Tour of the Guanapo River
 First, David Reznick introduces the fish you might meet as you walk upstream.

Our tour begins in the lower river. The fish communities are most diverse here, but the surrounding landscape has been deforested.

Moving upstream, we reach the forest's edge...

Just upstream, we find ourselves under intact forest canopy.

The river narrows and we encounter a quartz boulder wedged between the gorge walls. The quartz boulder forms the barrier for many fish species.

Moving upstream from the quartz boulder, the rains come and the river swells. 

The water levels return to normal the following day and we continue upstream under clear skies.

We leave the main river behind to explore a tributary, the Caigual River. A series of cataracts excludes all but the killifish, Rivulus hartii.

Finally, we reach one of our experimental sites, where we have introduced guppies. The stream here is flanked by second growth forest and the remnants of coffee and cacao plantations.

David discusses the geology and topography of our study sites.

With night falling quickly, we must leave the river for the hills above.

We pause for a moment to get a broad overview of the watershed we've explored from a ridge above.