Ecosystem services in European protected areas: Ambiguity in the views of scientists and managers?

Protected Areas are a key component of nature conservation. They can play an important role in counterbalancing the impacts of ecosystem degradation. For an optimal protection of a Protected Area it is essential to account for the variables underlying the major Ecosystem Services an area delivers, and the threats upon them. Here we show that the perception of these important variables differs markedly between scientists and managers of Protected Areas in mountains and transitional waters. Scientists emphasise variables of abiotic and biotic nature, whereas managers highlight socio-economic, cultural and anthropogenic variables. This indicates fundamental differences in perception. To be able to better protect an area it would be advisable to bring the perception of scientists and managers closer together. Intensified and harmonised communication across disciplinary and professional boundaries will be needed to implement and improve Ecosystem Service oriented management strategies in current and future Protected Areas.

Salinity as a barrier for ship hull-related dispersal and invasiveness of dreissenid and mytilid bivalves.

The benthic stages of Dreissenidae and Mytilidae may be dispersed over long distances while attached to ship hulls. Alternatively, larvae may be transported by water currents and in the ballast and bilge water of ships and vessels. To gain insight into dispersal potential and habitat suitability, survival of the benthic stages of two invasive dreissenid species (Dreissena polymorpha and Mytilopsis leucophaeata) and one mytilid species (Mytilus edulis) chosen based on their occurrence in fresh, brackish and sea water, respectively, were tested in relation to salinity. They were exposed to various salinities in mesocosms during three long-term experiments at outdoor temperatures. Mussel survival was studied without prior acclimation, reflecting conditions experienced when attached to ship hulls while travelling along a salinity gradient from fresh or brackish water to sea water, or vice versa. Initially, mussels react to salinity shock by temporarily closing their valves, suspending ventilation and feeding. However, this cannot be maintained for long periods and adaptation to higher salinity must eventually occur. Bivalve survival was monitored till the last specimen of a test cohort died. The results of the experiments allowed us to distinguish favorable (f.: high tolerance) and unfavorable (u.: no or low tolerance) salinity ranges in practical salinity units (PSU) for each species, viz. for D. polymorpha 0.2-6.0 PSU (f.), 7.0-30.0 PSU (u.), for M. leucophaeata 0.2-17.5 PSU (f.), 20.0-30.0 PSU (u.) and for M. edulis 10.5-36.0 PSU (f.), 0.2-9.0 and 40 PSU (u.). At the unfavorable salinities, all mussels died within 14 days of initial exposure with the exception of M. edulis (23-30 days). The maximum duration of survival of single specimens of D. polymorpha was 318 days at a salinity of 3.2 PSU, of M. leucophaeata 781 days at 15.0 PSU and of M. edulis 1052 days at 15.0 PSU. The number of days survived was compared with the duration of actual ship voyages to estimate the real world survival potentials of species dependent of salinity changes, travel distances and durations. The conclusion is that salinity shocks during the trip were survived within the favorable salinity range but that the species tolerate only for a few weeks the unfavorable salinity range. This functions as a barrier for dispersal. However, at faster and more frequent shipping in the future salinity can become no longer very important as a dispersal barrier.

Contaminant exposure in relation to spatio-temporal variation in diet composition: A case study of the little owl (Athene noctua).

We assessed dietary exposure of the little owl Athene noctua to trace metal contamination in a Dutch Rhine River floodplain area. Diet composition was calculated per month for three habitat types, based on the population densities of six prey types (earthworms, ground beetles and four small mammal species) combined with the little owl's functional response to these prey types. Exposure levels showed a strong positive relationship with the dietary fraction of earthworms, but also depended on the dietary fraction of common voles, with higher common vole fractions resulting in decreasing exposure levels. Spatio-temporal changes in the availability of earthworms and common voles in particular resulted in considerable variation in exposure, with peaks in exposure exceeding a tentative toxicity threshold. These findings imply that wildlife exposure assessments based on a predefined, average diet composition may considerably underestimate local or intermittent peaks in exposure.

Toxicological risks for small mammals in a diffusely and moderately polluted floodplain.

The ecotoxicological risk of heavy metal pollution in diffusely polluted floodplains is largely unclear, as field-based data are scarce. This study investigated cadmium (Cd) and lead (Pb) accumulation in the liver and kidneys of small mammal species (voles, mice and shrews) from a moderately polluted Dutch floodplain. The Cd and Pb concentrations were compared with effect concentrations (ECs). Reported ECs in literature varied considerably, with the lowest values frequently exceeded by our values, whereas the highest values were encountered only occasionally. Cd and Pb levels were highest in the shrew species, particularly in Sorex araneus. Although toxicological effects at the specimen level were present in these floodplains, effects at population level are thought to be limited, as a result of the animals' relatively short life expectancies (due to recurrent floods) and the rapid maturation of small mammals. Exceptionally high tissue metal concentrations in some specimens of all species indicated local hotspots with peaks in metal concentrations. Sanitizing such local hotspots might reduce toxicological risks.

Modeling the influence of environmental heterogeneity on heavy metal exposure concentrations for terrestrial vertebrates in river floodplains.

To analyze the influence of environmental heterogeneity on heavy metal exposure concentrations for terrestrial vertebrates in river floodplains, a spatially explicit exposure model has been constructed (SpaCE-model: Spatially explicit cumulative exposure model). This model simulates the environmental use of individual organisms by selecting model cells to be foraged in within a multicelled, heterogeneous landscape. Exposure durations and exposure concentrations are calculated for the selected cells, whereby exposure concentrations are dependent on the availability and contaminant concentrations of different diet items in each cell. The model was applied to a selection of 10 terrestrial vertebrate species, including six small mammalian and four top predator species. It was parameterized for cadmium contamination in a 285-ha, embanked floodplain area along the Rhine River in The Netherlands. Simulations of 1,000 individuals for each species resulted in intraspecies variation in exposure concentrations of between 11 and 39%, with the smallest values generally corresponding to the species with the largest home ranges. Comparison of the model results with cadmium concentrations measured in four of the species from the study area showed that the predicted variation accounted for 12 to 16% of the variation in the measurements. This indicates that environmental heterogeneity governs a minor part of the variation in metal exposure concentrations that can actually be observed in river floodplains.

Spatial distribution and internal metal concentrations of terrestrial arthropods in a moderately contaminated lowland floodplain along the Rhine River.

Soil metal concentrations, inundation characteristics and abundances of 14 arthropod taxa were investigated in a moderately contaminated lowland floodplain along the Rhine River and compared to the hinterland. Internal metal concentrations were determined for the orders of Coleoptera (beetles) and Araneida (spiders) and were related to soil concentrations. The floodplain was characterized by larger arthropod abundance than the hinterland, in spite of recurrent inundations and higher soil metal concentrations. Most arthropod taxa showed increasing abundance with decreasing distance to the river channel and increasing average inundation duration. For Cd, Cu, Pb and Zn, significant relations were found between arthropod concentrations and concentrations in soil. Significant relations were few but positive, indicating that increasing soil concentrations result in increasing body burdens in arthropods. For arthropod-eating vertebrates, these results might imply that larger prey availability in the floodplain coincides with higher metal concentrations in prey, possibly leading to increased exposure to metal contamination.

Cadmium accumulation in herbivorous and carnivorous small mammals: meta-analysis of field data and validation of the bioaccumulation model Optimal Modeling for Ecotoxicological Applications.

Environmental risk assessment procedures often use bioaccumulation as a criterion for hazard identification of a polluted location. Field studies regarding metal concentrations in food chains, however, have provided widely different information, because accumulation is shown to vary between the extremes of bioreduction and biomagnification. Bioaccumulation models provide insight regarding species-specific uptake and elimination kinetics of metals and assist in the interpretation of field data. Here, we use the bioaccumulation model OMEGA (Optimal Modeling for Ecotoxicological Applications) to estimate cadmium accumulation in herbivorous voles and carnivorous shrews. In addition to model validation, a meta-analysis of cadmium accumulation data is performed, because earlier studies generally have focused on relationships between cadmium concentrations in either specific tissues (kidney and liver) or whole-body concentrations and total soil levels. Additionally, we included the food-small mammal relationship. Our results show that cadmium whole-body concentrations are significantly related to cadmium levels in food items such as earthworms and plants. In addition, a significant relationship is found between cadmium accumulation in the liver and kidney of small mammals and total soil levels. Cadmium concentrations in shrews typically are an order of magnitude higher than metal levels in voles as a result of higher metal accumulation in earthworms compared to plants. Model predictions for both voles and shrews are in good agreement with field observations; deviations generally are within a factor of five. Small mammals prevent cadmium toxicity by binding this metal to metallothionein, which likely results in low elimination rates. Comparison with empirical elimination rates shows that rate constants of loss are accurately predicted assuming that cadmium is only released via growth dilution.

The effect of turbation on zinc relocation in a vertical floodplain soil profile.

Turbation is hypothesized to affect the redistribution of heavy metals in polluted floodplain soils by effects on mobility. This hypothesis was tested in microcosms by turbation of zinc-spiked sediment top layers. Manual turbation caused a fast decrease of the zinc content in the upper 15 cm of the soil, even though turbation was only applied to the upper two centimetres. It was especially zinc attached to colloid and organic matter particles that was redistributed from the top layer. Percolation processes resulted in the attached zinc being drained to depths of more than 15 cm. The decrease in zinc content of the topsoil was even stronger in combination with inundation. No indications were found for the redistribution of zinc as a result of an increase of the extractability with 0.01 M CaCl2 or changes in pH. The findings suggest that mechanical turbation and bioturbation may redistribute heavy metals from topsoils in polluted floodplains just after inundation as observed in these turbation experiments.