Larval growth and settlement of the European oyster (Ostrea edulis) as a function of food quality measured as fatty acid composition

Larval growth rate and settlement of the European flat oyster Ostrea edulis were experimentally studied as a function of the composition of dietary fatty acids. Diets differing in fatty acid composition were composed by mixtures of the microalgae Isochrysis galbana, Pavlova lutheri and Chaetoceros calcitrans. Fatty acid content in the tissue of the feeding larvae, analyzed by gas chromatography and mass spectrometry, reflected the composition in the diet. Larval growth rate was significantly correlated to the three omega-3 polyunsaturated fatty acids (PUFA) C18:3, C18:4 and C22:6, with minor differences for neutral and polar lipids. No relation between growth rate and the omega-3 PUFA C20:5 was detected, a PUFA often implied as essential for bivalves. It is suggested that naturally occurring variability in fatty acid composition may constrain larval growth. In settlement experiments in both still water and flume flow little substrate selectivity was found for some contrasting substrates. It is concluded that differences in dietary fatty acids may explain as much of settlement success as the variability of substrates. Received: 12 October 1998 / Accepted: 6 April 1999     

Values and willingness-to-pay for sustainability-certified mobile phones

ABSTRACT

This study investigated whether endorsement of personal values is associated with willingness to pay more for mobile phones with an environmental or social sustainability label. Participants were students in Sweden, Norway and Germany. A self-report inventory was used to measure willingness to pay and the importance attached to values of Schwartz’s circular model. In Sweden and Norway, participants were willing to pay, on average, 18% extra for a mobile phone with labels for environmental or social sustainability. In Germany, the corresponding share was 12%. To strive for self-enhancement values, that is, social status and prestige, as well as control and dominance over people and resources, was associated with a lower willingness to pay for mobile phones with labels for environmental or social sustainability in all three countries. Furthermore, women were willing to pay more than men for mobile phones with both kinds of sustainability labels. In Sweden and Norway, participants were, on average, willing to pay more for a mobile phone with a label for social sustainability compared to a mobile phone with a label for environmental sustainability.     

Ecological limitations and appropriation of ecosystem support by shrimp farming in Colombia

Shrimp farming in mangrove areas has grown dramatically in Asia and Latin America over the past decade. As a result, demand for resources required for farming, such as feed, seed, and clean water, has increased substantially. This study focuses on semiintensive shrimp culture as practiced on the Caribbean coast of Colombia. We estimated the spatial ecosystem support that is required to produce the food inputs, nursery areas, and clean water to the shrimp farms, as well as to process wastes. We also made an estimate of the natural and human-made resources necessary to run a typical semiintensive shrimp farm. The results show that a semiintensive shrimp farm needs a spatial ecosystem support—the ecological footprint—that is 35–190 times larger than the surface area of the farm. A typical such shrimp farm appropriates about 295 J of ecological work for each joule of edible shrimp protein produced. The corresponding figure for industrial energy is 40:1. More than 80% of the ecological primary production required to feed the shrimps is derived from external ecosystems. In 1990 an area of 874–2300 km² of mangrove was required to supply shrimp postlarvae to the farms in Colombia, corresponding to a total area equivalent to about 20–50% of the country’s total mangrove area. The results were compared with similar estimates for other food production systems, particularly aquacultural ones. The comparison indicates that shrimp farming ranks as one of the most resource-intensive food production systems, characterizing it as an ecologically unsustainable throughput system. Based on the results, we discuss local, national, and regional appropriation of ecological support by the semiintensive shrimp farms. Suggestions are made for how shrimp farming could be transformed into a food production system that is less environmentally degrading and less dependent on external support areas.     

Common criteria for the redefinition of Intermediate Less Favoured Areas in the European Union

This article defines eight key climate, soil and terrain criteria that have been developed for the future delimitation of the Intermediate Less Favoured Areas (LFAs) support, a measure of the Common Agricultural Policy. The LFA scheme has existed since 1975 and is a broad mechanism for improving the viability of agriculture in areas with natural handicaps. The common criteria have been developed for the European Commission's Directorate-General for Agriculture and Rural Development to satisfy the objectives in the Rural Development Policy 2007–2013 (Axis II), which aim to improve the environment and the countryside by more sustainable land management. The criteria were developed by experts, coordinated by the European Commissions Joint Research Centre, to meet the requirement for a robust and harmonised approach of identifying areas that experience natural constraints to agriculture throughout the EU 27 Member States. The criteria proposed are: temperature, heat stress, drainage, soil texture and stoniness, soil rooting depth, soil chemical properties, soil moisture balance and slope. Each criterion is described and an indicative threshold for assessment of its impact on agriculture is provided. The criteria are currently being tested by the EU Member States for a future possible legislation.     

Ecological costs on local adaptation of an insect herbivore imposed by host plants and enemies

Herbivore populations may become adapted to the defenses of their local hosts, but the traits that maximize host exploitation may also carry ecological costs. We investigated the patterns and costs of local adaptation in the pine processionary moth, Thaumetopoea pityocampa, to its host plants, Pinus nigra and P. sylvestris. The two hosts differ in needle toughness, a major feeding impediment for leaf-eating insects. We observed a west-to-east gradient of increasing progeny size in the Italian Alps, matching the pattern in toughness of their respective local host plant. Eastern populations that feed on the native P. nigra with tough needles had larger eggs, and neonate larvae with larger head capsules, than western populations that feed on the native P. sylvestris and the introduced P. nigra with softer foliage. In a reciprocal transfer experiment that involved the eastern-most and the western-most populations of T. pityocampa from this region, and excluded natural enemies, we found evidence for local adaptation to the host plant. Specifically, larvae from the western population only performed well when raised on their local hosts with soft needles, and they suffered near-complete mortality on the tough foliage at the eastern site. In contrast, larvae from the eastern population survived equally well at both sites. Local adaptation involved a trade-off between progeny size and the number of offspring. We hypothesized that an additional cost, imposed by natural enemies, may be associated with increased egg size: we also observed a west-to-east gradient of increased egg parasitism. We tested this hypothesis in a common garden by exposing eggs of both populations to parasitism by two native egg parasitoids, Ooencyrtus pityocampae and Baryscapus servadeii. The eastern population suffered a higher level of parasitoid attack by O. pityocampae than the western population, and performance of hatched adults of both parasitoids was enhanced in large eggs. Thus, increased neonate quality (larger eggs yielding larger larvae) confers an advantage on tough foliage but incurs the ecological cost of increased parasitism, which may constrain further adaptation by this herbivore.     

The effect of different holding conditions for environmental monitoring with caged rainbow trout (Oncorhynchus mykiss)

Biomarkers in fish can be a useful tool for environmental monitoring of aquatic ecosystems when diffuse pollution is becoming more important and new chemicals are being created continuously. There are, however, a number of drawbacks with this method. Because of environmental variability, health status of wild fish populations may differ between years, leading to unrepresentative results in long term studies. Furthermore, genetic or adaptive differences between populations complicate the interpretation of studies on different sites. The use of farmed fish, placed in cages, can reduce these problems. However, experimental conditions are likely to differ between sites. For practical reasons it may, e.g., be neccesary to use different types of caging. Here, the use of net cages and flow through tanks has been compared for a number of biomarkers. Rainbow trout (Oncorhynchus mykiss) were placed in net cages and flow through tanks in the river G?ta Alv, in western Sweden, during three different periods in 2004 and 2005. No differences between types of caging were found for any biomarker. Therefore, the results suggest that net cages and flow through tanks can be used and compared in environmental monitoring using biomarkers in caged rainbow trout. However, efforts should be taken to reduce differences in experimental conditions, e.g., light intensity and feeding levels.     

Microbial secondary metabolites in school buildings inspected for moisture damage in Finland, The Netherlands and Spain

Secondary metabolites produced by fungi and bacteria are among the potential agents that contribute to adverse health effects observed in occupants of buildings affected by moisture damage, dampness and associated microbial growth. However, few attempts have been made to assess the occurrence of these compounds in relation to moisture damage and dampness in buildings. This study conducted in the context of the HITEA project (Health Effects of Indoor Pollutants: Integrating microbial, toxicological and epidemiological approaches) aimed at providing systematic information on the prevalence of microbial secondary metabolites in a large number of school buildings in three European countries, considering both buildings with and without moisture damage and/or dampness observations. In order to address the multitude and diversity of secondary metabolites a large number of more than 180 analytes was targeted in settled dust and surface swab samples using liquid chromatography/mass spectrometry (LC/MS) based methodology. While 42%, 58% and 44% of all samples collected in Spanish, Dutch and Finnish schools, respectively, were positive for at least one of the metabolites analyzed, frequency of detection for the individual microbial secondary metabolites - with the exceptions of emodin, certain enniatins and physcion - was low, typically in the range of and below 10% of positive samples. In total, 30 different fungal and bacterial secondary metabolites were found in the samples. Some differences in the metabolite profiles were observed between countries and between index and reference school buildings. A major finding in this study was that settled dust derived from moisture damaged, damp schools contained larger numbers of microbial secondary metabolites at higher levels compared to respective dust samples from schools not affected by moisture damage and dampness. This observation was true for schools in each of the three countries, but became statistically significant only when combining schools from all countries and thus increasing the sample number in the statistical analyses.     

Biosynthetic origin of carbon-based secondary compounds: cause of variable responses of woody plants to fertilization?

Summary. We propose that variation in the responses of carbon-based secondary compounds to fertilization in woody plants has a biosynthetic cause. The synthesis of phenylpropanoids and derived compounds (e.g., condensed tannins) competes directly with the synthesis of proteins, and therefore with plant growth, because of a common precursor, phenylalanine. In contrast, the biosynthesis of terpenoids and of hydrolyzable tannins proceeds presumably without direct competition with protein synthesis. Therefore, accelerated plant growth induced by fertilization may cause a reduction in concentrations of phenylpropanoids but may affect less or not at all the levels of other classes of secondary compounds. A meta-analysis based on fertilization experiments with 35 woody plant species supported the predicted differences fertilizing significantly decreased concentrations of phenylpropanoids but not of terpenoids or hydrolyzable tannins. Received 14 May 1998; accepted 23 June 1998.     

Atmospheric deposition, retention, and stream export of dioxins and PCBs in a pristine boreal catchment

The mass-balance between diffuse atmospheric deposition of organic pollutants, amount of pollutants retained by the terrestrial environment, and levels of pollutants released to surface stream waters was studied in a pristine northern boreal catchment. This was done by comparing the input of atmospheric deposition of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and PCBs with the amounts exported to surface waters. Two types of deposition samplers were used, equipped with a glass fibre thimble and an Amberlite sampler respectively. The measured fluxes showed clear seasonality, with most of the input and export occurring during winter and spring flood, respectively. The mass balance calculations indicates that the boreal landscape is an effective sink for PCDD/Fs and PCBs, as 96.0-99.9 % of received bulk deposition was retained, suggesting that organic pollutants will continue to impact stream water in the region for an extended period of time.