Fossil chrysophycean cyst flora in a small meromictic lake in southern Ontario, and its paleoecological interpretation

摘要

Fossil chrysophycean cysts were identified and counted from the laminated sediment core from Crawford Lake. Thirty-two morphotypes have been described, most of them for the first time. The detailed description of the cysts is presented, including scanning electron photomicrographs. The abundance of certain morphotypes appears to be related to lake paleoproductivity. On this basis, fossil cyst flora have been divided into three characteristic groups: eutrophicndash;, mesotrophicndash;, and oligotrophicndash;meromictic forms. Our data demonstrate that chrysophycean cyst distribution can reflect lake conditions and, therefore, are potentially useful in paleoecological studies.