Background document for carbonate mounds

Hall-Spencer JM, Stehfest KM & Wheeler AJ (2010) Background document for carbonate mounds. OSPAR Commission, 489/201021pp. ISBN 978-1-907390-30-2

Quantum dynamics in strong fluctuating fields

A large number of multifaceted quantum transport processes in molecular systems and physical nanosystems can be treated in terms of quantum relaxation processes which couple to one or several fluctuating environments. A thermal equilibrium environment can conveniently be modelled by a thermal bath of harmonic oscillators. An archetype situation provides a two-state dissipative quantum dynamics, commonly known under the label of a spin-boson dynamics. An interesting and nontrivial physical situation emerges, however, when the quantum dynamics evolves far away from thermal equilibrium. This occurs, for example, when a charge transferring medium possesses nonequilibrium degrees of freedom, or when a strong time-dependent control field is applied externally. Accordingly, certain parameters of underlying quantum subsystem acquire stochastic character. Herein, we review the general theoretical framework which is based on the method of projector operators, yielding the quantum master equations for systems that are exposed to strong external fields. This allows one to investigate on a common basis the influence of nonequilibrium fluctuations and periodic electrical fields on quantum transport processes. Most importantly, such strong fluctuating fields induce a whole variety of nonlinear and nonequilibrium phenomena. A characteristic feature of such dynamics is the absence of thermal (quantum) detailed balance.Comment: review article, Advances in Physics (2005), in pres

Diving into the vertical dimension of elasmobranch movement ecology

This is the final version. Available on open access from the American Association for the Advancement of Science via the DOI in this recordData and materials availability: Processed data and code used in the analysis are accessible from the Zenodo Repository: 10.5281/zenodo.6885455Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements.Bertarelli FoundationResearch EnglandMoore FoundationPackard FoundationInstituto Politecnico NacionalDarwin InitiativeGeorgia AquariumRolex Awards for EnterpriseWhitley Fund for Natur

Network analysis of acoustic tracking data reveals the structure and stability of fish aggregations in the ocean

Aggregations in the distribution of individuals are an almost universal phenomenon in living organisms. Groups of animals that display collective coordinated movement without forming stable social bonds such as fish schools are a special type of aggregation. In tropical tuna fisheries, aggregating behaviour is directly exploited through the use of artificial fish aggregating devices (FADs). Hence, understanding the dynamics of schooling behaviour and the potential impacts of FADs upon it may have ramifications for tuna management. As a novel way of quantifying spatiotemporal co-occurrences of animals, we applied network statistics to acoustic tracking data to identify the co-occurrences of individual yellowfin tuna, Thunnus albacares, in an array of FADs and determine the frequency and temporal dynamics of these co-occurrences. We observed large interannual variation in movement rates of tuna between FADs, and corresponding interannual variability in the mean number of spatiotemporal associates for each individual as well as the temporal stability of associations. When movement rates were high, associations within FAD aggregations decayed to randomness three times faster than when movement rates were lower. This raises the possibility that if FADs are sufficiently close for fish to perform frequent between- FAD movements, school mixing may be increased and cohesion reduced

Video-based CPR Analysis System

In comparison to other behaviours, large predators expend relatively large amounts of energy foraging for prey, based on expected high return. Documenting how they manage costs and benefits of feeding is difficult, particularly for marine predators. In July and August of 2004 and 2005, we combined animal-borne video, accelerometry and depth sensors to examine the underwater behaviour during white shark (Carcharodon carcharias) breaching at Seal Island, South Africa (34.1373°S, 18.5825°E)—where sharks launch from the water while attacking Cape fur seals (Arctocephalus pusillus pusillus). We show that breaching begins at depths up to 20 m, is characterised by a brief (~ 7 to 16 s) ascent to the surface during which pitch angle increases by ~ 30° and both tail-beat frequency and swim speed (determined using biomechanical principles) increase by a maximum of 6.5-fold (0.39–2.50 Hz and 1.0–6.5 m s−1, respectively). Sharks also demonstrated the ability to rapidly adjust their approach to the seal during ascent. Dominant tail-beat frequency during breaching was 2.1–4.2 times higher (0.83–1.67 Hz) than during non-predatory ascents (0.4 Hz), suggestive of the large increase in power required to breach. Examination of foraging behaviour through biologger deployments may play an increasingly important role in predicting the resource requirements of large predators and developing appropriate conservation measures, as their populations are generally under threat world-wide