Phytoplankton

Microplankton - 20-200um - Plankton net

Nanoplankton - 2-20um - settling plates

Picoplankton - < 2um - Clorophyll flourometry

Paradox of the plankton

Many species in open water diversity changes all of the time for an environment that seems to be static because:

- competition

- seasonal spawning

- light levels angle changes throughout day

- short generation time

Dark adapted - photosynthetic rate is optimum at low light - Blue-greens & Reds

Light adapted - photosynthetic rate is optimum at high light - Greens & Browns

Compensation curve - shows the depths at which photosynthesis is higher than respiration. Delineates compensation depth - where photosynthesis equals respiration; different for different lakes with different trophic levels/visibility.

Eutrophic - high nutrients: N, P04, N03, organic matter, algae - cloudy water

Oligotrophic - low nutrients; high mountain streams - clear water

Macronutrients: Carbon, Hydrogen, nitrogen (limiting in seawater), oxygen, phosphorus (limiting in fresh water), sulfur, calcium, magnesium.

Micronutrients: Mangenese, Iron, Copper, Zinc, Silica

Heterotrophic/ chemotrophic algae- Getting energy from something other than the sun- sulfur vent algae.

Monod Equation - determines the limiting nutrient. Takes the growth rate of a population looks at concentration of nutrients. Graphed curves into equation. Different curves for different temperatures.

Carbon is the single most important nutrient for algae. Carbon Equation Carbonate cycle: H2O + CO2 <-> H2CO3(carbonic acid) <-> HCO3(Bicarbonate) <-> CO3^2-(Carbonate)

pH changes with algae using up CO2 and HCO3 driving it up

Phytoplankton blooms can push pH to 9 during the day and at night as they respire CO2 and push pH back down. Coral reefs need higher pH - global warming kills corals by using the ocean as a CO2 sink and driving pH down.

Nitrogen cycle: NH3 +02<-> NO2 +O2 <-> NO3^-1

Ammonia: NH3 + H2O = NH4(OH)- Toxic to fish & animals as well as NO2. Nitrosomonas spp. converts NH4 -> NO2 Nitrobacter spp. converts NO2-> NO3 which is not toxic to fish and animals.

NO3 utilized by algae to create amino acids needed by animals.

Phosphorus - Often limiting factor in fresh water. Phosphate, PO4 - form normally seen in freshwater systems and used by algae. A few years ago most detergents were phosphate based. Phosphate rich waster water from sewage plants caused nutrient enrichment. Algae blooms used all the O2 at night and killed fish.