Alternation of dry and rainy season leads to heavy annual changes of many parameters in tropical freshwaters (water level, available water surface, temperature, conductivity, availability of food resources, existents of proper breeding areas etc.). The fish fauna is well adapted in this regions and uses the newly formed aquatic habitat for grazing, hunting, breeding, nursing and/or hiding - on the other hand the top predators will profit of the decreasing water level in the dry season by a concentration of prey fish. Such systems are very productive and contribute much to the nutritition of the population.

The subproject W07 is dealing with the composition and changes of fish communities in ephemeral savannah waters. Of special interest are: migrations to ephemeral waters, cost and profit of staying in such habitats, as well as human impact to these ecosystems. Special questions to the migration subtask is what species migrate to which point of time and what the triggering parameters are. The cost/profit subtask accents the food webs of ephemeral waters and their use as hiding, breeding and growing up areas. Furthermore the human impact to this areas will be investigated.