Marine Primary Producers
OCN 201 Biology Lecture 4
http://video.conncoll.edu/f/pasiv/lucid/Cyanophora-900.html http://micro.magnet.fsu.edu/moviegallery/ Photo: Fuhrman Lab; University of Southern California http://www.cellsalive.com/howbig.htm What are phytoplankton?
A: photoautotrophs B: organoheterotrophs C: chemoautotrophs D: photoheterotrophs E: chemoheterotrophs Light Variations Light intensity decreases with depth and with latitude Sunlight
Light
Temperature
Pressure
Deep sea is dark, cold, and high pressure
!3 Why does light matter? Energy Photosynthesis feeds the ocean!
Food “Primary producers” make the food that the whole marine food web depends upon
!4 TOTAL light and COLOR Spectrum Vary with depth
Red Yellow Green Blue UV
20 to 100 m
about 600 m
!5 The Pelagic Divisions (By Light)
EUPHOTIC “Good” Light Photosynthesis! About 20 to 100 m
DISPHOTIC Twilight
about 600 m APHOTIC No Light
• The production of organic compounds from atmospheric or aquatic carbon dioxide, principally through the process of photosynthesis (or chemosynthesis) • Carried out by autotrophs • On land primary producers are mostly macroscopic • In the sea nearly all primary production is by microscopic phytoplankton Terrestrial vs Marine Biomes grasslands and forests
http://www.sarasota.wateratlas.usf.edu/seagrass/
http://images6.fanpop.com/image/ Kelp Forest Locations Macroalgae & Seagrasses limited to coastal areas Macroalgae & Seagrasses
Exception:
Sargassum a planktonic macroalga Photosynthetic bacteria Photosynthetic picoeukaryotes
Coccolithophore Dinoflagellate Diatom
Most Life in the Sea is Microscopic! MARINE PHYTOPLANKTON How Many?
Diatoms & Dinoflagellates
Thousands
Flagellates & Coccolithophores Millions Hundreds of Millions
Cyanobacteria & Picoeukaryotes MARINE PHYTOPLANKTON Activity? Together, these tiny phytoplankton produce half the oxygen on the planet! 100 Diatoms & Dinoflagellates >10 µm 90 10% 2 to 10 µm 80 20% 70 0.2 to 2 µm
60
Flagellates & Coccolithophores 50
40 70% 30
20 Percent of Primary Production Percent 10
0 Cyanobacteria & Picoeukaryotes North Pacific Ocean Prokaryotic Phytoplankton (Cyanobacteria)
Most abundant in the ocean: • Prochlorococcus • Synechococcus (there are others)
Responsible for most of the primary productivity in the open ocean
...and about half of the oxygen on the planet! How many cyanobacteria in a liter of seawater?
A: ten B: thousands C: hundreds of thousands D: one million E: hundreds of millions varies a lot Eukaryotic Phytoplankton have Plastids that originated as symbiotic cyanobacteria
Chloroplasts
Nucleus
http://blogs.scientificamerican.com/
A protist’s relationship with its plastids may be permanent or temporary Some Eukaryotes Steal Plastids from Others This process is called kleptoplasty Eukaryotic Phytoplankton
• Picoeukaryotes (0.2 -2 µm) • Dinoflagellates (5-2000 µm) • Diatoms (2-2000 µm) • Coccolithophores (5 - 20 µm) How many photosynthetic eukaryotes in a liter of seawater?
A: ten B: one thousand C: hundreds of thousands D: about a million varies a lot!! E: hundreds of millions Picoeukaryotes Ostreococcus - smallest free-living eukaryote
François Yves Bouget in Le Journal du CNRS Epifluorescence micrograph
UniversiElectron micrograph
Chloroplast
Wenche Eikrem and Jahn Throndsen, Picoeukaryotes Micromonas pusilla
Mitochondrion
Nucleus
Chloroplast
http://hypnea.botany.uwc.ac.za/phylogeny/classif/prasinophyceae/images/microm.jpg Diatom Coccolithophore
cyanobacterium Silica frustule Calcium carbonate plates
Cellulose thecal plates picoeukaryote
Dinoflagellates Dinoflagellates
• Not all are photosynthetic (heterotrophs, autotrophs, mixotrophs) • Some perform kleptoplasty • Some are bioluminescent DIATOMS • All are photosynthetic • Have “shells” of silica (glass houses) • Many different shapes ChaetocerousFragilaria CoscinodiscusNavicula
http://bioloc.oce.orst.edu/SherrLab/ Siliceous Sediments If composed of diatoms it is called “Diatomaceous Earth”
http://www.marinebio.net/marinescience/02ocean/mgbottom.htm What is diatomaceous earth used for?
A: swimming pool filters B: ingredient of dynamite C: DNA purification D: abrasive agent in toothpaste E: insecticide Coccolithophores
Emiliania huxleyi Summary • Kelp and sea grasses important in nearshore in nutrient rich areas BUT most primary producers are microscopic • Photosynthetic bacteria (cyanobacteria) are most abundant primary producers on the planet • The larger photosynthetic planktonic eukaryotes are also very abundant • Some important groups: diatoms & coccolithophores have hard shells that create massive (and inspirational) mineral deposits