ecosystems perairan

8/13/2019 Ecosystems Perairan

1/67

Ecosystems Ecology is the study of inter-relationships between organisms and their environment. Its

aim it to explain why organisms live where they do.

Ecosystem A reasonably self-contained area together with all itsliving organisms

Habitat The physical or abiotic part of an ecosystem, i.e. adefined area with specific characteristics where the

organisms live, e.g. oak forest, deep sea, sand dune,rocky shore, moorland, hedgerow, garden pond, etc

Community The living or biotic part of an ecosystem, i.e. all theorganisms of all the different species living in onehabitat.

Biotic Any living or biological factor Abiotic Any non-living or physical factor.

Population The members of the same species living in onehabitat.

Species A group of organisms that can successfully interbreed


2/67

Abiotic factorsphysiological adaptations of organisms only allow

them to live in a certain range of pH, light, tempetc it is part of what defines their niche.

Biotic factors (interactions between organisms)Intraspecific competition occurs betweenindividuals of the same specieseg for a patch of soil to grow on, or a nesting siteor food .


3/67

Food Chains and WebsEach stage in a food chain is called a trophic level, and the

arrows represent the flow of energy and matter throughthe food chain.Food chains always start with photosynthetic producers

(plants, algae, plankton and photosynthetic bacteria)

because, uniquely, producers are able to extract bothenergy and matter from the abiotic environment

All other living organisms get both their energy and matterby eating other organisms


4/67

Food Chains and Webs


5/67

Producer An organism that produces food from carbon dioxide and water

using photosynthesis. Can be plant, algae, plankton or bacteria.

Consumer An animal that eats other organisms

Herbivore A consumer that eats plants (= primary consumer).

Carnivore A consumer that eats other animals (= secondary consumer).

Top carnivore A consumer at the top of a food chain with no predators.

Omnivore A consumer that eats plants or animals.Vegetarian A human that chooses not to eat animals (humans are omnivores)

Autotroph An organism that manufactures its own food (= producer)

Heterotroph An organism that obtains its energy and mass from other

organisms

(=consumers + decomposers)

Plankton Microscopic marine organisms.

Phytoplankton Plant plankton i.e. microscopic marine producers.

Zoo lankton Animal lankton i.e. microsco ic marine consumers.


6/67

Ecological Pyramids

In general as you go up a food chain the size of theindividuals increases and the number of individualsdecreases.

These sorts of observations can be displayed inecological pyramids, which are used to quantify food

chains. There are three kinds:


7/67

1.Pyramids of Numbers

These show the numbers of organisms at each trophic levelin a food chain.

The width of the bars represent the numbers using a linearor logarithmic scale, or the bars may be purely qualitative.The numbers should be normalised for a given area for aterrestrial habitat (usually m), or volume for a marinehabitat (m).

Pyramids of numbers are most often triangular (orpyramid) shaped, but can be almost any shape. In thepyramids below,


8/67

A : shows a typical pyramid of numbers for carnivores;

B :shows the effect of a single large producer such as a tree; and C:shows a typical parasite food chain .


9/67

2.Pyramids of Biomass These convey more information, since they consider the

total mass of living organisms (i.e. the biomass) at eachtrophic level.

The biomass should be dry mass (since water stores noenergy) and is measured in kg m -2.

The biomass may be found by drying and weighing theorganisms at each trophic level, or by counting them andmultiplying by an average individual mass.

Pyramids of biomass are always pyramid shaped, since if atrophic level gains all its mass from the level below, then itcannot have more mass than that level (you cannot weighmore than you eat). The "missing" mass, which is not eatenby consumers, becomes detritus and is decomposed.


10/67

2.Pyramids of Biomass


11/67

3.Pyramids of Energy

Food chains represent flows of matter and energy, so twodifferent pyramids are needed to quantify each flow.

Pyramids of energy show how much energy flows into eachtrophic level in a given time, so the units are usuallysomething like kJ m -2 y-1.

Pyramids of energy are always pyramidal (energy cannot becreated), and always very shallow, since the transfer ofenergy from one trophic level to the next is very inefficientThe missing energy, which is not passed on to the nextlevel, is lost eventually as heat .


12/67

3.Pyramids of Energy


13/67

Energy Flow in Ecosystems Three things can happen to the energy taken in by the

organisms in a trophic level:

It can be passed on to the biomass of the next trophic levelin the food chain when the organism is eaten.

It can become stored in detritus. This energy is passed onto decomposers when the detritus decays.

It can be converted to heat energy by inefficient chemical

reactions, radiated by warm bodies, or in friction due tomovement. The heat energy is lost to the surroundings, andcannot be regained by living organisms.


14/67


15/67

Material Cycles in Ecosystems

Matter cycles between the biotic environment and in theabiotic environment. Simple inorganic molecules (such asCO2, N2 and H 2O) are assimilated (or fixed) from the abioticenvironment by producers and microbes, and built into

complex organic molecules (such as carbohydrates, proteinsand lipids).These organic molecules are passed through food chains andeventually returned to the abiotic environment again assimple inorganic molecules by decomposers. Without eitherproducers or decomposers there would be no nutrient cyclingand no life.


16/67


17/67


18/67

The Carbon Cycle


19/67


20/67

The Nitrogen Cycle


21/67

. Eutrophication

Eutrophication refers to the effects of nutrients on aquatic ecosystems.

These naturally progress from being oligotrophic (clean water with fewnutrients and algae) to eutrophic (murky water with many nutrients andplants) and sometimes to hypertrophic (a swamp with a mass of plantsand detritus).

This is in fact a common example of succession. In the context ofpollution eutrophication has come to mean a sudden and dramaticincrease in nutrients due to human activity, which disturbs andeventually destroys the food chain.

The main causes are fertilisers leaching off farm fields into thesurrounding water course, and sewage (liquid waste from houses andfactories). These both contain dissolved minerals, such as nitrates and

phosphates, which enrich the water


22/67


23/67


24/67


25/67


26/67


27/67


28/67


29/67


30/67


31/67


32/67


33/67


34/67


35/67


36/67


37/67


38/67


39/67


40/67


41/67


42/67


43/67


44/67


45/67


46/67


47/67


48/67


49/67


50/67


51/67


52/67


53/67


54/67


55/67


56/67


57/67


58/67


59/67


60/67


61/67


62/67


63/67


64/67


65/67


66/67


67/67

ecosystems perairan

Documents