Search Results (146)

Rare earth elements (REEs) are important strategic resources, widely used in various technological fields, especially heavy rare earth elements (HREEs). China has extensive rare earth deposits, with diverse mineral types and a complete range of rare earth elements, characterized by a “heavy south, light north” resource distribution pattern. The rare earth-bearing collophane in the Zhijin area of Guizhou is a typical marine sedimentary phosphorite deposit with large reserves and a high heavy rare earth content. This study investigates the rare earth-bearing collophane in the Zhijin area using X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) to analyze its mineral composition and occurrence characteristics. In terms of flotation, a reverse flotation process for magnesium removal was adopted. By optimizing the flotation parameters, including grinding fineness, collector dosage, pH regulator dosage, and depressant dosage, the optimal flotation conditions were determined. A further mineralogical analysis was conducted on both the flotation concentrate and tailings. The results show that the main minerals in the rare earth-bearing collophane of Zhijin are fluorapatite and dolomite, with dolomite as the primary gangue mineral, and rare earth elements are mainly hosted in fluorapatite. The optimal flotation conditions were achieved when the grinding fineness was −74 μm with an 83% passing rate, XF-1 was used as the collector at a dosage of 300 g/t, sulfuric acid (H₂SO₄) as the pH regulator at 6 kg/t, and phosphoric acid (H₃PO₄) as the depressant at 3 kg/t. By employing an optimal reagent regime and implementing a reverse flotation process consisting of one roughing and one scavenging stage, a phosphate concentrate was obtained with a P₂O₅ grade of 31.61% and an REO content of 0.161%. The P₂O₅ recovery reached 84.22%, while the REO recovery was 78.65%. Compared to the raw ore, the P₂O₅ grade increased by 11.52 percentage points, and the REO content improved by 0.051 percentage points. Mineralogical analysis of the flotation concentrate and tailings revealed that dolomite was effectively removed by reverse flotation, while rare earth elements were successfully enriched in the phosphate concentrate. In conclusion, this study provides an efficient flotation separation process for rare earth-bearing collophane and dolomite, while also offering technical support for the efficient recovery of rare earth resources. This research has significant theoretical and practical implications. Full article

The present dataset served to evaluate the plankton community composition and abundance in Nuevo Gulf (42°42′ S, 64°30′ W), a World Heritage Site in Argentinian Patagonia and part of the Valdés Biosphere Reserve. It reports zooplankton abundance (>300 µm) and phytoplankton concentration (10–200 μm) during the spring and summer seasons from 2019 to 2021. Special attention was given to the taxonomic classification of zooplankton, leading to the first identification of jellyfish species within the Gulf and the detection of an unreported copepod for the area (Drepanopus forcipatus). Samples were collected at two depths—a surface and a deeper layer—to assess vertical distribution patterns of plankton communities and explore potential environmental drivers influencing their variability. This dataset provides a valuable baseline for future studies analyzing temporal variations in the Gulf’s plankton communities. Moreover, it encourages the local scientific community to contribute data and promote open access to marine biodiversity records in the region. Full article

Coral reef and their ecological services of food production and shoreline protection are threatened by unsustainable use. To better understand their status, multiple approaches to estimating fisheries sustainability were compared, namely fisheries-independent stock biomass and recovery rates, fisheries-dependent landed catches, balanced harvest and gear use metrics, and fish length measurements. A community biomass recovery was established over a 45-year no-fishing stock recovery time series from seven fisheries reserves and compared to catch- and length-based estimates of sustainability. The logistic production rates (r = 0.09 ± 0.06 95% confidence interval (CI)) and maximum equilibrium total biomass (~150 ± 30 tons/km²) indicated a broad range of potential maximum sustainable yields, with a likely range of 1.1 to 3.9 (95% CI; mean = 3.8) tons/km²/year. In contrast, the mean annual linear biomass growth rates in reserves were lower but less variable than logistic surplus production estimates, ranging from 2.1 to 3.5 (mean = 2.8 tons/km²/year). Realized catches at landing sites were lower still, ranging from 1.43 to 1.52 (mean = 1.48 ± 0.2 tons/km²/y). Differences between production estimates and capture were largely attributable to changes in taxonomic composition and an imbalance in the estimated proportionality of production potential versus actual capture rates. Lost potential capture was likely due to differences in the vulnerability of taxa to fishing and a lack of compensatory increased production among fishing-resistant taxa. Large proportional losses of catch were measured among snappers, unicorn fish, sweetlips, goatfish, and soldierfish, while smaller proportional gains in the catch samples were found among resident herbivorous rabbitfish, parrotfish, and groupers. Many of these declining taxa have vulnerable schooling life histories that are likely to require special habitat and reserve characteristics. Evaluations of sustainability from length measurements found 17 or 7% of total and 12% of caught species had sample sizes minimally sufficient for evaluation (>30 individuals from 413 catches, 2284 captured individuals composed of 144 species) of length and spawning metrics of sustainability. Seven of these species met length-based and three met spawning potential ratio thresholds for sustainability. Consequently, length-based evaluations had poor species coverage and therefore we were unable to evaluate the sustainability of the larger fish community. Recommendations for future research include a better understanding of the consequences of variability in spillover and proportionality of production potential for sustainability. Management recommendations are to focus management on the recovery of species abundant in unfished locations but not contributing to fisheries yield. Full article

The Peruvian coast covers more than 3000 km along the Pacific Ocean, being one of the richest seas in terms of biodiversity, productivity, fishing, and renewable energy potential. Marine renewable energy (MRE) in both offshore and coastal environments of Peru is, currently, a huge reserve of practically unused renewable energy, with inexhaustible potential. In this context, renewable energies from hydroelectric, biomass, wind, and solar sources have been applied in the country, but geothermal, waves, tidal currents, and tidal range sources are currently underdeveloped. This article presents the enormous source of sustainable blue energy for generating electrical energy that exists in Peru from waves and tidal resource potential. In addition, this article presents the main opportunities, gaps, and key issues for the implementation of marine renewable energy (MRE), with emphasis on: (i) showing the available potential in the northern, central, and southern Pacific Ocean territories of Peru, (ii) characterizing the marine energy best available technologies to implement, (iii) the environmental and socio-economic impacts of marine renewable energy, and (iv) discussion of challenges, opportunities, and future directions for developments in the marine energy sector. Finally, the article concludes that the greatest possibilities for exploiting the abundant marine renewable energy (MRE) resource in Peru are large spaces in both offshore and coastal environments on the Pacific Ocean that can be considered for harvesting energy. These issues will depend strongly on the implementation of regulations and policies for the strategic use for planning of marine resources, encouraging research and development (R&D) for creating sustainable innovations, incentives for project finance mechanisms, and developing specialized local human capital, considering the sustainability of livelihoods of coastal communities and ecosystems. Full article

Convolvulus persicus L. is an endangered narrow-range taxon, characteristic of the habitats along the coastal regions of the Caspian and the Black Seas. The aims of our research were to update the actual distribution area and the genetic evaluation of three representative populations from the western coastline of the Black Sea located in Sulina, Agigea, and Durankulak. ISSR amplifications were used to assess the genetic intrapopulation diversity and the genetic differentiation among populations. The average genetic polymorphism was 57.8 ± 16.03%. The intrapopulation genetic diversity parameters indicated that the Agigea population exhibits a higher genetic diversity, with this small population being part of the Agigea Marine Dunes Reserve. Although the interpopulation genetic distance was reduced (0.176–0.223) and the distribution of the total variation (AMOVA) was 57% within the population and 43% among the populations, the interpopulation genetic differentiation (PhiPT) was high (0.428, p < 0.001), probably due to the large geographical distances between the remaining populations. The populations’ genetic structures showed a lower genetic distance between the Agigea and Sulina samples. The clonability test supported the vegetative multiplication on the Durankulak and Sulina beaches. Our results showed that the genetic diversity and the distance among the populations in C. persicus were influenced by habitat conditions, destruction, and fragmentation, but also by conservation measures. Full article

As a key element of spatial governance, marine protected areas (MPAs) have been increasingly established in various countries, with lessons learned from terrestrial environmental protection. Nevertheless, the development of MPAs in China continues to trail behind that of their land-based counterparts. Here, following the leverage points perspective of sustainability interventions, this article presents a systematic analysis of the governance and evolution of China’s MPAs, identifying key areas for improvement. The analysis encompasses the number, effectiveness, legal framework, governance structure, value, and paradigm of MPAs, and highlights the associated governance challenges facing China. Drawing on relevant experiences from the United States, Australia, and the European Union, the article offers valuable insights for informing China’s future MPA strategies. The study concludes that while China has made significant progress in the development of MPAs, further efforts are needed, including paradigm shifts, refinement of the legal system, optimization of governance structures, and enhancement of MPA effectiveness. Full article

The great white shark (Carcharodon carcharias), a keystone predator vital to marine ecosystem stability, is increasingly exposed to anthropogenic threats, including endocrine-disrupting chemicals (EDCs). This study highlights the use of non-invasive epidermal biopsies to assess physiological and ecological parameters in 28 live specimens sampled from the Dyer Island Nature Reserve, South Africa. Epidermal tissue was analyzed for vitellogenin (Vtg), a biomarker of estrogenic exposure, while dermal tissue was used for stable isotope analyses of carbon and nitrogen, essential for understanding the feeding habitat of white sharks. Vitellogenin, typically restricted to sexually mature females, was unexpectedly detected in males and immature females, indicating significant exposure to estrogenic pollutants. This finding raises concerns about the potential reproductive and population-level impacts on this vulnerable species. Stable isotope analyses confirmed that dermal tissue alone is sufficient for trophic studies, eliminating the need for deeper muscle sampling. By demonstrating that epidermal and dermal tissues provide critical data for both biomarkers and isotopic studies, this research supports the adoption of minimally invasive techniques. Shallower biopsies reduce stress on the animals, making this method a valuable tool for conservation research and management of C. carcharias. Full article

Reducing carbon emissions and increasing carbon sinks have become the core issues of the international community. Although coastal blue carbon ecosystems (such as mangroves, seagrass beds, coastal salt marshes and large algae) account for less than 0.5% of the seafloor area, they contain more than 50% of marine carbon reserves, occupying an important position in the global carbon cycle. However, with the rapid development of the economy and the continuous expansion of human activities, coastal wetlands have suffered serious damage, and their carbon sequestration capacity has been greatly limited. Ecological restoration has emerged as a key measure to reverse this trend. Through a series of measures, including restoring the hydrological conditions of damaged wetlands, cultivating suitable plant species, effectively managing invasive species and rebuilding habitats, ecological restoration is committed to restoring the ecological functions of wetlands and increasing their ecological service value. Therefore, this paper first reviews the research status and influencing factors of coastal wetland carbon sinks, discusses the objectives, types and measures of various coastal wetland ecological restoration projects, analyzes the impact of these ecological restoration projects on wetland carbon sink function, and proposes suggestions for incorporating carbon sink enhancement into wetland ecological restoration. Full article

Estuarine wetlands are the transition zone between marine, freshwater, and terrestrial ecosystems and are more ecologically fragile. In recent years, the spread of exotic vegetation, specifically Spartina alterniflora, in the Yellow River estuary wetlands has significantly encroached upon the habitats of native species such as Phragmites australis, Suaeda glauca Bunge, and Tamarix chinensis Lour. With advances in land prediction modeling, predicting wetland vegetation distribution can aid management and decision-making for ecological restoration. We selected the core area as the study object and coupled the hydrological model MIKE 21 with the PLUS model to predict the potential future distribution of invasive and dominant species in the region. (1) Based on the fine classification results from satellite images of GF1/G2/G5, we gained an understanding of the changes in wetland vegetation types in the core area of the reserve in 2018 and 2020. (2) Using public data such as ERA5 and GEO as input for basic environmental data, using MIKE 21 to provide high-spatial-resolution hydrodynamic parameters for the PLUS model as an environmental driver, we modeled the spatial distribution of various wetland vegetation in the Yellow River estuary wetland in Dongying under different artificial restoration measures. (3) We predicted the 2022 distribution of typical vegetation in the region, used the classification results of GF6 as the actual distribution, compared the spatial distribution with the actual distribution, and obtained a kappa coefficient of 0.78; the predicted values of the model are highly consistent with the true values. This study combines the fine classification results of vegetation based on hyperspectral remote sensing, the construction of a coupled model, and the prediction effect of typical species, providing a reference for constructing and optimizing the vegetation prediction model of estuarine wetlands. It also allows scientific and effective decision-making for the management of ecological restoration of delta wetlands. Full article

Marine bacterioplankton perform a very important role in the cycles of carbon, nitrogen, phosphorus, and other elements in coastal waters. The impacts of environmental factors on bacterial community structure are dynamic and ongoing. This study investigated the spatiotemporal distributions of elements and their influences on bacterioplankton communities in the coastal waters around the Changli Gold Coast National Nature Reserve in northern China. The results demonstrate the significant temporal variability of phosphorus, nitrogen, and carbon in spring and summer, influenced by natural environmental factors and anthropogenic activities. In spring, increased biological activity, particularly phytoplankton growth, may elevate TOC and POC levels near the river estuaries, while in summer, microbial decomposition likely stabilized carbon concentrations. The seasonal variation in the bacterioplankton community was obvious. Bacteroidetes were enriched in spring samples and Cyanobacteriota proliferated in summer. The dominated genera in the spring, including Planktomarina, an unclassified NS5_marine_group (belonging to Flavobacteriaceae), and the OM43_clade (Methylophilaceae), showed significant positive correlation with salinity, TDP, TOC, POP, and DO levels, while Synechococcus_CC9902 (Synechococcus), PeM15_unclassified (Actinobacteria), and HIMB11 (Rhodobacteraceae), which all dominate in summer samples, are significantly positively correlated with TN, TDN, temperature, and ammonium levels. In summer in particular, the increase in human activities and river inputs greatly improves nutrient levels and promotes the propagation of photosynthetic microorganisms. These results indicate that the nutrient elements and environmental physical conditions are affected by seasonal changes and human activities, which have significant effects on the community structure of bacterioplankton. This study highlights the importance of ongoing monitoring in estuarine coastal areas, especially in protected areas like the Changli Reserve, to manage eutrophication risks and maintain ecological balance. Full article

The Yucatan Peninsula (YP) presents heterogeneous environments in a karstic landscape that has been formed from permeable sedimentary rocks dating from the Cretaceous period. Its aquifers now face significant pressure from tourism, agriculture, soil use changes and population growth. Aquifer delimitation typically relies on environmental and socioeconomic criteria, overlooking the subterranean fauna. Stygobiotic crustaceans are highly diverse in the YP’s subterranean karstic systems, expressing adaptations to extreme environments while often also displaying the primitive morphology of evolutionary relics. With distributions restricted to specific environments, they are potential markers of water reserves. A literature review recovered records of 75 species of crustaceans from 132 subterranean systems in the YP, together with geomorphological, hydrological, hydrogeochemical and historical precipitation data. Fourteen UPGMA clusters were informative for mapping species composition, whereby the “Ring of Cenotes”, “Caribbean Cave” and “Cozumel Island” regions were delineated as consolidated aquifers. These aquifers are distinguished by abiotic factors as well: freshwater species dominate the Ring of Cenotes, while marine-affinity species characterize the Caribbean Cave and Cozumel Island aquifers. Stygobiotic crustaceans, being linked to geologically ancient water reserves and having a restricted distribution, offer a complementary tool for aquifer delimitation. Their presence suggests long-term and stable water availability. The use of these unique organisms for integrative aquifer delimitation can provide a way to improve the monitoring networks of regional aquifers. Full article

A marine nature reserve is an area designated by law for the special protection and management of sea areas, coasts, estuarine wetlands, islands, and other sea areas needing special protection, including objects of exceptional conservation value. The purpose of these reserves is to protect the natural environment and natural resources of the sea. The construction of China’s marine protected areas can be traced back to establishing the Snake Island Nature Reserve in 1963. Over the past six decades, China has established a network of marine protected areas, including marine nature reserves and marine specially protected areas (including marine parks), which have played a pivotal role in safeguarding the marine environment and biodiversity, promoting the integration of land and sea, and defending the country’s maritime rights and interests. Nevertheless, the construction of China’s marine nature reserves is a challenge to solve. It is imperative to further advance the construction and development of China’s marine nature reserves by enhancing the spatial planning of marine nature areas, streamlining the management system, and delineating the rights and interests associated with using sea areas. Full article

Managing fishery resources is crucial to ensure the marine environment continues to provide diverse goods and services. To overcome difficulties of classical methods used for fish stock management, molecular tools have shown potential to address this issue assessing both targeted and non-targeted species. This study aims to evaluate the spatiotemporal diversity of fish using 12S rRNA gene eDNA metabarcoding sequencing in the Berlengas archipelago and compare two seawater eDNA sampling sources: samples collected by fishermen during their activities and those collected by our research team. The results indicated that autumn presented the highest diversity and that the area around Berlenga Island was the richest area, increasing biodiversity across the region. Fisher-collected samples were generally less diverse than those by the research team but detected species typical of deeper and open-ocean habitats, validating this sampling method. Our study also highlighted eDNA’s role in monitoring fish species by detecting unexpected species for the region, such as Atlantic salmon (Salmo salar) and Atlantic cod (Gadus morhua), while cautioning against false positives like orange clownfish (Amphiprion percula) and blue tilapia (Oreochromis aureus). Future optimisation of our eDNA sampling methodology could better refine marine ecosystem dynamics around the UNESCO Biosphere Reserve of the Berlengas Archipelago, Portugal. Full article

Prince Mohammed bin Salman Royal Reserve (PMBSRR or the Reserve) is located in the northwest of Saudi Arabia and covers an area of 24,500 km² of both marine and terrestrial ecosystems. Bat surveys have been undertaken between 2022 and 2024 across PMBSRR as part of the Reserve’s groundbreaking conservation efforts and this is the first published checklist of the bat species present within the Reserve. Survey methods included bat capture, roost inspection, and acoustic recordings. Tissue and faecal samples were taken during the surveys and compared to a global database to confirm the species present. The survey results confirmed the presence of 18 species belonging to 14 genera of eight families. This research has greatly expanded our knowledge on the diversity of bats within the Kingdom, increasing the reported bat species in the Tabuk region by seven species, with the addition of Rhyneptesicus nasutus, Rhinolophus hipposideros, Nycteris thebaica, Tadarida aegyptiaca, Rhinopoma microphyllum, Taphozous nudiventris, and Taphozous perforatus and increasing the number of species within Saudi Arabia by one species, with the addition of Vansonia rueppellii. Full article

The aim of this paper is to provide evidence of the species-specific export of adult fishes for some species or group of species from six well-enforced Mediterranean marine protected areas (MPAs): Cerbère-Banyuls and Carry-le-Rouet in France and Medes, Cabrera, Tabarca, and Cabo de Palos in Spain. We estimated the distance at which spillover of those individual or groups of species occur by directly assessing the existence of gradients of biomass across the MPA boundaries by means of underwater visual census, asuming that such gradients will be specifics in terms of structure (sharpness, slope, and intercept) for every species and group of species. A significant “reserve effect” was observed for biomass of some of the individual and grouped species in all MPAs. Decreasing gradients of biomass differ among taxons and are not related with the insular nature of the location. Different gradients of biomass resulted from the interaction between species characteristics and some ecological and structural drivers, and we did not find regular patterns for each taxa among MPAs, even though the same species can exhibit different gradient structure and/or spillover distances in the same MPA depending on the orientation. Habitat patch distribution and continuity seems the most important environmental factor explaining the existence and pattern of gradients at species level, interacting with fish home range and fishing pressure close to the limits of the MPAs. Managers should take in account the surrounding distribution of habitats in terms of complexity and quality in order to optimize the spillover capacity of the MPAs. Full article