Ecological vulnerability in wildlife: application of a species-ranking method to food chains and habitats.

Nature development in The Netherlands is often planned on contaminated soils or sediments. This contamination may present a risk for wildlife species desired at those nature development sites and must be assessed by specific risk assessment methods. In a previous study, we developed a method to predict ecological vulnerability in wildlife species by using autecological data and expert judgment; in the current study, this method is further extended to assess ecological vulnerability of food chains and terrestrial and aquatic habitats typical for The Netherlands. The method is applied to six chemicals: Cd, Cu, Zn, dichlorodiphenyltrichloroethane, chlorpyrifos, and ivermectin. The results indicate that species in different food chains differ in vulnerability, with earthworm-based food chains the most vulnerable. Within and between food chains, vulnerability varied with habitat, particularly at low trophic levels. The concept of habitat vulnerability was applied to a case study of four different habitat types in floodplains contaminated with cadmium and zinc along the river Dommel, The Netherlands. The alder floodplain forest habitat contained the most vulnerable species. The differences among habitats were significant for Cd. We further conclude that the method has good potential for application in mapping of habitat vulnerability.

Ecological vulnerability in wildlife: an expert judgment and multicriteria analysis tool using ecological traits to assess relative impact of pollutants.

Nature development in The Netherlands often is planned on contaminated soils and sediments of former agricultural land and in floodplain areas; however, this contamination may present a risk to wildlife species desired at those nature development sites. Specific risk assessment methods are needed, because toxicological information is lacking for most wildlife species. The vulnerability of a species is a combination of its potential exposure, sensitivity to the type of pollutant, and recovery capacity. We developed a new method to predict ecological vulnerability in wildlife using autecological information. The analysis results in an ordinal ranking of vulnerable species. The method was applied to six representative contaminants: copper and zinc (essential metals, low to medium toxicity), cadmium (nonessential metal, high toxicity), DDT (persistent organic pesticide, high toxicity), chlorpyrifos (persistent organophosphate insecticide, high toxicity), and ivermectin (persistent veterinary pharmaceutical, low to medium toxicity). High vulnerability to the essential metals copper and zinc was correlated with soil and sediment habitat preference of a species and with r-strategy (opportunistic strategy suited for unstable environments). Increased vulnerability to the bioaccumulating substances cadmium and DDT was correlated with higher position of a species in the food web and with life span and K-strategy (equilibrium strategy suited for stable environments). Vulnerability to chlorpyrifos and ivermectin was high for species with a preference for soil habitats. The ecological vulnerability analysis has potential to further our abilities in risk assessment.

Tenax extraction mimics benthic and terrestrial bioavailability of organic compounds.

Biota to sediment accumulation factors (BSAFs) are widely used to describe the potential accumulation of organic contaminants in organisms. From field studies it is known that these BSAFs can vary dramatically between sediments of different origin, which is possibly explained by the variation in bioavailability of organic contaminants in sediments. In the present study it is shown that the variability in BSAF values for different sediment samples obtained at two Dutch freshwater sites could largely be explained by the variation in Tenax-extractable concentrations in these sediments. Variations of a factor of about 50 could be explained. The ratio between concentrations in biota and Tenax-extractable concentrations in sediment varied slightly between sediments and contaminant class, but was close to the theoretically expected value of 2. This is a strong indication that Tenax-extractable concentrations of contaminants in sediments are an excellent indicator of available concentrations.