Human activities have resulted in the loss of over 90% of sharks in most ocean basins and one in four species of elasmobranch are now listed at risk of extinction by the IUCN. How this collapse will ...affect the ability of populations to recover in the face of continued exploitation and global climate change remains unknown. Indeed, important ecological and biological information are lacking for most shark species, particularly estimates of genetic diversity and population structure over a range of spatial scales. Using 15 microsatellite markers, we investigated genetic diversity and population structure in gray reef sharks over their Indo-Pacific range (407 specimens from 9 localities). Clear genetic differentiation was observed between the Indian and the Pacific Ocean specimens (F
= 0.145***). Further differentiation within the Pacific included a West and East cleavage as well as North-Central and South-Central Pacific clusters. No genetic differentiation was detected within archipelagos. These results highlight the legacy of past climate changes and the effects of large ocean expanses and circulation patterns on contrasting levels of connectivity at global, regional and local scales. Our results indicate a need for regional conservation units for gray reef sharks and pinpoint the isolation and vulnerability of their French Polynesian population.
Bait-based remote underwater video (BRUV) systems are effective devices for remotely observing fish and other marine organisms in challenging environments. The development of a long duration (24 h) ...surface BRUV observation surveys allowed the monitoring of scarce and elusive pelagic sharks and the direct impact on non-targeted species of longline fishing in the Western Mediterranean. Technological limitations, such as the limited storage capacity and a single surface camera, were improved by (i) adding a deep camera equipped with light (below 80 m depth) and (ii) replacing Gopros with a multi-camera video surveillance system (surface and depth) with a storage capacity of several days and access to real-time observation. Based on a deployment effort of 1884 h video data, we identified 11 blue sharks (Prionace glauca) and one bluntnose sixgill shark (Hexanchus griseus), a deep-sea species that scarcely swims at the surface. The real-time observation capability was a powerful tool for reducing logistical costs and for raising environmental awareness in educational and outreach programmes.
Morphological classification is a key piece of information to define samples of galaxies aiming to study the large-scale structure of the universe. In essence, the challenge is to build up a robust ...methodology to perform a reliable morphological estimate from galaxy images. Here, we investigate how to substantially improve the galaxy classification within large datasets by mimicking human classification. We combine accurate visual classifications from the Galaxy Zoo project with machine and deep learning methodologies. We propose two distinct approaches for galaxy morphology: one based on non-parametric morphology and traditional machine learning algorithms; and another based on Deep Learning. To measure the input features for the traditional machine learning methodology, we have developed a system called CyMorph, with a novel non-parametric approach to study galaxy morphology. The main datasets employed comes from the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7). We also discuss the class imbalance problem considering three classes. Performance of each model is mainly measured by Overall Accuracy (OA). A spectroscopic validation with astrophysical parameters is also provided for Decision Tree models to assess the quality of our morphological classification. In all of our samples, both Deep and Traditional Machine Learning approaches have over 94.5% OA to classify galaxies in two classes (elliptical and spiral). We compare our classification with state-of-the-art morphological classification from literature. Considering only two classes separation, we achieve 99% of overall accuracy in average when using our deep learning models, and 82% when using three classes. We provide a catalog with 670,560 galaxies containing our best results, including morphological metrics and classification.
STUDY QUESTION
How does vitrification affect oocyte viability?
SUMMARY ANSWER
Vitrification does not affect oocyte viability in oocyte donation cycles.
WHAT IS KNOWN ALREADY
Oocyte vitrification is ...performed routinely and successfully in IVF and oocyte donation programs.
STUDY DESIGN, SIZE, DURATION
This is a prospective study performed between June 2009 and February 2012 to compare ongoing pregnancy rates and other indices of viability between fresh and vitrified oocytes. A total of 99 donations with more than 16 oocytes (MII) in which oocytes were allocated both to a synchronous recipient (fresh oocytes) and to an asynchronous recipient (vitrified oocytes) were included.
PARTICIPANTS/MATERIALS, SETTING, METHODS
The participants were consenting couples (donors and recipients) from the oocyte donation program. On the day of retrieval, the oocytes allocated to the synchronous recipient were inseminated and those allocated for banking were denuded of cumulus and vitrified. Vitrified oocytes were microinjected with spermatozoa 2 h after warming. Embryo transfer was performed on Day 2 of development in both groups, and the remaining embryos were cryopreserved on Day 3. Clinical pregnancy was defined by a positive fetal heartbeat at 6 weeks.
MAIN RESULTS AND ROLE OF CHANCE
A total of 989 oocytes were warmed and 85.6% survived. No significant differences were observed between fresh and vitrified oocytes: fertilization rate (80.7 versus 78.2%), ongoing embryo rate (71.0 versus 68.2%) or good-quality embryo rate (54.1 versus 49.8%). The mean number of embryos transferred was similar in both groups (1.82 ± 0.44 versus 1.90 ± 0.34). The implantation rate (33.3 versus 34.0%) and the multiple pregnancy rate (27.7 versus 20.8) were also similar between both groups (P > 0.05). The live birth rate per cycle was 38.4% in the recipients of fresh oocytes and 43.4% in the recipients of vitrified oocytes (P > 0.05). Eighty five frozen embryo transfers were also evaluated. Comparing embryos from fresh and vitrified oocytes there were no significant differences in the embryo survival rate (70.1 versus 65.8%), clinical pregnancy rate (40.8 versus 33.3%) or implantation rate (21.8 versus 26.8%).
LIMITATIONS, REASONS FOR CAUTION
The oocytes were donated by healthy, young women (≤35 years) and these results cannot be extrapolated to other populations.
WIDER IMPLICATIONS OF THE FINDINGS
Outcomes obtained with vitrified oocytes are as good as with fresh oocytes and the use of vitrification can be extended to new applications, e.g. accumulation of oocytes from successive stimulations for preimplantation genetic diagnosis, for patients at risk of ovarian hyperstimulation syndrome or in patients needing to preserve their fertility.
STUDY FUNDING/COMPETING INTEREST(S)
This work was done under the auspices of the Càtedra d'Investigació en Obstetrícia i Ginecologia of the Universitat Autònoma de Barcelona.
Baited remote underwater video systems (BRUVs) are efficient devices for remotely characterising the assemblage and relative density of fishes and other marine organisms. However, technological ...constraints (e.g., battery life and limited storage memory) typically limit deployment times to <2 h making it very difficult to capture the presence of marine species, including rare and elusive ones. We developed an extended duration (24 h) BRUV to enable fisheries-independent surveying of a pelagic shark population in the western Mediterranean. Video data revealed seven visits (three nocturnal, four diurnal) by blue sharks (Prionace glauca) over a period of 1355 h. In the future, this cost-effective device could be fitted with a wireless video transmitter to provide real-time observations of marine animals for scientific or ecotourism purposes.
Most arguments invoked so far by the scientific community in favour of shark conservation rely on the ecological importance of sharks, and have little impact on management policies. During a 57-month ...study, we were able to individually recognise 39 sicklefin lemon sharks that support a shark-feeding ecotourism activity in Moorea Island, French Polynesia. We calculated the direct global revenue generated by the provisioning site, based on the expenses of local and international divers. The total yearly revenue was around USD5.4 million and the 13 sharks most often observed at the site had an average contribution each of around USD316699. Any one of these sharks represents a potential contribution of USD2.64 million during its life span. We argue that publicising economic values per individual will be more effective than general declarations about their ecological importance for convincing policy makers and fishers that a live shark is more valuable than a dead shark for the local economy. Studies monitoring the potential negative ecological effects of long-term feeding of sharks should, however, be conducted to ensure these are also considered. Besides declarations about the non-consumptive direct-use value of sharks, as promoted by ecotourism, the calculation of their other economic values should also benefit shark conservation.
We analyzed a tiger shark (estimated 2.8 m total length) bite on a snorkeler. The removal of the terminal part of the leg suggests a predatory motivation for the bite. This is the first documented ...bite by a tiger shark in French Polynesia waters for the past 75 years.
When sharks bite humans, the removal of large pieces of flesh or bones indicates a feeding motivation. The shark size can be assessed through average interdental distances. Prompt and effective emergency first‐aid measures are crucial for survival.
Abstract
The Mistaken Identity Hypothesis (MIH) interprets shark bites on surfers, swimmers and snorkelers as ‘mistakes’ stemming primarily from similarities in the visual appearance of ocean users ...and the sharks typical prey. MIH is now widely accepted as fact by the general public and some sections of the scientific community despite remaining unproven. This hypothesis assumes that ‘mistaken’ shark bites on humans result primarily from confusing visual cues and ignores the important role of other senses (e.g. hearing) in discriminating potential prey. A far simpler ‘natural exploration’ hypothesis can reasonably explain not only shark bites that have been characterized as ‘mistaken identity’ events but also those that cannot be reasonably explained by MIH (e.g. shark bites that occur in very clear water). Simply stated, sharks don’t make ‘mistakes’ but instead continually explore their environments and routinely investigate novel objects as potential prey by biting them.
Clipperton, an uninhabited and remote coral atoll from the Eastern Pacific, is an important steppingstone area that harbors a high marine biodiversity. Despite its biogeographic importance, little ...information on the ecological status of its coral reefs is available from the last decade. Herein, we characterized the benthic coral community and health status among four different shallow reef-zones (North to South) of Clipperton during the Tara Pacific expedition in 2018. The benthic composition (expressed as coverage percentage), as well as occurrence of potential disease-like phenotypes, in particular a pink-spotted coral phenotype was assessed. Average live coral cover on Clipperton reefs was 66% (range 55–85%), differing between sites, with massive
Porites
and branching
Pocillopora
corals dominating the benthic community with an average 48% (32–66%), and 15% (3–21%), respectively. While Clipperton reefs exhibited significant live coral cover overall, and no other disease-like phenotypic were observed, the pink-spotted coral phenotype was common, with a higher occurrence in massive corals (
Porites
27%, and
Pavona
31%). This observation may be related to the combined effects of previously heatwaves, and local inputs of guano-derived nutrients discharged during storms and hurricanes, which may suggest that even highly remote reefs supporting high coral cover can be subject to local and global threats. An alternative hypothesis is that the observation of a healthy reef with high coral cover and high incidence of pink-spotted coral phenotype in the absence of other diseases might reflect potential infection with the parasitic trematode
Podocotyloides stenometra
. While this hypothesis will have to be confirmed by histological and molecular analysis, it may be possible that larvae of this trematode may experience favorable conditions due to periodic nutrient input frorm the nutrient-rich lagoon or via guano run-off of Clipperton Island.
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