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Genomic survey of edible cockle (Cerastoderma edule) in the Northeast Atlantic: a baseline for sustainable management of its wild resources.
Get PDFKnowledge on correlations between environmental factors and genome divergence between populations of marine species is crucial for sustainable management of fisheries and wild populations. The edible cockle ( Cerastoderma edule) is a marine bivalve distributed along the Northeast Atlantic coast of Europe and is an important resource from both commercial and ecological perspectives. We performed a population genomics screening using 2b-RAD genotyping on 9309 SNPs localized in the cockle's genome on a sample of 536 specimens pertaining to 14 beds in the Northeast Atlantic Ocean to analyse the genetic structure with regard to environmental variables. Larval dispersal modelling considering species behaviour and interannual/interseasonal variation in ocean conditions was carried out as an essential background to which compare genetic information. Cockle populations in the Northeast Atlantic displayed low but significant geographical differentiation between populations ( F ST = 0.0240; p < 0.001), albeit not across generations. We identified 742 and 36 outlier SNPs related to divergent and balancing selection in all the geographical scenarios inspected, and sea temperature and salinity were the main environmental correlates suggested. Highly significant linkage disequilibrium was detected at specific genomic regions against the very low values observed across the whole genome. Two main genetic groups were identified, northwards and southwards of French Brittany. Larval dispersal modelling suggested a barrier for larval dispersal linked to the Ushant front that could explain these two genetic clusters. Further genetic subdivision was observed using outlier loci and considering larval advection. The northern group was divided into the Irish/Celtic Seas and the English Channel/North Sea, while the southern group was divided into three subgroups. This information represents the baseline for the management of cockles, designing conservation strategies, founding broodstock for depleted beds and producing suitable seed for aquaculture production. </p
Blood, lead and spheres: a hindered settling equation for sedimentologists based on metadata analysis
Get PDFA revision of the popular equation of Richardson and Zaki (1954a, Transactions of the Institute of Chemical Engineering, 32, 35–53) for the hindered settling of suspensions of non-cohesive particles in fluids is proposed, based on 548 datasets from a broad range of scientific disciplines. The new hindered settlingequation enables predictions of settling velocity for a wide range of particle sizes and densities, and liquid densities and viscosities, but with a focus on sediment particles in water. The analysis of the relationship between hindered settling velocity and particle size presented here shows that the hindered settling effectincreases as the particle size decreases, e.g., a 50% reduction in settling velocity is reached for 0.025 mm silt and 4 mm pebbles at particle concentrations of 13% and 25%, respectively. Moreover, hindered settling starts to influence the settling behaviour of sediment particles at volumetric concentrations of merely a fewpercent. For example, the particle settling velocity in flows that carry 5% silt is reduced by at least 22%. These observations suggest that hindered settling greatly increases the efficiency of natural flows to transport sediment particles, but also particulate carbon and pollutants, such as plastics, over large distances
Ultrafast Secure Key Distribution Based on Random DNA Coding and Electro-Optic Chaos Synchronization
Get PDFWe propose and numerically demonstrate an ultrafast secure key distribution based-on random DNA coding and the chaos synchronization in two identical electro-optic oscillators (EO) with common injection. High-quality synchronization between the responses of EOs with extremely sensitivity to the mismatching of time delay and phase bias is observed. It is noted that the random DNA coding and the delay DNA-XOR in the post-processing can greatly amplify the randomness of the synchronized sequences acquired by symmetrically dual-threshold sampling the correlated physical entropies, and enhance the security of key distribution by providing additional encryption. According to our study, high rate key distribution of over 10 Gb/s can be fulfilled with a good consistency, which can be used for the commercial communication networks
The influence of tides on the North West European shelf winter residual circulation
Get PDFTides contribute to the large-scale residual circulation and mixing of shelf seas. However, tides are typically excluded from global circulation models (GCMs) so their modelled residual circulation (and mixing) in shelf seas may be systematically wrong. We focus on circulation as it is relatively unexplored, and affects shelf temperature and salinity, potentially biasing climate impact studies. Using a validated model of the North West European Shelf Seas (NWS), we show the essential role of tides in driving the residual circulation, and how this affects the NWS temperature and salinity distribution. Over most of the NWS, removing the tides increases the magnitude of residual circulation while in some regions (such as the Irish Sea) it leads to a reduction. Furthermore, we show that modelling the NWS without tides leads to a cold fresh bias in the Celtic Sea and English Channel (of >0.5°C, and >0.5 psu). This shows that NWS tidal dynamics are essential in the transport of heat and matter, and so must be included in GCMs. We explore two processes by which the tides impact the residual circulation and investigate whether these could be parameterised within non-tidal GCMs: (1) Enhancing the seabed friction to mimic the equivalent energy loss from an oscillating tidal flow; (2) Tidal Phase-driven Transport (TPT), whereby tidal asymmetry drives a net transport due to the phase between tidal-elevation and velocities (equivalent to the bolus term in oceanographic literature). To parameterise TPT, we calculate a climatology of this transport from a harmonic analysis from the tidal model and add it as an additional force in the Navier Stokes equations in the non-tidal model. We also modify the bed drag coefficient to balance the bed stress between the simulations – hypothesising that using this modified drag coefficient will simulate the effect of the tides. This tends to improve the mean and variability of the residual circulation, while the TPT improves the spatial distribution and temporal variability of the temperature and salinity. We show that our proof-of-concept parameterisation can replicate the tidally-driven impact on the residual circulation without direct simulation, thus reducing computational effort
Gas compressor noise does not influence tree swallow nestling condition or immune response
Get PDFAnthropogenic noise pollution, such as that derived from traffic and industrial machinery, has been identified as an urgent conservation priority as it is often louder and more prevalent than natural acoustic stimuli, and can act as a stressor on wildlife. Research in avian systems has shown that anthropogenic noise can affect physiology and reproductive success of adult birds – but effects on juvenile birds have been less-studied despite their being potentially more vulnerable during the nestling period. What studies have been done have shown remarkable variability in juvenile response to anthropogenic noise, suggesting that effects are highly context- and species-specific. Here, we investigate the effects of gas compressor noise, an increasingly prevalent and biologically relevant noise stressor produced during natural gas production, on juvenile tree swallows (Tachycineta bicolor). Gas compressors generate considerable sound pressure as they work to pressurize gas pipelines for downstream distribution. We predicted that exposure to increased noise during incubation and the nestling period would result in smaller chicks in poorer body condition and with a dampened immune response. Surprisingly, we found no evidence for any of these predictions, providing further evidence that noise effects on juvenile birds is highly variable, and we explore ways in which individual birds may compensate for the effects of disturbance at the nest
Constraints on Rice Cultivation in Eastern Madagascar: Which Factors Matter to Smallholders, and Which Influence Food Security?
Get PDFRepresentative range of acoustic point source measurements in the Chukchi Sea
Get PDFThe use of stationary, active acoustics provides an effective approach to characterize and monitor temporal variability in the abundance and behavior of pelagic organisms, especially in seasonally ice-covered waters of high latitude marine ecosystems. However, point measurements from stationary echosounders are limited in their spatial coverage. A quantification of the spatial area represented by point measurements (i.e., representative range) is required to ensure effective biological characterization and monitoring. Here, concurrent mobile and stationary active acoustic data collected during summers of 2015 and 2017 are used to assess the representative range of fish and zooplankton density measurements from the Chukchi Ecosystem Observatory located at Hanna Shoal, Northeast Chukchi Sea. Six methods used to calculate representative ranges of backscatter means and variances resulted in representative ranges between approximately 0.3 and 86 km, depending on the year and calculation method. Such relatively large representative ranges reflect the tight bio-physical associations and large characteristic environmental length scales of the NE Chukchi Sea. Between years, up to 10-fold variations in representative ranges were attributed to interannual changes in water mass characteristics and associated species assemblages. Differences of 1–2 orders of magnitude in our calculated ranges among methods are attributed to differences in the rationale and associated assumptions of each approach. The choice of method and resulting representative range depends on monitoring goals: detection of change, mapping of spatial distributions, characterization of spatial variance, or interpolation of temporal variability over space. Our comparison of stationary acoustic to mobile surveys extends the understanding of spatiotemporal variability of marine organism distributions in the NE Chukchi Sea and informs cost-effective design of observing systems to monitor and predict impacts of environmental change
What Next After MBSR/MBCT? An Open Trial of an 8-Week Follow-on Program Exploring Mindfulness of Feeling Tone (vedanā)
Get PDFObjectivesThe effectiveness of mindfulness-based programs (MBPs) has been established in many randomized controlled trials. However, effect sizes are often modest, and there remains ample scope to improve their effectiveness. One approach to this challenge is to offer a “follow-on” course to people who have completed an MBP and are interested in further skill development. We developed and tested a new 8-week course for this purpose based on awareness of feeling tone (vedanā), an understudied aspect of mindfulness in many current MBPs, incorporating new developments in neuroscience and trauma sensitivity. We examined its effectiveness and the frequency and severity of unpleasant experience and harm.MethodsIn an open trial, 83 participants, 78 of whom had previously taken part in an MBP (majority MBSR or MBCT), completed the program in nine groups. Participants completed questionnaires before and after and gave qualitative written feedback at completion.ResultsParticipants reported significantly reduced depression (d = 0.56), stress (d = 0.36), and anxiety (d = 0.53) and increased well-being (d = 0.54) and mindfulness (d = 0.65) with 38% meeting criteria for reliable change on anxiety and depression. As expected, about three-quarters of participants reported some unpleasant experiences associated with mindfulness practice during the course, but none reported harm. Five participants showed “reliable deterioration” (an increase) in either depression or anxiety, but four of these five also gave anonymous qualitative feedback describing benefits of the course.ConclusionsFindings support the added value of a follow-on course based on the exploration of feeling tone for participants who have a range of previous mindfulness experience
Operationalizing marketable blue carbon
Get PDFThe global carbon sequestration and avoided emissions potentially achieved via blue carbon is high (∼3% of annual global greenhouse gas emissions); however, it is limited by multidisciplinary and interacting uncertainties spanning the social, governance, financial, and technological dimensions. We compiled a transdisciplinary team of experts to elucidate these challenges and identify a way forward. Key actions to enhance blue carbon as a natural climate solution include improving policy and legal arrangements to ensure equitable sharing of benefits; improving stewardship by incorporating indigenous knowledge and values; clarifying property rights; improving financial approaches and accounting tools to incorporate co-benefits; developing technological solutions for measuring blue carbon sequestration at low cost; and resolving knowledge gaps regarding blue carbon cycles. Implementing these actions and operationalizing blue carbon will achieve measurable changes to atmospheric greenhouse gas concentrations, provide multiple co-benefits, and address national obligations associated with international agreements