2. What does phytoplankton mean?
Phyto – light
Plankton – floating
There are 40,000 species of phytoplankton
(PP) available in the sea – mostly naked or
invisible to the human eye
PP makes 50 – 90 % of oxygen that we
breathe
Micro-algae makes the marine forms to live
longer
3. Phytoplankton
Photic Zone
• Can’t move against currents (float or
weakly move)
• >40% of global primary productivity
• Autotrophs
• Form base of ocean food web
• OXYGEN for all life
5. Cyanobacteria
Photosynthetic bacteria Use chlorophyll a
Prokaryotic (No nucleus, few organelles)
Intertidal, estuaries, coral reefs
Reproduce by cell fission
Nitrogen fixation: convert Nitrogen gas
(N2) to nitrates or ammonia
– Limiting nutrient
Some symbiotic
– Live in diatoms
– Epiphytes on seagrass
6. Stromatolites
Fossils >3 billion years old
•- Amount of O2 in earth's
early atmosphere
•Photosynthesis
byproducts: O2 & calcium
carbonate (lime)
– Build limestone domes
– Vertical growth =
- photosynthesis
•Modern stromatolites: hypersaline lagoons
(too extreme for animal grazers)
7. Division Chrysophyta (2 Classes)
Most with hardened cell walls or internal skeletons:
silica or calcium carbonate (CaCO3)
•Some have flagella for motility
Chaetoceras
Coccolithophore
Coscinodiscus
17. Red Tides (Dinoflagellate Bloom)
Mass development of dinoflagellates discolor water
Often caused by excess nutrients
•Enter ocean from land (runoff)
•Fertilizer, sewage
18. Red Tide Impacts:
•Toxic to marine life: accumulates in clams,
mussels, scallops, fish, mammals
•Death to some species, Human poisoning after
consumption (30 min.)
•Symptoms:
•Paralytic: paralysis, asthma, heart
attack (rare)
•Neurotoxic: tingling, paralysis,
memory loss
•Diarrhetic: cramps, vomiting, diarrhea
19. Nutrient Availability
•Photosynthesis only provides
carbon,hydrogen, oxygen (C6H12O6)
Also require Calcium, silica,
nitrogen,phosphorus, iron, etc.
•Most dissolved nutrients in cold water near
seafloor (marine snow)
– Below photic zone, isolated by pycnocline
•Upwelling & convection transports cold,
nutrient rich water to surface