Publications

Abstract Blue carbon ecosystems (BCEs) exhibit remarkable capacities for organic carbon (C) storage, making them a promising nature‐based climate solution. However, the lack of robust, spatially explicit estimates of C stocks in BCEs presents a major challenge to incorporating them into national and global C accounting and climate mitigation strategies. For the first time, we develop spatially explicit estimates of both soil and living biomass C stocks in BCEs across China by integrating open‐access remote sensing, climate, and soil property data with 2,899 site measurements using a data‐driven method. Our C stock estimates reveal that mean C stocks in BCEs significantly decrease with increasing latitude. We estimate the total C storage within China's BCEs at 121.1 ± 48.4 Tg C, with soil accounting for 90% of the total C storage. Tidal marshes and flats contribute a total of 64.7 ± 8.7 Tg C, while mangroves store a much smaller amount (4.4 ± 1.4 Tg C) due to their limited spatial extent. Seagrasses store a total of 52.0 ± 38.3 Tg C, which is significantly larger than previous estimates. These findings underscore the significant potential of BCEs protection and restoration for China's climate mitigation efforts. Our spatially explicit C stock estimates for China's BCEs provide essential data for national and global C accounting and can serve as baselines for quantifying the impacts of climate change and anthropogenic activities on BCEs C stocks. Additionally, this study offers a practical framework for comprehensively assessing C stocks in BCEs at the national scale.

Abstract About 15 Tg of plastic are estimated to enter the ocean yearly, with this figure growing exponentially every year. Assessments of floating marine plastic amount to 0.2% of the expected plastic stock, implying that 99.8% is stored in a sink yet to be identified. Marine sediments are believed to be the ultimate sink for oceanic plastic, however, there is currently no global estimate of the plastic load stored there. Here, we synthesize available estimates of micro‐ and mesoplastic stocks in marine sediments and, by integrating stocks across different habitats, we conservatively estimate a load of 170 Tg (25–900 Tg) of nonfibrous plastic globally accumulated in marine sediments from 1950 to 2010, most of which at intermediate depths (200–2000 m). This estimate, despite the uncertainty, is two to three orders of magnitude higher than the floating plastic stock and confirms marine sediments as a major plastic sink.

The Arctic climate is changing rapidly. The warming and resultant longer open water periods suggest a potential for expansion of marine vegetation along the vast Arctic coastline. We compiled and reviewed the scattered time series on Arctic marine vegetation and explored trends for macroalgae and eelgrass ( Zostera marina ). We identified a total of 38 sites, distributed between Arctic coastal regions in Alaska, Canada, Greenland, Iceland, Norway/Svalbard, and Russia, having time series extending into the 21st Century. The majority of these exhibited increase in abundance, productivity or species richness, and/or expansion of geographical distribution limits, several time series showed no significant trend. Only four time series displayed a negative trend, largely due to urchin grazing or increased turbidity. Overall, the observations support with medium confidence (i.e., 5–8 in 10 chance of being correct, adopting the IPCC confidence scale) the prediction that macrophytes are expanding in the Arctic. Species distribution modeling was challenged by limited observations and lack of information on substrate, but suggested a current (2000–2017) potential pan-Arctic brown macroalgal distribution area of 655,111 km 2 (140,433 km 2 intertidal, 514,679 km 2 subtidal), representing an increase of about 45% for subtidal- and 8% for intertidal macroalgae since 1940–1950, and associated polar migration rates averaging 18–23 km decade –1 . Adjusting the potential macroalgal distribution area by the fraction of shores represented by cliffs halves the estimate (340,658 km 2 ). Warming and reduced sea ice cover along the Arctic coastlines are expected to stimulate further expansion of marine vegetation from boreal latitudes. The changes likely affect the functioning of coastal Arctic ecosystems because of the vegetation’s roles as habitat, and for carbon and nutrient cycling and storage. We encourage a pan-Arctic science- and management agenda to incorporate marine vegetation into a coherent understanding of Arctic changes by quantifying distribution and status beyond the scattered studies now available to develop sustainable management strategies for these important ecosystems.

The data is displayed in an excel file with spreadsheets representing each of the following data sets: Field kelp loggings Nuuk, Field kelp loggings Disko, Field ETR Disko, Lab time series pH CO2, Lab CO2 End time series, Lab time series consumption CO2, Lab ETR max and Lab time series no macroph. The txt document attached provides a full description of each of them.

Soils in terrestrial and coastal blue carbon ecosystems are an important carbon sink. National carbon inventories require accurate assessments of soil carbon in these ecosystems to aid conservation and nature-based climate change mitigation strategies. Here we harmonise measurements from Australia’s terrestrial and blue carbon ecosystems and apply a multiscale spatial machine learning model to estimate soil carbon stocks and drivers of variation. We find that climate and vegetation are the primary drivers of variation at the continental scale, with ecosystem type, terrain, clay content, mineralogy and nutrients drive subregional variations. We estimate that in the top 0–30cm soil layer, terrestrial ecosystems hold 27.6 Gt C (19.6–39.0 Gt C), and blue carbon ecosystems hold 0.35 GtC (0.20–0.62 GtC). Tall open eucalypt and mangrove forests have the largest soil carbon content by area, while eucalypt woodlands and hummock grasslands have the largest total carbon stock due to their large area. Our findings suggest these are important ecosystems for conservation and nature-based mitigation climate change strategies.

Understanding the vertical distribution of elasmobranch species and associated ecological dynamics can be a crucial component of developing effective conservation strategies, particularly in light of their global population decline. Previous studies have primarily focused on horizontal extent and movement patterns of elasmobranchs, with limited knowledge about their vertical distribution. This knowledge gap stems from limited access to technological advancements and reliance on surface data from fisheries operations. Today, advancements in observing platforms such as electronic tracking, remotely operated vehicles and submersibles, and reductions in costs for drop cameras and BRUVs, allow for direct observation of animals at great depths, facilitating improved understanding of their ecological and trophic niches. This study reports new global depth records for three elasmobranch species observed in the Saudi Arabian Red Sea ( Carcharhinus altimus , Rhinobatos punctifer, Iago omanensis ), also presenting ethological evidence on Iago omanensis feeding behavior. Our findings have significant implications for conservation strategies and the development of targeted conservation measures. The provisioning of data on new depth ranges allows places like NEOM to better manage and protect deep sea habitats, due to the presence of species occurring at those depths.

Marine protected areas (MPAs) have emerged as potentially important conservation tools for the conservation of biodiversity and mitigation of climate impacts. Among MPAs, a large percentage has been created with the implicit goal of protecting shark populations, including 17 shark sanctuaries which fully protect sharks throughout their jurisdiction. The Commonwealth of the Bahamas represents a long-term MPA for sharks, following the banning of commercial longlining in 1993 and subsequent designation as a shark sanctuary in 2011. Little is known, however, about the long-term behavior and space use of sharks within this protected area, particularly among reef-associated sharks for which the sanctuary presumably offers the most benefit. We used acoustic telemetry to advance our understanding of the ecology of such sharks, namely Caribbean reef sharks ( Carcharhinus perezi ) and tiger sharks ( Galeocerdo cuvier ), over two discrete islands (New Providence and Great Exuma) varying in human activity level, over 2 years. We evaluated which factors influenced the likelihood of detection of individuals, analyzed patterns of movement and occurrence, and identified variability in habitat selection among species and regions, using a dataset of 23 Caribbean reef sharks and 15 tiger sharks which were passively monitored in two arrays with a combined total of 13 acoustic receivers. Caribbean reef sharks had lower detection probabilities than tiger sharks, and exhibited relatively low habitat connectivity and high residency, while tiger sharks demonstrated wider roaming behavior across much greater space. Tiger sharks were associated with shallow seagrass habitats where available, but frequently transited between and connected different habitat types. Our data support the notion that large MPAs afford greater degrees of protection for highly resident species such as Caribbean reef sharks, yet still may provide substantial benefits for more migratory species such as tiger sharks. We discuss these findings within the context of species-habitat linkages, ecosystem services, and the establishment of future MPAs.

Abstract Marine heatwaves can lead to rapid changes in entire communities, including in the case of shallow coral reefs the potential overgrowth of algae. Here we tested experimentally the differential thermal tolerance between algae and coral species from the Red Sea through the measurement of thermal performance curves and the assessment of thermal limits. Differences across functional groups (algae vs. corals) were apparent for two key thermal performance metrics. First, two reef‐associated algae species ( Halimeda tuna and Turbinaria ornata ) had higher lethal thermal limits than two coral species ( Pocillopora verrucosa and Stylophora pistillata ) conferring those species of algae with a clear advantage during heatwaves by surpassing the thermal threshold of coral survival. Second, the coral species had generally greater deactivation energies for net and gross primary production rates compared to the algae species, indicating greater thermal sensitivity in corals once the optimum temperature is exceeded. Our field surveys in the Red Sea reefs before and after the marine heatwave of 2015 show a change in benthic cover mainly in the southern reefs, where there was a decrease in coral cover and a concomitant increase in algae abundance, mainly turf algae. Our laboratory and field observations indicate that a proliferation of algae might be expected on Red Sea coral reefs with future ocean warming.