Handling intensity and the short- and long-term survival of elephant seals: addressing and quantifying research effects on wild animals

This study addresses the consequences of repeated human handling on the survival of an endangered phocid, the southern elephant seal and the implications for wildlife research. Southern elephant seal pups were repeatedly handled during the first six weeks of their lives. The possibility that such anthropogenic research may have altered the very parameters that were being investigated is a topical and relevant study area that we address here. Our results show that there were no measurable effects on pups that were repeatedly handled and subjected to invasive research methods with respect to survivorship in the short term (the 24-day nursing period) nor in the long term (the first year of life and beyond) and hence fitness one year after handling. In support of this conclusion we were unable to detect any significant differences in the survival rates of the most intensively handled seals and the least intensively handled seals.     

Pollenkörner,Punktverteilungen auf der Kugel und Informationstheorie

The Science of Nature -     

Are dioxin-like contaminants responsible for the eel (Anguilla anguilla) drama?

Eel populations worldwide are dangerously close to collapsing. Our study is the first to show that current levels of dioxin-like contaminants are strong candidates because of their devastating effects on development and survival of eel embryos. Female and male silver eels were artificially stimulated to maturation and reproduction by treatment with carp pituitary extracts and hCG, respectively. During maturation of female European silver eels, about 60 g fat per kg eel is incorporated in the oocytes. Together with the fat, however, persistent organic pollutants such as dioxin-like polychlorinated biphenyls (PCBs) are incorporated too. The total dioxin-like toxic potency of the individual gonad batches was determined as 2,3,7,8-tetrachlorodibenzo-p-dioxine equivalents (TEQs), using an in vitro reporter gene assay. The observed differences in development and survival showed a significant negative correlation with the TEQ levels in the gonads, already at levels far below the maximal allowable level for fish consumption, i.e., 4 ng TEQ/kg fish. The clear inverse relationship between the TEQ level and the survival period of the fertilised eggs strongly suggests that the current levels of dioxin-like compounds seriously impair the reproduction of the European eel. The peak of the environmental levels of dioxin-like PCBs and the decline of eel coincide worldwide, further suggesting that, in addition to other threats, these contaminants contributed significantly to the current collapse in eel populations.     

Schwermetalle in Regenwürmern Baden-Württembergs

Goal and Scope

Since 1984 the Environmental Protection Agency (LfU) of the State of Baden-Wuerttemberg has been investigating the heavy metal burden of earthworms from representative long-term forest observation plots. These investigations are aimed at elucidating and assessing adverse effects of pollutants on the soil biocenosis.

Methods

At first only lead and cadmium were measured in the worms; in repetitive measurements over the years further metals or metalloid elements such as aluminum, arsenic, chromium, cobalt, copper, manganese, mercury, nickel, thallium, vanadium, and zinc were added to the agenda.

Results and Conclusion

The frequency distribution of the metals in the earthworms was characterized statistically. For the first time state-wide background values, normal values and threshold values were established for all the elements measured. A comparable study with a similar range of parameters is known neither nationally nor internationally. Time trend studies have been available for lead and cadmium since 1985/86, and for zinc since 1987. The studies show a steady decrease of the heavy metals on a state-wide average and especially in the ‘Odenwald’ and ‘Black Forest’ hills with their formerly highly polluted earthworm habitats. Today, the level of these metals in the earthworms is low with few exceptions. This holds true for other heavy metals as well.

Recommendations and Perspectives

The state-wide decreasing very low heavy metal burden of forest observation plots far from known emission sources can be considered a success of air pollution abatement measures. Because of the ongoing atmospheric deposition of heavy metals, regular observation should continue in order to estimate time trends and to recommend the reduction of emissions when precautionary values (part 2) are exceeded.     

Recognizing local people's priorities for tropical forest biodiversity

Tropical forest people often suffer from the same processes that threaten biodiversity. An improved knowledge of what is important to local people could improve decision making. This article examines the usefulness of explicitly asking what is important to local people. Our examples draw on biodiversity surveys in East Kalimantan (Indonesian Borneo). With local communities we characterized locally valued habitats, species, and sites, and their significance. This process clarified various priorities and threats, suggested refinements and limits to management options, and indicated issues requiring specific actions, further investigation, or both. It also shows how biological evaluations are more efficient with local guidance, and reveals potential for collaborations between local communities and those concerned with conservation. Such evaluations are a first step in facilitating the incorporation of local concerns into higher-level decision making. Conservationists who engage with local views can benefit from an expanded constituency, and from new opportunities for pursuing effective conservation.     

What drives conversion of tropical forest in Carrasco Province, Bolivia?

The conversion of closed forest (CCF) in Carrasco Province, Bolivia, was monitored using a series of four midresolution satellite images from 1986 to 2002. The conversion of forests into nonforests from 1986 to 2002 was 1.5% annually. Inclusion of conversions into open forest doubles the annual CCF rate to 3.1%. Five predictors of CCF were tested in a spatial model: land tenure regime, distance from roads, distance from settlements, topography, and soil suitability for farming. Only three out of the five predictors tested were found to be reliable predictors of CCF: land tenure regime, distance from roads, and distance from settlements. University reserve and indigenous land show substantially less CCF than national park and untitled land. In addition the spatial model shows that the greater the distance of forest from roads or settlements, the less CCF. Topography and soil suitability for farming lack predictive power for CCF and are therefore excluded from the spatial model.