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Historically, considerations of the carbon budget of bivalve shellfish have disproportionately focused on the cycling of carbon in shell alone, overlooking respiratory release and the potential role of bivalve shellfish habitats in the stabilization of sediment, and therefore of carbon.Data on carbon cycling are key to providing essential evidence to inform evaluation of management strategies and the business case for restoration of European flat oyster (Ostrea edulis) habitats. The purpose of this study was to examine the flat oyster carbon budget at the scale of the individual and to set out a framework to enable future comparisons of carbon budgets between ecosystems.Through the combination of previously established work with measurements of calcification and respiration both in situ and ex situ, a carbon budget at the scale of a single oyster was determined.In consideration of the flat oyster carbon budget, the inclusion of the deposition of sedimentary carbon, as well as carbon stored in shell, balanced with the release of carbon through respiration and calcification suggests that these habitats are unlikely to be significant carbon sinks in the context of global climate change mitigation. However, the recovery of flat oyster beds is likely to facilitate the accretion of substantial carbon stocks that are nevertheless important in conservation management. [ABSTRACT FROM AUTHOR]

Benthic marine invertebrates, such as oysters, rely on larval recruitment for their populations to persist. This can be by self‐recruitment to the natal population or recruitment from geographically distant populations.Marine invertebrate larvae are increasingly understood to influence their dispersal through vertical migrations, based on a combination of responses to external cues and the larvae's ontogenetic stage.This study examined the larval behaviour of the European oyster Ostrea edulis in laboratory experiments. The aim was to establish if larvae show systematic behaviour that could affect dispersal. Vertical distribution, swimming speeds, and behaviour of O. edulis larvae were quantified throughout their ontogenetic development, and under scenarios of light/dark, food/no food, and two temperatures.Most O. edulis larvae concentrated at the bottom of the aquarium, independent of developmental stage or treatment, and consistently over time. Larvae behaved actively in ~50% of all bottom observations, indicating a behavioural function other than resting. At the surface, larvae frequently formed aggregations. In the water column, larvae swam with high vertical directionality and their distribution was homogenous. Swimming speeds ranged from 0.001 to 9.07 mm s−1.Advection close to the seabed is slower than in any other part of the water column. The demersal preference of O. edulis may be targeted towards increasing the likelihood of self‐recruitment, which is consistent with the larvae's preference to settle in the presence of conspecifics. Stronger hydrodynamic environments are likely to override the larvae's demersal behaviour. It is recommended to restore European oyster beds at sufficient scale, density, and rugosity to promote retention of larvae within the natal population and minimize larval loss and mortality, as well as to account for the observed behaviours in networks of restoration sites. [ABSTRACT FROM AUTHOR]

Globally, momentum to restore damaged habitats has been increasing. For example, the number of European shellfish restoration projects has quadrupled in the past 3 years. In line with the increasing focus on both restoration and climate change mitigation efforts, this study highlights how these two practices can complement each other.This experimental study quantifies the active and passive sediment deposition associated with the European flat oyster (Ostrea edulis) and the organic and inorganic carbon fractions of the deposits. Treatments included 'dead', 'live', and control to account for (i) passive deposition, (ii) biodeposition and passive deposition, and (iii) background deposition respectively. By utilizing these data, the expected carbon deposition associated with a restored flat oyster bed was investigated.The experiment was conducted ex situ, with natural seawater input. Covariate data on temperature, suspended particulate influx, salinity, and oxygen availability were recorded. Enhanced sedimentation (2.9 times) and organic carbon deposition (three times) were observed in the presence of living oysters, compared with the control. The shell structure of the oysters had no influence on passive sedimentation in this study.By developing a full understanding of the ecosystem services (functioning, supporting, regulating, and cultural) provided by a habitat, it becomes possible to quantify overall ecosystem function. This evidence is key in advising policymakers, restoration funders, and marine spatial planners on the connection between keystone species restoration, ecosystem service restoration, and conservation management.The enhancement of benthopelagic coupling by the European flat oyster, evidenced here for the first time, is contextualized from the perspective of quantification of ecosystem service provision for both restoration practices and blue carbon store management. The data produced in this study are discussed comparatively with work that has focused on other species from both Europe and the USA. [ABSTRACT FROM AUTHOR]

Modiolus modiolus L. (horse mussel) reefs are a priority marine habitat of high conservation value that is currently listed as endangered and/or threatened across its European distribution. Population structure, density or shell morphology may influence the biodiversity of a reef, either directly or indirectly. Thus, such metrics are important considerations for successful conservation management of these biodiversity hotspots. Population structure, shell morphology and growth rates were examined in M. modiolus reefs across the UK range of the habitat to examine differences between key populations, including those near the Lleyn Peninsula in Wales (southern range), off Port Appin in Western Scotland (mid-range) and in Scapa Flow in the Orkney Isles, Scotland (northern range). Additionally, the influence of physical conditions (temperature and tidal flow) to growth rate and predicted maximum shell length for each population was examined. Growth rates were determined using acetate peels of sectioned shells. Lower juvenile abundance was observed in Scapa Flow. Small, narrow-shaped shells were found to be characteristic of North Lleyn mussels, and larger, globular-shaped shells were characteristic of mussels in Scapa Flow and off Port Appin. Mussels in Scapa Flow were slower growing, yet reached a longer asymptotic length (L ∞) than mussels of Port Appin and North Lleyn. Growth curves from sites within this study were analysed with other published data. A trend of higher L ∞ at higher latitudes and at lower flow rates was observed. Variations in growth and age are discussed in relation to flow regimes, connectivity to other reefs, density and latitude. [ABSTRACT FROM AUTHOR]

Modiolus modiolus reefs have disappeared from most of their historical distribution range in Strangford Lough (Northern Ireland) while remnant populations are highly fragmented., This study investigated morphological differences in Strangford Lough and Irish Sea M. modiolus with an aim to provide sound scientific advice to managers involved in shellfish reef restoration programmes including translocation., By characterizing shape ecophenotypes within target and source areas it is possible to select morphologically similar source stocks to increase survival and self sustainability of the restored population., Linear and geometric shell shape analyses identified significant differences among M. modiolus populations from the Irish Sea and Strangford Lough. Three different phenotypes within the Strangford Lough metapopulation were identified. It is hypothesized that substrate type, tidal current strength and population thinning caused by mobile fishing gear influenced such morphological differences., This investigation confirmed, for the first time, phenotypic variability in M. modiolus which could affect future supplementation programmes aiming to restore degraded populations., Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Grey seals (Halichoerus grypus) are a species of conservation concern that require Marine Protected Area management and population status assessment under the EU Habitats Directive. Aerial surveys are commonly used to monitor grey seal pup production at their globally important UK colonies. However, in Wales more than half of pups are born in cryptic breeding habitats such as sea caves. These cryptic habitats preclude the use of aerial monitoring methods and necessitate ground-based counts, which are costly in resources. In this study, we compare a ground-based pup production census with a reduced effort plot-sampling survey to estimate pup production, derive a total population size and assess cost effectiveness. Pup production in North Wales was estimated at 91 (95% confidence interval: 70–112) by the plot-sampling design and was a good approximation of the ‘true’ value of 96 derived from the census. The total population size in North Wales was estimated at between 242 and 307 grey seals. The plot-sampling design reduced survey effort by 46% and saved 30% on logistical costs compared to the full census. We outline the suitability of this method as part of a monitoring programme for grey seal pup production and suggest our approach may be applicable to other regions where grey seals use cryptic breeding habitat. [ABSTRACT FROM PUBLISHER]