Positive polarotaxis in a mayfly that never leaves the water surface: polarotactic water detection in Palingenia longicauda (Ephemeroptera)

Tisza mayflies, Palingenia longicauda (Olivier 1791), swarm exclusively over the river Tisza (from which the name of the mayfly was derived). This river is bordered by a high vertical wall of trees and bushes, which hinder P. longicauda to move away horizontally from the water. During swarming, Tisza mayflies fly immediately above the river in such a way that their cerci touch the water frequently or sweep its surface. This continuous close connection with water and the vertical wall of the shore and riparian vegetation result in that Tisza mayflies never leave the water surface; consequently, they need not search for water. Several Ephemeroptera species move away far from water and return to it guided by the horizontal polarization of water-reflected light. To reveal whether also P. longicauda is or is not polarotactic, we performed a field experiment during the very short swarming period of Tisza mayflies. We show here that also P. longicauda has positive polarotaxis, which, however, can be observed only under unnatural conditions, when the animals are displaced from the water and then released above artificial test surfaces. P. longicauda is the first species in which polarotactic water detection is demonstrated albeit it never leaves the water surface, and thus, a polarotactic water detection seems unnecessary for it. The polarotactic behaviour of Tisza mayflies explains the earlier observation that these insects swarm above wet asphalt roads running next to river Tisza.     

Management of municipal solid waste incineration residues

The management of residues from thermal waste treatment is an integral part of waste management systems. The primary goal of managing incineration residues is to prevent any impact on our health or environment caused by unacceptable particulate, gaseous and/or solute emissions. This paper provides insight into the most important measures for putting this requirement into practice. It also offers an overview of the factors and processes affecting these mitigating measures as well as the short- and long-term behavior of residues from thermal waste treatment under different scenarios. General conditions affecting the emission rate of salts and metals are shown as well as factors relevant to mitigating measures or sources of gaseous emissions.     

Resilience to natural hazards: How useful is this concept?

Resilience is widely seen as a desirable system property in environmental management. This paper explores the concept of resilience to natural hazards, using weather-related hazards in coastal megacities as an example. The paper draws on the wide literature on megacities, coastal hazards, hazard risk reduction strategies, and resilience within environmental management. Some analysts define resilience as a system attribute, whilst others use it as an umbrella concept for a range of system attributes deemed desirable. These umbrella concepts have not been made operational to support planning or management. It is recommended that resilience only be used in a restricted sense to describe specific system attributes concerning (i) the amount of disturbance a system can absorb and still remain within the same state or domain of attraction and (ii) the degree to which the system is capable of self-organisation. The concept of adaptive capacity, which has emerged in the context of climate change, can then be adopted as the umbrella concept, where resilience will be one factor influencing adaptive capacity. This improvement to conceptual clarity would foster much-needed communication between the natural hazards and the climate change communities and, more importantly, offers greater potential in application, especially when attempting to move away from disaster recovery to hazard prediction, disaster prevention, and preparedness.     

Forest conservation delivers highly variable coral reef conservation outcomes

Coral reefs are threatened by human activities on both the land (e.g., deforestation) and the sea (e.g., overfishing). Most conservation planning for coral reefs focuses on removing threats in the sea, neglecting management actions on the land. A more integrated approach to coral reef conservation, inclusive of land-sea connections, requires an understanding of how and where terrestrial conservation actions influence reefs. We address this by developing a land-sea planning approach to inform fine-scale spatial management decisions and test it in Fiji. Our aim is to determine where the protection of forest can deliver the greatest return on investment for coral reef ecosystems. To assess the benefits of conservation to coral reefs, we estimate their relative condition as influenced by watershed-based pollution and fishing. We calculate the cost-effectiveness of protecting forest and find that investments deliver rapidly diminishing returns for improvements to relative reef condition. For example, protecting 2% of forest in one area is almost 500 times more beneficial than protecting 2% in another area, making prioritization essential. For the scenarios evaluated, relative coral reef condition could be improved by 8-58% if all remnant forest in Fiji were protected rather than deforested. Finally, we determine the priority of each coral reef for implementing a marine protected area when all remnant forest is protected for conservation. The general results will support decisions made by the Fiji Protected Area Committee as they establish a national protected area network that aims to protect 20% of the land and 30% of the inshore waters by 2020. Although challenges remain, we can inform conservation decisions around the globe by tackling the complex issues relevant to integrated land-sea planning.     

Comparative sensitivity of 20 bioassays for soil quality

Increasing evidence suggests that the use of a single bioassay will never provide a full picture of the quality of the environment. Only a test battery, composed of bioassays of different animal and plant species from different trophic levels will reduce uncertainty, allowing an accurate assessment of the quality of the environment. In the present study, a test battery composed of 20 bioassays of varying biological endpoints has been compared Apart from lethality and reproductive failure in earthworms, springtails, nematoda, algae and vascular plants, these endpoints also included bioavailibility of metals (bacteria), heat-shock induction (nematodes, algae), DNA damage (bacteria, earthworm, vascular plants), β-galactosidase (Daphnia) and esterase activity (algae) and a range of immunological parameters (earthworm). Four chemicals (cadmium, phenol, pentachlorophenol and triflurahn) — each representing a different toxic mode of action — were applied in a dilution series (from 1 mg/kg up to 1000 mg/kg) onto OECD standard soil. The tests have been performed both on these artificially contaminated soil samples and on aqueous extracts subsequently obtained from these soils. The results show that the immunological parameters and the loss of weight in the earthworms were among the most sensitive solid phase assays. Esterase inhibition and heat-shock induction in algae were shown to be extremely sensitive when applied to soil extracts. As previously shown at the species level, no single biological endpoint was shown to be the most sensitive for all four modes of toxic action.     

Trophic upgrading of food quality by protozoans enhancing copepod growth: role of essential lipids

 Protozoa are known for their intermediary trophic role in transferring organic matter from small size planktonic particles to mesozooplankton. This study concentrates on the possible addition of biochemical value during this transfer, by new production of compounds that are essential in copepod food. In laboratory experiments, copepods could not be raised on a diet of the chlorophycean Dunaliella sp., though they readily consumed this alga. Dunaliella sp. contained all essential amino acids, but was deficient in highly unsaturated fatty acids and in sterols. In contrast to copepods, the heterotrophic dinoflagellate Oxyrrhis marina grew well on Dunaliella sp., producing significant amounts of the long-chain fatty acids docosahexaenoic acid and eicosapentaenoic acid, in addition to cholesterol and brassicasterol. Using this O. marina grown on Dunaliella sp. to feed Temora longicornis and Pseudocalanus elongatus, both copepod species rapidly developed from young nauplius larvae to maturity on the dinoflagellate diet. Hence, in this experimental food-chain the inadequate chlorophycean food was biochemically upgraded by the protozoan to high-quality copepod food. The results indicate that highly unsaturated fatty acids and/or sterols are essential compounds, which can be produced by protozoans. Due to their intermediate size, the mechanism of trophic upgrading by protozoans may bridge the gap of essential nutrients between the microbial loop and higher trophic levels. Received: 11 January 1999 / Accepted: 3 June 1999     

Embeddedness of climate change adaptation: established procedures and contending discourses for flood protection in Espoo,Finland

Calls for more stakeholder participation and cooperation, the acknowledgement of uncertainties as well as for flexible and robust solutions have become frequent in the literature on climate change adaptation. Recent studies show that these calls are taken up only reluctantly in local adaptation compared to sectoral and technical solutions. The aim of this study is to examine to which extent adaptation as an embedded process within the local context allows for stakeholder participation, cooperation and the robustness and flexibility of adaptation measures. It applies an analytical approach, combining an action framework of adaptation and document-based discourse analysis, to assess both the procedural and the substantive viewpoint of an adaptation case in Finland. This twofold approach provides insight into how the adaptation process and content influence and condition each other. The analysis highlights how new approaches to adaptation have to compete with prevailing discourses and institutionalised practices, as public authorities take the dominant role in adaptation, striving for certain and safe solutions. This process has few participatory elements and leaves little leeway to address uncertainty.     

Water quality status and trends in agriculture-dominated headwaters; a national monitoring network for assessing the effectiveness of national and European manure legislation in The Netherlands

Large nutrient losses to groundwater and surface waters are a major drawback of the highly productive agricultural sector in The Netherlands. The resulting high nutrient concentrations in water resources threaten their ecological, industrial, and recreational functions. To mitigate eutrophication problems, legislation on nutrient application in agriculture was enforced in 1986 in The Netherlands. The objective of this study was to evaluate this manure policy by assessing the water quality status and trends in agriculture-dominated headwaters. We used datasets from 5 agricultural test catchments and from 167 existing monitoring locations in agricultural headwaters. Trend analysis for these locations showed a fast reduction of nutrient concentrations after the enforcement of the manure legislation (median slopes of ?0.55 mg/l per decade for total nitrogen (N-tot) and ?0.020 mg/l per decade for total phosphorus (P-tot)). Still, up to 76 % of the selected locations currently do not comply with either the environmental quality standards (EQSs) for nitrogen (N-tot) or phosphorus (P-tot). This indicates that further improvement of agricultural water quality is needed. We observed that weather-related variations in nutrient concentrations strongly influence the compliance testing results, both for individual locations and for the aggregated results at the national scale. Another important finding is that testing compliance for nutrients based on summer average concentrations may underestimate the agricultural impact on ecosystem health. The focus on summer concentrations does not account for the environmental impact of high winter loads from agricultural headwaters towards downstream water bodies.