What limits the growth of phytoplankton?

Question

It is limited by the amount of water that runs off into the ocean.

It is limited by the number of fish eating the phytoplankton directly.

It is limited by the amount of nutrients in the water.

It is limited by the depth of the water in the ocean.

Answer 1

Phytoplankton growth is primarily limited by the amount of nutrients in the water. While factors such as light availability, temperature, and salinity can also influence phytoplankton growth, the availability of key nutrients—such as nitrogen, phosphorus, and iron—is often the most critical limiting factor in marine environments. In nutrient-poor areas, even if conditions are otherwise suitable for growth, phytoplankton populations may remain low due to the lack of these essential nutrients. Therefore, the correct response would be:

It is limited by the amount of nutrients in the water.