Week 2 - Phytoplankton distribution Flashcards
(15 cards)
What factors control phytoplankton growth?
Bottom up factors such as light, nutrients, temperature, and pCO2
Bottom up factors refer to the resources available to phytoplankton that influence their growth rates.
What factors control the loss of phytoplankton biomass?
Top down factors including grazing, sinking, and viral infection
Top down factors refer to the pressures exerted by predators and environmental conditions that lead to a reduction in phytoplankton populations.
Why is it important to understand both bottom up and top down factors in phytoplankton dynamics?
To accurately model phytoplankton behavior over time scales that cannot be reliably observed
Understanding these factors together allows researchers to predict phytoplankton population dynamics more effectively.
What is the significance of seasonal succession in phytoplankton populations?
Different groups of phytoplankton may dominate as environmental conditions vary through the season
Seasonal changes influence the composition and abundance of phytoplankton species in aquatic environments.
What characterizes the Margalef’s mandala for high nutrient, high turbulence environments?
Large cells, high maximum growth rates, grazer defense
This environment typically supports diatoms that thrive under such conditions.
What characterizes the Margalef’s mandala for low nutrient, low turbulence environments?
Effective competition for resources, small cells, reduction of cellular nutrient requirements
Prochlorococcus is an example of phytoplankton that thrives in these conditions.
Describe the seasonal cycle in the North Atlantic sub tropical gyre near Bermuda.
Winter bloom when mixed layer penetrates nitracline, followed by oligotrophic summer stratified period
This seasonal cycle affects the types of phytoplankton present at different times of the year.
What types of phytoplankton dominate during the winter bloom in the North Atlantic?
Eukaryotes such as diatoms and coccolithophores
These groups are typically more abundant during nutrient-rich conditions.
What characterizes the seasonal succession at HOT?
Highly stratified oligotrophic system with low nutrients in surface throughout the year and dominated by Prochlorococcus
This system lacks strong spring or winter blooms due to insufficient mixing.
In stratified low nutrient systems, what are the sources of nitrogen?
Regenerated nitrogen (NH4+) and low inputs of new nutrients (NO3-) through mixing
The availability of nitrogen is crucial for phytoplankton growth in these environments.
What does a low f-ratio indicate in stratified low nutrient systems?
Low new production compared to total production, with a typical value around 0.1
This suggests that most production comes from recycled nutrients rather than new inputs.
What are the potential nitrogen sources for Prochlorococcus?
- High-light adapted Prochlorococcus: NH3
- Low-light adapted Prochlorococcus: NH3 and NO2−
- Marine Synechococcus: NH3, NO2−, and NO3
Different ecotypes of Prochlorococcus have adapted to utilize specific nitrogen sources based on their environmental conditions.
What adaptation has occurred in some Prochlorococcus ecotypes regarding nitrogen sources?
Loss of the ability to grow on new nitrogen sources
This adaptation reflects their evolution in low-nutrient environments.
How do growth rate and chlorophyll content vary in Prochlorococcus?
They vary with light intensity, showing adaptation to varying light and nutrient conditions
This variability is key to understanding how different ecotypes thrive in diverse aquatic environments.
What does gene loss in Prochlorococcus ecotypes indicate?
Adaptation to different degrees of oligotrophy
Gene loss can lead to reduced metabolic capabilities and specialization in low-nutrient environments.
