BIOL Fishes Exam 3●Great Lakes “HOMES”○Huron, Ontario, Michigan, Erie, Superior●Bathymetry - refers to the depth of the water○Laker Erie a very shallow lake●Speciation - not much in the past 10,000 years○African Cichlids- most speciose group known on earth. Species Flock○Lake Victoria- massive amount of species. Pollution, overfishing decreased speciation. ■Nile Perch was introduced and the population of Cichlids fell off dramatically. ●Atlantic Salmon - first fish lost in the Great Lakes due to human activity, overfishingNatural Migration Pattern●Barriers - ○In the US mountain ranges run from North to South, as opposed to Europe where they run East to West. ○In the us this did not cut off species migration due to glaciation as it did on the European continent. ●Migration - anywhere from geographic time and space to fish lifetime or season. ○Pleistocene Period - advances of ice sheets, glaciersand movement caused a great deal of changes and migration. ○Glaciers - glaciated/unglaciated, complex and dynamic magins at the edges.■Ohio - was glaciated⅔○Refugia - a location which supports an isolated or relict population of a once more widespread species. An area in which a population of organisms can survive through a period of unfavorable conditions, especially glaciation.■Glacial melting causes water masses to become connected allowing migration. ■Connections outside of the Great Lakes, disappeared over time○Mississippi Refugium - 80-90% of fish from Mississippi River drainage. ■Warm water taxa■Connections from glacial refugium caused diversity that shouldn't be there. ■Gars, Sturgeons, ancient lineages that were present there■Centrarchids, Perchids, Cyprinids○Atlantic Refugium- migration to Lake Ontario■Sea Lamprey to Lake Ontario■Alewife, Herring■Atlantic Salmon- from Atlantic seaboard migration●1st species lost from Great Lakes due to human activity●Landlocked in Ontario because of blocked spawning migrations via mill dams○Arctic Refugium - ■Cold water taxa■Lake Trout Human Mediated Migration Pattern●3 Methods- ○Ballast Water○Navigation Canals○Fish Stocking●Ballast Water Invasions- ○Human induced invasions○Most invasive species are bad for the ecosystem○Ships can carry invasive species in their ballast water○Ballast Water- used to change buoyancy of ship, picked up invasive species of fish■Eurasian Rulf - invaded Lake Superior via ballast water1
