•Smallest unicellular eukaryote•Ubiquitous throughout top 200m•Tremendous blooms•Armored coating makes the surface more reflective•Cools deeper ocean water•Contributes to global warming bc metabolism
increases the amount of dissolved CO2 in the water
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3
Domain Eukaryotes – have a nucleiSupergroup Chromista- chloroplasts derived from red algae
Division Dinophyta- 3,310 spp. of dinoflagellates
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whirling flagella
Pyrrhos = “fire”bioluminescent
• Pigments? Chl a & c, carotenoid- B carotene, xanthophyll peridinin
gyroxanthin diester
•Carbon Storage? Starch
Division Dinophyta: Dinoflagellates
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• Chloroplasts? Triple membraneThylakoids in stacks of 3
Xanthophyll Peridinin- a light harvesting carotenoid- unique in its high ratio of peridinin to chlorophyll 8:2- makes red tides red
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• Can be heterotrophic (eats food) or autotrophic (makes own food), or both!
•Obligate heterotrophs- secondary loss of plastids
• Use flagella to capture prey
All h t i h sts p t in ds th t n b
Division Dinophyta
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• All have trichocysts, protein rods that can be ejected, exact function is unknown
•Mucocysts- simple sacs that release mucilage
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Dinophyta Life HistoryHaplontic: 1N thallus, the zygote is the only diploid stage
Normal conditions:Asexual
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Stressful conditions:Fuse with another dinophyta to form hypnozygote (resilient resting stage)
Dinophyta Morphology
• Posses two unequal flagella (at right angles to each other)• Cell wall made up of cellulose plates (a carbohydrate)• Both flagella are hairy (not mastigonemes)
Tranverse undulipodium (fl ll )
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(flagellum)
Longitudinal undulipodium (flagellum)
Dinophyta Movement• Have a slight capacity to move into more favorable areas to increase productivity
• Use flagella to move
• Longitudinal flagellum propels in the opposite direction
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• Transverse flagellum this flagella allows for turning and maneuvering
• Some dinoflagellates (<5%) have eyespots that allow detection of light source (mostly fresh water)
• Trichocysts???
Thecal Plates(Cellulose)
Apical Pore
Epicone
Girdle or
Dinophyta Morphology-Genus determined by number & arrangement of
thecal plates
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LongitudinalUndulipodium
SulculGroove
Trichocyst Pores
TransverseUndulipodium
Girdle orCingulum
Hypocone
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Spines• Larger SA/V• Helps to stay suspended in water column
• Causes red tides when in high concentrations• Produces brevetoxin, a type of neurotoxin. • Poisons humans who eat shellfish that have been filtering it.
Domain Eukaryotes – have a nucleiSupergroup Chromista- chloroplasts derived from red algae
Division Bacillariophyta -13,437 spp diatoms
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• Spines to slow sinking• Dense blooms can cause damage to fish gills
Chaetoceros
• Unicells or in chains• Common in rocky
intertidal
Navicula
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Pseudo-Nitzschia
• Produces anti-herbivory compound Domoic Acid• Accumulate in anchovies, eaten by birds death and strange behavior
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Only phytoplankton with economic value
Petroleum & Natural Gas:•Formed over millions of years from dead diatoms
Diatomaceous earth:Mi d f fil i fil ( )
Division bacillariophyta-diatoms
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•Mined for filtration purposes , water filters (porous)•Pesticides (plugs up trachea)
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Dinophyta, Haptophyta, & Bacillariophyta
34Phytoplankton
Primary Production• Phytoplankton are at the base of marine food chains or webs primary producers
•Primary Production: the amount of light energy converted to organic compounds by an ecosystems autotrophs during a given time period
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autotrophs during a given time period
• Chlorophyll a is often measured as a proxy for primary production by phytoplankton
•Important players phytoplankton produce over 99% of the food supply for marine animals
Primary Production• Phytoplankton are the major contributors to primary production in the open oceans………………………………………………………………..and globally!
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•Photosynthesis carried out primarily by:•Phytoplankton – open ocean•Macroalgae – along the coast
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Phytoplankton are the base of pelagic food webs
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Light• Major factor limiting new cell production
• Limited to growth in the ph ti n n th s f
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photic zone – near the surface
• Photic zone•euphotic zone <200m (good light)•disphotic zone 200-1000m (small but measurable light)
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Light
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• Compensation depth = depth at which photosynthesis is equal to respiration (net production = 0)
• Below this depth = phytoplankton die (can’t grow and deplete reserves)
• Above this depth = phytoplankton grow and are happy 7
Nutrients•Major factor limiting new cell production
(especially N, Fe, Si for diatoms)
•Nutrient Sources:• Rivers, streams, and agriculture (runoff)• Upwelling• Defecation
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• Defecation• Decomposition• Nitrogen fixers
•Nutrient uptake:• Advantage of small size• Simple diffusion to supply nutrients and remove wastes - large SA/V ratio
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Stratification influences:• time spent in the photic zone• nutrient availability (e.g. nutrients sink)
•The photic zone is often shallower than the upper mixed layer but cells circulating in the mixed layer are continually brought into the photic zone
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g p•Nutrients are generally low in surface waters and higher at depth•Pycnocline limits vertical mixing to the upper regions of lakes and oceans, once cells sink below it they are lost from the pop.
Importance of Iron
• In nitrogen rich waters – what is limiting???
• NH4+ (Amonium) is utilized directly
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•NO3- (Nitrate) assimilation by nitrate reductase
requires iron
• Algae need iron to utilize Nitrate (NO3-) as a nitrogen
source
Importance of Iron
John Martin’s Hypothesis• 1988 (MLML)• Iron limits phytoplankton production in nutrient rich seas
“With half a shipload of Fe, I could give you an ice age”
Reasoning: • Phyto bloom would take CO2out of the atmosphere • CO2 is a greenhouse gas causing global warming
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•Iron addition experiment in the Pacific (500 km south of the Galapagos Islands– Mid October 1993 ) – added Fe to 64 sq km
•John died of cancer before he could see the outcome
• Phytoplankton ↑ 85X
• Expt. repeated in the Southern Ocean with similar results
g g g
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Satellite picture of a phytoplankton bloom in the Southern Ocean induced by iron fertilization
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Eutrophication
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Too much of a good thing (primarily in lakes and nearshore coastal habitats):• Excess nutrients can cause eutrophication, often from runoff• Over enrichment of N + P• Excessive growth of algae out-competes other organisms, decay of biomass results in anoxia• A big problem in the Baltic Sea
Ecology
Population Growth of Phytoplankton
Pop growth rate of new cell production rate of
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Pop growth = rate of new cell production – rate of cell loss (sedimentation/sinking + grazing)
•Floating and sinking•Grazing
Floating and Sinking• Most phytoplankton are denser than water + tend to sink
• Stay suspended by water movements and viscous (resistance of fluid to something moving through it) drag (mechanical force of a solid moving through a fluid)
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• Viscous drag slows sinking rates
• Shape: Elongate cells have more SA/V ratio than spherical cells –slow sinking in elongate
•Spines to prevent sinking•Some species replace carbohydrates with lipids as a
storage product (oils = more buoyant)•Swimming with flagella (phototaxis)•Ionic exchange:
• Move ions in and out of cell to increase or
Adaptations to slow sinking or aid in resuspension
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• Move ions in and out of cell to increase or decrease density
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Grazers•Suspension feeding (filter water)
• Direct feeding
• May remove size specific individuals
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• May remove less resistant Phytoplankton species –non-toxic spp
• Results in patchy distributions
Grazers may also increase Phytoplankton populations by releasing nutrients through excretion (positive effect)
GrazersPhytoplankton defenses:
o Increase rates of production
o Mucilage sheaths
o Thick walls
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o Hard external coverings
o Spines are more for buoyancy but could also protect
o Form colonies (become too large for some zooplankton to handle
o Chemical deterrents (toxic species) – e.g. Paralytic Shellfish Poisoning
Phytoplankton as indicators of changing environments
• Phytoplankton depend upon sunlight, water, and nutrients
• Variance in any of these factors over time will affect phytoplankton concentrations
• Phytoplankton respond very rapidly to environmental
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Phytoplankton respond very rapidly to environmental changes
• Changes in the trends for a given phytoplankton population (i.e. density, distribution, or pop growth rates) will alert scientists that environmental conditions are changing
•Oil companies monitor Haptophyta populations
Red tideincrease nutrients in water (nitrogen & phosphorous)occur Spring to Fall
(April – September in northern hemisphere)2 million dinoflagellates/liter
1.blooms are not associated with tides 2.not all algal blooms cause reddish discoloration of water 3 not all algal blooms are harmful even those involving red
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3.not all algal blooms are harmful, even those involving red discolouration
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Harmful Algal Blooms:1. the production of neurotoxins which cause mass
mortalities in fish, seabirds and marine mammals 2. human illness or death via consumption of seafood
contaminated by toxic algae3. mechanical damage to other organisms,
such as disruption of epithelial gill tissues in fish, resulting in asphyxiation
4.oxygen depletion of the water column (hypoxia or
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yg p ( ypanoxia) from cellular respiration and bacterial degradation
Seafoam: a complicated biochemical amalgamcrushed phytoplankton- consist of inorganic and
organic particles of proteins, carbohydrates, and lipidsproteins provide surface tension to allow the bubbles
