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Filippo Bargnesi Stefano Gridelli Carlo Cerrano Francesco Ferretti 《水产资源保护:海洋与淡水生态系统》2020,30(5):915-927
- Sharks are globally exposed to several anthropogenic threats, which, in many cases, have severely reduced their distribution and have impacted populations. In the Mediterranean Sea, because of its long history of exploitation and the relatively short span of scientific monitoring, reconstructing shark baselines is challenging. Many vulnerable species declined in population abundance and geographic distribution before it was possible to adequately track these changes. Consequently, for many of these species, current conservation assessments are now suffering from a severe case of shifting baseline syndrome, whereby their historical occurrence in the area is questioned.
- The sand tiger shark (Carcharias taurus) is one of these cases. Characterized by high philopatry, restricted home range, and low interchange between populations, its Mediterranean population may have been severely impacted by the high historical fishing pressure in the region before scientific monitoring began.
- In this study, the history of the abundance and distribution of C. taurus in the Mediterranean Sea was reconstructed through a comprehensive search of occurrence records in the literature and in museum collections. Between 1810 and 2008, 31 occurrence records and 54 publications provided information on the presence of the species in the area. These records were sparse but systematic over time and indicated occurrence hot spots in the south‐western Mediterranean Sea and in the eastern Adriatic Sea.
- The presence of ten sightings of juveniles from a total of 18 sightings with length information suggested local parturition. Habitat and extinction models indicate that the area has suitable oceanographic conditions for the occurrence of the species and that the species cannot be considered extinct in the Mediterranean Sea. Our study suggests that there is still hope for the recovery of the species and underlines the crucial role of historical investigations to reconstruct the history of large elasmobranchs in the Mediterranean Sea.
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Juliana Gaeta Ivn Acevedo Violeta Lpez‐Mrquez Rui Freitas Raúl Cruz Rodrigo Maggioni Rogelio Herrera Annie Machordom 《水产资源保护:海洋与淡水生态系统》2020,30(5):868-881
- Declines in Panulirus echinatus Smith, 1869 populations along their wide distribution in the Atlantic Ocean have spurred efforts to improve their fisheries management and conservation. In this study, the genetic structure of these populations is reported for the first time.
- In a survey of 18 species‐specific polymorphic microsatellite markers, 152 individuals were genotyped from five Atlantic oceanic islands, covering most of the insular distribution range of the species. The analyses revealed that P. echinatus is genetically partitioned into two stocks in the Atlantic Ocean. A highly significant genetic structure was observed between north‐east and south‐west Atlantic populations based on fixation index, discriminant analysis of principal components, and structure and barrier analysis.
- We suggest that the Equatorial Circulation System represents a biophysical barrier that effectively limits migration among Atlantic subtropical gyre systems, as has been described for other species. Other physical and ecological barriers, such as the Mid‐Atlantic Ridge itself, the distance between the eastern and western sides of the Atlantic (Mid‐Atlantic Barrier) and water mass differences, as well as other biological aspects, may also influence larval dispersal and modulate the insular distribution of this species.
- The results show the existence of two distinct genetic stocks of P. echinatus and have implications for fisheries management in the Atlantic Ocean, including their independent management according to their individual status. The Cabo Verde and the Canarian populations (north‐east Atlantic) showed the lowest level of genetic variability in comparison with the south‐western populations. A combination of factors that have occurred or are occurring in the Canary Islands, such as overfishing and volcanic eruptions, is likely to explain the reduced abundance of this lobster species in the area.
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Luisa Garofalo Angela Mastrogiacomo Paolo Casale Rossella Carlini Claudia Eleni Daniela Freggi Donatella Gelli Leyla Knittweis Carmen Mifsud Toni Mingozzi Nicola Novarini Dino Scaravelli Giovanni Scillitani Marco Oliverio Andrea Novelletto 《水产资源保护:海洋与淡水生态系统》2013,23(6):868-884
- that the north Adriatic, the Tunisian continental shelf, the waters around Malta and the Italian Ionian Sea represent important areas for the conservation of rookeries in Greece, Libya and Turkey, respectively;
- that waters off the Italian peninsula and the islands of Lampedusa and Malta are mainly inhabited by individuals of Mediterranean origin, with a major contribution from the nearest and largest colonies, while Atlantic turtles are restricted to the western areas;
- that specific migratory routes exist from rookeries to foraging grounds;
- a poor bi‐parental genetic structuring, which suggests a high male‐mediated gene flow in the Mediterranean;
- mixing of small turtles in waters distant from natal rookeries, and recovery of structuring for large‐sized individuals; and
- that uncommon mtDNA haplotypes are more powerful markers than microsatellite alleles in assessing an individual's origin, owing to their higher geographic specificity.
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Gaetano Catanese Iole Di Capua Mikel Iriondo Angelo Bonanno Andone Estonba Gabriele Procaccini 《水产资源保护:海洋与淡水生态系统》2020,30(7):1313-1324
- Single nucleotide polymorphism (SNP) markers in anchovy (Engraulis encrasicolus) egg samples were analysed to detect their origin on a small spatial scale (200 km) by assigning genotypes to adult anchovy stocks. The novelty of this work is the application of a rapid high‐throughput method for genotyping each single anchovy egg, in a single execution, using a set of 96 genome‐wide SNPs in a dynamic array system with microfluidic technology (Fluidigm 96.96).
- The existence of two ecotypes in E. encrasicolus had already been identified based on SNP polymorphism in the Atlantic Ocean and in the Mediterranean Sea, showing that habitat type (offshore versus coastal/estuarine) is the most important component of genetic differentiation among populations of anchovy.
- In this work, anchovy egg genotypes from areas of the Western Mediterranean were assigned to adult populations. Only two localities in which adult anchovies were sampled represented donor populations for the coastal/estuarine egg genotypes. Although some degree of mixing among the hauls could exist, the assignment of egg groups to adult populations led to distinguishing the contributions of distinct ecotypes to new wild generations. We can conclude that the high rate of egg dispersion caused by marine currents and the different degrees of local retention could explain the genetic heterogeneity observed in the adult populations, where eggs from neighbouring spawning sites tend to mix.
- The results highlight that this technique represents a new and useful tool for addressing evolutionary questions, breed recognition, assignment, and connectivity assessment of individual eggs, and anchovy population dynamics, for the management of stocks.
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Riccardo Melis Laura Vacca Andrea Bellodi Alessandro Cau Cristina Porcu Maria Cristina Follesa Rita Cannas 《水产资源保护:海洋与淡水生态系统》2020,30(1):86-103
- Genetic information is crucial for the conservation of Dipturus oxyrinchus (Linnaeus, 1758), a threatened large skate with declining populations over most of its geographical range. The main aim of the present study was to investigate the genetic structure, connectivity and demographic history of the longnosed skate in Sardinia (western Mediterranean Sea).
- Patterns of population structure were assessed in 175 specimens from six sampling sites. Variation in two mitochondrial genes (cytochrome c oxidase subunit I (COI) and control region) highlighted high genetic diversity and low but significant genetic differentiation among sites, which clustered into three groups corresponding to the north‐west, north‐east and south Sardinian coasts.
- The observed genetic structuring could presumably depend on a combination of past geological events, contemporary restrictions to dispersal and biological characteristics of the species (e.g. site‐fidelity, no pelagic larval stage, limited dispersal of juveniles and/or adults).
- Demographic analyses showed signs of past population expansion, but substantial current stability of Sardinian populations. From a conservation perspective, these results are encouraging, and indicate that Sardinian populations are still large and stable, and seem not to have suffered negative side‐effects from the ever‐growing fishing pressure in the region.
- The occurrence of genetic structuring strongly supported the close monitoring of populations to identify any erosion of their gene pool, and high genetic variability of the Sardinian D. oxyrinchus populations could thus represent priority populations for conservation purposes, providing potential sources for recolonization in cases of local extinctions in other areas of the distribution range of the species.
- When the sequences from Sardinia were compared with those available from other areas, the data seem to exclude the possibility that the Atlantic and Mediterranean host totally isolated populations or even different species, as recently suggested. However, additional markers and a larger sampling sites are needed to confirm these findings.
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M. Teresa González Fabiola A. Sepúlveda Patricia M. Zárate J. Antonio Baeza 《水产资源保护:海洋与淡水生态系统》2021,31(3):620-634
- The porbeagle shark Lamna nasus is a large highly migratory shark distributed in cold and temperate marine waters of the North Atlantic and Southern Hemisphere (SH). According to the International Union for Conservation of Nature, the porbeagle is assessed globally as Vulnerable and regionally as Critically Endangered in the North Atlantic and the Mediterranean Sea. This study explored, for the first time, the population genetics of L. nasus at a regional (south-east Pacific Ocean) and global scale.
- In this study, the null hypotheses of no genetic discontinuities among populations (i) within the SH, and (ii) between the SH and Northern Hemisphere (NH) were tested. Also, the demographic history of L. nasus in different ocean basins was assessed. Two mitochondrial markers (Control Region [CR] and cox1) well suited for population genetics inferences in sharks were used.
- Spatial–genetic analyses suggested two genetic clusters co-occurring in the south-eastern Pacific Ocean. A two-way ANOVA using the cox1 but not the CR mtDNA fragment detected an effect of genetic identity on shark body size. Phylogeographic analyses, haplotype networks, and analyses of molecular variance demonstrated genetic differences between populations from the NH and SH but not among populations in the SH.
- Migration estimates indicated limited current maternal gene flow between the two hemispheres but high gene flow within hemispheres. Two well-defined haplotype groups with star-like shapes inhabited all ocean basins in the SH. These results could reflect a historical scenario of reproductive isolation and more recent mixture among previously isolated populations in the SH. A Bayesian skyline plot analysis indicated sudden population expansion in the SH occurring ~100–125 kya.
- This study highlights the need for additional studies focusing on the population genomics (using nuclear markers, i.e. single nucleotide polymorphisms) and the general biology of L. nasus to explore the existence of genetically dissimilar populations in the SH. Such studies will help implementing efficient genetic monitoring programmes.
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Yellapu Srinivas Anant Pande Swapnali Gole P.V.R. Prem Jothi K. Madhu Magesh Sameeha Pathan Sohini Dudhat Rukmini Shekar Chinmaya Ghanekar Devanshi Kukadia Jeyaraj Antony Johnson Samrat Mondol Kuppusamy Sivakumar 《水产资源保护:海洋与淡水生态系统》2021,31(4):818-829
- India plays a significant role in dugong conservation by having the largest population within South Asia. The status of dugongs in India is largely unknown due to a paucity of reliable ecological data. This study generated mitochondrial control region sequences from ~10% of dugong individuals from existing populations within India. Furthermore, data generated in this study were compared with the global data to assess genetic lineages, population structure, and genetic diversity of Indian populations.
- Multiple analyses suggest that the Indian dugong populations are part of a single genetic cluster, comprising South Asia, North-west Indian Ocean, and South-west Indian Ocean populations. Despite small population size, they retain high genetic diversity with unique mitochondrial DNA haplotypes within South Asia. Within India, novel haplotypes are observed from all dugong habitats sampled, with overall high haplotype diversity (0.85 ± 0.04) but low nucleotide diversity (0.005 ± 0.001). Indian populations exhibit genetic differentiation with higher within-population variance (63.41%) than among populations (36.59%). Two of the haplotypes observed in India are shared with Sri Lanka, implying genetic connectivity between these populations.
- The genetic data from Indian dugong populations provide critical insights into the identification of dugong corridors and important dugong conservation zones in India. We suggest site-specific interventions, including the creation of new marine protected areas and boundary reorganization and expansion of other existing protected areas, to ensure population connectivity. In addition, simultaneous efforts towards seagrass meadow restoration, reduction of dugong mortalities, and community participation in dugong conservation are recommended for population recovery of this threatened marine herbivore.
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Joanna Day David Power Rosemary Gales John Bannister Maxine P. Piggott Kerstin Bilgmann Robert Harcourt Luciano B. Beheregaray Luciana M. Möller 《水产资源保护:海洋与淡水生态系统》2021,31(6):1452-1465
- Understanding the factors driving population structure in marine mammals is needed to evaluate the impacts of previous exploitation, current anthropogenic threats, conservation status, and success of population recovery efforts.
- Sperm whales are characterized by a worldwide distribution, low genetic diversity, complex patterns of social and genetic structure that differ significantly within and between ocean basins, and a long history of being commercially whaled. In Australia, sperm whales from the (International Whaling Commission assigned) southern hemisphere ‘Division 5’ stock were very heavily exploited by whaling.
- The present study assessed the potential effects of whaling on the genetic diversity of sperm whales in Australia and the population genetic structure of these whales within a global context. A combination of historical and contemporary sperm whale samples (n = 157) were analysed across six regions, from south-eastern Australia (‘Division 6’ stock in the Pacific Ocean) to south-western Australia (‘Division 5’ stock in the Indian Ocean).
- Sperm whales sampled from the ‘Division 5’ and ‘Division 6’ stocks belong to the same population based on nuclear and mitochondrial DNA (mtDNA) analyses. Four novel sperm whale mtDNA haplotypes were identified in animals from Australian waters. Levels of genetic diversity were low in Australian sperm whales but were similar to those previously reported for populations in the Indian and Pacific Oceans.
- Given the genetic distinctiveness of sperm whales in Australian waters from other regions in the Pacific and Indian Oceans, and the lack of recovery in population numbers, further scientific studies are needed to increase our understanding of population dynamics and the effectiveness of threat management strategies in this species.
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Marta Azzolin Alexandre Gannier Elena Papale Giuseppa Buscaino Barbara Mussi Giandomenico Ardizzone Cristina Giacoma Daniela Silvia Pace 《水产资源保护:海洋与淡水生态系统》2021,31(Z1):36-50
- The short-beaked common dolphin is a highly vocal species, with a wide distribution in all oceans, including the Mediterranean and the Black Seas. In the Mediterranean Sea, the short-beaked common dolphin inhabits both pelagic and neritic waters.
- Osteological collections and the literature show that short-beaked common dolphins were widespread and abundant in much of the Mediterranean Sea until the late 1960s. During recent decades the species has declined in the whole basin, and, in 2003, it was listed as Endangered in the IUCN Red List.
- Genetic studies strongly suggest that the Mediterranean and the Eastern North Atlantic populations are isolated from each other. Genetic differentiation within the Mediterranean Sea, between the Eastern Mediterranean (Ionian Sea) and Western Mediterranean populations, is also reported.
- The aim of this study was to investigate the geographical variation in the characteristics of whistles of free-ranging short-beaked common dolphins living in the Mediterranean Sea, and to evaluate if whistle acoustic structure is the result of adaptation to local environment characteristics or of a possible genetic diversification.
- Recordings were collected from 1994 to 2012 throughout the basin, employing multiple platforms. Twenty-six independent acoustic detections were made, and 704 whistles were extracted and considered for statistical analysis.
- Whistle analysis enabled the identification of distinct geographical units of short-beaked common dolphin within the Mediterranean Sea. Genetic isolation is probably the major cause of the geographic variance of the Mediterranean short-beaked common dolphin whistle structure, which may reflect some evolutionary adaptations to particular ecological conditions or may be the by-product of morphological evolution.
- The results of the present study show that intra-Mediterranean variability of whistle structure reflects the path of genetic studies, highlighting the possible use of acoustic data in combination with other sources of data (genetic, morphological, etc.) to identify geographic areas where discrete management units occur.
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We analysed the genetic diversity of Melicertus kerathurus (Penaeidae), a commercially valuable penaeid shrimp that is distributed in the Mediterranean Sea and eastern Atlantic Ocean.
We examined the polymorphism of a 494 bp DNA segment of the mitochondrial COI region in 173 individuals, sampled in nine Mediterranean
and two Atlantic samples, covering the whole range of the species from the tropical waters of the Gulf of Guinea to the eastern
part of the Mediterranean Sea. The mean nucleotide and haplotype diversities were π = 0.00275 and h = 0.718, respectively, for the global data set, with the highest values occurring in the African samples and the lowest in
the Adriatic Sea. A clear sample differentiation was found (F
st = 0.194), but this did not reflect a geographical pattern and there were only faint traces of an Atlantic–Mediterranean subdivision.
Mismatch analysis and a high significant negative value of Tajima’s D suggested that M. kerathurus is not at mutation drift-equilibrium, but underwent a recent expansion after a period of low effective sample size. A postglacial
recolonisation of the Mediterranean from an Atlantic refuge could be hypothesised based on these data. 相似文献
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Jay R. Rooker David H. Secor Vincent S. Zdanowicz Gregorio De Metrio Lidia Orsi Relini 《Fisheries Oceanography》2003,12(2):75-84
Chemical signatures in the otoliths of teleost fishes represent natural tags that may reflect differences in the chemical and physical characteristics of an individuals' environment. Otolith chemistry of Atlantic bluefin tuna (Thunnus thynnus) was quantified to assess the feasibility of using these natural tags to discriminate juveniles (age 0 and age 1) from putative nurseries. A suite of six elements (Li, Mg, Ca, Mn, Sr and Ba) was measured in whole otoliths using solution‐based inductively coupled plasma mass spectrometry. Otolith chemistry of age‐1 T. thynnus collected from the two primary nurseries in the Mediterranean Sea and western Atlantic Ocean differed significantly, with a cross‐validated classification accuracy of 85%. Spatial and temporal variation in otolith chemistry was evaluated for age‐0 T. thynnus collected from three nurseries within the Mediterranean Sea: Alboran Sea (Spain), Ligurian Sea (northern Italy), and Tyrrhenian Sea (southern Italy). Distinct differences in otolith chemistry were detected among Mediterranean nurseries and classification accuracies ranged from 62 to 80%. Interannual trends in otolith chemistry were observed between year classes of age‐0 T. thynnus in the Alboran Sea; however, no differences were detected between year classes in the Tyrrhenian Sea. Age‐0 and age‐1 T. thynnus collected from the same region (Ligurian Sea) were also compared and distinct differences in otolith chemistry were observed, indicating ontogenetic shifts in habitat or elemental discrimination. Findings suggest that otolith chemistry of juvenile T. thynnus from different nurseries are distinct and chemical signatures show some degree of temporal persistence, indicating the technique has considerable potential for use in future assessments of population connectivity and stock structure of T. thynnus. 相似文献
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Lorenzo Angeletti Simonepietro Canese Frine Cardone Giorgio Castellan Federica Foglini Marco Taviani 《水产资源保护:海洋与淡水生态系统》2020,30(2):402-411
- In the Recent, brachiopods only seldom occur in benthic communities. A biotope dominated by Megerlia truncata was identified in 2013 by exploration of the south‐easternmost Adriatic margin by Remotely Operated Vehicle (ROV).
- Emerging rocky substrates next to the shelf break at approximately 120 m appear intensively exploited by this eurybathic rhynchonelliformean brachiopod, attaining a population of more than 300 individuals per m2.
- Calcareous red algae are almost ubiquitous at this site and preferentially encrust sectors of the substrate where brachiopods are minimal.
- This Megerlia biotope is a novel finding for this part of the Mediterranean Sea, similar to a situation previously observed in the Western Basin, off the Mediterranean French coast.
- It is proposed that this remarkable brachiopod biotope and the adjacent rhodolith bed are considered important for conservation management.