Eco-labelling: A new deal for a more durable fishery management?

To what extent can eco-labelling become a durable instrument for managing natural resources and the environment ? Having analysed the concept and the issues, this article will evaluate, using a case study, its appropriateness for the long-term management of a particular small Breton fishery.The analysis will focus particularly on the existence of the consumer willingness to pay a supplement for eco-labelled fish. From an econometric model, the author will clarify the factors which could explain to a significant degree, this predisposition to pay. This empirical study uses several surveys, some of which were carried out over the course of 2006 in Brittany and involved around 450 consumers.     

A method for monitoring building construction in urban sprawl areas using object-based analysis of Spot 5 images and existing GIS data

Urban sprawl has been identified as one of the most negative effects of global population growth on the environment and biodiversity. Frequent monitoring of urban sprawl is needed to limit the impact of this ongoing phenomenon. This paper proposes precise monitoring of building construction using an object-based classification methodology applied to Spot 5 images with a 2.5 m resolution. An application at a regional scale on Reunion Island in the Indian Ocean shows that this building extraction methodology has limitations in the production of reference urban maps because of difficulties in defining the shape and the number of buildings compared to classical photo-interpretation of aerial photography. However, these results are of great value for planning in urban sprawl areas where up-to-date information is lacking because of the rapid pace of house construction and residential development.     

Insuring future climate catastrophes

The combined influences of a change in climate patterns and the increased concentration of property and economic activity in hazard-prone areas has the potential of restricting the availability and affordability of insurance. This paper evaluates the premiums that private insurers are likely to charge and their ability to cover residential losses against hurricane risk in Florida as a function of (a) recent projections on future hurricane activity in 2020 and 2040; (b) insurance market conditions (i.e., soft or hard market); (c) the availability of reinsurance; and (d) the adoption of adaptation measures (i.e., implementation of physical risk reduction measures to reduce wind damage to the structure and buildings). We find that uncertainties in climate projections translate into a divergent picture for insurance in Florida. Under dynamic climate models, the total price of insurance for Florida (assuming constant exposure) could increase significantly by 2040, from $12.9 billion (in 1990) to $14.2 billion, under hard market conditions. Under lower bound projections, premiums could decline to $9.4 billion by 2040. Taking a broader range of climate change scenarios, including several statistical ones, prices could be between $4.7 and $32.1 billion by 2040. The upper end of this range suggests that insurance could be unaffordable for many people in Florida. The adoption of most recent building codes for all residences in the state could reduce by nearly half the expected price of insurance so that even under high climate change scenarios, insurance premiums would be lower than under the 1990 baseline climate scenario. Under a full adaptation scenario, if insurers can obtain reinsurance, they will be able to cover 100 % of the loss if they allocated 10 % of their surplus to cover a 100-year return hurricane, and 63 % and 55 % of losses from a 250-year hurricane in 2020 and 2040. Property-level adaptation and the maintenance of strong and competitive reinsurance markets will thus be essential to maintain the affordability and availability of insurance in the new era of catastrophe risk.     

Effect of temperature on an alga‐grazer trophic transfer: A dual stable isotope (13C, 15N) labeling experiment

In this study, we examined the impact of temperature on the carbon and nitrogen trophic transfers from a macroalga to a macro‐grazer by the use of dual ¹³C‐ and ¹⁵N‐labeling. Using an experimental approach in mesocosms, individuals of the urchin Psammechinus miliaris were maintained for 1 month at 17°C (mean summer temperature in the Bay of Brest) and at 20°C (maximum summer temperature) and fed with ¹³C‐ and ¹⁵N‐labeled Solieria chordalis. The results showed that the urchins’ ¹³C uptake was 0.30 µg¹³C g dry weight (DW)^?1 at 17°C and 0.14 µg¹³C g DW^?1 at 20°C at the end of the experiment. The lower uptake at the higher temperature may be attributed to a decrease in metabolic activity at 20°C, involving lower feeding and/or respiration rates. Conversely, no significant effect of temperature was detected on ¹⁵N uptake. At the end of the experiment, the urchins’ ¹⁵N uptake was 0.04 µg¹⁵N g DW^?1 at 17°C and 0.03 µg¹⁵N g DW^?1 at 20°C. This suggests that temperature may affect carbon and nitrogen trophic fluxes differently. The use of dual isotope labeling offers interesting prospects and needs to be further extended in order to better understand trophic interactions in marine communities and the consequences of current environmental changes, such as global warming.     

Using stable isotope analysis to determine the effects of ocean acidification and warming on trophic interactions in a maerl bed community

Ocean acidification and warming are likely to affect the structure and functioning of marine benthic communities. This study experimentally examined the effects of ocean acidification and warming on trophic interactions within a maerl bed community by using stable carbon and nitrogen isotope analysis. Two three-month experiments were conducted in winter and summer seasons with four different combinations of pCO₂ (ambient and elevated pCO₂) and temperature (ambient and +3°C). Experimental assemblages were created in tanks held in the laboratory and were composed of calcareous (Lithothamnion corallioides) and fleshy algae (Rhodymenia ardissonei, Solieria chordalis, and Ulva sp.), gastropods (Gibbula magus and Jujubinus exasperatus), and sea urchins (Psammechinus miliaris). Our results showed higher seaweed availability for grazers in summer than winter. Therefore, grazers were able to adapt their diet seasonally. Increased pCO₂ and temperature did not modify the trophic structure in winter, while shifts in the contribution of seaweed were found in summer. Combined acidification and warming increased the contribution of biofilm in gastropods diet in summer conditions. Psammechinus miliaris mostly consumed L. corallioides under ambient conditions, while the alga S. chordalis became the dominant food source under high pCO₂ in summer. Predicted changes in pCO₂ and temperature had complex effects on assemblage trophic structure. Direct effects of acidification and warming on seaweed metabolism may modify their abundance and biomass, affecting their availability for grazers. Climate change may also modify seaweeds' nutritive value and their palatability for grazers. The grazers we investigated were able to change their diet in response to changes in algal assemblages, an advantage given that warming and acidification alter the composition of algal communities.