High primary production means high phytoplankton populations and most likely high zooplankton populations because zooplankton feed on phytoplankton.

The growth of phytoplankton populations is dependent on light levels and nutrient availability.

A clear water phase occurs, as phytoplankton populations become depleted due to increased predation by growing numbers of zooplankton.

Cold temperatures and decreased light availability result in lower rates of primary production and decreased phytoplankton populations.

He concedes that phytoplankton populations have been limited by toxic and somewhat deoxidized water at the bottom of tanks, as well as light limitations.

So, ocean regions with high concentrations of phytoplankton will appear as certain shades, from blue-green to green, depending upon the type and density of the phytoplankton population there.

This has a limiting effect on photosynthesis and can inhibit the growth of phytoplankton populations, which form the basis of oceanic food chains and are a primary source of atmospheric oxygen.

Scientists have found that there can be wide ranges of δC values in phytoplankton populations over a geographic region.

Protozoa are capable of reproductive rates equal to or exceeding that of their phytoplankton prey, therefore preventing any significant increase in phytoplankton populations, including blooms.

These factors affect only near-shore waters, although they show that increased phytoplankton populations are not universally benign.