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Vertical distribution of the zoobenthos in southeastern Lake Michigan with evidence of seasonal variation*

1981; Wiley; Volume: 11; Issue: 1 Linguagem: Inglês

10.1111/j.1365-2427.1981.tb01244.x

1365-2427

Thomas F. Nalepa, Andrew Robertson,

Freshwater macroinvertebrate diversity and ecology

SUMMARY. The vertical distribution of the zoobenthos in southeastern Lake Michigan was investigated monthly from May to November 1976. The organisms could be divided into two categories: one in which the majority of the population occurred in the upper 1 cm of substrate ( Pontoporeia , naidids, chironomids, cyclopoids, harpacticoids, cladocerans, turbellarians, ostracods, rotifers, sphaeriids and gastropods) and one in which the majority of the population occurred deeper (immature tubificids without hair setae, Stylodrilus heringianus , enchytraeids, nematodes, and tardigrades). The vertical distribution of these infaunal forms showed a marked seasonal variation. They were found in the superficial sediments in the spring, but deeper in the sediments in the autumn. This trend coincided with the seasonal occurrence of a detrital layer that overlay the sandy substrate in the spring but was absent in the autumn.