Biomarkers and environmental risk assessment: guiding principles from the human health field

Although the potential use of biomarkers within environmental risk assessment (ERA) has long been recognised their routine use is less advanced compared with clinical human health risk assessment, where a number of familiar biomarkers (such as blood pressure and serum cholesterol) are in common usage. We have examined how biomarkers are incorporated into human health risk assessment and have identified several 'required elements'. These include identification of the (clinical) assessment endpoint at the outset, rational selection of the biomarker(s) (the measurement endpoint), biomarker 'validation' (e.g. QA/QC) and biomarker 'qualification' (evidence linking the measurement and assessment endpoints). We discuss these elements in detail and propose that their adoption will facilitate the routine use of biomarkers in environmental risk assessment. Furthermore, our analysis highlights the need for cooperation between those working with biomarkers within human and environmental risk assessment to exchange best practice between common disciplines for mutual advantage.     

Impacts on CPUE from vessel fleet composition changes in an Australian lobster (Jasus edwardsii) fishery

The Australian Victorian Western Zone rock lobster fishery is assessed using standardised catch-per-unit-effort (CPUE). Nominal CPUE declined over 1978–2009, but this underrepresents the estimated decline in abundance, and since 2009 standardised CPUE rose notably less than nominal CPUE. This study identified vessel as a key factor that explains the discrepancy between nominal and standardised CPUE. The composition of the fleet changed since 2009, under the pressure of constraining total allowable catch quotas, with vessels exiting the fishery having substantially lower estimated catchability, which increased the average catchability of the remaining fleet. New diagnostic indices were constructed to quantify discrepancies between trends in nominal and standardised CPUE that assisted in identifying periods during which both catchability and fleet composition changed.     

Accessibility to food retailers and socio‐economic deprivation in urban New Zealand

The spatial locations of food retailers are considered to be an influential aspect of population consumption patterns. Such contextual relationships are often related to socio‐economic deprivation, with disparities in accessibility having important implications. This study used Geographic Information Systems and an Enhanced Two‐Step Floating Catchment Area model of spatial accessibility to further understand such relationships within urban areas of New Zealand. Findings, while mixed, indicate that there is generally increased accessibility to all food retailers in highly deprived areas. Understanding these socio–spatial relationships in local environments has important implications for policy initiatives, health outcomes and sustainable development.     

Thermal regimes in a large upland salmon river: a simple model to identify the influence of landscape controls and climate change on maximum temperatures

Temperature observations at 25 sites in the 2000 km² Dee catchment in NE Scotland were used, in conjunction with geographic information system (GIS) analysis, to identify dominant landscape controls on mean monthly maximum stream temperatures. Maximum winter stream temperatures are mainly controlled by elevation, catchment area and hill shading, whereas the maximum temperatures in summer are driven by more complex interactions, which include the influence of riparian forest cover and distance to coast. Multiple linear regression was used to estimate the catchment‐wide distribution of mean weekly maximum stream temperatures for the hottest week of the 2‐year observation period. The results suggested the streams most sensitive to high temperatures are small upland streams at exposed locations without any forest cover and relatively far inland, while lowland streams with riparian forest cover at locations closer to the coast exhibit a moderated thermal regime. Under current conditions, all streams provide a suitable thermal habitat for both, Atlantic salmon and brown trout. Using two climate change scenarios assuming 2·5 and 4 °C air temperature increases, respectively, temperature‐sensitive zones of the stream network were identified, which could potentially have an adverse effect on the thermal habitat of Atlantic salmon and brown trout. Analysis showed that the extension of riparian forests into headwater streams has the potential to moderate changes in temperature under climate change. Copyright © 2010 John Wiley & Sons, Ltd.     

Sustainability of deep-sea fisheries

As coastal fisheries around the world have collapsed, industrial fishing has spread seaward and deeper in pursuit of the last economically attractive concentrations of fishable biomass. For a seafood-hungry world depending on the oceans' ecosystem services, it is crucial to know whether deep-sea fisheries can be sustainable.The deep sea is by far the largest but least productive part of the oceans, although in very limited places fish biomass can be very high. Most deep-sea fishes have life histories giving them far less population resilience/productivity than shallow-water fishes, and could be fished sustainably only at very low catch rates if population resilience were the sole consideration. But like old-growth trees and great whales, their biomass makes them tempting targets while their low productivity creates strong economic incentive to liquidate their populations rather than exploiting them sustainably (Clark's Law). Many deep-sea fisheries use bottom trawls, which often have high impacts on nontarget fishes (e.g., sharks) and invertebrates (e.g., corals), and can often proceed only because they receive massive government subsidies. The combination of very low target population productivity, nonselective fishing gear, economics that favor population liquidation and a very weak regulatory regime makes deep-sea fisheries unsustainable with very few exceptions. Rather, deep-sea fisheries more closely resemble mining operations that serially eliminate fishable populations and move on.Instead of mining fish from the least-suitable places on Earth, an ecologically and economically preferable strategy would be rebuilding and sustainably fishing resilient populations in the most suitable places, namely shallower and more productive marine ecosystems that are closer to markets.     

The 3D facies architecture and petrophysical properties of hyaloclastite delta deposits: An integrated photogrammetry and petrophysical study from southern Iceland

Hyaloclastites develop where lava interacts with water resulting in deposits that have a unique and often complex range of petrophysical properties. A combination of eruptive style and emplacement environment dictates the size, geometry and distribution of different hyaloclastite facies and their associated primary physical properties such as porosity, permeability and velocity. To date, links between the 3D facies variability within these systems and their petrophysical properties remain poorly understood. Hjörleifshöfði in southern Iceland presents an exceptional outcrop exposure of an emergent hyaloclastite sequence >1 km wide by >200 m high and enables an investigation of the distribution of the hyaloclastite deposits at seismic scale. Within this study we present a photogrammetry-based 3D model from part of this recent hyaloclastite delta and incorporate previous work by Watton et al. (Journal of Volcanology and Geothermal Research, 2013, 250, 19) to undertake detailed facies interpretation and quantification. Laboratory petrophysical analyses were performed on 34 core plugs cut from key field facies samples, including P- and S-wave velocity, density, porosity and permeability at both ambient and confining pressure. Integration of the 3D model with the petrophysical data has enabled the production of pseudo-wireline logs and property distribution maps which demonstrate the variability of physical properties within hyaloclastite sequences at outcrop to seismic scale. Through comparison of our data with examples of older buried hyaloclastite sequences we demonstrate that the wide-ranging properties of young hyaloclastites become highly uniform in older sequences making their identification by remote geophysical methods for similar facies variations more challenging. Our study provides an improved understanding of the petrophysical property distribution within hyaloclastite sequences and forms a valuable step towards improving the understanding of similar subsurface sequences and their implications for imaging and fluid flow.     

Sea ice,hydrological, and biological processes in the Churchill River estuary region,Hudson Bay

A conceptual scheme for the transition from winter to spring is developed for a small Arctic estuary (Churchill River, Hudson Bay) using hydrological, meteorological and oceanographic data together with models of the landfast ice. Observations within the Churchill River estuary and away from the direct influence of the river plume (Button Bay), between March and May 2005, show that both sea ice (production and melt) and river water influence the region's freshwater budget. In Button Bay, ice production in the flaw lead or polynya of NW Hudson Bay result in salinization through winter until the end of March, followed by a gradual freshening of the water column through April–May. In the Churchill Estuary, conditions varied abruptly throughout winter–spring depending on the physical interaction among river discharge, the seasonal landfast ice, and the rubble zone along the seaward margin of the landfast ice. Until late May, the rubble zone partially impounded river discharge, influencing the surface salinity, stratification, flushing time, and distribution and abundance of nutrients in the estuary. The river discharge, in turn, advanced and enhanced sea ice ablation in the estuary by delivering sensible heat. Weak stratification, the supply of riverine nitrogen and silicate, and a relatively long flushing time (∼ 6 days) in the period preceding melt may have briefly favoured phytoplankton production in the estuary when conditions were still poor in the surrounding coastal environment. However, in late May, the peak flow and breakdown of the ice-rubble zone around the estuary brought abrupt changes, including increased stratification and turbidity, reduced marine and freshwater nutrient supply, a shorter flushing time, and the release of the freshwater pool into the interior ocean. These conditions suppressed phytoplankton productivity while enhancing the inventory of particulate organic matter delivered by the river. The physical and biological changes observed in this study highlight the variability and instability of small frozen estuaries during winter–spring transition, which implies sensitivity to climate change.