Cycling Systems Essay, Research Paper

Decaying material sinks to the bottom of ponds/lakes/seas.

Problem ? the producers ( phytoplankton)

are at the surface ( where there is light ) so nutrients from decay must be

brought to the surface by water currents. 1.

Winter ? Water

circulates freely. Cold water at surface

sinks, circulating nutrients but cold temperatures and little light reduce

productivity. 2.

Spring ? Nutrients

are available , increased temperatures and increased daylight result in

increased productivity ( Spring bloom) 3.

Summer ? Warm water

rises and so colder water is trapped below a thermocline so nutrients are trapped at the bottom. Nutrients at top are quickly used up by

plants resulting in decrease in productivity and decreased number of consumers

dependent on plant life. 4.

Autumn ? Water at

surface cools and sinks allowing recycling of the nutrients and increased

productivity (Autumn bloom). Growth is limited by reducing temperatures and

light availability.