CH10 Ecology

Parts 1 to 3

• The sun is the source of all energy.

• Producers harness the sun's energy & convert it to usable sugars through the process of photosynthesis. They are at the bottom of every food chain.

• Herbivores, or primary consumers, feed directly on and get their energy from plants.

• Carnivores, or secondary consumers,  consume herbivores, gaining their energy by feeding on other animals. 

• Tertiary consumers, apex predators.

• Decomposers are in their own trophic levels.

• Detritivores feed on organic debris of decomposing plants and animals. aka not decomposers

Energy:

• As energy passes up the food chain, a huge amount is lost at every stage.

• Plants: 100% energy

• Primary consumers: 10% energy

• At each level of the food chain, the amount of life supported decreases.

• 10% rule

  • most of the energy absorbed by the organism is used for growth & respiration

  • energy lost as heat energy

  • waste such as faeces are not eaten by consumers

  • parts of the body that contain energy are not eaten by consumers

• Flow of energy in the ecosystem is non-cyclic: energy is lost back to the environment and is not recycled back to the organism that released it

• which is why all living things need to constantly rely on the sun's energy for survival

• a step in the food chain of an ecosystem

• classified according to feeding behaviour

• Number of steps from start of the food chain is a measure of its trophic level

• A pyramid of numbers represents the number of each organisms at each trophic level in relation to each other. It may be narrower at the bottom, because a number of producers can feed a much larger number of consumers etc etc.

• A pyramid of biomass represents the biomass of the organisms at each trophic level in relation to each other. Almost always widest at bottom. Unit is grams/m2.

Carbon cycle, carbon sinks:

• photosynthesis and fossilization absorb carbon dioxide from the environment

• combustion, respiration and decomposition release carbon dioxide from the environment

• a carbon sink is a reservoir that stores large amounts of CO2 for a large amount of time, and it absorbs more than it releases

• oceans and forests, for example, store carbon in the form of carbon compounds for long periods of time

• get most energy in deeper, cooler waters, but reside in shallower waters

• when they die, their bodies are deposited onto the ocean floor in a harmless state

• when the surface water becomes warmer, phytoplankton stop mixing with the cooler water, cutting off access to a vital supply of energy

• nitrogen compound urea can be released into the ocean - it acts as a fertiliser to produce larger concentrations of phytoplankton

• too much phytoplankton lowers O2 concentration in water, causing entire ecosystems to be harmed

Parts 4 and 5

Eutrophication

Causes

1. excess fertiliser on farms not absorbed by plants is washed away into water bodies when it rains

2. improper sewage discharge into water bodies

3. excess nutrients such as nitrates and phosphates

Effects

• rapid growth of algae - algal bloom

• when the layer of algae is thick, it blocks light from entering the water and reaching aquatic plants submerged in water

• aquatic plants cannot photosynthesise and die

• during decomposition, bacteria uses oxygen and releases more nutrients into the water bodies

• bacteria reproduces rapidly

• oxygen is depleted, other organisms will die, leading to an unbalanced ecosystem

Bioaccumulation, bioamplification/biomagnification DDT

This is when living organisms take in non-biodegradable substances, which cannot be broken down and removed from the bodies, and stay/accumulate in the bodies of organisms over time.

It is the gradual build-up/accumulation of a chemical substance in the body of a living organism over a period of time.

These chemicals end up in the environment as a result of human activities which pollute the environment with harmful chemicals.

Concentrations are very small, but as animals feed on their food for a lifetime, the concentration of these chemicals increases up the trophic level. DDT concentration rises to 1000% at every step in the tropic level. Calcium carbonate reacts with DDT, birds will have weird beaks, egg shells thinning. 

Water pollution by sewage: cholera and typhoid. Can cause eutrophication. Biochemical oxygen demand (BOD). 

The increase in concentration of the toxic chemical substances at each higher trophic level is called bioamplification/biomagnification.

Minamata disease is a neurological disease caused by severe mercury poisoning. Signs and symptoms include ataxia, numbness in the hands and feet, general muscle weakness, loss of peripheral vision, and damage to hearing and speech. In extreme cases, insanity, paralysis, coma, and death follow within weeks of the onset of symptoms. A congenital form of the disease affects fetuses in the womb, causing microcephaly, extensive cerebral damage, and symptoms similar to those seen in cerebral palsy.

Minamata disease was first discovered in the city of Minamata, Kumamoto Prefecture, Japan, in 1956, hence its name. It was caused by the release of methylmercury in the industrial wastewater from a chemical factory owned by the Chisso Corporation, which continued from 1932 to 1968. It has also been suggested that some of the mercury sulfate in the wastewater was also metabolized to methylmercury by bacteria in the sediment.[1] This highly toxic chemical bioaccumulated and biomagnified in shellfish and fish in Minamata Bay and the Shiranui Sea, which, when eaten by the local population, resulted in mercury poisoning.