Spatial cost-benefit analysis of blue restoration and factors driving net benefits globally.

Marine coastal ecosystems, commonly referred to as blue ecosystems, provide valuable services to society but are under increasing threat worldwide due to a variety of drivers, including eutrophication, development, land-use change, land reclamation, and climate change. Ecological restoration is sometimes necessary to facilitate recovery in coastal ecosystems. Blue restoration (i.e., in marine coastal systems) is a developing field, and projects to date have been small scale and expensive, leading to the perception that restoration may not be economically viable. We conducted a global cost-benefit analysis to determine the net benefits of restoring coral reef, mangrove, saltmarsh, and seagrass ecosystems, where the benefit is defined as the monetary value of ecosystem services. We estimated costs from published restoration case studies and used an adjusted-value-transfer method to assign benefit values to these case studies. Benefit values were estimated as the monetary value provided by ecosystem services of the restored habitats. Benefits outweighed costs (i.e., there were positive net benefits) for restoration of all blue ecosystems. Mean benefit:cost ratios for ecosystem restoration were eight to 10 times higher than prior studies of coral reef and seagrass restoration, most likely due to the more recent lower cost estimates we used. Among ecosystems, saltmarsh had the greatest net benefits followed by mangrove; coral reef and seagrass ecosystems had lower net benefits. In general, restoration in nations with middle incomes had higher (eight times higher in coral reefs and 40 times higher in mangroves) net benefits than those with high incomes. Within an ecosystem type, net benefit varied with restoration technique (coral reef and saltmarsh), ecosystem service produced (mangrove and saltmarsh), and project duration (seagrass). These results challenge the perceptions of the low economic viability of blue restoration and should encourage further targeted investment in this field.

Análisis de Rentabilidad Espacial de la Restauración Azul y de los Factores Determinantes del Beneficio Neto Mundial Resumen Los ecosistemas costeros marinos, llamados comúnmente ecosistemas azules, proporcionan servicios valiosos para la sociedad, pero se encuentran bajo una amenaza creciente a nivel mundial causada por una variedad de determinantes, incluyendo la eutrofización, el desarrollo, el cambio en el uso de suelo, la reclamación de tierra y el cambio climático. Algunas veces se necesita de la restauración ecológica para facilitar la recuperación en los ecosistemas costeros. La restauración azul (es decir, en los sistemas costeros marinos) es un campo en desarrollo, con proyectos que a la fecha han sido a pequeña escala y costosos, lo que resulta en la percepción de que la restauración puede no ser viable económicamente. Realizamos un análisis de rentabilidad mundial para determinar los beneficios netos de la restauración de ecosistemas de arrecife de coral, manglar, marisma y pastos marinos en donde el beneficio está definido como el valor monetario de los servicios ambientales. Estimamos los costos a partir de estudios de caso de restauración publicados y usamos un método de transferencia de valor ajustado para asignar los valores de beneficio a estos estudios de caso. Los valores de los beneficios fueron estimados como el valor monetario proporcionado por los servicios ambientales de los hábitats restaurados. Los beneficios superaron los costos (es decir, fueron beneficios netos positivos) de la restauración de todos los ecosistemas azules. El beneficio promedio consistió en que la proporción de costos para la restauración del ecosistema fue 8-10 veces mayor que en los estudios anteriores de la restauración de los arrecifes de coral y los pastos marinos, probablemente debido a que usamos estimaciones de costo más bajas. Entre los ecosistemas, las marismas tuvieron los mayores beneficios netos seguidos por los manglares; los arrecifes de coral y los pastos marinos tuvieron los beneficios netos más bajos. En general, la restauración en los países con niveles medios de ingreso tuvo más beneficios netos (ocho veces más en los arrecifes de coral y 40 veces más en los manglares) que aquellos países con niveles altos de ingreso. En cuanto al tipo de ecosistema, el beneficio neto varió de acuerdo con la técnica de restauración (arrecife de coral y marisma), servicio ambiental producido (manglar y marisma) y duración del proyecto (pastos marinos). Estos resultados desafían las percepciones de la baja viabilidad económica que tiene la restauración azul y deberían fomentar una mayor inversión focalizada en este campo.

Deciphering mollusc shell production: the roles of genetic mechanisms through to ecology, aquaculture and biomimetics.

Most molluscs possess shells, constructed from a vast array of microstructures and architectures. The fully formed shell is composed of calcite or aragonite. These CaCO3 crystals form complex biocomposites with proteins, which although typically less than 5% of total shell mass, play significant roles in determining shell microstructure. Despite much research effort, large knowledge gaps remain in how molluscs construct and maintain their shells, and how they produce such a great diversity of forms. Here we synthesize results on how shell shape, microstructure, composition and organic content vary among, and within, species in response to numerous biotic and abiotic factors. At the local level, temperature, food supply and predation cues significantly affect shell morphology, whilst salinity has a much stronger influence across latitudes. Moreover, we emphasize how advances in genomic technologies [e.g. restriction site-associated DNA sequencing (RAD-Seq) and epigenetics] allow detailed examinations of whether morphological changes result from phenotypic plasticity or genetic adaptation, or a combination of these. RAD-Seq has already identified single nucleotide polymorphisms associated with temperature and aquaculture practices, whilst epigenetic processes have been shown significantly to modify shell construction to local conditions in, for example, Antarctica and New Zealand. We also synthesize results on the costs of shell construction and explore how these affect energetic trade-offs in animal metabolism. The cellular costs are still debated, with CaCO3 precipitation estimates ranging from 1-2 J/mg to 17-55 J/mg depending on experimental and environmental conditions. However, organic components are more expensive (~29 J/mg) and recent data indicate transmembrane calcium ion transporters can involve considerable costs. This review emphasizes the role that molecular analyses have played in demonstrating multiple evolutionary origins of biomineralization genes. Although these are characterized by lineage-specific proteins and unique combinations of co-opted genes, a small set of protein domains have been identified as a conserved biomineralization tool box. We further highlight the use of sequence data sets in providing candidate genes for in situ localization and protein function studies. The former has elucidated gene expression modularity in mantle tissue, improving understanding of the diversity of shell morphology synthesis. RNA interference (RNAi) and clustered regularly interspersed short palindromic repeats - CRISPR-associated protein 9 (CRISPR-Cas9) experiments have provided proof of concept for use in the functional investigation of mollusc gene sequences, showing for example that Pif (aragonite-binding) protein plays a significant role in structured nacre crystal growth and that the Lsdia1 gene sets shell chirality in Lymnaea stagnalis. Much research has focused on the impacts of ocean acidification on molluscs. Initial studies were predominantly pessimistic for future molluscan biodiversity. However, more sophisticated experiments incorporating selective breeding and multiple generations are identifying subtle effects and that variability within mollusc genomes has potential for adaption to future conditions. Furthermore, we highlight recent historical studies based on museum collections that demonstrate a greater resilience of molluscs to climate change compared with experimental data. The future of mollusc research lies not solely with ecological investigations into biodiversity, and this review synthesizes knowledge across disciplines to understand biomineralization. It spans research ranging from evolution and development, through predictions of biodiversity prospects and future-proofing of aquaculture to identifying new biomimetic opportunities and societal benefits from recycling shell products.

A global assessment of the vulnerability of shellfish aquaculture to climate change and ocean acidification.

Human-induced climate change and ocean acidification (CC-OA) is changing the physical and biological processes occurring within the marine environment, with poorly understood implications for marine life. Within the aquaculture sector, molluskan culture is a relatively benign method of producing a high-quality, healthy, and sustainable protein source for the expanding human population. We modeled the vulnerability of global bivalve mariculture to impacts of CC-OA over the period 2020-2100, under RCP8.5. Vulnerability, assessed at the national level, was dependent on CC-OA-related exposure, taxon-specific sensitivity and adaptive capacity in the sector. Exposure risk increased over time from 2020 to 2100, with ten nations predicted to experience very high exposure to CC-OA in at least one decade during the period 2020-2100. Predicted high sensitivity in developing countries resulted, primarily, from the cultivation of species that have a narrow habitat tolerance, while in some European nations (France, Ireland, Italy, Portugal, and Spain) high sensitivity was attributable to the relatively high economic value of the shellfish production sector. Predicted adaptive capacity was low in developing countries primarily due to governance issues, while in some developed countries (Denmark, Germany, Iceland, Netherlands, Sweden, and the United Kingdom) it was linked to limited species diversity in the sector. Developing and least developed nations (n = 15) were predicted to have the highest overall vulnerability. Across all nations, 2060 was identified as a tipping point where predicted CC-OA will be associated with the greatest challenge to shellfish production. However, rapid declines in mollusk production are predicted to occur in the next decade for some nations, notably North Korea. Shellfish culture offers human society a low-impact source of sustainable protein. This research highlights, on a global scale, the likely extent and nature of the CC-OA-related threat to shellfish culture and this sector enabling early-stage adaption and mitigation.

Coral restoration - A systematic review of current methods, successes, failures and future directions.

Coral reef ecosystems have suffered an unprecedented loss of habitat-forming hard corals in recent decades. While marine conservation has historically focused on passive habitat protection, demand for and interest in active restoration has been growing in recent decades. However, a disconnect between coral restoration practitioners, coral reef managers and scientists has resulted in a disjointed field where it is difficult to gain an overview of existing knowledge. To address this, we aimed to synthesise the available knowledge in a comprehensive global review of coral restoration methods, incorporating data from the peer-reviewed scientific literature, complemented with grey literature and through a survey of coral restoration practitioners. We found that coral restoration case studies are dominated by short-term projects, with 60% of all projects reporting less than 18 months of monitoring of the restored sites. Similarly, most projects are relatively small in spatial scale, with a median size of restored area of 100 m2. A diverse range of species are represented in the dataset, with 229 different species from 72 coral genera. Overall, coral restoration projects focused primarily on fast-growing branching corals (59% of studies), and report survival between 60 and 70%. To date, the relatively young field of coral restoration has been plagued by similar 'growing pains' as ecological restoration in other ecosystems. These include 1) a lack of clear and achievable objectives, 2) a lack of appropriate and standardised monitoring and reporting and, 3) poorly designed projects in relation to stated objectives. Mitigating these will be crucial to successfully scale up projects, and to retain public trust in restoration as a tool for resilience based management. Finally, while it is clear that practitioners have developed effective methods to successfully grow corals at small scales, it is critical not to view restoration as a replacement for meaningful action on climate change.