Anadromous Fish as Keystone Species in Vertebrate Communities

Many wildlife species feed on anadromous fishes of several life-history stages. There is evidence for some wildlife species that the availability of anadromous fish is critically important for survival or reproduction. In some regions anadromous fishes in fresh water appear to be keystone food resources for vertebrate prediators and scavengers, forging an ecologically significant link between aquatic and terrestrial ecosystems. The spatial distribution of anadromous fish in fresh water, including the occurrence of runs in very small streams, has important consequences for wildlife biology (social interactions, distribution, activity patterns, possibly survivorship) and conservation of biodiversity.     

Methodology and measurement of adenylate energy charge ratios in environmental samples

A method for measuring ATP, ADP and AMP levels in environmental samples was devised, and applied to seawater and bacterial cell extracts. This procedure is specifically designed for measuring the extremely low concentrations of total adenine nucleotides ([A_T]=[ATP]+[ADP]+[AMP]) that are apt to occur in most natural ecosystems (i.e., 10 ng A_T ml^-1 of sample extract). Although the current assay methodology can be used with purified firefly luciferase reagents, it has been suitably modified to accept crude luciferase preparations as well. ATP, ADP and AMP levels have been measured, and the corresponding energy charge (EC) ratios determined for seawater samples collected off the Southern California coast. The EC ratios ranged from 0.50 to 0.89, with peak values corresponding to the subsurface maxima in ATP and chlorophyll a concentrations, and the minimum values corresponding to the deepest water sampled (1500 m). The measurement of adenylate energy charge ratios in environmental samples can be a useful indicator of mean community metabolic activity and potential for cell growth.     

Entscheidungsanalytische Simulation formalisierter Umweltmediationsabläufe

Goal and Scope

During the last 10 years environmental mediation has become a popular instrument in Germany to solve environmental conflicts. Environmental mediation is a voluntary negotiation process that is supported by a neutral third person and in which those involved in a conflict jointly search for solutions that are acceptable to all. The simulation of mediation processes can be used to determine the main factors that influence the progression of the conflict and to assess the potential and limits of environmental mediation.

Methods

In this article a decision-theoretical, dynamic model is discussed which is used to simulate a formalized mediation process. It covers, over and above the standard assumptions, the role of emotions. They are the missing link between a state of conflict, and rational, utility maximizing behavior as it is postulated in standard economics.

Results and Conclusions

With this model, the effects of several different parameter sets have been tested. Here, the willingness of the parties to negotiate and to agree to a compromise solution is discussed as well as the role of the integrated emotions which are envy and anger.

Outlook

Due to the large amount of data produced by the model, the evaluation has so far mainly focused on the results of the mediation process. For future research, a more detailed analysis of the simulation runs as well as experiments can help to make the model more realistic.