Distribution and abundance of periphyton and phytoplankton species in two subarctic Canadian rivers

摘要

Periphytic and planktonic algal populations were sampled over a yearly cycle in the Ogilvie and Swift rivers located in the northern and southern Yukon, respectively. Diatoms and green algae dominated periphytic assemblages during spring, summer, and fall, whereas the bulk of the overwintering cells was diatoms. The 96 species of periphytic diatoms were dominated byAchnanthes minutissimaKuuml;tz., an unidentified species ofAchnanthes, Cocconeis placentulaEhr.,Diatoma hiemalevar.mesodon(Ehr.) Grun.,Diatoma tenuevar.elongatumLyngb.,Anomoeoneis vitrea(Grun.) Ross, andFragilaria crotonensisKitton. Most diatoms encountered are also generally abundant in more temperate locations. Periphytic green algae were dominated byMougeotiasp.,Oedogoniumsp.,Ulothrixsp., andStigeocloniumsp. In high flow regions of the Ogilvie River the red algaLemanea fucinaBory was extremely abundant. Phytoplankton was sparse and generally represented by the same species as found in periphytic habitats. Results indicate that the phytoplankton cells were probably derived from sloughed periphytic cells.Achnanthes minutissima, Diatoma tenuevar.elongatum, Fragilaria construensvar.binodis(Ehr.) Grun.,Fragilaria vaucheriae(Kuuml;tz.) Peters, andSynedra ulna(Nitz.) Ehr. were the most abundant species in the plankton.