Aquatic leeches (Hirudinea) as bioindicators of organic chemical contaminants in freshwater ecosystems

Freshwater leeches from an industrially polluted creek were found to contain very high residues of chlorophenols, when compared with fish, tadpoles and most other benthic invertebrates. Leeches are recommended as possible bioindicators of aquatic organic contamination.     

Auditing International Environmental Agreements: The Role of Supreme Audit Institutions

Environmental problems are often transboundary in nature. International cooperation to solve them has resulted in a growing number of environmental agreements. Supreme Audit Institutions, which are the highest national audit institutions in a country and are responsible for auditing the regularity of governmental expenditure and receipts, can contribute to the success of international cooperation by auditing government compliance with international environmental obligations and commitments. This is a new challenge for supreme audit institutions. To encourage and support this work a Workgroup on Environmental Auditing of the International Organisation of Supreme Audit Institutions has developed guidelines, which are presented in this article. The possible practical role of audit institutions is illustrated by the audit on the Convention on the Prevention of Marine Pollution by Ships, in which eight European audit institutions cooperated. This article is published in a personal capacity and does not necessarily reflect the views of the Netherlands Court of Audit.     

Changes in soil nitrogen and phosphorus under different broiler production systems

In a field study, soils of four conventional free-range and organic broiler runs were analyzed for N and P concentrations in the years 2000 and 2001. Zones of different use intensity by broilers were identified on the free runs and mean zonal nutrient contents were compared with each other. Intensity of use by birds and spatial distribution of soil nutrient concentrations were found to be related to each other. Fecal N input by broilers resulted in accumulation of soil mineral nitrogen (N(min)) contents down to a 90-cm sampling depth. In highly frequented "hot spots," plant requirement as defined by the German "N-Basis-Sollwert" (110 kg/ha N(min)) for grassland was exceeded in all four cases. This implies an increased environmental risk of ammonia volatilization and nitrate leaching. Fecal P input by broilers resulted in accumulation of plant-available and thus mobile soil P (phosphorus extracted with calcium-acetate-lactate [P(CAL)] and phosphorus extracted with water [P(w)]) in the most intensely used zones. In these areas, soil P contents exceeded 90 mg/kg P(CAL) (upper limit of soil test P defined in Germany for optimum plant yield) by as much as 217 mg/kg, which indicates an enhanced risk of P loss from the soil via runoff or leaching. The conclusion might be drawn that, with regard to nutrient loss from free-run soils, intensive indoor production in a closed system may be more environmentally neutral than conventional free-range or organic production. However, to put this into perspective, the scope of the environmental risk connected with spatially limited point accumulation of nutrients should be considered. Furthermore, an environmental evaluation must also account for the fate and environmental effects of the broiler litter produced inside the broiler house.     

An automated system to control and manipulate the flight activity of captive birds

Biologists have long been interested in the behavioural and physiological mechanisms that regulate flight. The manipulation of physical activity of birds under captive conditions, however, faces the experimenter with some technical problems. In this article, we describe a simple automated system that allows control and manipulation of the flight activity of captive birds and use it for the first time to induce blood oxidative stress in male zebra finches (Taeniopygia guttata). Finches subjected to a short-term flight effort regime had an increase of plasma oxidative damage and a decrease of thiol concentration in red blood cells and of body mass, respectively. However, no change in red blood cell glutathione peroxidase was observed. This simple experiment shows that our automated system may be successfully used to induce changes in the physiological state of small birds.     

Do female association preferences predict the likelihood of reproduction?

Sexual selection acting on male traits through female mate choice is commonly inferred from female association preferences in dichotomous mate choice experiments. However, there are surprisingly few empirical demonstrations that such association preferences predict the likelihood of females reproducing with a particular male. This information is essential to confirm association preferences as good predictors of mate choice. We used green swordtails (Xiphophorus helleri) to test whether association preferences predict the likelihood of a female reproducing with a male. Females were tested for a preference for long- or short-sworded males in a standard dichotomous choice experiment and then allowed free access to either their preferred or non-preferred male. If females subsequently failed to produce fry, they were provided a second unfamiliar male with similar sword length to the first male. Females were more likely to reproduce with preferred than non-preferred males, but for those that reproduced, neither the status (preferred/non-preferred) nor the sword length (long/short) of the male had an effect on brood size or relative investment in growth by the female. There was no overall preference based on sword length in this study, but male sword length did affect likelihood of reproduction, with females more likely to reproduce with long- than short-sworded males (independent of preference for such males in earlier choice tests). These results suggest that female association preferences are good indicators of female mate choice but that ornament characteristics of the male are also important.     

New insights into the benefits of flood warnings: Results from a household survey in England and Wales

The flood defence agency in England and Wales has been pursuing a programme of flood warning system enhancement, engaging householders at risk in improving their warning responses. The immediate aim of this paper is to test and revise a model of economic benefits of warnings, but the survey data also generate insights into the constraints acting upon flood warning responses. Damage saving is less than previously anticipated: warning reliability and householder availability problems limit savings. Warnings are less likely to be received by those in lower social grades, and flood warning lead time is a factor in avoiding damage. The survey data indicate the complexities involved in improving flood warning response, and provide policy pointers.     

Risk communication in emergency response to a simulated extreme flood

Risk communication in flood incident management can be improved through developing hydrometeorological and engineering models used as tools for communicating risk between scientists and emergency management professionals. A range of such models and tools was evaluated by participating flood emergency managers during a 4-day, real-time simulation of an extreme event in the Thamesmead area in the Thames estuary close to London, England. Emergency managers have different communication needs and value new tools differently, but the indications are that a range of new tools could be beneficial in flood incident management. Provided they are communicated large model uncertainties are not necessarily unwelcome among flood emergency managers. Even so they are cautious about sharing the ownership of weather and flood modelling uncertainties.     

Seasonal migrations of plaice (Pleuronectes platessa) through the Dover Strait

Analysis of paired-haul mid-water trawling experiments conducted in the five months November to March during the years 1985 and 1988 revealed the seasonal pattern of migration of plaice (Pleuronectes platessa L.) moving through the Dover Strait between the Southern Bight of the North Sea and the English Channel. Mid-water catches of maturing fish were highest on south-going tidesprior to peak spawning (late January), while catches of spent fish, were highest on north-going tidesafter peak spawning. Detailed analysis of the catch data provided evidence that males complete their pre-spawning migration earlier, and their post-spawning migration later, than female fish and consequently spend more time on the spawning ground. Catches of immature female fish indicated a migration south following that of the mature fish. This dummy run may be a method by which immature plaice use the presence of high densities of mature and spawning fish to learn the location of the spawning ground. The analysis also indicated that differences in catch rates between day and night are unlikely to be the result of gear avoidance by day. The results confirm that selective tidal-stream transport is a key migratory mechanism for plaice in areas of fast tidal streams on the European continental shelf.