LAKE BIOME Presented By: Jason Palonis

What is a Lake? Lakes are enclosed basins which can trap standing water Another definition is a body of fresh or salt water of considerable size that is surrounded by land. On Earth a body of water is considered a lake when it is inland, not part of the ocean, and is larger and deeper than a pond.

Where are Lakes Found? Lakes are located through out the world The majority of lakes on Earth are fresh water, and most lie in the Northern Hemisphere at higher latitudes. More than 60 percent of the world's lakes are in Canada.

Most Notable Lakes The largest lake by surface area: 117,350 km² is Lake Michigan-Huron. The deepest lake is Lake Baikal in Siberia, with a bottom at 1,637 m (approx 1 mile). The longest lake is Lake Tanganyika, with a length of about 660 km (410 miles). The world's oldest lake is Lake Baikal (25 million years old) , followed by Lake Tanganyika (Tanzania). The world's highest lake is the crater lake of Ojos del Salado, at 6,390 meters (20,965 ft). The world's lowest lake is the Dead Sea, bordering Israel and Jordan at 418 m (1,371 ft) below sea level. It is also one of the lakes with highest salt concentration.

Structure & Stratification Epilimnion- Water is warmer and typically has a higher pH and dissolved oxygen concentration than the hypolimnion. Freezes in winter. Metalimnion- (thermo cline) Temperature & oxygen changes rapidly with depth Hypolimnion. Typically the coldest layer of a lake in summer, and the warmest layer during winter. 4 °C throughout the year

Zonation The Littoral zone is the near shore area where sunlight penetrates all the way to the sediment and allows aquatic plants (macrophytes) to grow. In most lakes, the sunlit zone is called the photic zone and occurs within the epilimnion. The Limnetic zone is the open water area where light does not generally penetrate all the way to the bottom. The bottom sediment, known as the Benthic zone, has a surface layer abundant with organisms.

Types of Lake Organisms Note which zone each is found in Macrophytes: large leafy plants Plankton: Suspended small organisms controlled by currents Benthos: Bottom dwellers Nekton: Larger, mobile organisms

Typical Macrophytes Littoral Zone submersed Floating leaved Emergent

Typical Zooplankton Limnetic Zone ------------------- 0.5 mm Rotifer:grazer on phytoplankton Copepod: grazer on phytoplankton Water flea: grazer on phytoplankton

Typical Benthos Benthic Zone Midge larvae bivalves Dragonfly nymph

Typical Nekton Go where they please.. Bass: a piscivore (fish eater) Bluegill: a planktivore and benthivore Catfish: a detritivore (scavenger)

Human Influences Usually a negative influence on lake ecology. Introduction of nutrients and toxic chemicals. Industry Farming Introduction of non native flora and fauna to lake ecosystems. Central American Water Hyacinth Eurasian Zebra Mussel

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