Short-Term Colonization Patterns of Lotic Macroinvertebrates

Abstract

To establish colonization of gravel-filled trays by aquatic invertebrates, we used concurrent simultaneous placement/sequential removal and sequential placement/simultaneous removal sampling schedules over 12-d intervals in a river of central Alberta. Colonization trays collected more taxa and greater numbers of animals than did unit area (Hess) samples of the natural substrate. There was no correlation between rank of abundance of the 10 most prevalent taxa found in colonization trays and in Hess samples. The two sampling schedules produced significantly different estimates of colonization rate and numbers for 6 of 10 abundant taxa. From hypothetical colonization curves derived for Baetis tricaudatus Dodds larvae from information on drift tendencies and settling abilities, we suggest that temporal pattern of tray colonization is strongly dependent on fluctuations in mean current velocity and short-term changes in upstream benthic density.