Document: KAR-3-51-5

Habitat selection patterns based on enhanced and limited growth and survival of juvenile fishes in an estuarine nursery.

POLIVKA, K.*

University of Chicago, Chicago, IL ¹

Abstract:
River and stream habitats that merge with coastal marine environments offer a range of habitat choices for organisms. My research with freshwater fish indicates that estuaries can serve as high productivity nursery areas, with prey availability 2-3 times higher than those in upstream areas. Fish enjoyed high growth in the estuary, and two freshwater species (Cottus asper and C. aleuticus) grew at rates 2-3 times greater than those upstream. Different models of habitat selection predict the extent to which an animal incorporates habitats of different profitability and risk into its life history. Experimental tests of whether biotic interactions limited the rewards of selecting estuaries for C. aleuticus demonstrated that intraspecific competition reduced growth rates and survivorship only slightly but the presence of Leptocottus armatus, a marine relative, reduced survivorship of C. aleuticus nearly four-fold. In laboratory experiments, C. aleuticus moved to patches of 2-3 times greater food density about 1.5 times as often as they moved to patches that had the same food density as the patch in which they were initially placed. These results indicate the ability of C. aleuticus to select the more profitable estuary on the basis of higher food availability relative to upstream habitats and that the extent to which this pattern of habitat selection maximizes fitness is limited, in part, by biotic interactions.

Keywords: fishes, estuaries, habitat selection

This abstract is being presented at: 8:15 AM in session:
Oral Session #57: Ocean-Going Fish and Mammals.