1,374,344 research outputs found
The scaling of diving time budgets : insights from an optimality approach
No full textThe authors acknowledge the Natural Environment Research Council for support with this work (grant NER/A/S/2003/00616).Simple scaling arguments suggest that, among air-breathing divers, dive duration should scale approximately with mass to the one-third power. Recent phylogenetic analyses appear to confirm this. The same analyses showed that duration of time spent at the surface between dives has scaling very similar to that of dive duration, with the result that the ratio of dive duration to surface pause duration is approximately mass invariant. This finding runs counter to other arguments found in the diving literature that suggest that surface pause duration should scale more positively with mass, leading to a negative scaling of the dive-pause ratio. We use a published model of optimal time allocation in the dive cycle to show that optimal decisions can predict approximate mass invariance in the dive-pause ratio, especially if metabolism scales approximately with mass to the two-thirds power (as indicated by some recent analyses) and oxygen uptake is assumed to have evolved to supply the body tissues at the required rate. However, emergent scaling rules are sensitive to input parameters, especially to the relationship between the scaling of metabolism and oxygen uptake rate at the surface. Our results illustrate the utility of an optimality approach for developing predictions and identifying key areas for empirical research on the allometry of diving behavior.Peer reviewe
Fishing for drifts : detecting buoyancy changes of a top marine predator using a step-wise filtering method
No full textThis research was partly funded by a Natural Environment Research Council grant [NE/E018289/1]. Further, a PhD studentship in Marine Biology partially funded by the Natural Environment Research Council [NE/L501852/1] and the University of St Andrews 600th Scholarship supported this work.In southern elephant seals (Mirounga leonina), fasting and foraging related fluctuations in body composition are reflected by buoyancy changes which can be monitored by changes in drift rate. Here, we present an improved knowledge-based method for detecting buoyancy changes from compressed and abstracted dive profiles received through telemetry. We applied this step-wise filtering method to the dive records of 11 southern elephant seals, which identified 0.8% to 2.2% of all dives as drift dives. At the beginning of the migration, all individuals were strongly negatively buoyant. Over the following 75 to 150 days, the buoyancy reached a peak close to or at neutral buoyancy, indicative of a seal’s foraging success. Ground-truthing confirmed that this new knowledge-based method is capable to reliably detect buoyancy changes in the dive records of drift diving species using abstracted dive profiles. This affirms that the abstraction algorithm conveys sufficient detail of the geometric shape of drift dives for them to be identified. It also suggest that using this step-wise filtering method, buoyancy changes could be detected even in old datasets with compressed dive information, for which conventional drift dive classification previously failed.Peer reviewe
Dive tourism and local communities: active participation or passive impacts? Case studies from Malaysia.
No full textFor many Less Developed Countries international tourism has long been considered a driver for economic development (OECD, 1967). However, tourism has also been heavily criticised for its negative environmental and cultural impacts and significant economic leakages due to the dependence of many host countries on large trans-national corporations (Mowforth and Munt, 2003). Specialist tourism forms such as eco-tourism or small-scale locally owned tourism have been promoted in response to these criticisms,with benefits advocated for local communities, greater cultural awareness by tourists and
more controllable environmental impacts (Weaver, 2001; Scheyvens, 2002; Hampton,2005).
Using local participation approaches, this Working Paper examines dive tourism
as a form of niche tourism and assesses its impacts on local host communities. It investigates whether, or to what extent, active local participation is possible, and how far host communities are merely exposed to ‘passive’ impacts of dive tourism.
The study covered three research locations in Malaysia and revealed that many
aspects of local community life were affected by dive tourism. Besides physical changes such as new infrastructure, the study showed varied economic impacts for local communities through the existence (or lack of)employment/business opportunities, and differing levels of economic linkages, notably the purchase of goods and services between the dive industry and host villages. Local participation varied between locations and a number of obstacles to increased participation were revealed. Furthermore, impacts
on local culture and society were observed as well as a lack of participation in possible cultural productions (handicrafts, performances) by local host communities. As a consequence of the dive industry’s initiatives however, positive educational impacts were noted, especially concerning environmental awareness and English language acquisition
Diving dangerously: Exploring human health and resource trade-offs of extreme dive profiles in a Caribbean dive fishery. [graduate project].
No full textDive fishers around the world employ compressed air diving to harvest marine living resources in the quest for livelihoods. Fishers can suffer catastrophic health consequences while targetting these fisheries resources that are in states of overexploitation. While the health effects of diving fisheries have been well documented, the underlying drivers of unsafe dive practices remain unaddressed. Applying an ethnographic approach, this study examined why fishers undertake unsafe dive profiles in the Caribbean Spiny Lobster (Panulirus argus) and Queen Conch (Lobatus gigas) small-scale dive fishery of Grenada. Semi-structured, qualitative interview data from fishers were supplemented by direct and participant observation, and analyzed using a thematic, grounded theory approach. Factors promoting unsafe dive practices, vulnerabilities in the fishery as well as dive related risk factors were identified. Unsafe dive profiles are largely driven by uncertainties in the market for catch, which are also influenced by changes in the ecology of the fishery. Three approaches exist for fisheries managers: reduce vulnerabilities affecting fishers, address underlying drivers, and mitigating diving risk factors. Under appropriate management and socio-economic regimes, it is not inconceivable that the Grenadian dive fishery could be a safe, sustainable and economically viable model
Dive Deeper Journeys with Moby-Dick
No full textAn easy-to-navigate guide to Herman Melville's epic American novel, Dive Deeper consists of 135 brief chapters, along with Etymology, Extracts, and Epilogue, each keyed to a phrase, issue, image, sensibility or notion in corresponding chapters of the original.Cover -- Table of Contents -- A Note to Readers -- Etymology -- Extracts -- Moby-Dick: Chapters 1 - 135 -- Epilogue -- Acknowledgments -- Credits -- Notes -- Index -- A -- B -- C -- D -- E -- F -- G -- H -- I -- J -- K -- L -- M -- N -- O -- P -- Q -- R -- S -- T -- U -- V -- W -- Y -- ZAn easy-to-navigate guide to Herman Melville's epic American novel, Dive Deeper consists of 135 brief chapters, along with Etymology, Extracts, and Epilogue, each keyed to a phrase, issue, image, sensibility or notion in corresponding chapters of the original.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
Dive tourism, communities and small islands: lessons from Malaysia and Indonesia
No full textCoastal tourism is growing rapidly across South-East Asia, especially in small islands. Islands and coastal areas face significant issues of how to manage the rapid growth of tourism whilst retaining economic benefits for the local host community. First, the paper sets the context and charts the scale and significance of international dive tourism, especially in less developed countries. The paper draws upon extensive fieldwork in small island destinations in Malaysia and Indonesia and explores how to research this area and the particular practicalities of fieldwork. Next the paper analyses the main socio-economic impacts of dive tourism drawing upon findings published in Haddock-Fraser and Hampton (2012); Daldeniz and Hampton (2013) and Hamzah and Hampton (2013) before introducing new analysis that is 'work in progress.' Finally, the paper concludes by considering lessons for other destinations in South-East Asia learning from success, and helping avoid mistakes being repeated
Project DIVE (Drilling the Ivrea-Verbano zonE): A joint petrological, geochemical, and geophysical exploration of the lower continental crust
No full textDespite the structural complexity of the Alps at numerous scales, geological and geophysical investigations have respectively mapped and imaged tremendous amounts of information near the surface and at depth. However, there is an inherent gap between the two sets of approaches, leaving the middle and lower crust poorly constrained. This has been one of the main motivations to initiate the ICDP project DIVE (Drilling the Ivrea-Verbano zonE), in which three geological sites of the Ivrea-Verbano Zone will be explored through scientific drilling. In this zone, near-complete sections of the continental crust are exposed at the surface, and with careful geological preparation and geophysical site surveys we have targeted three areas with a great potential of further discoveries during DIVE. Almost all physical and chemical properties will be characterized on the recovered rock core samples, in borehole logging investigations, and additional surveys around each site. Taken together, these should cover a large range of spatial scales covering at least 6 orders of magnitude (mm to km), investigate structures and their variations in bulk properties within the lower crust, and the transition to mantle rocks in an unprecedented way. The interdisciplinary approach not only allows to correlate numerous geophysical and petrological properties, but with modelling it will also allow to investigate the causative relationships.
The detailed aims, preparatory steps, as well as the current status of project DIVE, will be presented at the conference. By that time, drilling of the first hole is expected to start near Ornavasso, followed by a second hole in Megolo (both in Val d’Ossola). For the third site near Balmuccia, which is planned for later, site survey results will be presented
Efficient abstracting of dive profiles using a broken-stick model
No full textThis work was supported by SMRU Ltd (now SMRU Marine) in the form of a PhD fellowship (T.P.). Completion of the manuscript was supported by a National Research Foundation Scarce Skills Postdoctoral Fellowship at the University of Cape Town, South Africa (T.P.). The CTD-SRDL data presented in this manuscript were collected as part of a project funded by the Natural Environment Research Council (NERC) grants NE/E018289/1 and NER/D/S/2002/00426.For diving animals, animal-borne sensors are used to collect time-depth information for studying behaviour, ranging patterns and foraging ecology. Often, this information needs to be compressed for storage or transmission. Widely used devices called conductivity-temperature-depth satellite relay data loggers (CTD-SRDLs) sample time and depth at high resolution during a dive and then abstract the time-depth trajectory using a broken-stick model (BSM). This approximation method can summarize efficiently the curvilinear shape of a dive, using a piecewise linear shape with a small, fixed number of vertices, or break points. We present the process of abstracting dives using the BSM and quantify its performance, by measuring the uncertainty associated with the profiles it produces. We develop a method for obtaining a confidence zone and an index for the goodness-of-fit (dive zone index, DZI) for abstracted dive profiles. We validate our results with a case study using dives from elephant seals (Mirounga spp.). We use generalized additive models (GAMs) to determine whether the DZI can be used as a proxy for an absolute measure of fit and investigate the relationship between the DZI and the dive shape. We found a strong correlation between the residual sum of squares (RSS) for the difference between the detailed and abstracted profiles, and the DZI and maximum residual (R4), for dives resulting from CTD-SRDLs (69% deviance explained). On its own, the DZI explained a lower percentage of deviance which was variable for abstracted dives with different numbers of break points. We also found evidence for systematic differences in the DZI for different dive shapes (65% deviance explained). Although the proportional loss of information in the abstraction of time-depth dive profiles by BSM is high, what remains is sufficient to infer goodness-of-fit of the abstracted profile by reversing the abstraction process. Our results suggest that together the DZI and R4 can be used as a proxy for the RSS, and we present the method for obtaining these metrics for BSM-abstracted profiles.Peer reviewe
NLeSC/DiVE: 1.2
No full textAn interactive 3D web viewer of up to million points on one screen that represent data. Provides interaction for viewing high-dimensional data that has been previously embedded in 3D or 2D. Based on graphosaurus.js and three.js. For a Linux release of a complete embedding+visualization pipeline please visit https://github.com/sonjageorgievska/Embed-Dive
Exploration dive finding the frogfish
No full textA couple months back, my team and I went to Perhentian Island in Terengganu for a project called exploration dive. We were assisted by Mr Azharil Art from D’Lagoon Dive Centre, which was recommended by Mr Saiful Bahri Yakup, our team member who is a very well experienced diving instructor. We spent quite some time there with a few numbers of dive trip pursuing research related to marine life and the underwater environment. Nonetheless, this writing will only enumerate our work focusing on frogfish, including its behaviour, habitat, and species
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