2.2 Energy and Biomass in ecosys (1, 2, 3, 4)

Primary energy source for terrestrial ecosystems

The sun

Energy source for deep-sea ecosystems

Geothermal energy in the benthos

Insolation

Solar radiation that reaches the Earth

Albedo

A measure of the reflectivity of a surface

Light absorption by plants

Less than 2% of all light reaching Earth's surface

Photosynthesis equation

CO2 + H2O → glucose + O2

Chemotrophs

Organisms that derive energy from chemicals released from the earth's mantle

Cellular respiration equation

glucose + O2 → CO2 + H2O

Cellular respiration location

In the mitochondria of cells

1st Law of Thermodynamics

Energy cannot be created or destroyed, only transformed or transferred

2nd Law of Thermodynamics

Entropy increases, causing energy to be lost as heat during transfers

Trophic level

The position an organism occupies in a food chain

Meaning of arrows in food webs

They show energy flow

Energy transfer efficiency between trophic levels

Estimated to be about 10%

Reason terrestrial food chains are limited to 4-5 trophic levels

High energy loss at each step

Detritivores vs Saprotrophs definition

Detritivores ingest dead organic matter and digest it internally; saprotrophs secrete digestive enzymes externally and absorb the resulting nutrients.

Importance of decomposers

Recycle matter, release nutrients, and dispose of dead organisms

Three types of ecological pyramids

Numbers, biomass, and productivity (energy).

Pyramid of numbers limitation

Can be inverted and is the least accurate ecological pyramid.

Pyramid of biomass measurement

Measured as dry weight after removing water.

Pyramid of productivity units

Joules per square meter per year (J m⁻² yr⁻¹).

Gross Productivity

The total gain in biomass by an organism.

Net Productivity

Biomass remaining after fecal and respiratory losses.

Gross Secondary Production (GSP) formula

Food eaten minus fecal loss.

Net Secondary Production (NSP) formula

Gross secondary production minus respiratory losses (GSP minus R).

Sustainable Yield definition

Biomass extracted without reducing the ecosystem's natural capital.

Persistent Organic Pollutants (POPs) examples

Non-biodegradable organic molecules.

Bioaccumulation definition

Toxins build up within the body of an organism over time.

Biomagnification definition

Toxins become more concentrated as they move up trophic levels.