421 research outputs found
Green turtles highlight connectivity across a regional marine protected area network in west Africa
Networks of marine protected areas (MPAs) are invaluable for the protection of species
with high dispersal capacity, yet connectivity within networks is poorly understood. We
demonstrate the connectivity within the regional MPA network in West Africa (RAMPAO),
mediated by the largest green turtle population in the eastern Atlantic Ocean. We
equipped with satellite tags 45 female green turtles nesting in the Bijagó
s Archipelago,
Guinea-Bissau, and tracked them during internesting, migration, and foraging to quantify
the degree of coverage the RAMPAO network provides during each of these critical
periods. During the internesting period, turtles were largely concentrated around the
nesting islands, with a mean of 94.8% (SD 0.1%, range: 46% - 100%, n = 40 turtles) of
tracking positions falling within MPA limits. Among the 35 turtles successfully tracked into
the foraging period, we identified variable migratory strategies, with 12 turtles remaining
near-resident at distances of 40-90 km from breeding sites, 10 turtles migrating 300-400
km to The Gambia and Senegal, and 13 turtles traveling >1000 km to northern Mauritania.
Of the 35 foraging turtles, 26 used MPAs, with a mean of 78.0% (SD 34.8%, range: 3.7% -
100%) of their tracking positions falling within the limits of RAMPAO MPAs, across
Guinea-Bissau, Senegal and Mauritania. Migration corridors with high concentrations of
passing turtles were mostly located nearshore, and 21% of these high passage areas fell
within the MPA network. Overall, we found that this population connects five RAMPAO
MPAs, yet some foraging sites (e.g., in the Bijagó
s) and important migration areas (e.g.,
Cap-Vert peninsula) described here are currently unprotected. These results are relevant
to any considerations of MPA extension or establishment within the regional network,
which would contribute towards meeting the Convention on Biological Diversity targets for
national marine protected area estate coverage. By documenting biological connectivity
across RAMPAO, this study represents an important example of the relevance of
international protected area networks for green turtle conservation and for wider
conservation action at a regional scale.Fundação para a Ciência e Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio
Foraging ecology of Mediterranean juvenile loggerhead turtles: insights from C and N stable isotope ratios
Bycatch is one of the key threats to juvenile marine turtles in the Mediterranean Sea. As fishing methods are regional or habitat specific, the susceptibility of marine turtles may differ according to inter- and intra-population variations in foraging ecology. An understanding of these variations is necessary to assess bycatch susceptibility and to implement region-specific management. To determine if foraging ecology differs with region, sex, and size of juvenile loggerhead turtles (Caretta caretta), stable isotope analysis of carbon and nitrogen was performed on 171 juveniles from a range of foraging regions across the central and eastern Mediterranean Sea. Isotope ratios differed with geographical region, likely due to baseline variations in δ13C and δ15N values. The absence of sex-specific differences suggests that within an area, all comparably sized animals likely exploit similar foraging strategies, and therefore, their susceptibility to fisheries threats will likely be similar. The isotope ratios of juveniles occupying the North East Adriatic and North Levantine basin increased with size, potentially due to increased consumption of more prey items at higher trophic levels from a more neritic source. Isotope ratios of juveniles with access to both neritic and oceanic habitats did not differ with size which is consistent with them consuming prey items from both habitats interchangeably. With foraging habitats exploited differently among size classes in a population, the susceptibility to fisheries interactions will likely differ with size; therefore, region-specific management approaches will be needed
Measurement of Charged Pion Production Yields off the NuMI Target
The fixed-target MIPP experiment, Fermilab E907, was designed to measure the
production of hadrons from the collisions of hadrons of momenta ranging from 5
to 120 GeV/c on a variety of nuclei. These data will generally improve the
simulation of particle detectors and predictions of particle beam fluxes at
accelerators. The spectrometer momentum resolution is between 3 and 4%, and
particle identification is performed for particles ranging between 0.3 and 80
GeV/c using , time-of-flight and Cherenkov radiation measurements. MIPP
collected events of 120 GeV Main Injector protons striking a
target used in the NuMI facility at Fermilab. The data have been analyzed and
we present here charged pion yields per proton-on-target determined in bins of
longitudinal and transverse momentum between 0.5 and 80 GeV/c, with combined
statistical and systematic relative uncertainties between 5 and 10%.Comment: 15 pages, 13 figure
Search for the exotic resonance in the NOMAD experiment
A search for exotic Theta baryon via Theta -> proton +Ks decay mode in the
NOMAD muon neutrino DIS data is reported. The special background generation
procedure was developed. The proton identification criteria are tuned to
maximize the sensitivity to the Theta signal as a function of xF which allows
to study the Theta production mechanism. We do not observe any evidence for the
Theta state in the NOMAD data. We provide an upper limit on Theta production
rate at 90% CL as 2.13 per 1000 of neutrino interactions.Comment: Accepted to European Physics Journal
Pion yield from 450 GeV/c protons on beryllium
This paper reports on the charged pion production yields measured by the SPY/NA56 experiment for 450 GeV/c proton interactions on beryllium targets. The present data cover a secondary momentum range from 7 GeV/c to 135 GeV/c in the forward direction. An experimental accuracy ranging from 5 to 10\%, depending on the beam momentum, has been achieved, limited mainly by the knowledge of the beam acceptance. These results will be relevant in the calculation of neutrino fluxes in present and future neutrino beams
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