Hydrology and Biodiversity

World Wildlife Fund presents:

Extreme Hydrological Conditions and Complex Channel Topology Drives Population Divergence and Speciation in the Lower Congo River

Date: November 12^th, 2009

Time: 4:30-5:30pm (lecture); 5:30-6:30pm (reception)

Admission: FREE!!

Registration: http://www.worldwildlife.org/science/fellowships/fuller/item1816.html

Location: World Wildlife Fund Headquarters

1250 24^th Street, NW

Washington, DC 20037

Unlike most of the rest of the Congo River, the lower Congo downstream of Pool Malebo to the port town of Matadi is highly channel-constrained with a peculiarly complex hydrology that appears to have isolated it from the remainder of the basin. Channel topology itself is highly heterogeneous, punctuated by underwater canyons of extreme depth. Water velocities are also extreme, even in areas without surface rapids, and recent measurements taken with pirogue-deployed Acoustic Doppler Current Profilers (ADCP) have revealed complex flow patterns within the water column including shifting counter directional flows and descending and ascending “walls” of fast moving water. Analysis of remotely sensed data provides an additional view of the numerous macrohabitats and channel features that characterize this hydrologically complex stretch of river. Using the latest remote sensing technologies, and with much on-the-ground sampling and systematic analysis, we are beginning to get a much clearer picture of just how the geomorphological template of the river has played a major role in isolating populations and generating high levels of divergence among diverse clades of fishes.

To date we have documented well over 300 fish species and of these upward of 80 appear to be endemic to the lower Congo region. With such unexpectedly high levels of species richness and endemism associated with a unique hydrological regime, this short stretch represents a model system for exploring the interplay of complex hydraulic conditions, channel features of extreme depth, and diversity generation cast within a broad systematic framework.