The fate of trace metals during the metamorphosis of chironomids (diptera, chironomidae)

The fate of the trace metals zinc, cadmium and copper during the metamorphosis of chironomids was studied under field and experimental conditions. Field observations demonstrated a significant decrease in the trace metal body burden of larvae and imagines of Stictochironomus histrio Fabricius. No such difference were noted between successive developmental stages of Chironomus anthracinus Zett. The exuviae of both species contained small amounts of trace metals. Experiments, in which larvae of S. histrio and C. riparius Meigen were individually exposed, showed that larvae of both species accumulated substantial amounts of zinc and cadmium. For these metals, a transfer to pupae and imagines occurred. However, pupae had a lower body burden than larvae, and imagines a lower body burden than the pupae. Copper was also accumulated in the larvae, but it was excreted almost completely before the pupal stage. Elimination pathways of the trace metals during metamorphosis and the ecotoxicological consequences of trace metal transfer are discussed.     

European nature conservation legislation and spatial planning: For better or for worse?

The implementation of the Birds and Habitats directives has been problematic in many member states of the EU. In the Netherlands, many decision-making processes have ended in judicial intervention. This paper analyses the problematic implementation of both directives in the Netherlands. It shows that nature conservation legislation has gained importance in decision-making processes, but that this does not automatically mean that nature conservation goals have been achieved. Because of the emphasis that is placed on the procedural aspects of decision making, the costs involved have increased, while the substantial goals of the European Birds and Habitats directives are fading into the background.     

Entrepreneurship in climate governance at the local and regional levels: concepts,methods, patterns,and effects

This editorial sets the scene for a special issue on climate governance entrepreneurship at the local and regional levels. To make climate governance work, much policy activity is needed at the local and regional levels. Entrepreneurs are actors who aim to affect change by using their agency. They target policy decisions at the local and regional levels, which might subsequently turn to other governance levels to expand their influence. The scientific discussion about governance entrepreneurs is characterized by a lack of conceptual clarity, by methodological challenges, and by several research gaps. Regarding the latter, at present, it is especially unclear when and why entrepreneurs become active, which factors they take into account when they select their strategies, and what explains the effects of entrepreneurial activity on the emergence of innovations in climate governance. All contributions to this special issue engage with one or several of these conceptual, methodological, and empirical challenges, thus advancing the state of art in the field. Highlights from the special issue include the development of a simple conceptual frame that connects actors, contexts, strategies, and outcomes in a systematic way. Some promising methodological avenues are described, since the special issue contains not only some qualitative case studies but also some studies that take a long-term perspective by following policy development for decades, and a study that proposes a census approach. Empirically, the contributions in this special issue shed light on a range of factors explaining levels of entrepreneurial activity, and they carefully trace impacts over time. We conclude by sketching an agenda for further work in this realm.

     

The determination and distribution of Zn in surface water samples collected in the northeast Atlantic Ocean

Dissolved Zn concentrations were determined in surface water samples collected on-line along transects in the eastern North Atlantic in spring (March 1998). Two frontal zones could be identified in the research area by a change in salinity, temperature and nutrient concentrations. One zone was identified at 42 degrees N, separating the North Atlantic central water (NACW) and the Atlantic surface water (ASW) from each other, and another one crossing the continental slope at 12 degrees and 8 degrees E, respectively. Variability in Zn concentrations was observed near these zones, not only as a result of a change of water mass, but also due to external Zn sources. Surface Zn concentrations were 0.5-1 nM and 2 nM in the NACW and ASW, respectively, increasing to 4 nM over the continental shelf and finally 5-6 nM in the English Channel. Contributions of Zn derived from shelf sediments appear to be the major source for the enriched surface values in the continental zone.     

Long‐distance flights and high‐risk breeding by nomadic waterbirds on desert salt lakes

Understanding and conserving mobile species presents complex challenges, especially for animals in stochastic or changing environments. Nomadic waterbirds must locate temporary water in arid biomes where rainfall is highly unpredictable in space and time. To achieve this they need to travel over vast spatial scales and time arrival to exploit pulses in food resources. How they achieve this is an enduring mystery.  We investigated these challenges in the colonial‐nesting Banded Stilt (Cladorhynchus leucocephalus), a nomadic shorebird of conservation concern. Hitherto, Banded Stilts were hypothesized to have only 1–2 chances to breed during their long lifetime, when flooding rain fills desert salt lakes, triggering mass‐hatching of brine shrimp. Over 6 years, we satellite tagged 57 individuals, conducted 21 aerial surveys to detect nesting colonies on 14 Australian desert salt lakes, and analyzed 3 decades of Landsat and MODIS satellite imagery to quantify salt‐lake flood frequency and extent. Within days of distant inland rainfall, Banded Stilts flew 1,000–2,000 km to reach flooded salt lakes. On arrival, females laid over half their body weight in eggs. We detected nesting episodes across the species’ range at 7 times the frequency reported during the previous 80 years. Nesting colonies of thousands formed following minor floods, yet most were subsequently abandoned when the water rapidly evaporated prior to egg hatching. Satellite imagery revealed twice as many flood events sufficient for breeding‐colony initiation as recorded colonies, suggesting that nesting at remote sites has been underdetected. Individuals took risk on uncertain breeding opportunities by responding to frequent minor flood events between infrequent extensive flooding, exemplifying the extreme adaptability and trade‐offs of species exploiting unstable environments. The conservation challenges of nest predation by overabundant native gulls and anthropogenic modifications to salt lakes filling frequencies require investigation, as do the physiological and navigational mechanisms that enable such extreme strategies.     

Parentage analyses suggest female promiscuity and a disadvantage for athletic males in the colour-polymorphic lizard Podarcis melisellensis

Although laboratory measurements of whole-animal performance have become a standard tool in evolutionary biology, if and how interindividual variation in performance translates into differential fitness remains poorly understood. Particularly rare are studies that have connected performance to mating and reproductive success in the field. In this study, we use DNA microsatellite parentage analyses to study the fitness gradient in a colour-polymorphic lizard, Podarcis melisellensis. We report on two surprising findings. First, contrary to our expectations, individual sprint speed and bite force capacity correlated negatively, not positively, with male mating and reproductive success. Second, we found an unexpected degree of promiscuity in females. Also, contrary to traditional parental investment theory, the variation in mating success and reproductive success was as high in females as in males. Our results call for a better integration of whole-animal performance and life history traits, and for a reconsideration of the ideas on the likeliness of sexual selection acting on female phenotypes.     

Older can be better: physiological costs of paternal investment in the Florida scrub-jay

In species that undergo actuarial senescence, the value of current reproduction is predicted to increase relative to the value of future reproduction with age, as the probability of survival to another reproductive event is reduced. Therefore, life history theory predicts that aging animals should increase their investment in reproduction. However, an increase in reproductive investment may carry significant costs to the breeding individuals. We recorded provisioning rates of Florida scrub-jay male breeders, followed by their immediate capture to assess body condition and collect blood for an in vitro test of immunocompetence and an assay of baseline corticosterone for a measure of stress. Older males provisioned offspring and brooding mates at the highest rates. There was no evidence of any physiological deficits in males with high provisioning rates, independent of age. It appears that birds that survive to old age are high quality birds that maintain good physiological condition, which complements the value of experience and permits maximal investment in offspring.