SURVEY OF COPEPODA (CRUSTACEA: HEXANAUPLIA) FROM THE PLANKTON OF LAKE ERIE AND MEIOBENTHOS OF LAKE ONTARIO AND LAKE SUPERIOR

Abstract

Copepoda are a diverse subclass of crustaceans which are ubiquitous in aquatic systems, inhabiting the largest oceans, the smallest ponds, and several specialized environments. These crustaceans display an impressive variety of life history strategies and may be planktonic, meiobenthic, or parasitic. In the Laurentian Great Lakes and elsewhere, copepods occupy an important position in the food web and make significant contributions to both planktonic and meiobenthic biomass. Understanding their species composition and taxonomy is therefore necessary to assess long term community trends which may be responses to abiotic or biotic variables.Historically the Great Lakes have been an epicenter for aquatic nonindigenous species introductions in North America. As a result, the copepod community of the Great Lakes is comprised of both indigenous and nonindigenous species. However, no new nonindigenous crustacean species had been documented in these lakes since 2006 prior to my work on these groups. The rate of species introductions could have slowed, but only careful investigations of each group can determine if new species are added or not. This thesis presents the results of such investigations for Copepoda. A detailed examination of the planktonic Cyclopoida of western Lake Erie revealed the presence of two nonindigenous species previously unknown from the Great Lakes basin. Thermocyclops crassus (Fischer, 1853) became the first newly detected nonindigenous species in 2014, followed by Mesocyclops pehpeiensis (Hu, 1943) in 2016. The detection of these nonindigenous taxa from the plankton of Lake Erie motivated me to examine the seldom studied meiobenthic copepod community of Lake Ontario. As a result in 2018 I carried out a survey of benthic Harpacticoida across Lake Ontario. The survey provided novel data on the presence, abundance, and distribution of native and nonnative harpacticoids in the lake. The study found three nonindigenous harpacticoids in the lake, one of which Schizopera borutzkyi (Monchenko, 1967) was the most abundant taxa. My studies of harpacticoid copepods continued in 2018 when I reported a new distributional record of the rare indigenous species Gulcamptus huronensis (Reid, 1996) from Lake Superior. In an effort to document the copepod community of the Great Lakes the following works are provided concerning: the detections of nonindigenous cyclopoids from the plankton of Lake Erie (2014 and 2016), a survey of meiobenthic harpacticoids from Lake Ontario (2018), and a report of the rare harpacticoid species G. huronensis from the meiobenthos of Lake Superior (2018).