes, i.e. protected secondary habitats can be a vital component of a resilient site network. Our findings are useful in understanding how a predator copes with a serious decline in its preferred food stocks. This study has wide applicability in planning the management of coastal wetlands and shellfisheries as well as the design of resilient protected area networks in the light of environmental change.

Could impact investing catalyse an ecosystem wide recovery for native oysters and native oyster beds? Lessons learned from the Zoological Society of London's Rhino Impact Investment Bond that could shape the future of oyster restoration

Abstract Ostrea edulis populations have declined by more than 95% since the mid‐1800s due to historical over‐harvesting, disease, competition from invasive species, and predators. Once the basis of a thriving fishery, it is now one of the most threatened habitats in Europe and restoration is high on the conservation agenda. Impact investing is a novel financing model that attracts investors who put creating positive, measurable social outcomes at the heart of their decision‐making process, while also seeking a financial return. Impact bonds, more specifically, are instruments designed to link these investors with beneficial projects and financial returns. Payoff is derived from the success or failure of a service provider in delivering pre‐agreed outcomes. The Rhino Impact Investment is such a project, which aims to increase black rhino numbers by using an impact bond structure, where capital is directed to fund evidence‐based management interventions, and financial gain or loss to the investors depends on the scale to which rhino numbers increase or decrease across a portfolio of project sites. The authors present a hypothetical impact bond model that could be used to address the decline in O. edulis. Investors provide capital that is dispersed among a portfolio of restoration sites to implement interventions designed to increase oyster habitat and numbers. At maturity, outcome payers reimburse investors with their capital plus or minus a rate of return based on independent verification of the outcomes achieved or not achieved. The Rhino Impact Investment project is the only current impact bond model aimed at species recovery and, as such, there is very little evidence to go on with regards to the legal and regulatory framework surrounding such instruments and the restoration of ecological systems and biodiversity. More work is needed on a regulatory and project level to take feasibility testing to the next stage.

Microfibers in Mytilus species(Mollusca, Bivalvia)from Southern California Harbors, Beaches, and Supermarkets

Plastic microfibers are an emerging threat to terrestrial and aquatic habitats worldwide. They are equivalent in size to planktonic organisms, making them available to a range of invertebrates. Bivalve mollusks can ingest and accumulate plastics via digestion and adherence to soft tissue. We determined the frequency and characteristics of microfiber pollution from wild Mytilus californianus and farmed Mytilus edulis populations that were collected from southern California harbors, beaches, and supermarkets (n=4 per site). Mussel organic matter was dissected using 30% H2O2. After adding a saline solution to separate the fibers, the liquid was filtered by vacuum filtration. The remaining fibers were examined with a magnification of 1~8x. In this short-term survey, the abundance of microfibers by sample and by shell length showed a significant difference between the harbor and beach sites. However, there was not a significant difference between the wild and farmed mussels examined. This study revealed widespread microfiber pollution and uptake by mussels in these locations and reinforces how bivalves can be used as a bioindicator of microfiber pollution. KEYWORDS: Microplastic; Microfiber; Mytilus; Biomonitoring; Bivalvia; Seafood; Human Health

Biotic and abiotic factors influencing haplosporidian species distribution in the cockle Cerastoderma edule in Ireland

The Phylum Haplosporidia consists of four genera (Minchinia, Haplosporidium, Urosporidium and Bonamia) that are endoparasitic protists of a wide range of marine invertebrates including commercial bivalve species. Characterization of haplosporidian species remains a challenge due to their patchy spatial and temporal distributions, host-restricted occurrence, and poorly known life cycles. However, they are commonly associated with significant mortality events in bivalves. Due to the recent sporadic mortality events that have occurred in cockles in Europe, the objectives of this study were to determine the diversity, distribution and seasonality of haplosporidian species in Cerastoderma edule populations at several Irish sites. The role of abiotic (temperature, salinity and dissolved oxygen in water) and biotic (cockle size and age) factors as drivers or inhibitors of haplosporidian infection were also assessed. Cockles (n = 998) from the intertidal were sampled from April/July 2018 to April 2019 at three sites with no commercial fishing activity on the south coast (Celtic Sea) and one site on the northeast coast (Irish Sea) with an active commercial fishery. Screening of the cockles by molecular techniques (PCR, Sanger sequencing) and by histopathology was carried out. Two species were identified and confirmed in Irish C. edule for the first time, Minchinia mercenariae -like (14.8%) and Minchinia tapetis (29.6%). Similar to other haplosporidian parasites, the Minchinia spp. detected in our study were present year-round at all sites, except for M. tapetis in Youghal Bay (Celtic Sea). Coinfection of both Minchinia species was only observed in Cork Harbour (Celtic Sea) and Dundalk Bay (Irish Sea), where Minchinia spp. showed a higher presence compared to Youghal Bay and Dungarvan Harbour (Celtic Sea). Moreover, haplosporidians detected with generic primers, were present at all of the sample sites throughout the year but had a higher occurrence during the winter months and were positively correlated with dissolved oxygen. Likewise, smaller and older C.edule seemed to be more vulnerable to the haplosporidian infection. Furthermore, haplosporidian distribution displayed spatial variability between and within sample sites, with the highest presence being observed in cockles at one of the commercially fished Dundalk beds, while the lowest presence was observed in cockles at the second Dundalk bed that was more influenced by freshwater runoff when the tide was out. Findings from this study provide additional information on the distribution and seasonal presence of novel haplosporidian species and their potential abiotic and biotic drivers/inhibitors of infection.