Question

Most of the oceanic biomass lives in the photic zone (upper 600' or 200m). Why is light such a limiting factor to life (both plant and animal) in the ocean?

Answer 1

Light plays an vital role in the photosynthesis of plant.

Light is called limiting factor because it is source of environmental condition which limits the growth, distribution and abundance of organisms within ecosystem.

Temperature is important almost all the organisms in order to perform their mebolic functions. Correct temperature is required for the catalysing the enzymes.

In the ocean phytoplanktons such as algae are the plants which make food by the help of photosynthesis. So because this these small plants live on the ocean surface of the water (upeer 600 to 200 Meyer) to collect energy from the sun and produce nutrients for their growth and development.

Example for ocean algae is green algae. Chlorophyll helps to give green colour.

Marine animals like fishes which may affect with high temperature so they remain in the ocean at 600 meter or in the depth. Sunlight may affect the biological and metabolic activities of the marine animals. Temperature above the 35 degree Celsius can causes the denature, breakdown of enzymes and reducing metabolic activity.

So to prevent from sunlight marine animals like fishes never live at the surface of water of ocean but in the range of 600 meters which is called photic zone.