FRESHWATER

ECOLOGY

Freshwater ecology Types and limiting

factors Classification Lentic communities Lotic and springs

- The study of freshwater ecosystem

- Freshwater ecosystems are a subset of Earth’s aquatic ecosystems. They include lakes, ponds, streams, springs, and wetlands.

Freshwater habitats can be classified by

different factors, including temperature, light

penetration, transparency, etc. Freshwater

ecosystems can be divided into lentic

ecosystems and lotic ecosystems.

Classified on the basis of depth and flow of

water

A. Light Penetration 1. Aphotic zone 2. Photic zone B. Distance from the shore and depth of

the body of water 1. Limnetic zone 2. Profundal zone 3. Benthic zone

C. Amount of Organic Matter 1. Oligotrophic – deep cold small surface

area relative to depth nutrient-poor phytoplankton are sparse, not very productive don’t contain much life waters often very clear sediments low in decomposable organic matter

2. Mesotrophic - moderate nutrient content moderate amount of phytoplankton reasonably productive

EUTROPHIC – shallow warm large surface area relative to depth nutrient-rich phytoplankton more plentiful and productive waters often murky high organic matter content in benthos leads to high decomposition rates and potentially low oxygen

Temperature Current - Largely determine the

distribution if vital gases, salts and small organisms

Transparency - Turbidity Can be measured using an instrument called a Secchi disk

Concentration of respiratory gases - Oxygen and carbon dioxide concentration are often limiting in the fresh water environment

Concentration of biogenic salts Nitrates and phosphates seem to be limiting in a freshwater ecosystem ; calcium and other salts

Lentic ecosystem (Nonflowing water) Calm freshwater

habitat or standing water; it refers to standing or relatively

still water; from the Latin “lentus”, which means sluggish.

Lotic ecosystem (Flowing water) Washed or the running

water; refers to flowing water; from the Latin ‘lotus’, to wash

LakesPonds

Inland wetlands

Lakes - is a body of relatively still fresh water of considerable size, localized in a basin, that is surrounded by land; vary in depth of 1m to more than 200 m

Formed by glacial erosion and deposition, shifts in Earth’s crust, uplifting ,ountains or displacing rock strata, craters of some extinct volcanoes, landslides

By nongeologic activity beaver dams streams to make shallow but often extensive ponds; humans create lakes by rivers and streams for power, irrigation or water shortage and smaller ponds for recreating fishing and wildlife

Light penetration-influenced by silt and other materials and natural attenuation

Temperature-vary seasonally and with depth Oxygen-can be limiting especially in

summer, because only a small proportion of of the water is in direct contact with air and respiration by decomposers.

These three strongly influence the distribution and adaptations of life in lakes and ponds

Ponds- body of standing water, either natural or man-made, that is usually smaller than a lake.

Swamp - is a wetland that is forested

Bog - is a wetland that accumulates peat, a deposit of dead plant material—often mosses, and in a majority of cases, Sphagnum moss.

The waters are usually flowing and exhibit a longitudinal gradation in temperatures, concentration of dissolved material, turbidity, and atmospheric gases, from the source to the mouth

Include rivers and streams (outlets of ponds and lakes); some emerge from glaciers and flows in a direction dictated by the lay of the land

Spring – kind of freshwater habitat where water flows out of the ground

River - is a body of water with current moving in one general direction.

RIVER CONTINUUM

Stream- a thin body of water which has a continuous flow of water, often referred to as a creek or a brook. TWO SUBHABITATS 1. Turbulent riffle – shallow water where

velocity of current is great enough; site of primary production in the stream; periphyton or aufwuchs, diatoms, cyanobacteria, and water moss dominate

2. Pool – deeper water where velocity of current is reduced; site of decomposition; major site of CO2 production during summer or fall necessary for the maintenance of a constant supply of bicarbonate in solution.

Fast Stream Streamlined form Caddisflies, water

moss(Fontinalis), hevy-branched filamentous algae

Slow Stream Larval forms of insects

have flattened bodies and broad flat limbs that enable them to cling to stones

Smallmouth bass with compressed bodies

Snails, burrowing mayflies, catfish, water striders

Shredders – insect larvae that feed on coarse particulate organic matter (CPOM); includes caddisflies (Tricoptera) and stoneflies (Plecoptera)

Collectors – pick up the fine particulate organic matter (FPOM) from what shredders and microbes broken up,

Include filtering collectors and gathering collectors

Grazers – feed on the algal coting of stones and rubbles ; includes the beetle larvae, water penny, and a number of mobile caddisfly larvae

Gougers – burrow into water-logged limbs and trunks of fallen tree

Horizontal zone – obvious to the eye Littoral zone – shallow water zone; surrounds

most lakes and ponds, in which light reaches the bottom, stimulating the growth of rooted plants

Limnetic zone – open water; extends to the depth of light penetration; inhabiting this zone are microscopic phytoplanktons (autotrophs) and zooplanktons (heterotrophs) and nektons (free-swimming organisms)

Profundal zone – depth of light is compensated ; the point at which respiration balances photosynthesis; depends on a rain of organic material from the limnetic zone for energy

Vertical zone – influenced by depth of light penetration Benthic zone/bottom region – common to both

littoral and profundal zones Primary place for decomposition

Limnetic Zone- phytoplanktons like

desmids, diatoms, filamentous algae

Zooplanktons like tiny crustaceans

Nektons like fish like summer fishes large mouth bass, pike, muskellurge; and winter fish like lake trout

Depends on the temperature and availability of oxygen is limited because of depletion by decomposers

Only during spring and fall turnovers that life is abundant in this zones

Mostly decomposed substances are found here

Organisms can tolerate cool temperatures and low oxygen levels

Anaerobic bacteria Periphyton/Aufwuchs which colonize the

leaves of submerged aquatic plants; on stones, woods froming a crustlike growth of cyanobacteria

Algae and diatoms are fast-growing and lightly attached

VERTEBRATES INVERTEBRATES

Nature with our intelligent help,can cope with man’s physiological

needs and wastes, but she has no homeostatic mechanisms to cope with bulldozers, concrete, and the kind of agroindustrial air, water,

and soil pollution that will be hard to contain as long as the human population itself remains out of

control.(Odum, 1971 p. 36 1st Ed.)

Thank You!!!