Conservation of Organisms in Dendritic Systems

Conservation of aquatic organisms living in dendritic stream networks is challenging due to constraints on the movement of individuals and their genes through geometrically complex systems that are frequently fragmented by impoundments or degraded habitat.  Much of conservation theory was developed around species that are distributed in habitats arranged in contiguous, two-dimensional planar landscapes.  For organisms in these landscapes, dispersal and/or connectivity of populations may occur via multiple pathways including flight and long distance migrations.  Conservation of species living in lotic systems and with life cycles confined to aquatic habitats, such as freshwater fishes and unionid mussels, present very different situations.  Due to the hierarchical, dendritic nature of rivers and streams where these species reside, there are constraints to dispersal, population connectivity, and gene exchange.  Thus, studies of metapopulation dynamics or those that investigate relationships between habitat patchiness, fragmentation, connectivity, and dispersal mechanisms for organisms living in dendritic systems must consider the alternative geometries that these systems present in comparison to those for organisms in more typical planar landscapes.  In North America, a substantial proportion of the imperiled fauna is constrained to stream systems.  In this symposium, we gather ecosystem modelers, population geneticists, and biologists to describe current ideas in dendritic conservation biology and continue to develop appropriate theory to assess the status of these animals.