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The blue shark Prionace glauca is a top predator with one of the widest geographic distributions of any shark species, yet classified as critically endangered in the Mediterranean Sea, and Near Threatened globally. Previous genetic studies did not reject the null hypothesis of a single global population across the worldwide species range. Blue shark situation was proposed as a possible archetype of the ‘grey zone of population differentiation’, coined to designate cases where population structure may be too recent or too faint to be detected using a limited set of markers. Here, blue shark samples collected throughout its global range were sequenced using a specific ddRAD method (DArTseq; Georges et al. 2018), which recovered 37,655 genome-wide single nucleotide polymorphisms (SNPs). Two main groups emerged, with Mediterranean Sea and Northern Atlantic samples significantly differentiated from the Indo-west Pacific samples. Significant pairwise FST values indicated further genetic differentiation within the Atlantic Ocean, and between the Atlantic Ocean and the Mediterranean Sea. Reconstruction of recent demographic history suggested the divergence between northern and southern oceanic populations emerged about 500 generations ago and revealed a drastic reduction in effective population size from a large ancestral population. Our results illustrate the power of high-density genome scans to detect population structure and reconstruct demographic history in highly migratory marine species. As the management of the blue shark fishery, either as target or as bycatch, does not account for this delineation, we strongly recommend that the results presented here be considered in future stock assessment and management plans.

Investigations of how past human societies managed during times of major climate change can inform our understanding of potential human responses to ongoing environmental change. In this study, we evaluate the impact of environmental variation on human communities over the last four millennia in the southern Lake Titicaca basin of the Andes, known as Lake Winaymarka. Refined paleoenvironmental reconstructions from new diatom-based reconstructions of lake level together with archaeological evidence of animal and plant resource use from sites on the Taraco Peninsula, Bolivia, reveal frequent climate and lake-level changes within major cultural phases. We posit that climate fluctuations alone do not explain major past social and political transformations but instead that a highly dynamic environment contributed to the development of flexible and diverse subsistence practices by the communities in the Titicaca Basin.

The great physiological, behavioral and morphological plasticity of salmonids contributed to the success of their introduction into a wide range of habitats. However, rainbow trout (Oncorhynchus mykiss) is the only salmonid species to live in the tropics. Like for any cold-water species, water temperature is assumed to be a major constraint to the presence and expansion of rainbow trout. In this study, we collected detailed records of the introduction history of rainbow trout at 35 sites across the island over 80 years, and we document the presence of self-sustainable trout at each site. We explored the linear relationship between water temperature and elevation.

The current management of the bigeye tuna (Thunnus obesus) fishery in the Western and Central Pacific Ocean (WCPO) is based on a “single-stock” paradigm. We investigated the spatial and temporal distribution of the neutral and potentially adaptive genetic diversity in samples collected from waters near Micronesia, Marshall, Phoenix and Gilbert Islands and French Polynesia using genotyping by sequence and single nucleotide polymorphisms (SNP). Analysis of 144 individuals and 2,682 SNP did not provide any substantial evidence to challenge the current assumption of panmixia in the WCPO using putatively neutral loci. However, there was a signal of potentially adaptive divergence (FST range 0.11–0.24) of samples collected in 2013 in the exclusive economic zone of the Phoenix Islands, possibly because of exposure to differing selective constraints. The geographic origin of these tuna remains to be determined, as the samples originate from tagging cruises that sample large schools of tuna, and some of those tuna have subsequently showed substantial movement. We highly recommend further studies involving large sample sizes of larvae and young-of-the-year across the region and over multiple years to uncover the underlying processes that are potentially driving adaptive divergence and to infer any biological significance it may have on conservation and management of tropical bigeye tuna fishery stock., The genomic analyses in this work were funded by the University of the South Pacific Strategic Research Themes Intramural Program project no. F1006-R1001-71502-622. Funding for the tuna tissue bank was provided by the WCPFC as part of Project 35b.

International audience; In this work, we present first experimental results on the micro-structuration of monocrystalline strontium titanate (100)-SrTiO3. A self-organized structure appears on its surface due to irradiation with 0.71 MeV/u 129Xe23+ and 0.55 MeV/u 136Xe19+ swift heavy ions at room temperature and under grazing incidence. The resulting wave-like structure appears normal to the direction of the ion beam. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses were undertaken to probe microstructural properties below the surface, revealing in particular surface amorphization at high fluences. Such amorphous surface layers, further irradiated at high fluences, may lead to an anisotropic plastic deformation (hammering) effect, inducing the observed self-organized structure due to the grazing angle configuration. This surface morphology was characterized by atomic force microscopy (AFM). A dependency of the periodicity as well as the width of the undulations on the irradiation angle was found as they evolve in the same way. As the ripple formation depends on the irradiation parameters, the characteristics of these patterns can be controlled and thus opens the possibilities for custom surface structuration.

The most important question in sampling is “Is the sample representative of the target population?” This question is necessary to understand how valid the sample taken is to the original population and if generalizations can be made from the sample. Samples taken for water quality measurement range from 1 mL for bacterial contamination to 100 mL or up to 1000 L for protozoan parasites. With larger samples taken, the confidence in detecting rare events increases dramatically. Here we illustrate that hollow fiber filters as routinely used for kidney dialysis can be adapted for environmental use. The filters retain all organisms down to viral particles and organic matter above 70 kDA, the molecular cutoff for urea, one of the waste products removed in kidney dialysis. With these filters, 50 liters of water can be filtered in about 90 minutes. Backflush of the filters recovers viable cells with minimal cell lysis that can be processed downstream for molecular analysis. Recovery rates were as high as 89% and 75% for phytoplankton and bacteria, respectively., We would like to thank the Roscoff Culture Collection and IEO VIGO for providing algal cultures, Dr. Ian Probert for filtration equipment for the Roscoff experiments and the Spanish National Research Council (CSIC) for funding the project PIE201950E07 for the experiments performed by CENIM. This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant agreement No. 778069 EMERTOX.

International audience; Tunas are the focus of significant fisheries in the Pacific Ocean, where landings of four species - skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacares), bigeye tuna (Thunnus obesus) and albacore tuna (Thunnus alalunga) - constitute approximately 70 % of the global tuna catch. Stock assessments for skipjack, yellowfin and bigeye tunas in the Pacific Ocean currently assume eastern and western stocks. For albacore tuna, separate North Pacific Ocean and South Pacific Ocean stocks are currently assumed. In each case, these geographic definitions reflect the historical development of fisheries management across the Pacific rather than biological considerations. There is widespread agreement that uncertainties surrounding the stock structures of these four tuna species could have important impacts on the population dynamics models used to assess their status and inform management options. Knowledge of stock structure is also essential for improved modelling of the effects of climate change on tuna distribution and abundance and associated implications for fisheries. This paper reviews current knowledge and understanding of the stock structures of skipjack, yellowfin, bigeye and South Pacific albacore tunas in the Pacific Ocean, by exploring available literature relating to their biology, movement and spatial dynamics. As a guide for future research in this area, we identify the main uncertainties in defining the stock structure of these four tunas in the Pacific, including i) spawning dynamics; ii) the degree of spawning area fidelity and localised residency; iii) the provenance of individuals in, and proportional contributions of self-replenishing populations to, fishery catches within the Pacific Ocean; iv) linkages with adjacent 'stocks', v) the effects of climate change on stock structure and proportional contributions of self-replenishing populations to fisheries; and vi) the implications of improved knowledge of tuna stock structure for stock assessment and climate change model assumptions and fisheries management. We also briefly propose some approaches that future studies could use to address these uncertainties.

Studies on freshwater Perkinsea are scarce compared to their marine counterparts; they are therefore not well ecologically characterized. In this study, we investigated the diversity, distribution and ecological role of Perkinsea in freshwater ecosystems. Our approach included (1) the phylogenetic analyses of near full-length SSU and LSU sequences of freshwater Perkinsea, (2) a meta-analysis of public Perkinsea 18S ribosomal RNA gene sequences available from the freshwater environments (25 lakes, 4 rivers), (3) microscopic observations of Perkinsea associated with planktonic communities and (4) single amplified genome analysis. Whereas Perkinsea appear to be rare in river ecosystems (85 reads), they are found in almost all of the lakes studied. However, their diversity does vary considerably between lakes (from 0 to 2 463 Operational Taxonomic Units (OTUs)). Phylogenetic analysis showed that the Parvilucifera/Dinovorax/Snorkelia and Perkinsus/Xcellia/Gadixcellia clades resulted from an initial speciation event. This second clade is further split into well-supported, monophyletic groups, including a clade dominated by freshwater representatives, which is further structured into three distinct subclades: freshwater clade 1, freshwater clade 2 and a freshwater and brackish clade. The Perkinsea Single Amplified Genome (SAG) as well as most of the abundant Operational Taxonomic Units (OTUs) fall into freshwater clade 2. The tyramide signal amplification-fluorescent in situ hybridization method showed an internal association between Perkinsea and the colonial phytoplankton Sphaerocystis. The Single Amplified Genome (SAG) annotation contained 698 genes and gene ontology terms could be assigned to 486 protein-coding genes. Although the number of genes appears to be low (10.6% of the entire gene set assessed by BUSCO), the analysis of the proteome revealed some putative secreted virulence factors. This study showed a large distribution of Perkinsea across lake ecosystems and potential parasitic association with phytoplankton. However, further investigations are needed for a better knowledge on the role of these microorganisms in freshwater ecosystems.

Delineating the stock structure of highly-mobile, wide-ranging fishes subject to exploitation is a challenging task, yet one that is fundamental to optimal fisheries management. A case in point are stocks of skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacares), bigeye tuna (Thunnus obesus) and albacore tuna (Thunnus alalunga) in the Pacific Ocean, which support important commercial, artisanal, subsistence, and recreational fisheries, and contribute roughly 70 % of global commercial tuna catches. Although some spatial and temporal structuring is recognised within these stocks, growing evidence from a range of approaches suggests that the stock structure of each tuna species is more complex than is currently assumed in both stock assessment and climate change models, and in management regimes. In a move towards improving understanding of the stock structure of skipjack, yellowfin, bigeye and South Pacific albacore tunas in the Pacific Ocean, an international workshop was held in Nouméa, New Caledonia, in October 2018 to review knowledge about their movement and stock structure in the region, define and discuss the main knowledge gaps and uncertainties concerning their stock structure, and develop biological sampling approaches to support the provision of this information. Here, we synthesise the discussions of this latter component. For each tuna species, we identify several general sampling considerations needed to reduce uncertainty, including i) the need for broadscale sampling in space, ideally covering each species’ distribution, targeting adults in spawning condition and adopting a phased approach; ii) the need for temporally-repeated sampling of the same geographical areas to assess stability in observed patterns over time; iii) the need to resolve patterns in spatial dynamics, such as those resulting from movements associated with the seasonal extensions of poleward flowing currents, from underlying stock structure, iv) the importance of adopting a multidisciplinary approach to stock identification, and v) the need for careful planning of logistics and coordination of sampling efforts across agencies. Finally, we present potential sampling designs that could be adopted to help overcome uncertainties around the initial identification of stocks and the provenance, mixing and proportional contributions of individuals in harvested assemblages, as well as how these uncertainties could be accounted for in fisheries management via the use of management strategy evaluation., Funding support for the workshop was provided by Conservation International as part of the GEF-funded, World Bank-implemented Ocean Partnerships for sustainable fisheries and biodiversity conservation (OPP), a sub-project of the Common Oceans ABNJ Program led by UN-FAO.

The trend in modern medicine is to transition care from the hospital to home or other nonacute settings as soon as possible. Increasingly, nutrition support professionals are being asked to help facilitate discharge and/or manage patients who require prolonged intravenous fluid and/or nutrition after having been stabilized during a hospitalization. This updated tutorial reviews many of the concepts and challenges that must be considered for successful care that helps to focus on the patients and their quality of life.

A multidecadal-scale lake-level reconstruction for Lago Wiñaymarca, the southern basin of Lake Titicaca, has been generated from diatom species abundance data. These data suggest that ~6500 cal yr BP Lago Wiñaymarca was dry, as indicated by a sediment unconformity. At ~4400 cal yr BP, the basin began to fill, as indicated by the dominance of shallow epiphytic species. It remained somewhat saline with extensive wetlands and abundant aquatic plants until ~3800 cal yr BP, when epiphytic species were replaced by planktic saline-indifferent species, suggesting a saline shallow lake. Wiñaymarca remained a relatively shallow lake that fluctuated on a multidecadal scale until ~1250 cal yr BP, when freshwater planktic species increased, suggesting a rise in lake level with a concomitant decrease in salinity. The lake became gradually fresher, dominated by deep, freshwater species from ~850 cal yr BP. By ~80 cal yr BP, saline-tolerant species were rare, and the lake was dominated by freshwater planktic diatoms, resembling the fresh and deep lake of today. These results reveal a more dynamic and chronologically specific record of lake-level fluctuations and associated ecological conditions that provide important new data for paleoclimatologists and archaeologists, to better understand human-environmental dynamics during the mid- to late Holocene.

Diatoms in ice cores have been used to infer regional and global climatic events. These archives offer high-resolution records of past climate events, often providing annual resolution of environmental variability during the Late Holocene. Recently, the first low-latitude tropical diatoms were described from the Quelccaya Summit Dome. Here, we document diatoms observed in ice cores from Quelccaya, spanning AD 1300 to 1815, along with those from two additional glaciers (Coropuna, and Sajama glaciers) in the tropical Andes, spanning AD 1764 to 1814. Diatom assemblages recovered from these three sites were rare, but differ in abundance and species composition through time. Assemblages are characterized by cosmopolitan and aerophilic species, mostly pennate diatoms. There were 44 taxa in all, with Pinnularia cf. borealis Ehrenberg being the most common species encountered in the samples. Eleven taxa were found at all three sites. Both Coropuna and Sajama had taxa that were unique to these locations, whereas Q...

Sharks constitute one of the most threatened clades (Selachimorpha) of all marine fish, and substantial management efforts are required to help the recovery of their populations worldwide. Despite its significant impact on population dynamics and conservation, sharks’ reproductive and philopatric behavior has received little attention in fisheries management. The scalloped hammerhead shark (Sphyrna lewini), an endangered species listed on the IUCN’s Red List and on the CITES’ Appendix II, is an apex predator that potentially exhibits female philopatry to mating grounds. We reconstructed, for the first time in an open ocean species, the relationship among 166 juvenile individuals caught in a recently discovered aggregation of the Rewa Delta, Fiji, and determined the sample population’s mating system using 6,437 SNPs. Using two software packages, COLONY2 and SNP PEDIGREE, results revealed very high consistency in the identification of full and half sib. Moreover, COLONY2 allowed us to identify an equal breeding sex ratio for each cohort analyzed for this population (1.04:1; 1.02:1), as well as several cases of multiple paternity and numerous matings of the same male with different females suggesting polygynandry for this species. These findings reveal additional information about the complex life history of the scalloped hammerhead shark., This work was primarily funded by The University of the South Pacific, Strategic Research Themes Program for Research and Innovation, and the Faculty of Science, Technology and Environment (Grant No. SRT/6175-3107-70766-617508 to CR).

Shark species have undergone drastic population declines in recent decades due to overfishing and habitat destruction; thus, establishing connectivity among the populations of various shark species is important to determine the appropriate units and spatial scale for conservation and management, particularly as this group is long-lived with late age of maturation. Consequently, we used DNA variation at 1,317 putatively neutral and 25 potentially adaptive single nucleotide polymorphisms (SNPs) to analyze population genetic structure among 174 unrelated individuals of scalloped hammerhead sharks (Sphyrna lewini) from the Rewa Delta and the Ba Estuary, where documented aggregations of neonates and young-of-the-year occur in the island of Viti Levu, Republic of Fiji. Results of the pairwise F analysis for the neutral loci revealed a small but significant genetic differentiation (F: 0.004; P-value = 0.0009). Furthermore, the 25 potentially adaptive loci (i.e., under putative selection) revealed a magnitude of differentiation four times bigger than the estimate obtained using neutral genetic diversity (F: 0.017; P-value = 0.0009). Interestingly, population assignment tests, using the neutral SNP data set and two different software packages, Admixture and assignPOP, provided evidence for the existence of up to four genetically differentiated populations among our samples. Assignment probabilities ranged from 0.98 ± 0.01 to 0.81 ± 0.03. Admixture and assignPOP assigned the same individuals to the same putative populations for all sampled neonates. Thus, our results provide unequivocal evidence that adult females from multiple genetically differentiated breeding populations contribute to these juvenile aggregation sites., The work was supported by the University of the South Pacific, SRT project F1006-R1001-71502-621.

Meteorological drought in the Great Plains of the U.S. has a significant influence on the hydrology of small drainage basins. Its effect on local surface water and groundwater systems is complicated when streamflow is regulated by flood-control reservoirs. An analysis of local precipitation, discharge, and groundwater records on annual, monthly, and daily intervals in the upper Neosho River of Kansas demonstrates the importance of frequent, small-scale monitoring to resource management. Natural, drought-induced, noflow conditions prior to reservoir construction were eliminated by sustained, low-volume, reservoir outflow over five drought cycles. Temporary bank storage, caused by reservoirinduced, high-flow pulses, was observed at the Emporia State University Campus Woods field station during a prolonged recent drought. Gaining and losing stream conditions were observed in multi-year monitoring but, in drought years, losing conditions occurred only when reservoir releases generated stream flow. In drought and non-drought years, relatively low groundwater levels coincided with seasonal growing periods, reflecting the importance of transpiration by riparian vegetation on stream-aquifer exchange. An understanding of the drought response of the individual elements of a floodplain hydrologic system is important to management of the integrated resource.

Population declines in shark species have been reported on local and global scales, with overfishing, habitat destruction and climate change posing severe threats. The lack of species-specific baseline data on ecology and distribution of many sharks, however, makes conservation measures challenging. Here, we present a fisheries-independent shark survey from the Fiji Islands, where scientific knowledge on locally occurring elasmobranchs is largely still lacking despite the location’s role as a shark hotspot in the Pacific. Juvenile shark abundance in the fishing grounds of the Ba Estuary (north-western Viti Levu) was assessed with a gillnet-and longline-based survey from December 2015 to April 2016. A total of 103 juvenile sharks identified as blacktip Carcharhinus limbatus (n = 57), scalloped hammerhead Sphyrna lewini (n = 35), and great hammerhead Sphyrna mokarran (n = 11) sharks were captured, tagged, and released. The condition of umbilical scars (68% open or semihealed), mean sizes of individuals (±SD) (C. limbatus: 66.5 ± 3.8 cm, S. lewini: 51.8 ± 4.8 cm, S. mokarran 77.4 ± 2.8 cm), and the presence of these species over recent years (based on fishermen interviews), suggest that the Ba Estuary area is a critical habitat for multiple species that are classified as “Near Threatened” or “Endangered.” Specifically, the area likely acts as a parturition ground over the studied period, and potentially as a subsequent nursery area. We identified subareas of high abundance and found that temperature, salinity and depth acted as small-scale environmental drivers of shark abundance. The data suggests a tendency for species-specific spatial use, both horizontally (i.e., between sampling areas) and vertically (i.e., across the water column). These results enhance the understanding of shark ecology in Fiji and provide a scientific basis for the implementation of local conservation strategies that contribute to the protection of these threatened species

Sharp declines in numerous shark populations around the world have generated considerable interest in better understanding and characterising their biology, ecology and critical habitats. The scalloped hammerhead shark (SHS, Sphyrna lewini) is subject to a multitude of natural and anthropogenic threats that are often exacerbated within the coastal embayments and estuaries used during SHS early life stages. In this study, we describe the temporal and spatial distribution, age class composition, and reproductive biology of SHS in the Rewa Delta (RD), Fiji. A total of 1054 SHS (including 796 tagged individuals; 101 of which were recaptured) were captured from September 2014 to March 2016 in the RD. A majority of the captures in this area were neonates and young-of-the-year (YOY) (99.8%). Significant seasonality in patterns of occurrence of both neonates and YOY individuals suggests a defined parturition period during the austral summer. Between the seven sampling sites in the RD we also found significant differences in SHS neonate catch per unit of effort, and average total length of individuals. According to the data, the RD is likely to represent an important nursery area for SHS up to one year of age.

Organisms develop local adaptations to cope with spatially and temporally variable environments such as estuarine habitats, where abiotic parameters such as salinity and temperature fluctuate continuously. Studying the regulation of gene expression in a variable environment allows us to understand the underlying molecular mechanisms of these adaptations and the relative roles of the genetic and plastic response. The transcriptomes of the European native Palaemon longirostris (PL) and the introduced P. macrodactylus (PM) shrimps are described and compared after an experiment simulating summer conditions in the Guadalquivir Estuary, Spain. Specimens, collected in the Guadalquivir Estuary, were maintained at a temperature and salinity of 20 °C and 5 ppt for the control, and 30 °C and 15 ppt for the stress treatment. A large amount of differential gene expression was observed: 16,013 and 2,594 for PL and PM respectively. Functionally annotated unigenes revealed some differences, with PL seemingly having to face stronger physiological stress than PM. Thus, PM seems to have greater resistance than PL under conditions of high temperature and salinity. These results constitute a step forward in the understanding of the underlying molecular mechanisms of genetic adaptation of native invertebrates, and alien taxa that have successfully invaded estuaries in temperate regions around the world.

20 páginas, 1 figura, 3 tablas., Recent studies have reported an unusually high frequency of nonamplifying alleles at microsatellite loci in bivalves. Null alleles have been associated with heterozygous deficits in many studies. While several studies have tested for its presence using different analytical tools, few have empirically tested for its consequences in estimating population structure and differentiation. We characterised 16 newly developed microsatellite loci and show that null alleles are ubiquitous in the wedge clam, Donax trunculus. We carried out several tests to demonstrate that the large heterozygous deficits observed in the newly characterised loci were most likely due to null alleles.Wetested the robustness of microsatellite genotyping for population assignment by showing that well-recognised biogeographic regions of the south Atlantic and south Mediterranean coast of Spain harbour genetically different populations., CR was supported by the Spanish Ministry of Education (Grant no PR2010-0601) and the Spanish Scientific Research Council (CSIC). This research was financially supported by Organismo Autonomo de Parque Nacionales Grant OAPN122_2010 to CR, EM, JAC and PD. ADM was supported by the Strategic Research Themes of the University of the South Pacific.

International audience; This paper details in-situ studies of modifications induced by swift heavy ion irradiation in a-Al2O3. This complex behaviour is intermediary between the behaviour of amorphizable and non-amorphizable materials, respectively. A unique combination of irradiation experiments was performed at the IRRSUD beam line of the GANIL facility, with three different characterisation techniques: in-situ UVeVis absorption, in-situ grazing incidence X-Ray diffraction and ex-situ transmission electron microscopy. This allows a complete study of point defects, and by depth profile of structural and microstructural modifications created on the trajectory of the incident ion. The a-Al2O3 crystals have been irradiated by 92 MeV Xenon and 74 MeV Krypton ions, the irradiation conditions have been chosen rather similar with an energy range where the ratio between electronic and nuclear stopping power changes dramatically as function of depth penetration. The main contribution of electronic excitation, above the threshold for track formation, is present beneath the surface to finally get almost only elastic collisions at the end of the projected range. Amorphization kinetics by the overlapping of multiple ion tracks is observed. In the crystalline matrix, long range strains, unit-cell swelling, local microstrain, domain size decrease, disordering of oxygen sublattice as well as colour centre formation are found. This study highlights the relationship between ion energy losses into a material and its response. While amorphization requires electronic stopping values above a certain threshold, point defects are predominantly induced by elastic collisions, while some structural modifications of the crystalline matrix, such as unit-cell swelling, are due to contribution of both electronic and nuclear processes.