Final answer:
In the ocean, phytoplankton growth, and thereby primary production, is limited by the availability of nitrogen in the Atlantic Ocean and by iron in the Pacific Ocean. These elements facilitate photosynthesis in phytoplankton and their scarcity can significantly limit ocean productivity.
Step-by-step explanation:
The element most likely to limit primary production in the ocean is different depending on the region. For instance, in the Atlantic Ocean, nitrogen is considered to be a limiting factor for the growth of phytoplankton. In contrast, in the Pacific Ocean, it is the availability of iron that limits phytoplankton proliferation. Both elements are essential for the production of chlorophyll, which is critical for photosynthesis. Moreover, the addition of these elements in significant amounts could potentially increase the growth of phytoplankton, leading to higher primary production.
Phytoplankton are fundamental to oceanic food webs, capturing about half of the energy that flows through the Earth's biosphere. However, their growth can be impeded by factors such as oil spills, which block sunlight and oxygen, necessary for their survival. In lakes and ponds, nitrogen and phosphorus act as limiting nutrients causing algal blooms that can lead to eutrophication and dead zones. Actions such as reducing sewage and runoff from fertilized areas would prevent these scenarios.