Upwelling occurs along the western edge of the lake and prevents stratification in this part of the lake. Primary productivity is moderate, about half that of Lake Erie. Water clarity is usually in the 5-10 m range, while the lake's retention time is about six years. These bluffs are generally 3-10 m in height, but are up to 100 m high in the area of the Scarborough Bluffs. Wind-blown shore sediment has created several barrier beaches , sand dunes and sand spits .
Small wetlands occur locally.
Some 85 fish species have been recorded in Lake Ontario. Though still present, lake trout and lake whitefish are no longer very common. At present the most abundant native species include yellow and brown bullhead, American eel, northern pike , yellow perch, walleye, sauger, smallmouth and largemouth bass. Various species of amphibians and reptiles are common in wetland areas. Numerous birds winter where open water permits, mainly gulls and various ducks.