Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Ecological resilience assessments are an important part of resilience-based management (RBM) and can help prioritize and target management actions. Use of such assessments has been limited due to a lack of clear guidance on the assessment process. This study builds on the latest scientific advances in RBM to provide that guidance from a resilience assessment undertaken in the Commonwealth of the Northern Mariana Islands (CNMI). We assessed spatial variation in ecological resilience potential at 78 forereef sites near the populated islands of the CNMI: Saipan, Tinian/Aguijan, and Rota. The assessments are based on measuring indicators of resilience processes and are combined with information on anthropogenic stress and larval connectivity. We find great spatial variation in relative resilience potential with many high resilience sites near Saipan (5 of 7) and low resilience sites near Rota (7 of 9). Criteria were developed to identify priority sites for six types of management actions (e.g., conservation, land-based sources of pollution reduction, and fishery management and enforcement) and 51 of the 78 sites met at least one of the sets of criteria. The connectivity simulations developed indicate that Tinian and Aguijan are each roughly 10 × the larvae source that Rota is and twice as frequent a destination. These results may explain the lower relative resilience potential of Rota reefs and indicates that actions in Saipan and Tinian/Aguijan will be important to maintaining supply of larvae. The process we describe for undertaking resilience assessments can be tailored for use in coral reef areas globally and applied to other ecosystems.
ISSN: 0006-3207

Droits : http://creativecommons.org/licenses/by-nc-nd/
hal-01224905
https://hal-univ-perp.archives-ouvertes.fr/hal-01224905
https://hal-univ-perp.archives-ouvertes.fr/hal-01224905/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01224905/file/1-s2.0-S0006320715300926-main.pdf
DOI : 10.1016/j.biocon.2015.09.001

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
IODP Site U1309 was drilled at Atlantis Massif, an oceanic core complex, at 30 degrees N on the Mid-Atlantic Ridge (MAR). We present the results of a bulk rock geochemical study (major and trace elements) carried out on 228 samples representative of the different lithologies sampled at this location. Over 96% of Hole U1309D is made up of gabbroic rocks. Diabases and basalts cross-cut the upper part of the section; they have depleted MORB compositions similar to basalts sampled at MAR 30 degrees N. Relics of mantle were recovered at shallow depth. Mantle peridotites show petrographic and geochemical evidence of extensive melt-rock interactions. Gabbroic rocks comprise: olivine-rich troctolites (>70% modal olivine) and troctolites having high Mg# (82-89), high Ni (up to 2300 ppm) and depleted trace element compositions (Yb 0.06-0.8 ppm); olivine gabbros and gabbros (including gabbronorites) with Mg# of 60-86 and low trace element contents (Yb 0.125-2.5 ppm); and oxide gabbros and leucocratic dykes with low Mg# (<50), low Ni (similar to 65 ppm) and high trace element contents (Yb up to 26 ppm). Troctolites and gabbros are amongst the most primitive and depleted oceanic gabbroic rocks. The main geochemical characteristics of Site U1309 gabbroic rocks are consistent with a formation as a cumulate sequence after a common parental MORB melt, although (lack of systematic) downhole variations indicate that the gabbroic series were built by multiple magma injections. In detail, textural and geochemical variations in olivine-rich troctolites and gabbronorites suggest chemical interaction (assimilation?) between the parental melt and the intruded lithosphere. Site U1309 gabbroic rocks do not represent the complementary magmatic product of 30 degrees N volcanics, although they sample the same mantle source. The bulk trace element composition of Site U1309 gabbroic rocks is similar to primitive MORB melt compositions; this implies that there was no large scale removal of melts from this gabbro section. The occurrence of such a large magmatic sequence implies that a high magmatic activity is associated with the formation of Atlantis Massif. Our results suggest that almost all melts feeding this magmatic system stays trapped into the intruded lithosphere.
ISSN: 0012-821X

hal-00413562
https://hal.archives-ouvertes.fr/hal-00413562
DOI : 10.1016/j.epsl.2008.12.034

Éditeur(s) : HAL CCSD EDP Sciences
Résumé : International audience
This study determined the movements of a Giant Grouper, Epinephelus lanceolatus, in which an acoustictag was surgically implanted and monitored by an array of six VR2W acoustic receiver units from August 2010 toJanuary 2013 in the remote, uninhabited Chesterfield Islands, Coral Sea (800 km West of New Caledonia). Our datarevealed a home reef area (residency rate of 44.9%) with an increased activity revealed by movements at dawn anddusk toward and between two adjacent reef passages, probably for foraging. The fish was absent from its residentreef between October and December 2010 and 2012, corresponding to the time known for spawning aggregationsof this species in New Caledonia. A skipped spawning seems to have occurred in 2011. We hope these data will becomplemented in the future by locating the spawning site or sites and thus provide adequate conservation measures.The Coral Sea links two World Heritage Sites, the Australian Great Barrier Reefs and the New Caledonian coral reefs.It would be fitting to create a Marine Protected Area for the Chesterfield Islands between these two major conservationareas of the sea.
ISSN: 0990-7440

hal-01238809
https://hal-univ-perp.archives-ouvertes.fr/hal-01238809
DOI : 10.1051/alr/2015006

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
ISSN: 2047-217X

hal-01429002
https://hal.archives-ouvertes.fr/hal-01429002
DOI : 10.1186/s13742-016-0118-5