FNR 45400 Lecture 9: Seasonality in Production
13 Feb 2019
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Document Summary
Terms to know: thermocline- a thin but distinct layer in a large body of fluid in which temperature changes more rapidly with depth than it does in the layers above or below. Important seasonal factors in marine ecosystems include thermal stratification and solar angle. In temperate marine ecosystems, there are four main phases. The first phase, otherwise known as the autotrophic phase, involves the initial development of the spring phytoplankton bloom. During this phase, lots of resources are available due to mixing that has occurred. Algae respiration is higher than heterotrophic respiration leading to a positive net productivity. This phase is usually dominated by diatoms and is initially uncontrolled due to grazers, such as calanoid copepods, not having the metabolic capacity to immediately respond to the bloom. In phase two, the phytoplankton bloom decreases due to consumers taking advantage of the bloom. This phase often has a lag associated with it and is controlled by grazing.
