General Limnology of Lakes Near Cook Inlet, Southcentral Alaska

Abstract

ABSTRACT Data from lakes on the Kenai Peninsula (n = 111) and in the Matanuska-Susitna Valley (n = 108) show that lakes near the Cook Inlet, Alaska are moderately stained, with low turbidity and are predominately oligotrophic with a potential for phosphorus limitation. In both locations measures of salinity (as measured by conductivity) and pH were heterogenous and tied to hydrologic flowpaths. Overall, seepage lakes had lower pH, salinity, alkalinity, Ca, Mg and Si than drainage lakes. In our data set, both seepage and drainage lakes on the Kenai had lower alkalinity, Ca, and Si than corresponding lake types in Mat-Su. Most zooplankton biomass (ZB) measurements in the Cook Inlet lakes were <100 μg L−1 and over one-third were <10 μg L−1. Values of ZB were low relative to empirical models and did not increase with lake trophic state. Each of these lakes supports a fish community and the well-known effects of food web structure via grazing by planktivorous fish likely account for the observed ZB values. Environmental measurements and their patterns match earlier studies and collectively describe extant features of lake resources in this region of the southern boreal forest in southcentral Alaska.