Population growth notes
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Transcript of Population growth notes
Population Growth Notes 1-2
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)
Dinoflagellate Population Explosion
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
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.
What happens when a resource is limited? Intraspecific or
Interspecific?
http://www.youtube.com/watch?v=0jZe_VGLRYI
What are the resources that would be limiting here?
Primary Productivity – notes # 4• What are the limiting
factors?
Nutrients Required by Marine Plants• Nitrate (NO3) – most limited nutrient in the ocean is nitrogen• Phosphate (PO4) – a source of phosphorus that is also limiting
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 1st)– Nutrients limited=decrease in phytoplankton #’s– See pages 348-349 in text
• 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
Plankton Populations Worldwide
Guess who loves a good
phytoplankton bloom?