208 research outputs found

    Harbour porpoise movement strategy affects cumulative number of animals acoustically exposed to underwater explosions

    Get PDF
    Anthropogenic sound in the marine environment can have negative consequences for marine fauna. Since most sound sources are intermittent or continuous, estimating how many individuals are exposed over time remains challenging, as this depends on the animals' mobility. Here we explored how animal movement influences how many, and how often, animals are impacted by sound. In a dedicated study, we estimated how different movement strategies affect the number of individual harbour porpoises Phocoena phocoena receiving temporary or permanent hearing loss due to underwater detonations of recovered explosives (mostly WWII aerial bombs). Geo-statistical distribution models were fitted to data from 4 marine mammal aerial surveys and used to simulate the distribution and movement of porpoises. Based on derived dose-response thresholds for temporary (TTS) or permanent threshold shifts (PTS), we estimated the number of animals affected in a single year. When individuals were free-roaming, an estimated 1200 and 24 000 unique individuals would suffer PTS and TTS, respectively. This equates to respectively 0.50 and 10% of the estimated North Sea population. In contrast, when porpoises remained in a local area, fewer animals would receive PTS and TTS (1100 [0.47%] and 15 000 [6.5%], respectively), but more individuals would be subjected to repeated exposures. Because most anthropogenic sound-producing activities operate continuously or intermittently, snapshot distribution estimates alone tend to underestimate the number of individuals exposed, particularly for mobile species. Hence, an understanding of animal movement is needed to estimate the impact of underwater sound or other human disturbance. © The authors 2016

    The Subak in Diaspora: Balinese Farmers and the Subak in South Sulawesi

    Get PDF
    The subak has a long history as an irrigators’ institution on Bali. It has also spread across Indonesia along with Balinese farmers who were resettled by colonial and post-colonial governments or who have migrated spontaneously since colonial times. While subaks have been much researched in Bali itself, little is known about subaks outside Bali. Luwu District in South Sulawesi is one of the areas where thousands of Balinese families settled in the last four decades. Based on research in this transmigration area, this paper analyzes the emergence and development of the subak in relation to the development of irrigation infrastructure of a state-built irrigation system. A comparison between two Balinese settlements in the same system shows that differences in infrastructural and managerial conditions and arrangements between parts of the irrigation system were major determinants of the institutional space allowed for the subak and ways in which the subaks developed

    How effectively do horizontal and vertical response strategies of long-finned pilot whales reduce sound exposure from naval sonar?

    Get PDF
    PJW was supported with studentships of The Netherlands Ministry of Defence (grant number 032.30370/01.02) and the VSB Foundation (grant number VSB.08/228-E) and Ren e Dekeling is acknowledged for making funding possible. The 3S project was supported by the US Office of Naval Research, The Netherlands Ministry of Defence, Royal Norwegian Navy and Norwegian Ministry of Defence, and by World Wildlife Fund Norway. PLT received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland) and their support is gratefully acknowledged.The behaviour of a marine mammal near a noise source can modulate the sound exposure it receives. We demonstrate that two long-finned pilot whales both surfaced in synchrony with consecutive arrivals of multiple sonar pulses. We then assess the effect of surfacing and other behavioural response strategies on the received cumulative sound exposure levels and maximum sound pressure levels (SPLs) by modelling realistic spatiotemporal interactions of a pilot whale with an approaching source. Under the propagation conditions of our model, some response strategies observed in the wild were effective in reducing received levels (e.g. movement perpendicular to the source's line of approach), but others were not (e.g. switching from deep to shallow diving; synchronous surfacing after maximum SPLs). Our study exemplifies how simulations of source-whale interactions guided by detailed observational data can improve our understanding about motivations behind behaviour responses observed in the wild (e.g., reducing sound exposure, prey movement).PostprintPeer reviewe

    Modeling potential masking of echolocating sperm whales exposed to continuous 1–2 kHz naval sonar

    Get PDF
    This study was sponsored by the U.S. Living Marine Resources program, Office of Naval Research (ONR) Grant Nos. N00014-18-1-2062 and N00014-20-1-2709, UK Defence Science and Technology Laboratory (DSTL), French Direction générale de l'armement (DGA), and the Netherlands Ministry of Defence.Modern active sonar systems can (almost) continuously transmit and receive sound, which can lead to more masking of important sounds for marine mammals than conventional pulsed sonar systems transmitting at a much lower duty cycle. This study investigated the potential of 1–2 kHz active sonar to mask echolocation-based foraging of sperm whales by modeling their echolocation detection process. Continuous masking for an echolocating sperm whale facing a sonar was predicted for sonar sound pressure levels of 160 dB re 1 μPa2, with intermittent masking at levels of 120 dB re 1 μPa2, but model predictions strongly depended on the animal orientation, harmonic content of the sonar, click source level, and target strength of the prey. The masking model predicted lower masking potential of buzz clicks compared to regular clicks, even though the energy source level is much lower. For buzz clicks, the lower source level is compensated for by the reduced two-way propagation loss to nearby prey during buzzes. These results help to predict what types of behavioral changes could indicate masking in the wild. Several key knowledge gaps related to masking potential of sonar in echolocating odontocetes were identified that require further investigation to assess the significance of masking.Publisher PDFPeer reviewe

    J0454-0309: Evidence for a strong lensing fossil group falling into a poor galaxy cluster

    Full text link
    We have discovered a strong lensing fossil group (J0454) at z=0.26, projected near the well-studied cluster MS0451-0305. Using multicolour Subaru/Suprime-Cam and CFHT/Megaprime imaging together with Keck spectroscopy we identify member galaxies. A VLT/FORS2 spectrum was taken to determine the redshifts of the brightest elliptical and the lensed arc. Using HST/ACS images we determine the group's weak lensing signal and model the strong lens system. This is the first time that a fossil group is analysed with lensing methods. The X-ray luminosity and temperature are derived from XMM-Newton data. We find two filaments extending over 4 Mpc, and within the virial radius we identify 31 members spectroscopically and 33 via the red sequence with i<22 mag. They segregate into spirals and a dynamically cooler central concentration of ellipticals with a velocity dispersion of 480 km/s. Weak lensing and cluster richness relations yield r200 = 830 kpc and M200 = 0.85 x 10^14 Msun. The brightest group galaxy (BGG) is inconsistent with the dynamic centre of J0454. It strongly lenses a galaxy at z~2.1, and we model the lens with a pseudo-isothermal elliptical mass distribution. A large external shear requires that the BGG must be offset from J0454's dark halo centre by at least 90-130 kpc. The X-ray halo is offset by 24 kpc from the BGG, shows no signs of a cooling flow and is well described by a beta-model. With L = 1.4 x 10^43 erg/s J0454 falls well onto standard X-ray cluster scaling relations, but appears cooler (1.1 keV) than expected (2 keV). We conclude that J0454 consists of two systems, a sparse cluster and an infalling fossil group, the latter seeding the BCG. An alternative explanation is that galaxies in a filament, projected along the line of sight, stream towards the denser fossil group.Comment: 20 pages, 17 figures; Identical to the publication in A+A. Small language corrections. Minor additions: We check the influence of individual galaxy haloes to the external shear (Sect. 8.1.1). Alternative interpretation of the data: Galaxies ina filament projected along the l.o.s. fall into the fossil group (Section 8.1.2

    The New Legal Pluralism

    Get PDF
    Scholars studying interactions among multiple communities have often used the term legal pluralism to describe the inevitable intermingling of normative systems that results from these interactions. In recent years, a new application of pluralist insights has emerged in the international and transnational realm. This review aims to survey and help define this emerging field of global legal pluralism. I begin by briefly describing sites for pluralism research, both old and new. Then I discuss how pluralism has come to be seen as an attractive analytical framework for those interested in studying law on the world stage. Finally, I identify advantages of a pluralist approach and respond to criticisms, and I suggest ways in which pluralism can help both in reframing old conceptual debates and in generating useful normative insights for designing procedural mechanisms, institutions, and discursive practices for managing hybrid legal/cultural spaces

    Beyond property: Rural politics and land-use change in the Colombian sugarcane landscape

    Full text link
    Analysing the sugarcane landscape in the flat valley of the Cauca River (Colombia) reveals that agricultural industrialization in the region required the concentration of land use by regional industrialists and the corresponding exclusion of landowners and poor peasants from territorial decision-making processes. The analytical lens used in this article, based on the use and control over land and land-based natural commons, allows for the characterization of three periods in a non-linear process of articulation and dispute between poor peasant and capitalist agents in the expansion of the sugarcane monoculture during the 20th century. The different constellations of social agents, governmental nexus, and capital enclosures have enacted through mechanisms that, beyond concentrating land property, have managed to deprive rural ethnic communities from their cultural and environmental heritage, traditional economies, and possible futures.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151270/1/joac12332_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151270/2/joac12332.pd

    Northern bottlenose whales in a pristine environment respond strongly to close and distant navy sonar signals

    Get PDF
    The research described in this paper was supported by US Office of Naval Research (ONR grants N00014-15-1-2533 and N00014-16-1-3059), US Strategic Environmental Research and Development Program (SERDP award RC-2337), the French Ministry of Defence (DGA) and the Netherlands Ministry of Defence. P.L.T. acknowledges support from the MASTS pooling initiative (Marine Alliance for Science and Technology for Scotland; supported by the Scottish Funding Council, grant reference HR09011, and contributing institutions). All relevant data and scripts are within the paper and its electronic supplementary material, or available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.fc5c0s4Impact assessments for sonar operations typically use received sound levels to predict behavioural disturbance in marine mammals. However, there are indications that cetaceans may learn to associate exposures from distant sound sources with lower perceived risk. To investigate the roles of source distance and received level in an area without frequent sonar activity, we conducted multi-scale controlled exposure experiments (n = 3) with 12 northern bottlenose whales near Jan Mayen, Norway. Animals were tagged with high-resolution archival tags (n = 1 per experiment) or medium-resolution satellite tags (n = 9 in total) and subsequently exposed to sonar. We also deployed bottom-moored recorders to acoustically monitor for whales in the exposed area. Tagged whales initiated avoidance of the sound source over a wide range of distances (0.8–28 km), with responses characteristic of beaked whales. Both onset and intensity of response were better predicted by received sound pressure level (SPL) than by source distance. Avoidance threshold SPLs estimated for each whale ranged from 117–126 dB re 1 µPa, comparable to those of other tagged beaked whales. In this pristine underwater acoustic environment, we found no indication that the source distances tested in our experiments modulated the behavioural effects of sonar, as has been suggested for locations where whales are frequently exposed to sonar.Publisher PDFPeer reviewe

    Military business and the business of the military

    Get PDF
    Contrary to dominant approaches that locate the causes for military entrepreneurialism in eastern Democratic Republic of the Congo predominantly in criminal military elites, this article highlights the importance of the Congolese military’s (FARDC) civilian context for understanding military revenue-generation. It analyses how the latter is shaped by structures of domination, signification and legitimisation that drive and are driven by the FARDC’s governance, private protection and security practices. It argues that these practices contribute to bestowing a degree of legitimacy on both the FARDC’s position of power and some of its revenue-generation activities. Furthermore, by emphasising that the FARDC’s regulatory and protection practices are partly the product of popular demands and the routine actions of civilians, the article contends that the causes of military revenue-generation are co-located in the military’s civilian environment. In this manner, it offers a more nuanced conceptualisation of military entrepreneurialism, thus opening up new perspectives on policy interventions in this area
    corecore