Scenario analysis of perspective change to support climate adaptation: lessons from a pilot study on Dutch river management

Climate adaptation is a complex task surrounded by uncertainty. To support climate adaptation policies, a new scenario approach is pursued to explore possible discontinuous future developments of societal perspectives on climate adaptation issues. The scenario approach was tested for a case study on Dutch river management. In a series of scenario development workshops, a select group of stakeholders explored the perspectives on the management of the River Meuse in the past, present, and future. The process was supported by an analytical perspectives mapping tool to illustrate and analyze the development of perspectives over time. The process and analytical tools contributed to insight into the drivers of perspective change for the case study at hand. Moreover, the stakeholders highlighted the potential of the approach for water management policy for creating awareness about the plurality of perspectives and the dynamics of perspective change, monitoring perspectives and perspective change as part of a flexible policy approach, and anticipating on the occurrence of shock events. Further work is required to better represent the social dynamics of perspectives change, to better empirically ground the perspective change model, and to apply integrated water models in the scenario development process to assess water–society interactions.     

Recruitment and attrition of associated plants under a shading crop canopy: Model selection and calibration

Associated plant and animal diversity provides ecosystem services within crop production systems. The importance of the maintenance or restoration of diversity is therefore increasingly acknowledged. Here we study the population dynamics of associated annual plants (‘weeds’) during the growth of a crop in a season and introduce a minimal model to characterize the recruitment and attrition of the associated plants under the influence of shading by the crop. A mechanistically based, logistic, light interception model was parameterized with light interception measurements in two single crops (barley and rye) and in mixtures of these cereals with peas. Population dynamics data were collected for the annuals Papaver rhoeas, Centaurea cyanus, Chrysanthemum segetum, and Misopates orontium. A minimal population dynamics model was identified for each annual plant species, using system identification techniques as model selection and calibration.     

On reducing the windfall profits in environmental subsidy programs

Investment subsidies are widely used to induce adoption of new technologies that can lower the (marginal) cost of reducing emissions. To economize on these subsidies, governments would like to distinguish between firms that need to receive a subsidy to adopt a new technology, and firms that would adopt that technology even without subsidies. We show that policies consisting of a menu of emission taxes and investment subsidies can potentially induce firms to self-select.     

Eine Weight-of-Evidence-Studie zur Bewertung der Sedimentbelastung und des Fischrückgangs in der Oberen Donau

Background and aim Despite intensive and continuous stocking and improvement of water quality since the 1970s, fish populations, especially those of the grayling (Thymallus thymallus), have declined over the last two decades in the upper Danube River (Germany). In order to assess 1) possible links between molecular/biochemical responses and ecologically relevant effects, and 2) if ecotoxicological effects might be related to the decline in fish catches in the upper Danube river, sediment samples and fish were collected at different locations and analyzed using a weight-of-evidence (WOE) approach with several lines of evidence. The objective of the presentation is to introduce the conceptual framework and to review results of the ongoing study. As previously addressed by Chapman and Hollert (2006) a variety of lines of evidence can be used in WOE studies. Briefly, 1) a comprehensive battery of acute and mechanism-specific bioassays was used to characterize the ecotoxicological hazard potential. 2) Histopathological investigations and the micronucleus assay with erythrocytes were applied, analyzing in situ parameters. 3) Diversity and abundance of benthic macroinvertebrates and fish as well as 4) persistent organic pollutants, endocrine disrupting substances, limnochemical parameters and the concentration of heavy metals were recorded. To identify organic contaminants a spotential causes of sediment toxicity assays, 5) effect directed analysis was applied.     

Amino acid metabolism and protein turnover in larval turbot (Scophthalmus maximus) fed natural zooplankton or Artemia

The present paper studied the influence of different food regimes on the free amino acid (FAA) pool, the rate of protein turnover, the flux of amino acids, and their relation to growth of larval turbot (Scophthalmus maximus L.) from first feeding until metamorphosis. The amino acid profile of protein was stable during the larval period although some small, but significant, differences were found. Turbot larvae had proteins which were rich in leucine and aspartate, and poor in glutamate, suggesting a high leucine requirement. The profile of the FAA pool was highly variable and quite different from the amino acid profile in protein. The proportion of essential FAA decreased with development. High contents of free tyrosine and phenylalanine were found on Day 3, while free taurine was present at high levels throughout the experimental period. Larval growth rates were positively correlated with taurine levels, suggesting a dietary dependency for taurine and/or sulphur amino acids. Reduced growth rates in Artemia-fed larvae were associated with lower levels of free methionine, indicating that this diet is deficient in methionine for turbot larvae. Leucine might also be limiting turbot growth as the different diet organisms had lower levels of this amino acid in the free pool than was found in the larval protein. A previously presented model was used to describe the flux of amino acids in growing turbot larvae. The FAA pool was found to be small and variable. It was estimated that the daily dietary amino acid intake might be up to ten times the larval FAA pool. In addition, protein synthesis and protein degradation might daily remove and return, respectively, the equivalent of up to 20 and 10 times the size of the FAA pool. In an early phase (Day 11) high growth rates were associated with a relatively low protein turnover, while at a later stage (Day 17), a much higher turnover was observed. Received: 19 March 1997 / Accepted: 14 April 1997     

Carbon conversion and metabolic rate in two marine sponges

The carbon metabolism of two marine sponges, Haliclona oculata and Dysidea avara, has been studied using a ¹³C isotope pulse-chase approach. The sponges were fed ¹³C-labeled diatoms (Skeletonema costatum) for 8 h and they took up between 75 and 85%. At different times, sponges were sampled for total ¹³C enrichment, and fatty acid (FA) composition and ¹³C enrichment. Algal biomarkers present in the sponges were highly labeled after feeding but their labeling levels decreased until none was left 10 days after enrichment. The sponge-specific FAs incorporated ¹³C label already during the first day and the amount of ¹³C label inside these FAs kept increasing until 3 weeks after labeling. The algal-derived carbon captured by the sponges during the 8-h feeding period was thus partly respired and partly metabolized during the weeks following. Apparently, sponges are able to capture enough food during short periods to sustain longer-term metabolism. The change of carbon metabolic rate of fatty acid synthesis due to mechanical damage of sponge tissue was studied by feeding sponges with ¹³C isotope–labeled diatom (Pheaodactylum tricornutum) either after or before damaging and tracing back the ¹³C content in the damaged and healthy tissue. The filtration and respiration in both sponges responded quickly to damage. The rate of respiration in H. oculata reduced immediately after damage, but returned to its initial level after 6 h. The ¹³C data revealed that H. oculata has a higher metabolic rate in the tips where growth occurs compared to the rest of the tissue and that the metabolic rate is increased after damage of the tissue. For D. avara, no differences were found between damaged and non-damaged tissue. However, the filtration rate decreased directly after damage.     

Additive effects of aboveground polyphagous herbivores and soil feedback in native and range-expanding exotic plants

Plant biomass and plant abundance can be controlled by aboveground and belowground natural enemies. However, little is known about how the aboveground and belowground enemy effects may add up. We exposed 15 plant species to aboveground polyphagous insect herbivores and feedback effects from the soil community alone, as well as in combination. We envisaged three possibilities: additive, synergistic, or antagonistic effects of the aboveground and belowground enemies on plant biomass. In our analysis, we included native and phylogenetically related range-expanding exotic plant species, because exotic plants on average are less sensitive to aboveground herbivores and soil feedback than related natives. Thus, we examined if lower sensitivity of exotic plant species to enemies also alters aboveground-belowground interactions. In a greenhouse experiment, we exposed six exotic and nine native plant species to feedback from their own soil communities, aboveground herbivory by polyphagous insects, or a combination of soil feedback and aboveground insects and compared shoot and root biomass to control plants without aboveground and belowground enemies. We observed that for both native and range-expanding exotic plant species effects of insect herbivory aboveground and soil feedback added up linearly, instead of enforcing or counteracting each other. However, there was no correlation between the strength of aboveground herbivory and soil feedback. We conclude that effects of polyphagous aboveground herbivorous insects and soil feedback add up both in the case of native and related range-expanding exotic plant species, but that aboveground herbivory effects may not necessarily predict the strengths of soil feedback effects.     

Present-day genetic composition suggests contrasting demographic histories of two dominant chaetognaths of the North-East Atlantic, <Emphasis Type="Italic">Sagitta elegans</Emphasis> and <Emphasis Type="Italic">S. setosa</Emphasis>

Sagitta elegans and S. setosa are the two dominant chaetognaths in the North-East (NE) Atlantic. They are closely related and have a similar ecology and life history, but differ in distributional ranges. Sagitta setosa is a typical neritic species occurring exclusively above shelf regions, whereas S. elegans is a more oceanic species with a widespread distribution. We hypothesised that neritic species, because of smaller and more fragmented populations, would have been more vulnerable to population bottlenecks resulting from range contractions during Pleistocene glaciations than oceanic species. To test this hypothesis we compared mitochondrial Cytochrome Oxidase II DNA sequences of S. elegans and S. setosa from sampling locations across the NE Atlantic. Both species displayed very high levels of genetic diversity with unique haplotypes for every sequenced individual and an approximately three times higher level of nucleotide diversity in S. elegans (0.061) compared to S. setosa (0.021). Sagitta setosa mitochondrial DNA (mtDNA) haplotypes produced a star-like phylogeny and a uni-modal mismatch distribution indicative of a bottleneck followed by population expansion. In contrast, S. elegans had a deeper mtDNA phylogeny and a multi-modal mismatch distribution as would be expected from a more stable population. Neutrality tests indicated that assumptions of the standard neutral model were violated for both species and results from the McDonald-Kreitman test suggested that selection played a role in the evolution of their mitochondrial DNA. Congruent with these results, both species had much smaller effective population sizes estimated from genetic data when compared to census population sizes estimated from abundance data, with a factor of ~10⁸–10⁹ difference. Assuming that selective effects are comparable for the two species, we conclude that the difference in genetic signature can only be explained by contrasting demographic histories. Our data are consistent with the hypothesis that in the NE Atlantic, the neritic S. setosa has been more severely affected by population bottlenecks resulting from Pleistocene range shifts than the more oceanic S. elegans.