Search Results (102)

Effective species identification is crucial for the conservation and management of marine mammals, particularly in regions such as the Mediterranean Sea, where several cetacean populations are endangered or vulnerable. In this study, we developed and validated a High-Resolution Melting (HRM) analysis protocol for the rapid, cost-effective, and reliable identification of the four representative marine cetacean species that occur in the Mediterranean Sea: the bottlenose dolphin (Tursiops truncatus), the striped dolphin (Stenella coeruleoalba), the sperm whale (Physeter macrocephalus), and the fin whale (Balaenoptera physalus). Species-specific primers targeting mitochondrial DNA regions (cytochrome b and D-loop) were designed to generate distinct melting profiles. The protocol was tested on both tissue and fecal samples, demonstrating high sensitivity, reproducibility, and discrimination power. The results confirmed the robustness of the method, with melting curve profiles clearly distinguishing the target species and achieving a success rate > 95% in identifying unknown samples. The use of HRM offers several advantages over traditional sequencing methods, including reduced cost, speed, portability, and suitability for degraded samples, such as those from the stranded individuals. This approach provides a valuable tool for non-invasive genetic surveys and real-time species monitoring, contributing to more effective conservation strategies for cetaceans and enforcement of regulations against illegal trade. Full article

We investigated the spatial structure and colony itinerancy of Audouin’s gull (Ichthyaetus audouinii) adult breeders across multiple breeding sites in the central Mediterranean Sea during 25 years of fieldwork. Using cluster analysis of marked individuals from different years and sites, we identified five spatial breeding units of increasing hierarchical scale—Breeding Sites, Colonies, Districts, Regions and Marine Sectors—which reflect biologically meaningful boundaries beyond simple geographic proximity. To determine the most appropriate scale for monitoring local populations, we applied multievent capture–recapture models and examined variation in survival and site fidelity across these units. Audouin’s gulls frequently change their location at the Breeding Site and Colony levels from one year to another, without apparent survival costs. In contrast, dispersal beyond Districts boundaries was found to be rare and associated with reduced survival rates, indicating that breeding Districts represent the most relevant biological unit for identifying local populations. The survival disadvantage observed in individuals leaving their District likely reflects increased extrinsic mortality in unfamiliar environments and the selective dispersal of lower-quality individuals. Within breeding Districts, birds may benefit from local knowledge and social information, supporting demographic stability and higher fitness. Our findings highlight the value of adopting a District-based framework for long-term monitoring and conservation of this endangered species. At this scale, demographic trends such as population growth or decline emerge more clearly than when assessed at the level of singular colonies. This approach can enhance our understanding of population dynamics in other mobile species and support more effective conservation strategies aligned with natural population structure. Full article

Recreational diving depends on healthy marine ecosystems, yet it can harm biodiversity through species displacement and habitat damage. Bombinhas, a biodiverse diving hotspot in southern Brazil, faces growing threats from human activity and climate change. This study assessed the ecological structure of Sepultura Beach (2018) for potential diving trails, comparing it with historical data from Porto Belo Island. Using visual censuses, transects, and photo-quadrats across six sampling campaigns, researchers documented 2419 organisms from five zoological groups, identifying 14 dominant species, including Haemulon aurolineatum and Diplodus argenteus. Cluster analysis revealed three ecological zones, with higher biodiversity at the site’s edges (Groups 1 and 3), but these areas also hosted endangered species like Epinephelus marginatus, complicating trail planning. A major concern was the widespread bleaching of the zoanthid Palythoa caribaeorum, a key ecosystem engineer, likely due to rising sea temperatures (+1.68 °C from 1961–2018) and declining chlorophyll-a levels post-2015. Comparisons with past data showed a 0.33 °C increase in species’ thermal preferences over 17 years, alongside lower trophic levels and greater ecological vulnerability, indicating tropicalization from the expanding Brazil Current. While Sepultura Beach’s biodiversity supports diving tourism, conservation efforts must address coral bleaching and endangered species protection. Long-term monitoring is crucial to track warming impacts, and adaptive management is needed for sustainable trail development. The study highlights the urgent need to balance ecotourism with climate resilience in subtropical marine ecosystems. Full article

The expansion of global maritime activities threatens marine ecosystems and biodiversity. Collisions between ships and marine megafauna profoundly impact vulnerable species such as whales, who serve as keystone predators. However, the specific regions most heavily affected by shipping traffic and the multi-species facing collision risk remain poorly understood. Here, we analyzed global shipping data to assess the distribution of areas with high shipping pressure and identify global hotspots for whale–ship collisions. The results reveal that high-pressure habitats are primarily distributed within exclusive economic zones (EEZs), which are generally consistent with the distribution of collision hotspots. High-pressure habitats exhibit significant spatial mismatch: 32.9% of Marine Protected Areas endure high shipping stress and yet occupy merely 1.25% of protected ocean area. Additionally, 25.1% of collision hotspots (top 1% risk) affect four or more whale species, forming critical aggregation in regions like the Gulf of St. Lawrence and Northeast Asian marginal seas. Most of these high-risk areas lack protective measures. These findings offer actionable spatial priorities for implementing targeted conservation strategies, such as the introduction of mandatory speed restrictions and dynamic vessel routing in high-risk, multi-species hotspots. By focusing on critical aggregation areas, these strategies will help mitigate whale mortality and enhance marine biodiversity protection, supporting the sustainable coexistence of maritime activities with vulnerable marine megafauna. Full article

The cryopreservation of ovarian tissues from fish has recently been carried out for several endangered and commercially valuable species. However, previous studies in this context have focused on the cryopreservation of immature ovaries—mainly through slow freezing and vitrification—which requires specialized freezing equipment or higher cryoprotectant concentrations to keep cell viability. Therefore, the aim of this study was to explore a convenient, rapid, efficient and less toxic method for the cryopreservation of ovaries at the stage of vitellogenesis from yellow drum (Nibea albiflora), an economically important marine fish. The ovaries at the stage of vitellogenesis were isolated and cut into blocks of approximately 1 cm³, then cryopreserved with 15% propylene glycol (PG), fetal bovine serum (FBS) and 0.2 M trehalose as cryoprotectants. Finally, the samples were treated using three different freezing procedures, including a −80 °C refrigerator, liquid nitrogen, and their combination. After 7 days, the tissues were thawed and digested, and the cell survival rates and gene expression levels were detected using cell viability assay kits and qRT-PCR, respectively. The results of the viability assay showed that the procedure of ovarian tissue storage at −80 °C in a refrigerator for 1 h, followed by transfer to liquid nitrogen, resulted in the highest cell survival rate (>90%). Furthermore, the germ cells at various phases were of normal size; presented a full, smooth surface and regular shape; and did not show any signs of cell rupture, atrophy, depression, granulation or cavitation. Furthermore, the qRT-PCR results revealed that genes related to reproductive development, such as vasa, foxl2, zp3 and gsdf, were all down-regulated under the optimal protocol, while the expression of the nanos2 gene (which is specifically distributed in oogonia) maintained a higher level, similar to that in the control group. This indicated that the viability of germ stem cells (oogonia) was not weakened after freezing and that oogonia could be isolated from the cryopreserved ovaries for germ cell transplantation. The present study successfully establishes an optimal cryopreservation protocol for ovarian tissues from Nibea albiflora, providing reference for the preservation of ovaries at the stage of vitellogenesis from other species. Full article

Anthropogenic threats from human activity have significantly altered global ecosystems, resulting in habitat destruction and fragmentation, biodiversity loss, and species extinction. The identification and establishment of protected areas for the conservation of threatened species is thus required to mitigate the impacts of these threats. This study identified priority conservation areas (PCAs) for endangered mammals, birds, amphibians, and reptiles in South Korea using ecological modeling. In particular, we used the MaxEnt model to determine the potential distributions of endangered species and Zonation software to prioritize conservation areas. In doing so, we aimed to identify key environmental factors that influence the distributions of the target species and to identify ecologically critical areas using gap analysis based on the first-grade areas on the ecology and nature map (ENM). The results indicated that the highest priority areas for endangered species varied by taxon, with endangered mammals found primarily in forested areas, endangered birds on inland plains, and endangered amphibians and reptiles within marine and stream regions. The gap analysis revealed a very low overlap between ecological areas and high-priority areas for endangered birds and amphibians. This suggests that the first-grade areas on the ENM mainly represent areas with high vegetational coverage. These findings highlight the need to reassess existing protected areas and designate PCAs for endangered species independently from the ENM. This study represents a foundational assessment that can be used to inform conservation planning and prompt continued ecological research in support of biodiversity conservation efforts. Full article

Nautilus pompilius, a ‘living fossil’ of the oceans, is crucial to the study of biological evolution and paleontology. However, the species’ habitat has been severely impacted by global climate change. Based on this, species distribution models and conservation gap analyses were conducted under current and future climate scenarios. The results revealed that the current habitats for N. pompilius were primarily located in the coastal waters of Australia, Indonesia, and the Philippines. Under the Representative Concentration Pathway (RCP) 4.5 scenario, suitable habitat is projected to decline by 4.8% in the 2050s and 5.3% in 2100s. This loss is expected to intensify under higher emission scenarios, particularly RCP 8.5, where the reduction could reach 15.4% in the 2100s. Conservation gap analysis indicates that while nearly 30% of suitable habitats fall within marine protected areas (MPAs), many vulnerable regions remain unprotected. Future MPA establishment should strategically address these conservation gaps, particularly in coastal waters such as the Gulf of Carpentaria, the Arafura Sea, and the southern edge of the Timor Sea. This study provides critical insights into the distribution patterns and conservation needs of N. pompilius, emphasizing the urgent need for targeted conservation efforts to protect this endangered species. Full article

Passive acoustic monitoring plays a critical role in the study of marine species, particularly in understanding the behavior of deep-diving endangered species like the Mediterranean sperm whale (Physeter macrocephalus). This paper presents an effective method for tracking sperm whales using synchronized acoustic data from four hydrophones. The tracking method estimates the location of sperm whales by measuring the time difference of arrival of detected clicks. The direction of arrival of the clicks and their reflections on the surface are then reconstructed to determine the position of the whale. The method was used to perform the first acoustic tracking study of sperm whale dives recorded in the Central Mediterranean Sea by the NEMO-O$\nu$DE cabled observatory, deployed at a depth of 2100 m in the Gulf of Catania. The data analyzed in this study were collected in August and October 2005 and include 49 five-minute recordings with the presence of sperm whale clicks. A Monte Carlo simulation revealed an estimated relative error of 2.7% in depth and 1.9% in the horizontal distance for the positioning of clicks. The algorithm successfully reconstructed 64 tracks of diving sperm whales and demonstrated its potential for monitoring within a 12 km radius. Moreover, a simultaneous tracking of a vessel and a sperm whale was performed, illustrating how the method can be used to study potential changes during dives in the presence of vessels. This method offers a reliable, non-invasive approach to studying sperm whale behavior, ecology, and interaction with anthropogenic activities. Full article

The degradation of marine and coastal resources, caused mainly by human activities, underscores the urgent need for conservation. In waters around the Sichang Islands, the Bryde’s whale is listed as an endangered marine species. The extensive human activities in this area have raised serious concerns about the possible negative influence on this species. To conserve the species effectively and efficiently, we need to understand where it distributes and how human activities influence its distribution. For this purpose, we use spatial modeling techniques alongside diverse databases encompassing various spatial and ecological factors to analyze the distribution of, and human activities’ impact on, the Bryde’s whale (Balaenoptera edeni) in the Sichang Islands, Thailand. We also use the MaxEnt model to predict habitat suitability and the result reveals key factors influencing whale occurrence across seasons. During the dry season, TSS (32.8%), chlorophyll-a (20.1%), and DO (15.9%) levels play significant roles, while DO (29.9%), NH₃ (29.4%), and distance to shore (13.3%) are crucial in the wet season. Furthermore, the Species Risk Assessment (SRA) model indicates the mooring area (14.95%) is the high-risk area for the Bryde’s Whale, particularly during the wet season. In contrast, moderate risks are observed during the dry season, notably in fishing zones (99.68%) and mooring areas (99.28%). The study also highlights that the factors mentioned above influence prey availability and habitat suitability for the Bryde’s whale and identifies potential threats posed by human activities, such as fishing and other maritime operations, that are likely to decrease water quality and prey abundance. These results are useful information for identifying sensitive areas and measures for risk mitigation, thus supporting the development of MSP or MPA plans. Full article

To develop safe and effective management policies, it is important to understand the physiologic effects of fishing interactions and scientific research methods on endangered marine species. In the present study, validated assays for plasma corticosterone, free thyroxine (fT4), and aldosterone were used to assess the endocrine status of 61 presumed healthy, wild Kemp’s ridley sea turtles (Lepidochelys kempii) that were captured for separate ecological studies using two capture methods (trawl net n = 40; manual capture n = 21). Plasma hormone concentrations were also assessed in relation to eight clinical plasma biochemical analytes. Corticosterone and aldosterone concentrations were moderately high after capture, with significantly higher concentrations in turtles captured by trawl net vs. manual capture. Free thyroxine concentrations were within previously published ranges for healthy individuals of this species. Clinical biochemical data revealed moderately elevated potassium and lactate concentrations in many individuals, with significantly greater lactate concentrations in trawl-captured turtles. Aldosterone concentrations were positively correlated with corticosterone. The results of the present study indicate that Kemp’s ridley sea turtles have robust adrenocortical activity immediately after capture, resulting in high plasma concentrations of corticosterone and aldosterone. Researchers who use such methods to access sea turtles can consider these results in planning careful and efficient field studies. Full article

Kelps are important habitat-forming species in shallow marine environments, providing critical habitat, structure, and productivity for temperate reef ecosystems worldwide. Many kelp species are currently endangered by myriad pressures, including changing water temperatures, invasive species, and anthropogenic threats. This situation necessitates advanced methods to detect kelp density, which would allow tracking density changes, understanding ecosystem dynamics, and informing evidence-based management strategies. This study introduces an innovative approach to detect kelp density with multibeam echosounder water column data. First, these data are filtered into a point cloud. Then, a range of variables are derived from these point cloud data, including average acoustic energy, volume, and point density. Finally, these variables are used as input to a Random Forest model in combination with bathymetric variables to classify sand, bare rock, sparse kelp, and dense kelp habitats. At 5 m resolution, we achieved an overall accuracy of 72.5% with an overall Area Under the Curve of 0.874. Notably, our method achieved high accuracy across the entire multibeam swath, with only a 1 percent point decrease in model accuracy for data falling within the part of the multibeam water column data impacted by sidelobe artefact noise, which significantly expands the potential of this data type for wide-scale monitoring of threatened kelp ecosystems. Full article

This study aims to explore the practice of Christian ocean stewardship on Taiwan’s marine wind farm policy, with a particular focus on the critically endangered Taiwanese humpback dolphins (Sousa chinensis taiwanensis). Marine wind farms, while integral to the shift toward renewable energy, present complex ethical challenges due to their adverse environmental impacts—particularly noise pollution, which poses a serious threat to vulnerable marine species. International laws have underscored the importance of preventing marine noise pollution. Although Taiwan has relevant laws and policies, their implementation and supervision in preventing marine noise pollution are inadequate. This study critically examines the anthropocentric frameworks that currently dominate Taiwan’s marine development policies, arguing that they inadequately address the moral obligations humans have toward the broader ecosystem. Through a theological reflection grounded in Christian stewardship ethics, this research advocates for a shift away from human-centered environmental policies towards a more holistic ethic that acknowledges the intrinsic value of all creation. It emphasizes that ethical stewardship requires not merely reducing harm but actively participating in the restoration and protection of ecosystems, thus extending beyond utilitarian considerations of human benefit. The plight of the Taiwanese humpback dolphin serves as a case study for exploring these ethical tensions, highlighting how the energy transition can inadvertently contribute to biodiversity loss if not approached with caution and moral responsibility. Building on this, this study proposed four key principles to guide future marine development. These principles advocate for respecting nature, responsible management, continuous innovation, and social participation and transparency. This approach not only helps guide Taiwan’s marine policies but also provides new perspectives and practical approaches for applying Christian ethics in the field of marine environmental protection. Full article

Southern Brazil is home to a large biodiversity of elasmobranchs from the Brazilian coast. Several genera and species of small sharks of the Triakidae family live in this marine environment. Studies on these shark species are scarce, with few genetic data and little information on animal population structures. The present study aimed to sequence the complete mitochondrial genome (mtDNA) of the endangered species Mustelus schmitti (narrownose smooth-hound shark) and to perform a phylogenetic analysis of the Triakidae family. The mtDNA sequenced here was 16,764 bp long and possessed the usual 13 mitochondrial protein coding genes (PCGs), 22 tRNAs, two rRNAs (12S and 16S) and a large D-loop DNA sequence, presenting an overall organization similar to other species from the genus Mustelus. Phylogenetic analyses were performed using a dataset containing this new mtDNA and 59 other mitochondrial genomes of the Carcharhiniformes species (including 14 from the Triakidae family), using the Maximum Likelihood (ML) method. All the species of the Triakidae family were clustered into a monophyletic topology group. In addition, polyphyly was observed in Galeorhinus galeus, Hemiatrakis japanica, Triakis megalopterus and Triakis semifasciata. In conclusion, this study contributes to a deeper understanding of the genetic diversity of sharks and represents an important step towards the conservation of these endangered animals. Full article

Northern Australia is considered a ‘lifeboat’ region for globally threatened shark and ray species (elasmobranchs), although much of the region is understudied. The Roper River in the Northern Territory’s Gulf of Carpentaria has been inadequately surveyed, with most elasmobranch data gained opportunistically through freshwater fish surveys. This study aimed to report the occurrence of elasmobranch species in the Roper River through targeted field surveys conducted between 2016 and 2024 and to review data from other sources. Four euryhaline species were recorded, comprising two sharks, a sawfish, and a stingray. Records of the globally Vulnerable speartooth shark (Glyphis glyphis) represented a significant range extension and the documentation of a new reproductive population. Records of the Critically Endangered largetooth sawfish (Pristis pristis) extended almost 400 km upstream, highlighting extensive use of the river system. A predominantly marine species, the Critically Endangered giant guitarfish (Glaucostegus typus) was observed in brackish estuarine waters, approximately 15 km upstream from the river mouth. Further research is required to develop a more thorough understanding of abundance, life history, and population connectivity for these species in this river system. Given the documentation of threatened species, the potential impacts of fisheries, water allocations, and climate change require assessment. Full article

In order to collect information on ichthyofauna of a deep-sea vulnerable marine ecosystem (VME) network along the Apulian margin (central Mediterranean Sea), two low-impact sampling tools were used in three VMEs characterized by cold-water corals (CWC), namely Bari Canyon (BC), off Monopoli (Mn), and off Santa Maria di Leuca (SML). Using an experimental longline, 53 deployments were carried out between a 314 and 650 m depth for a total of 217 fishing hours, whereas when using the baited lander MEMO (Marine Environment MOnitoring system), 31 deployments were carried out between 427 and 792 m, for a total of 223 h of video recordings. A total of 37 taxa were recorded, comprising 13 Chondrichthyes and 24 Osteichthyes. The similarities in species observed among the VMEs confirm the presence of a network of CWC-VMEs along the Apulian margin, whereas some differences detected are due to the different abundance of some species, such as Galeus melastomus, Helicolenus dactylopterus, and Phycis blennoides. The presence of commercial species, vulnerable/endangered cartilaginous fishes, and large and sexually mature individuals of G. melastomus, H. dactylopterus, and Pagellus bogaraveo in all the VMEs confirms that the network of CWC-VMEs along the Apulian margin can act as a network of refuge areas and an essential fish habitat (EFH) for species threatened by fishing activities. Full article