LAKES and PONDS ECOSYSTEM

Ponds and Lakes

Range in size from just a few square

meters to thousands of square

kilometers.

Ponds may be seasonal, lasting just a

couple of months (such as sessile

pools).

Lakes may exist for hundreds of

years or more.

Ponds and Lakes

May have limited species

diversity

Most ponds and lakes have

outlet streams and both are

generally temporary features

on the landscape

Formation of Lakes and Ponds:

Some of the oldest lakes and ponds (more than three hundred thousand years old) were formed by tectonic activity related to movement of Earth's crust.

EXAMPLE: Lake Baikal in Siberia formed from the movement of tectonic plates and is the largest freshwater lake by volume in the world.

Formation of Lakes and Ponds:

Lakes and ponds are formed through a variety of events, including glacial, tectonic, and volcanic activity.

Most lakes and ponds form as a result of glacial processes.

Formation of Lakes and Ponds:

Volcanic activity can also lead to lake and pond formation.

EXAMPLE: the collapse of a volcanic cone of Mount Mazama in Oregon led to the formation of Crater Lake, the seventh deepest lake in the world.

Lake Baikal

Crater Lake , Oregon

Ponds and Lakes

Temperature varies seasonally.

During summer the temp. is from 4°C near the bottom to 22°C at the top.

During winter the temp. is from 4° C while the top is 0° C (ice).

during the spring and fall seasons is a mixing of the top and bottom layers resulting in a uniform water temperature of around 4° C.

Ponds and Lakes

divided into four different “zones” determined by depth and distance from the shoreline

• littoral zone

• limnetic zone

•profundal zone

•Photic zone

•Benthic zone

Littoral

Zone Limnetic

Zone

Profundal

(aphotic)

zone

Photic

Zone

Benthic

Zone

Littoral Zone

warmest since it is shallow and can absorb more of the Sun’s heat

sustains a fairly diverse community

several species of algae (like diatoms)

rooted and floating aquatic plants

grazing snails

Clams

Insects

Crustaceans

Fishes

amphibians

Littoral Zone

the egg and larvae stages of some insects are found in this zone

vegetation and animals living in the littoral zone are food for other creatures such as turtles, snakes, and ducks

Limnetic Zone

near-surface open water surrounded by the littoral zone

well-lighted (like the littoral zone) and is dominated by plankton, both phytoplankton and zooplankton

plankton are small organisms that play a crucial role in the food chain – most life would not be possible without them

variety of freshwater fish also occupy this zone

Profundal Zone

much colder and denser

little light penetrates all the way through the limnetic zone into the profundal zone

Plankton have short life spans—when they die, they fall into the deep-water part of the lake/pond

Animals found are decomposers

Photic zone

Primary production in the photic zone is influenced by three major factors

Nutrients – oxygen, phosphorus, carbon

Light- For photosynthesis

Grazing pressure-the rate at which the plants are eaten by herbivores.

Photic zone

Nutrients, especially phosphate and nitrate, are often scarce in the photic zone because they are used up quickly by plants during photosynthesis.

External inputs of nutrients are received through:

Rainfall

Riverflow

Weathering of rocks and soil

Human activities- sewage dumping.

Benthic Zone

The area of the bottom.

Many groups and varieties of animals live here, a few are worms, crustaceans, and protozoa.

The life in this zone is mostly made up of bottom dwellers which get most of their food from dead and decaying organisms.

most of the organisms in the benthic zone are scavengers because they depend on dead flesh as their main food source.

LAKES ECOSYSTEM

Classification of Lake

Oligotrophic lakes- deep, nutrient-poor lakes in which the phytoplankton is not very productive.

The water is usually clear

Eutrophic lakes- shallow, nutrient-rich lakes with very productive phytoplankton.

The waters are usually murky due to large phytoplankton populations

the large amounts of matter being decomposed may result in oxygen depletion.

Lakes Ecosystem

A lake is bigger than a pond, and is too deep to

support rooted plants except near the shore.

Some lakes are big enough for waves to be

produced.

Lakes may exist for hundreds of years or more.

Lakes are often classified as oligotrophic or

eutrophic, depending on the amount of organic

matter produced.

Oligotrophic lake Eutrophic Lake

Examples of lakes

Taal volcano lakeMitchigan lake

Grasmere lake

Silver lake Lake lamonia

Layers of lake separated by density gradient.

1. Epilimnion

the top-most layer in a thermally stratified lake.It is warmer and typically has a higher pH and dissolved oxygen concentration than the hypolimnion. It typically mixed as a result of surface wind-mixing. Free to exchange dissolved gases (ieO2 and CO2) with the atmosphere. It contains the most phytoplankton.

2. Thermocline(sometimes metalimnion) is a thin but distinct layer in a large body of fluid (e.g. water, such as an ocean or lake, or air, such as an atmosphere).

Temperature changes more rapidly with depth than it does in the layers above or below.

Thermoclines may be a semi-permanent feature of the body of water in which they occur, or they may form temporarily in response to phenomena such as the radiative heating/cooling of surface water during the day/night.

Factors that affect the depth and thickness of a thermocline include seasonal weather variations, latitude, and local environmental conditions, such as tides and currents.

3. Hypolimnion

The hypolimnion is the dense, bottom layer of water in a thermally-stratified lake. It is the layer that lies below the thermocline.

Typically the hypolimnion is the coldest layer of a lake in summer, and the warmest layer during winter. Being at depth, it is isolated from surface wind-mixing during summer, and usually receives insufficient irradiance (light) for photosynthesis to occur.

In deep, temperate lakes, the bottom-most waters of the hypolimnion are typically close to 4°C throughout the year. The hypolimnion may be much warmer in lakes at warmer latitudes.

BLUE LAKE

Dal LakeMono Lake

Okanagan Lake Lake Titicaca

Lac Pavin in France is a meromictic crater lake

Lake Hoare

Bitterling Bullfrog Common Carp

Great Crested Grebe

Great White Pelican

Green and Gold

Bell Frog

Lake Trout

Largemouth Bass

Animals in Lakes and Ponds

PlatypusZambesi Softshell

Functions:

Lakes and ponds typically contain a diversity of organisms that perform different ecological functions.

Lakes and ponds are an important source of fresh water for human consumption

Water has a high capacity for heat.

Plankton which account for most of the photosynthesis on Earth found in lakes, ponds and oceans.

We fish from the ponds and we often eat the fish we catch. Most of the time our water comes from the lakes and ponds, but purified.

Environmental Problems:

Freshwater biomes have suffered mainly from pollution.

Runoff containing fertilizer and other wastes, and industrial dumping's enter into rivers, ponds, and lakes tend to promote abnormally rapid algae growth- ARTIFICIAL EUTROPHICATION

When algae die, dead organic matter ends up in the water.

THE END……