Keith S.A.,Bournemouth University |
Herbert R.J.,Bournemouth University |
Norton P.A.,ABP Marine Environmental Research Ltd |
Hawkins S.J.,Bangor University |
And 2 more authors.
Diversity and Distributions | Year: 2011
Aim Evidence indicates that species are responding to climate change through distributional range shifts that track suitable climatic conditions. We aim to elucidate the role of meso-scale dispersal barriers in climate-tracking responses. Location South coast of England (the English Channel). Methods Historical distributional data of four intertidal invertebrate species were logistically regressed against sea surface temperature (SST) to determine a climate envelope. This envelope was used to estimate the expected climate-tracking response since 1990 along the coast, which was compared with observed range expansions. A hydrodynamic modelling approach was used to identify dispersal barriers and explore disparities between expected and observed climate tracking. Results Range shifts detected by field survey over the past 20years were less than those predicted by the changes that have occurred in SST. Hydrodynamic model simulations indicated that physical barriers produced by complex tidal currents have variably restricted dispersal of pelagic larvae amongst the four species. Main conclusions We provide the first evidence that meso-scale hydrodynamic barriers have limited climate-induced range shifts and demonstrate that life history traits affect the ability of species to overcome such barriers. This suggests that current forecasts may be flawed, both by overestimating range shifts and by underestimating climatic tolerances of species. This has implications for our understanding of climate change impacts on global biodiversity. © 2010 Blackwell Publishing Ltd.
Pacheco A.,University of Algarve |
Ferreira O.,University of Algarve |
Williams J.J.,ABP Marine Environmental Research Ltd
Earth Surface Processes and Landforms | Year: 2011
In this study, the artificial opening of a new tidal inlet in an existing multiple inlet system is shown to significantly modify the adjacent nearshore and backbarrier morphology, as well as both updrift and downdrift shorelines. The study focuses on the dominant Faro-Olhão and Armona inlets in the Ria Formosa barrier island system of southern Portugal. The equilibrium state and future evolution of the system are inferred using a range of morphological and hydrodynamic indicators, including the evolution of the inlet cross-section, changes in tidal prism, and changes in the dimensions (length and area) of barrier islands. The results reveal how the morphology of an interconnected two-inlet bay system and the adjacent coastlines has evolved following the artificial opening and stabilization of Faro-Olhão inlet since 1929. A clear relationship between barrier island size, inlet cross-section/width, and tidal prism is demonstrated. Decadal time-scale changes in the tidal prism of the two interconnected inlets are shown to be the main mechanism responsible for morphological change, and have resulted in the remobilization of ebb-tidal delta sediments deposited during previous hydraulic configurations. These changes, in turn, have contributed to a narrowing of Armona inlet and an increase in the size of Culatra Island. The work highlights the importance of ebb-tidal deltas both as sand reservoirs and as conduits through which sand exchange between estuaries or lagoons and the open coast is regulated. It also shows the pivotal role of ebb-tidal deltas in trapping longshore-transported sediment and releasing it again during periods of increased wave activity. The findings have implications regarding the accurate assessment of the stability of multiple inlet systems. © 2011 John Wiley & Sons, Ltd.
Pacheco A.,University of Algarve |
Williams J.J.,ABP Marine Environmental Research Ltd. |
Ferreira O.,University of Algarve |
Garel E.,University of Algarve |
Reynolds S.,University of Plymouth
Estuarine, Coastal and Shelf Science | Year: 2011
This paper derives local formulae to estimate bed roughness and suspended transport and present a method to calculate net sediment transport at tidal inlet systems, combining field data and a range of well established empirical formulations. To accomplish this, measurements spanning a spring-tidal cycle of mean water levels, waves, near-bed flow turbulence and bed forms were obtained from the Ancão Inlet, Ria Formosa lagoon system, Portugal. High-resolution hydrodynamic data were gathered using acoustic equipments and by measuring sediment properties (grain-size diameter and bed form dimensions) under fair-weather conditions. The results compared favourably with available direct and indirect field observations of sediment transport rates. The approach appears to be robust and widely applicable and so can be applied to the same conditions in any tidal inlet system. This is of particular importance when attempting to understand sediment transport at inlet mouths, and has practical applications in a range of coastal engineering and coastal management areas concerned with navigation safety, coastal erosion, ecosystem health and water quality. The study discusses the applicability of the method on evaluating system flushing capacity, giving important insights on multiple inlet evolution, particularly with regard to their persistence through time. The methodological framework can be applied to assess the long-term stability of single- and multiple-inlet systems, provided that estimates of sediment storage at ebb-tidal deltas are available and sediment transport estimates during storm events are statistically considered. © 2011 Elsevier Ltd.
Hull S.,ABP Marine Environmental Research Ltd |
Dickie I.,Economics For The Environment Consultancy Ltd |
Tinch R.,Economics For The Environment Consultancy Ltd |
Saunders J.,ABP Marine Environmental Research Ltd
Marine Policy | Year: 2014
The concepts of ecosystem services and human welfare provide strong integrative frameworks that can be used to inform marine policy and management decisions that support sustainable development. A theoretical framework has been developed and applied to create a model for UK seas to measure changes in final ecosystem services, in terms of human welfare. The model that has been developed is explicitly spatial and temporal to facilitate its use in supporting marine planning decisions. The development and application of this framework to UK seas necessarily requires many assumptions to be made. The paper describes the development and population of the framework and discusses the practical limitations and challenges in seeking to develop and apply such models. Significant differences in long-term values of different services were identified under the different scenarios. All scenarios highlight the projected decline in oil and gas revenues which provide particular intense values at sites of extraction. These values are partially replaced by revenues from offshore renewables in some of the scenarios. Values associated with carbon sequestration, maritime transport, tourism and pollution assimilation are also very significant but more spatially diffuse. The study has demonstrated that it is possible to develop spatio-temporal models to evaluate changes in final ecosystem service benefits using existing data, although the approach necessarily requires many assumptions to be made. © 2014 Elsevier Ltd.
Pacheco A.,University of Algarve |
FaIsca L.,University of Algarve |
Almeida L.,University of Algarve |
Ferreira O.,University of Algarve |
And 2 more authors.
Coastal Engineering Journal | Year: 2012
This paper presents a statistical evaluation of two theoretical fitting methods logarithmic and power law commonly used to extrapolate velocities to unmeasured areas of a vertical profile, such as near-bottom velocities. Analysis of covariance (ANCOVA) was used to test the models' performance when applied to velocity data collected with a boat-mounted acoustic Doppler current profiler (ADCP) at the six tidal inlets of the Ria Formosa (southern Portugal) under spring-and neap-tide conditions. Results show that both models' goodness-of-fit is negatively correlated with velocity. Correlation also diminishes under ebb conditions, with no relation to velocity, but rather to transect depth. Both models consistently produce better simulations in inlets with a larger cross-sectional area, where turbulence scales are more attenuated due to spatial averaging. The logarithmic law model proved to be more robust across different velocities and channel morphologies and should be adopted as the preferred method for extrapolating velocity profiles when using boat-mounted ADCPs at confined channels and inlet entrances. © 2012 World Scientific Publishing Company and Japan Society of Civil Engineers.
Fletcher S.,University of Plymouth |
Saunders J.,ABP Marine Environmental Research Ltd |
Herbert R.J.H.,Bournemouth University
Journal of Coastal Research | Year: 2011
This paper presents an analysis of the marine ecosystem services delivered by the broad-scale habitats (EUNIS Level 3) that will be included in England's new Marine Protected Area (MPA) network developed under the Marine and Coastal Access Act (2009). The assessment of ecosystem services was undertaken through a systematic literature review to identify evidence for the existence of either beneficial ecosystem processes or beneficial ecosystem services provided by each broad-scale habitat. The review found that broad-scale marine habitats provide a wide range of ecosystem services, which in turn suggests that their protection genuinely provides both direct and indirect benefits to society. However, there was substantially more evidence of beneficial ecosystem processes than beneficial ecosystem services which potentially reflects the tendency to study how a habitat functions, rather than how it is (or could be) used. In particular, a clear research gap was found related to how marine features are used for sport and recreation, tourism, nature watching and other nonextractive activities. In addition, the role of such habitats in supporting overall environmental resilience was unclear. Despite the variability of the evidence base, this study is significant as it identified, for the first time, the extent of the evidence base for ecosystem services provided by broad-scale marine habitats within England's MPA network.
Humphreys J.,Bournemouth University |
Herbert R.J.H.,Bournemouth University |
Roberts C.,ABP Marine Environmental Research Ltd. |
Fletcher S.,University of Plymouth
Aquaculture | Year: 2014
The Pacific oyster (Crassostrea gigas) was introduced into British waters to support an industry suffering from the decline of the native oyster. Until recently significant conservation risk was thought to be negligible as British coastal waters were considered incompatible with the establishment of self sustaining populations. Those circumstances have changed. On warming southern coasts the Pacific oyster has naturalised and now occupies an intersection between two policy imperatives: one concerning the conservation of protected habitats, the other relating to livelihoods and the economics of coastal communities. This combined with inconsistencies of attitude and policy between immediate European Union neighbours has made the future management of the Pacific oyster contentious. In this context policy is influenced not just by scientific evidence but also by perceptions of the history and economics of the species in each member state. However whereas the conservation risk is increasingly well documented, the history and economics of the species are not. To balance the policy equation we reappraise the commercial history of the species in Britain and provide a first estimate of the full value to the British economy of British reared Pacific oysters, employing a novel approach to the economics of a single aquaculture species. The established view on the history of C. gigas in Britain has it introduced for aquaculture in 1965. Informed by formal taxonomic recognition of its synonymic relation with the Portuguese oyster, along with a search of primary sources, we provide a revised history with the first reliably documented introduction 75. years earlier, in 1890. The economic significance of the species, when conventionally reported as "value at first sale", is also underestimated. The full economic significance of a species is better represented by Gross Output and Gross Value Added through all stages of the value chain, but few if any estimates of these have been attempted for a single species. On the basis of an analysis of the 2011/12 market for British reared C. gigas from production to ultimate consumption, we estimate annual Gross Output to be over £13. million (more than five times the value at first sale), and GVA to be over £10. million. On the basis of the world market and comparisons with neighbouring state production, it is argued that British Pacific oyster production could be significantly increased once uncertainty over its management is resolved. © 2014 Elsevier B.V.
Symonds A.M.,ABP Marine Environmental Research Ltd.
Aquaculture Research | Year: 2011
An important consideration in the design of fish farms is the fate of the resultant particulate wastes. Consequently, this study is aimed at investigating the validity of an existing near-field regulatory model that assesses the fate of particulate wastes arising from fish farms. The results from the near-field regulatory model have been compared with those from a far-field model to assess the implications of the near-field model focusing on a 1km-by-1km area around the fish farm and ignoring any cumulative impacts of other fish farms in the area. The study has been undertaken at a site located on the west coast of Scotland encompassing Loch Shuna and Loch Melfort, which contain eight fish farms. The far-field dispersion modelling was undertaken using a layered three-dimensional tidal model with a coupled dispersion module. This study has demonstrated a number of benefits through using a far-field model to simulate particulate waste dispersion resulting from fish farms as opposed to using a near-field model. The far-field model accounts for the spatial variability in tidal currents, which can be important in coastal areas; it also allows the impacts of multiple fish farms operating in combination to be assessed over a larger area. In addition, it was found that compared with the far-field modelling, the near-field modelling has the potential to underestimate the benthic impacts of fish farms. © 2010 The Authors. Journal Compilation © 2010 Blackwell Publishing Ltd.
Thompson C.E.L.,UK National Oceanography Center |
Kassem H.,UK National Oceanography Center |
Williams J.,ABP Marine Environmental Research Ltd.
Journal of Coastal Research | Year: 2013
Sediment resuspension in the region outside the surf zone is known to contribute to the morphological response of barrier beaches to wave forcing, such as onshore bar migration processes. However, few measurements in this region exist, limiting our ability to quantify its contribution. These processes are complicated by the presence of bedforms in the nearshore, which alter the sand transport processes while modifying bed roughness in a complex feedback mechanism. The Hydralab IV funded BARDEX II experiments, which took place in the Delta Flume in 2012, were used to provide measurements of these processes in the nearshore of a sandy barrier beach (D50 = 0.42mm) under a range of wave conditions (Hs = 0.3 - 0.8 m; Tp = 4 - 12 s) and water levels, through deployment of a suite of acoustic instruments measuring flow velocity, near-bed turbulence, sediment resuspension profiles and bed morphology in cross-section and plan view. Initial findings indicate that sediment suspension in the nearshore appears to be controlled by a combination of near-bed turbulent bursting processes which results in near-instantaneous low concentration suspensions restricted to the bottom boundary layer, and vortex shedding from bedforms which results in higher concentration suspensions which are larger in scale than vertical eddy sizes, and perpetuate outside of the bottom boundary layer. © Coastal Education & Research Foundation 2013.
Cazenave P.W.,University of Southampton |
Dix J.K.,University of Southampton |
Lambkin D.O.,ABP Marine Environmental Research Ltd |
Mcneill L.C.,University of Southampton
Earth Surface Processes and Landforms | Year: 2013
The increasing availability of large, detailed digital representations of the Earth's surface demands the application of objective and quantitative analyses. Given recent advances in the understanding of the mechanisms of formation of linear bedform features from a range of environments, objective measurement of their wavelength, orientation, crest and trough positions, height and asymmetry is highly desirable. These parameters are also of use when determining observation-based parameters for use in many applications such as numerical modelling, surface classification and sediment transport pathway analysis. Here, we (i) adapt and extend extant techniques to provide a suite of semi-automatic tools which calculate crest orientation, wavelength, height, asymmetry direction and asymmetry ratios of bedforms, and then (ii) undertake sensitivity tests on synthetic data, increasingly complex seabeds and a very large-scale (39 000km2) aeolian dune system. The automated results are compared with traditional, manually derived, measurements at each stage. This new approach successfully analyses different types of topographic data (from aeolian and marine environments) from a range of sources, with tens of millions of data points being processed in a semi-automated and objective manner within minutes rather than hours or days. The results from these analyses show there is significant variability in all measurable parameters in what might otherwise be considered uniform bedform fields. For example, the dunes of the Rub' al Khali on the Arabian peninsula are shown to exhibit deviations in dimensions from global trends. Morphological and dune asymmetry analysis of the Rub' al Khali suggests parts of the sand sea may be adjusting to a changed wind regime from that during their formation 100 to 10ka BP. © 2012 John Wiley & Sons, Ltd.