A population grows through natality or birth when conditions are favorable. When a population of plankton grows rapidly it is known as a bloom. Population growth stops when conditions become less favorable and resources become limited. Resources like food, nutrients, shelter, and living space are limiting factors. When limiting resources are used up, the population reaches its carrying capacity, which is the largest sustainable population size given available resources.

1. Population Growth Notes 1-2

3. How Does a Population Grow? Natality=Birth When conditions are good, some organisms have more offspring than it takes to replace themselves When this happens to plankton, it is known as a “ bloom ” See Page 216 in your text (dinoflagellate bloom)

4. Dinoflagellate Population Explosion

5. What Makes A Population Stop Growing? Conditions become less favorable to support massive growth Resources get used up Limiting resources (w/o which a population can’t keep growing) include: Food & Nutrients Shelter/living space Carrying capacity = the largest population size that can be sustained by the available resources

6. Open vs. Closed Systems An open system indicates individuals emigrating (leaving) from an area and/or immigrating (coming) to an area Ex: birds on an island that use their resources may be able to survive on another island A closed system indicates individuals that are not capable of leaving the system. Ex: humans on earth are stuck here. If our resources become depleted or we reach carrying capacity, we may die.

7. What happens when a resource is limited? Intraspecific or Interspecific? http://www.youtube.com/watch?v=0jZe_VGLRYI

8. What are the resources that would be limiting here?

9. Primary Productivity – notes # 4 What are the limiting factors?

10. Nutrients Required by Marine Plants Nitrate (NO 3 ) – most limited nutrient in the ocean is nitrogen Phosphate (PO 4 ) – a source of phosphorus that is also limiting

11. Plankton Populations in LIS Notes - # 6 Spring Bloom-sunshine & nutrients not as limited, phytoplankton can go nuts! Why does bloom stop or slow in summer? Increase in sunlight warms surface waters, they become less dense, less well mixed Phytoplankton use up nutrients (usually Nitrate 1 st ) Nutrients limited=decrease in phytoplankton #’s See pages 348-349 in text

12. Fall Bloom – cool sunny days with lots of wind bring light and nutrients - plankton can go nuts again! Why does fall bloom stop or slow in winter? Light becomes limited Nutrients become limited as they are used up

13. Plankton Populations Worldwide

14. Guess who loves a good phytoplankton bloom?