Allochthonous inputs and land-water interactions in seasonal streams: tropical Asia and temperate Europe

Abstract

Land-water interactions have a major influence upon the "organic environment' and ecology of streams in both regions, but flow patterns determine the seasonality of tropical Asian streams while the timing of biological events in central European streams reflects temperature changes more closely. Organic loads transport by streams in both regions are dominated by dissolved organic matter, with coarse particulate organic matter (CPOM) comprising a relatively small proportion. CPOM loads are strongly influenced by spates; in Europe, CPOM inputs are highest during the autumn period of leaf fall. This CPOM peak is lacking in tropical Asia where litter inputs to streams are less seasonal. Because low-order streams in both regions receive significant inputs of allochthonous litter, and autochthonous preduction is often light limited, community metabolism is predominately heterotrophic, but shredder invertebrates which feed on CPOM are poorly represented in low-order, tropical Asian streams. Tropical Asian fish commumites, more diverse than in temperate Europe, include a large propriton of species which make use of allochthonous food sources. Direct consumption of food from terrestrial sources comprises a minor proportion of the diet of European fishes. Seasonal inundation of floodplains in tropical Asia brings about large-scale land-water interactions. -from Authors