You are here:
Quantifying Ichthyofaunal Zonation and Species Richness along a 2800 km Reach of the Rio Chama and Rio Grande (U.S.A.)
Citation:
MCGARVEY, D. J. Quantifying Ichthyofaunal Zonation and Species Richness along a 2800 km Reach of the Rio Chama and Rio Grande (U.S.A.). Ecology of Freshwater Fish. Blackwell Publishing, Malden, MA, 20(2):231-242, (2011).
Impact/Purpose:
see description
Description:
Ichthyofaunal zonation occurs when lotic fishes are partitioned into distinct assemblages, usually in response to longitudinally distributed habitats. Several studies have documented zonation within the Rio Grande, but this is the first to quantitatively test the zonation hypothesis along a continuous 2800-km river profile, extending from the Rio Chama headwaters to the Gulf of Mexico. Using a large, multi-source dataset, I detected three ichthyofaunal zones: a high gradient (∼1.5%) ‘upper’ zone, a moderate gradient (∼0.2%) ‘middle’ zone and a low gradient (<0.1%) ‘lower’ zone. Species richness was lowest in the upper zone and highest in the lower zone, and all zones contained large numbers of nonnative species. However, species richness did not accumulate in a consistent, downstream manner. Instead, it tracked local-scale changes in mean annual discharge. This demonstrates the strong effect of river regulation and irrigation withdraws on fish diversity in the Rio Grande.
