Acid–base regulation in the Dungeness crab (Metacarcinus magister)

Homeostatic regulation allows organisms to secure basic physiological processes in a varying environment. To counteract fluctuations in ambient carbonate system speciation due to elevated seawater pCO₂ (hypercapnia), many aquatic crustaceans excrete/accumulate acid–base equivalents through their gills; however, not much is known about the role of ammonia in this response. The present study investigated the effects of hypercapnia on acid–base and ammonia regulation in the Dungeness crab, Metacarcinus magister on the whole animal and isolated gill levels. Hemolymph pCO₂ and [HCO₃ ^?] increased in M. magister acclimated to elevated pCO₂ (330 Pa), while pH remained stable. Additionally, hemolymph [Na⁺], [Ca²⁺], and [SO₄ ^2?] were significantly increased. When challenged with varying pH during gill perfusion, the pH of the artificial hemolymph remained relatively unchanged. Overall, ammonia production and excretion, as well as oxygen consumption, were reduced in crabs acclimated to elevated pCO₂, demonstrating that either (amino acid) oxidation is reduced in response to this particular stress, or nitrogenous wastes are excreted in an alternative form.     

Alternative reproductive tactics and the impact of local competition on sex ratios in the ant Hypoponera opacior

The ant Hypoponera opacior exhibits alternative reproductive morphs of males and females associated with distinct sexual behaviours. Our long-term study reports strong seasonality in sexual production with a mating season in early and one in late summer. Winged (alate) reproductives emerge in June, swarm during the monsoon season and establish new colonies independently. In contrast, wingless worker-like (ergatoid) reproductives that appear in late August mate within their natal or adjacent nests and either do not disperse or establish new nests close by. These divergent dispersal patterns allowed us to analyse the impact of local factors on investment strategies by comparing sex allocation between and within the two reproductive events. The optimal sex ratio for ergatoid reproductives should be influenced both by competition for matings between brothers (local mate competition) and rivalry among young locally dispersing queens for workers, nest sites or food (local resource competition). The greater importance of local resource competition was demonstrated both by a male-biased sex ratio for wingless sexuals and a stronger increase in the number of males with total sexual production than for the number of queens. Microsatellite analysis revealed that inter-nest variation in relatedness asymmetry cannot explain split sex ratios in the August generation. Instead, nests with related ergatoid males raised a male-biased sex ratio contrary to the expectations under local mate competition. In conclusion, male bias in wingless H. opacior indicates that local mate competition is less strong than local resource competition among ergatoid queens over the help of workers during nest foundation.     

Expositionsszenarien nach REACH

Object and Background

Production and use of substances and formulations can result in exposures on humans and the environment. In October 2003, the European Commissions presented a proposal for the registration, evaluation, assessment and restriction of chemicals (REACH). Assessment of exposures will become an essential element of REACH for certain substances. For many manufacturers and users of substances and formulations these tasks are new. Pilot projects to REACH have shown so far that solutions and instruments for these tasks which meet the requirements of real life situations have yet to be developed.

Discussion and Conclusions

Within the REACH proposal, exposure scenarios are a main element of the chemical safety assessment. This article outlines the contents of exposure scenarios. It reflects experiences with exposure scenarios and discusses possibilities of standardization. It covers exposure steps/categories and possibilities to build product groups. Non-branch specific types of exposure situations are an important element of exposure scenarios. Therefore, exposure steps/categories should be contained in exposure scenarios. Nevertheless, these elements structure only a specific part of the information contained in exposure scenarios. Hence they cannot replace exposure scenarios. Exposure categories do not reveal the uses, the processes and the activities connected with the intended use of substances. These information are important parts of a complete exposure scenario. They are the basis for the following step of risk characterisation. In addition, they provide the necessary transparency regarding the use patteern of substances.     

Financial adaptation to disaster risk in the European Union

Increasing losses from weather related extreme events coupled with limited coping capacity suggest a need for strong adaptation commitments, of which public sector responses to adjustments to actual and expected climate stimuli are key. The European Commission has started to address this need in the emerging European Union (EU) climate adaptation strategy; yet, a specific rationale for adaptation interventions has not clearly been identified, and the economic case for adaptation to extremes remains vague. Basing the diagnosis on economic welfare theory and an empirical analysis of the current EU and member states’ roles in managing disaster risk, we discuss how and where the public sector may intervene for managing climate variability and change. We restrict our analysis to financial disaster management, a domain of adaptation intervention, which is of key concern for the EU adaptation strategy. We analyse three areas of public sector interventions, supporting national insurance systems, providing compensation to the affected post event as well as intergovernmental loss sharing through the EU solidarity fund, according to the three government functions of allocation, distribution, and stabilization suggested by welfare theory, and suggest room for improvement.