Biotic factors

WHAT ARE TROPHIC LEVELS

TROPHIC LEVELS ARE THE POSITION THAT AN

ORGANISM (OR GROUP OF ORGANISMS) OCCUPIES IN

THE FOOD CHAIN

MAJOR TROPHIC LEVELS ARE PRODUCERS,CONSUMER,AND

DECOMPOSER

PRODUCERS

• 6 CO2 + 6 H2O + SOLAR ENERGY = C6H12O6+ O2

• PHOTOSYNTHESIS – COMPLEX CHEMICAL REACTION IN WHICH PRODUCER USE CHLOROPHYLL TO CONVERT CARBON DIOXIDE INTO GLUCOSE AND OXYGEN

CONSUMERS

- RESPIRATION – THE CHEMICAL REACTION IN WHICH OXYGEN AND GLUCOSE PROVIDE ENERGY FOR AN ORGANISM

C6H12O6+ O2 = 6 CO2 + 6 H2O + ENERGY

ENERGY TRANSFERS

• HEAT LOSS TO ENVIRONMENT• CONVERTED TO LIGHT• LOST BETWEEN TROPHIC LEVELS• RE-RADIATED TO ATMOSPHERE

AS ENERGY IS EXCHANGED IT IS CONVERTED BUT NOT LOST.

MEASURING GROSS PRODUCTIVITY

• THE TOTAL GAIN IN ENERGY OR BIOMASS PER UNIT TIME WHICH COULD BE THROUGH PHOTOSYNTHESIS (GPP) OR ABSORBSION IN THE CONSUMER (GP)

MEASURING PRODUCTIVITY

• GPP – THE TOTAL AMOUNT OF ENERGY GAINED THROUGH PHOTOSYNTHESIS

• GP – THE TOTAL AMOUNT OF ENERGY GAINED IN PLANT CONSUMERS

MEASURING NET PRODUCTIVITY

• THE AMOUNT OF ENERGY THAT IS AVAILABLE AFTER THE ENERGY LOSS FROM RESPIRATION

MEASURING NET PRODUCTIVITY

• IT IS THE NET PRODUCTIVY WHICH REPRESENTS THAT AMOUNT OF ENERY AVAILABLE FOR THE NEXT HIGHER TROPHIC LEVEL

DATAB. TO CALCULATIONS

• GP FOR PHYTO = 190 g/m2/yr

• RESPIRATION FOR PHYTO = 64 g/m2/yr

• PHYTO EATEN BY ZOO = 56 g/m2/yr

• ZOO FECAL LOSS = 15 g/m2/yr

• ZOO RESPIRATION LOSS = 22 g/m2/yr

CLASS EJERCISES CALCULATIONS

1-CALCULATE THE PHYTOPLANKTONS NPP

• NPP = GPP-R = 190 - 64 = 126 g/m2/yr

2-CALCULATE THE ZOOPLANKTONS GP & NP

• GP = (PHYTO EATEN ZOO)-FECAL = 41 g/m2/yr• NP = GP-R = 41-22 = 19 g/m2/yr

GENERALLY, ONLY 10% OF THE ENERGY MAKES IT FROM THE LOWER LEVEL TO THE NEXT HIGHER LEVEL

Thanks. A. C. B.

Fuente• Wikispaces.com• Encarta.com