Haffray P.,French National Institute for Agricultural Research |
Malha R.,French National Institute for Agricultural Research |
Ould Taleb Sidi M.,British Petroleum |
Prista N.,University of Lisbon |
And 8 more authors.
Aquatic Living Resources | Year: 2012
The meagre Argyrosomus regius is a large Sciaenid fish known to reproduce in the eastern Atlantic and Mediterranean Sea in just five distinct and restricted geographic areas: along the Mauritanian coast and at estuary openings (Gironde, Tagus, Guadalquivir and Nile). The biological traits of A. regius (high dispersal capabilities, high fecundity, long larval phase, overlapping generations, reproduction until 40 years of age) are, in principle, favourable to high gene flow, which should lead to genetic homogeneity over large geographic scales. Nevertheless, the high geographic distances between the few reproductive areas leads one ask whether there is genetic differentiation in this species. In the present study, the genetic differentiation of the wild A. regius was investigated across most of its natural range from the Atlantic Ocean (France, Portugal, Spain, Mauritania) to the Mediterranean Sea (Egypt, Turkey), using 11 microsatellite markers previously identified in another Sciaenid, the red drum Sciaenops ocellatus. At least two very distinct groups could be identified, separated by the Gibraltar Strait. Genetic divergences (F ST values) were intermediate between the Atlantic samples (0.012-0.041), high between Egypt and the Atlantic (0.06-0.107) or Aegean Sea (0.081) and extremely high between the Aegean Sea and the Atlantic (0.098-0.168). A. regius exhibited a very high level of genetic differentiation rarely reported in marine fishes. These results also demonstrate the existence of a sixth independent spawning area in the Menderes delta (Turkey). Factors potentially involved in this very high genetic fragmentation are discussed, including physical barriers, glaciation pulses and biological traits. © 2012 EDP Sciences, IFREMER, IRD.
Lirman D.,University of Miami |
Bowden-Kerby A.,Corals for Conservation |
Schopmeyer S.,University of Miami |
Huntington B.,University of Miami |
And 5 more authors.
Aquatic Conservation: Marine and Freshwater Ecosystems | Year: 2010
Acropora cervicornis (staghorn coral) and Acropora palmata (elkhorn coral), once common features of shallow Caribbean reefs observed growing as large stands or thickets, are now found mainly as remnant pockets or isolated colonies at a fraction of their historical areal extent. In February 2010, a large, surviving population of A. cervicornis was surveyed at Cabezos del Cayo, Punta Rusia, Dominican Republic to document its present condition and potential threats to its persistence. The A. cervicornis surveyed at Cabezos del Cayo provides a rare glimpse of the habitat structure that these keystone components of coral reefs once provided. The staghorn population covers an area of 2 ha and is formed by interlocking skeletons of unusually large and thick A. cervicornis colonies. The large size of its colonies (maximum branch length 250 cm; average linear length of live tissue 471 cm; maximum number of branch tips 141 per colony; maximum branch diameter 5 cm) and the complex open canopy of these colonies, have not been described, to our knowledge, in the recent literature. The site is within Montecristi National Park but there is no active protection in this area and signs of overfishing are evident based on low fish abundance and complete lack of fish >20 cm in length. The stressors associated with this population include significant predation by gastropods and fireworms, overgrowth by macroalgae, damselfish 'gardening' activities, and white band disease. The management priority for the staghorn population at Cabezos del Cayo, Dominican Republic, should be to enforce the legal framework that is already in place for the protection of Montecristi National Park, limiting unsustainable and damaging fishing practices, and limiting land-based sources of pollution associated with increasing population numbers and future coastal development. Copyright © 2010 John Wiley & Sons, Ltd.
Eakin C.M.,National Oceanic and Atmospheric Administration |
Morgan J.A.,Systems Watch |
Heron S.F.,ReefSense Pty. Ltd |
Heron S.F.,James Cook University |
And 67 more authors.
PLoS ONE | Year: 2010
Background: The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. Methodology/Principal Findings: Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the iming and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. Conclusions/Significance: Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.