is the specific nutrient which limits primary production the same in both freshwater and marine communities?
The correct answer and explanation is:
The specific nutrient that limits primary production is not the same in both freshwater and marine communities.
In freshwater ecosystems, phosphorus is typically the nutrient that limits primary production. Phosphorus is an essential element for the growth of plants and algae, but it is often present in low concentrations in freshwater environments. When phosphorus is scarce, the growth of primary producers like phytoplankton and aquatic plants is restricted, even if other nutrients like nitrogen are abundant. This limitation can lead to lower productivity in freshwater bodies like lakes and rivers.
On the other hand, in marine ecosystems, nitrogen is usually the limiting nutrient for primary production. Nitrogen is vital for the synthesis of amino acids, proteins, and other cellular components. Although nitrogen is abundant in the atmosphere, it is often in a form that is not easily accessible to most marine organisms. In ocean waters, the availability of nitrogen, especially in the form of nitrate, often controls the growth of phytoplankton and other primary producers. This is particularly true in regions where nutrient cycling is not sufficient to replenish nitrogen quickly.
The different limiting nutrients in these two types of ecosystems are primarily due to differences in nutrient availability, water chemistry, and biological processes. In marine environments, nitrogen is often the limiting factor because it is more efficiently recycled in the ecosystem, while in freshwater environments, phosphorus is usually more scarce. Both nutrients are critical for primary producers, but their availability shapes the productivity of the respective ecosystems.