Program ID: Innovation Anthology #63
Program Date: 09/04/2007
Program Category: Environment, Natural Sciences
Aquatic Food Webs
Communities of fish are linked together by complex food webs, meaning "who eats who" as they go up the food chain.
But human use of rivers and lakes can dramatically alter these delicate predator-prey relationships.
For aquatic scientist Dr. Joe Rasmussen at The University of Lethbridge, a good illustration of the effect of a weir built on the Oldman River in southern Alberta.
DR. JOE RASMUSSEN: As the river starts to warm up in the summer, some of the species above the weir, like the Rocky Mountain whitefish, will start to move up to try to stay with the colder water. But instead of being replaced by species like the goldeye or the mooneye which are the warmer water species that would move in to replace it as the river warms up, we find that that’s not happening because they’re being blocked by the weir. So these species tend not to want to go up the fish ladder, And so we end up with Mountain whitefish living well above their preferred temperature above the weir because the competitors that would be moving up to make life miserable for them aren’t showing up.
Dr. Joe Rasmussen\'s research points to increase dewatering of rivers from irrigation and cimate change as further stressors on aquatic food webs.
Thanks today to The University of Lethbridge.
FOR INNOVATION ANTHOLOGY, I\'M CHERYL CROUCHER
Images
Dr. Joe Rasmussen
