|
"Your gateway to
understanding |
Lake Ecology
The
Algae (phytoplankton) make up the food web’s heart. These tiny plants use sunlight, phosphorus, and other nutrients for growth and reproduction. Algae are consumed by zooplankton (small crustaceans) in the lake’s waters, and also by benthic (bottom-dwelling) organisms such as amphipods and zebra mussels. Zooplankton are the primary food source for small fish such as young yellow perch, gizzard shad, and white perch. When these young fish are abundant, they have the potential to consume most of the lake’s large-bodied filter-feeding zooplankton like Daphnia. This allows algae blooms to occur, thus decreasing water clarity.
Small yellow perch and shad are important prey for yearling and older walleyes. In years when these forage fish are scarce, adult walleyes turn to eating their own young. When other food fish are plentiful, young walleyes are buffered from older walleyes’ predation. This results in high survival of young walleyes - what biologists call a strong “year class.”
The Oneida Lake food web has been shaped by thousands of years of natural succession and over two hundred years of human disturbance. Activities such as construction of the Erie-Barge Canal, development of the lake’s shoreline, and population growth within the watershed have altered the food web by introducing non-native species, destroying habitat, and changing the water quality.
Several examples support this point. Spawning areas for northern pike and pickerel have been drastically reduced through the separation of the lake from nearby wetlands. Extensive shoreline filling for cottage construction, beginning in the 1920s, eliminated acres of aquatic vegetation vital to these game fish. Non-native species such as purple loosestrife and zebra mussels arrived through the canal system. Decreased phosphorus inputs, combined with the filtering of algae by zebra mussels, increased water clarity. These changes have altered the dynamics of Oneida Lake’s fishery.
Sampling and Limnology Video (wmv - 23.6mb)
Clearwaters: Oneida Lake Watershed: A Valuable Diverse Ecosystem
Oneida Lake Education Initiative Information Homepage