Catchments as conservation units for riverine biodiversity

Abstract

The geological structure and longitudinal nature of river systems provide a possible barrier to the dispersal of lotic organisms. This has the potential to drive evolutionary processes such as genetic differentiation and subsequent allopatric speciation. In the conservation of lotic ecosystems population and evolutionary processes have largely been ignored. The traditional approach to river conservation has been focussed toward maintaining the physical habitat that provides the template for the biota. With a shift toward recognising the catchment as the primary operational unit for the conservation and management of lotic systems an examination of the biological relevance of these catchment units is required. This paper examines the structural influence of catchment units over population structure in lotic organisms and the extent to which catchments reflect populations and represent evolutionarily significant units. These being unique assemblages representing segments of biological diversity that share a common evolutionary lineage and contain the potential for a unique evolutionary future. This is of particular importance given the increased use of inter-basin water transfers to move water between historically isolated catchments and recognition of the catchment as the primary unit for the conservation and management of river ecosystems.


Keywords: integrated catchment management; population genetics; inter-basin water transfer; Evolutionary Significant Unit; stream


(Afr J Aqua Sci: 2000 25: 169-174)