Harvest patterns and effort dynamics of indigenous and non-indigenous commercial sectors of the eastern Torres Strait reef line fishery     

Ashley J. Williams  Aaron C. Ballagh  Gavin A. Begg  Cameron D. Murchie  Leanne M. Currey 《Continental Shelf Research》2008

The reef line fishery (RLF) in eastern Torres Strait (ETS) is unique in that it has both a commercial indigenous sector and a commercial non-indigenous sector. Recently, concerns have been expressed by all stakeholders about the long-term sustainability of the fishery. These concerns have been exacerbated by the lack of detailed catch and effort information from both sectors, which has precluded any formal assessment of the fishery. In this paper, we characterise the harvest patterns and effort dynamics of the indigenous and non-indigenous commercial sectors of the ETS RLF using a range of data sources including commercial logbooks, community freezer records, voluntary logbooks and observer surveys. We demonstrate that bycatch is a significant component of the catch for both sectors and identify substantial differences in harvest patterns and effort dynamics between the sectors. Differences between sectors were observed in species composition and spatial and temporal patterns in catch, effort and catch per unit effort. These results highlight the inherent variation in catch and effort dynamics between the two commercial sectors of the ETS RLF and provide valuable information for the development of future assessments and appropriate management strategies for the fishery. The more reliable estimates of harvest patterns and effort dynamics for both sectors obtained from observer surveys will also assist in resolving issues relating to allocation of reef fish resources in Torres Strait.  相似文献   

Determination of High Field Strength Elements, Rb, Sr, Mo, Sb, Cs, Tl and Bi at ng g⁻¹ Levels in Geological Reference Materials by Magnetic Sector ICP-MS after HF/HClO₄ High Pressure Digestion     

Zongshou Yu  Philip Robinson  Ashley T. Townsend  Carsten Mnker  Anthony J. Crawford 《Geostandards and Geoanalytical Research》2000,24(1):39-50

Six low abundance rock reference materials (basalt BIR-1, dunite DTS-1, dolerite DNC-1, peridotite PCC-1, serpentine UB-N and basalt TAFAHI) have been analysed for high field strength elements (Zr, Nb, Hf, Ta, Th and U), Rb, Sr, Mo, Sb, Cs, Tl and Bi at ng g⁻¹ levels (in rock) by magnetic sector inductively coupled plasma-mass spectrometry after HF/HClO₄ high pressure decomposition. The adopted method uses only indium as an internal standard. Detection limits were found to be in the range of 0.08 to 16.2 pg ml⁻¹ in solution (equivalent to 0.08 to 16.2 ng g⁻¹ in rock). Our data for high field strength elements, Rb, Sr, Mo, Sb, Cs, Tl and Bi for the six selected low abundance geological reference materials show general agreement with previously published data. Our Ta values in DTS-1 and PCC-1 (1.3 and 0.5 ng g⁻¹) are lower than in previously published studies, providing smooth primitive mantle distribution patterns. Lower values were also found for Tl in BIR-1, DTS-1 and PCC-1 (2, 0.4 and 0.8 ng g⁻¹). Compared with quadrupole ICP-MS studies, the proposed magnetic sector ICP-MS method can generally provide better detection limits, so that the measurement of high field strength elements, Rb, Sr, Mo, Sb, Cs, Tl and Bi at ng g⁻¹ levels can be achieved without pre-concentration, ion exchange separation or other specialised techniques.  相似文献   

Long-term effects of a toxic algal bloom on subtidal soft-sediment macroinvertebrate communities in Wellington Harbour, New Zealand   总被引：3，自引：1，他引：2  

Kerstin Krger  Jonathan P.A. Gardner  Ashley A. Rowden  Robert G. Wear 《Estuarine, Coastal and Shelf Science》2006,67(4):589-604

The long-term effects (>1 year) of a naturally occurring toxic plankton bloom (Karenia brevisulcata) on subtidal benthic macroinvertebrate communities were investigated in Wellington Harbour, a semi-enclosed temperate embayment in New Zealand. For 3 years communities were sampled at three different sites in the harbour. Analyses revealed that community recovery following the bloom was site-specific. Multivariate analyses indicated that at one site community composition was approaching recovery 3 years post-bloom. At the second site, a sequential recovery process was indicated, whereas at the third site the community composition oscillated from year to year, but did not show any signs of a sequential recovery process. The nature of the hydrodynamic regime was identified as a major factor influencing the observed recovery processes. Communities exposed to an active hydrodynamic regime were less affected by the bloom and differed little in their composition pre- and post-bloom, as they were naturally in a perpetual state of recovery as indicated by a dominance of r-selected species. The community at the hydrodynamically less active site was more affected by the bloom and exhibited temporal differences in composition consistent with successional models. Complete recovery to a pre-disturbance climax community dominated by K-selected species is likely to take 4–5 years, if not interrupted by other disturbances. Given the increased occurrence of harmful algal blooms worldwide, more monitoring and manipulative studies are needed to further evaluate the effects of such disturbances on macrobenthic communities.  相似文献   

Preface for the Special Volume on Exploration and Environmental Considerations of Deep Seabed Mineral Resources     

Kiseong Hyeong  Se-Jong Ju  David Billett  Ashley Rowden 《Ocean Science Journal》2018,53(2):285-286

  相似文献   

A satellite relative motion model including $$J_2$$ and $$J_3$$J3 via Vinti’s intermediary     

Ashley D. Biria  Ryan P. Russell 《Celestial Mechanics and Dynamical Astronomy》2018,130(3):23

Vinti’s potential is revisited for analytical propagation of the main satellite problem, this time in the context of relative motion. A particular version of Vinti’s spheroidal method is chosen that is valid for arbitrary elliptical orbits, encapsulating \(J_2\), \(J_3\), and generally a partial \(J_4\) in an orbit propagation theory without recourse to perturbation methods. As a child of Vinti’s solution, the proposed relative motion model inherits these properties. Furthermore, the problem is solved in oblate spheroidal elements, leading to large regions of validity for the linearization approximation. After offering several enhancements to Vinti’s solution, including boosts in accuracy and removal of some singularities, the proposed model is derived and subsequently reformulated so that Vinti’s solution is piecewise differentiable. While the model is valid for the critical inclination and nonsingular in the element space, singularities remain in the linear transformation from Earth-centered inertial coordinates to spheroidal elements when the eccentricity is zero or for nearly equatorial orbits. The new state transition matrix is evaluated against numerical solutions including the \(J_2\) through \(J_5\) terms for a wide range of chief orbits and separation distances. The solution is also compared with side-by-side simulations of the original Gim–Alfriend state transition matrix, which considers the \(J_2\) perturbation. Code for computing the resulting state transition matrix and associated reference frame and coordinate transformations is provided online as supplementary material.  相似文献   

The microscale cooling effects of water sensitive urban design and irrigation in a suburban environment     

Ashley?M.?BroadbentEmail authorView author&#;s OrcID profile  Andrew?M.?Coutts  Nigel?J.?Tapper  Matthias?Demuzere  Jason?Beringer 《Theoretical and Applied Climatology》2018,131(1-2):1-17

There is still considerable uncertainty about precipitation at high elevation in mountain terrain due to the relatively few in situ measurements available and to the particular variability of the parameter. In this study, several spatialization techniques were tested, some for climatological time scale and others for daily fields, for precipitation over the western Alps for the period of 1990–2012. The study domain and period were chosen for the quality of available in situ observations and density of the network. First, a weather-type classification was established with a technique based on canonical correlation analysis combining large- and regional-scale data. The spatialization techniques applied for the climatological time scale were adapted from the Aurelhy method which uses elevation and principal components of the topography as predictors. The spatialization techniques applied to daily fields were based on kriging of daily rain gauges and used the climatological fields as predictors. This study aims to validate the advantage of using the climatology of the weather type of the day as predictor for daily fields over a monthly climatology. The climatology of the weather type of the day seems to demonstrate some small improvement.Finally, annual means over the period of 1990–2012 were produced using several methods, including some from accumulation of daily fields and others from the spatialization of in situ station means. Precipitation at high elevations and vertical climatological gradients were particularly scrutinized. Annual means based on sums of daily fields seem to have better performances.This paper only presents results for precipitation but temperature was also analysed.  相似文献   

A Numerical Case Study of the Implications of Secondary Circulations to the Interpretation of Eddy-Covariance Measurements Over Small Lakes     

William T. Kenny  Gil Bohrer  Timothy H. Morin  Chris S. Vogel  Ashley M. Matheny  Ankur R. Desai 《Boundary-Layer Meteorology》2017,163(2):311-326

The CASES-99 experimental data are used to analyze turbulence behaviour under a range of stable conditions using an adaptive method based on Hilbert spectral analysis. The characteristic scales of intrinsic mode functions vary between different stratifications. The second-order Hilbert marginal spectra display clear separation between fine-scale turbulence and large-scale motions. After removing the large-scale motions, the statistical characteristics of the reconstructed signals confirm the distinction of different stratifications in the fine-scale range. The correlation coefficient analyses reveal that the Hilbert spectral analysis method separates turbulence from large-scale motions in the stable boundary layer.  相似文献   

Adaptive Delta Management for flood risk and resilience in Dordrecht,The Netherlands     

B.?GersoniusEmail author  J.?Rijke  R.?Ashley  P.?Bloemen  E.?Kelder  C.?Zevenbergen 《Natural Hazards》2016,82(2):201-216

Many countries across the world are experiencing strict austerity measures due to the economic crisis. As a consequence, public financing for stand-alone adaptation to flooding and drought will become scarcer in the (near) future, and this hampers the pursuit of resilience (i.e. the ability to remain functioning under a range of hazard magnitudes). In such times, key challenges for adaptation are further complicated by weaker investment dynamics and an increased tendency to ‘work in silos’. These are: to minimise regret with respect to maladaptation, which results from over- or under-investment in water hazard management; to exploit the opportunities for mainstreaming adaptation to flooding and drought into other investment agendas; and to deliver multiple benefits for society and the economy, such as increased biodiversity, liveability and competitiveness. These common challenges drive the best way in which to adapt to uncertain climate and socio-economic changes. In the Netherlands, the Delta Programme has developed and applied a structured and well-defined approach (called Adaptive Delta Management) for including and acting upon uncertainty around these future changes. This approach allows for greater transparency to decision-makers and stakeholders, because it adheres to four specific steps for strategy development. This paper presents the current understanding of Adaptive Delta Management and an illustration of the approach for the management of flood risk and resilience in Dordrecht. It examines the added value and limitations of Adaptive Delta Management concerning its application in the context of the Delta Programme, with a specific emphasis on the lessons learned from Dordrecht.  相似文献   

Late Holocene Environmental Reconstructions from Lake Solai,Kenya     

Michelle Goman  Gail M. Ashley  R. Bernhart Owen  Victoria C. Hover  Dev K. Maharjan 《The Professional geographer》2017,69(3):438-454

Playa lake systems tend to be overlooked archives of paleoenvironmental change due to the likelihood of a short and intermittent record of deposition. Groundwater-fed wetlands associated with these climate-sensitive playas, however, preserve changes in hydrologic budget and are thus valuable archives for semiarid regions. This study examines the paleoecological record of a groundwater-fed wetland from Lake Solai, Kenya. Biological proxies are used to reconstruct paleoenvironmental change and climate impacts over the past millennium. Dry conditions persisted between CE 1115 and 1490, followed by wetter conditions during the Little Ice Age. Near surface sediments indicate increasing anthropogenic impact through pastoralism.  相似文献   

Effect of biodeposits from mussel culture on macroinvertebrate assemblages at sites of different hydrodynamic regime   总被引：1，自引：0，他引：1  

Hartstein ND  Rowden AA 《Marine environmental research》2004,57(5):339-357

The present study examined for differences in macroinvertebrate assemblage composition inside and outside of mussel farm sites experiencing different hydrodynamic regimes. Multivariate analysis revealed that there were significant differences in macroinvertebrate assemblage composition (averaged across seasons) between samples taken inside and outside of the two relatively low energy sites, whilst no such difference was observed for the relatively high energy site. Taxa that best discriminated between the dissimilarities observed in macroinvertebrate assemblage composition inside and outside farms were principally polychaetes (more abundant inside) and ophiuroids (more abundant outside). Sediment total organic matter and number of mussel shells were the parameters that best explained the difference in macroinvertebrate assemblage observed at the two relatively sheltered farm study sites. No taxa or environmental variables were particularly good at discriminating or explaining differences observed inside and outside the relatively high energy farm site. The present study indicates there is a relationship between the hydrodynamic regime of a farm site, organic enrichment of seabed sediments by mussel biodeposits, and a subsequent modification of the macroinverebrate assemblages. This finding has implications for the site selection of mussel farms in coastal environments.  相似文献