RESEARCH NEEDS IN REGULATED RIVER ECOLOGY

The general effects of single dams on the downstream ecology of temper ature lotic systems are predictable, although some underlying causal m echanisms remain elusive. Few quantitative data of an ecological natur e are available for regulated tropical rivers, however, and it would n ot be prudent to uncritically apply principles and patterns developed from temperate rivers to fluvial systems of the tropics. New technique s of gradient analysis appear especially suited to examining spatial r ecovery gradients below dams at any latitude and portend to provide co nsiderable insight into the mechanisms responsible for such patterns. Few studies have specifically examined the influence of regulation on interactions between the river channel and the floodplain and virtuall y nothing is known of channel-aquifer interactions. A fuller understan ding of these interactive pathways is necessary to effectively regulat e discharge as part of river restoration strategies. Viewing regulated streams as experimental systems for addressing ecological questions h as proved to be useful and should be further exploited. It is conclude d that research and expertise in regulated stream ecology will increas ingly be needed as the rational basis for flow criteria to conserve, p rotect and enhance the societal values of regulated rivers world-wide.