Transcript Phytoplankton Lecture 1 Phytoplankton • Unicells • Filaments • Colonies – chains, or spheres.

Phytoplankton
Lecture 1
Phytoplankton
• Unicells
• Filaments
• Colonies – chains, or spheres
Overview
1.
2.
3.
4.
5.
6.
7.
Euphotic zone, diel vertical migration
P’plankton sizes and sampling issues
Flagellates, Coccolithophores, Dinoflagellates, Diatoms
Carbonate Compensation Depth
Deep sea sediments (calcareous vs silicious oozes)
Global Ocean primary productivity – patterns and trends
Grazing of phytoplankton and foodwebs – why are
estuaries so productive? (bloom and bust cycles
8. Harmful Algal Blooms (HABs) and dead zones
Phytoplankton
• Passive floating (planktos = “to wander”)
• Euphotic Zone (0-100m depth = 0.1% PAR)
• PAR = Photosynthetically Active Radiation
wavelengths of 400-700nm (blue to red)
1. Euphotic Zone
Deep Chl max
Pycnocline
Light Environment
I
• Water causes light attenuation
• Due to: suspended particles
(turbidity) and color (CDOM).
Turbidity a fnt of phytoplankton
and other “particles” (TSS)
• K = attenuation coefficient
• Beer-Lambert Law:
Iz = Io e-zK
• Msr with secchi disk or PAR
sensors
• PAR vs PUR
Z
LIGHT LIMITATION
Attenuation equation
Iz = Io e -kz
where e = natural logarithm
k = attenuation coefficient (extinction coefficient)
ln Iz = ln I0 – kz
1% Io
PHOTIC ZONE = 0.1% Surface Irradiance -> 100m (300ft)
PUR – Photosynthetically Useable Radiation – chlorophyll absorbs blue and red light
Left: Attenuation of daylight in the ocean in % per meter as a function of wavelength.
I: extremely pure ocean water; II: turbid tropical-subtropical water; III: mid-latitude
water; 1-9: coastal waters of increasing turbidity. Incidence angle is 90° for the first
three cases, 45° for the other cases. Right: Percentage of 465nm light reaching
indicated depths for the same types of water. From Jerlov (1976).
Diel Vertical Migration
• Phytoplankton cells can regulate buoyancy
using gases or oils/fats to sink or float.
• Cells are more abundant at depth during the
night and migrate to the surface during the day
for photosynthesis.
• Allows cells to reach nutrient rich waters near
the pycnocline (deeper) and escape predation at
night.
• Influences distribution of zooplankton and higher
trophic levels:
http://userwww.sfsu.edu/~bioocean/research/min
itowers/minitower.html
2. Size and Sampling
• Size: “normal” (40-80+um), nanno- (2-20um), pico- (0.22um), ultra- (<0.2um)
• Concentrate with plankton net (many liters required),
microscopy cell counts (need training to id correctly).
• Filter down 50-1000ml sample (GF/F = 0.7um) to
concentrate pigments: chls + accessory pigments
• Analysis by HPLC (High Performance Liquid
Chromatography)
• Chl signal is used in Remote Sensing (SeaWIFS satellite)
Phytoplankton Monitoring Network
• http://www.chbr.noaa.gov/PMN/index.htm
• Sample every 2 weeks using a 20um net
for 3 minutes.
• Identify cells at 100x under microscope
• Record number in approx 1ml sample on
gridded microscope slide.
• Enter data to online database.
Dinoflagellates
Diatoms
http://www.whoi.edu/page.do?pid=11913&tid=282&cid=40526
HPLC uses pigment ratios to determine
Pigment Table
Pigment Molecules
CHLOROPHYLL
CAROTENES
Pigment Molecules
Fucoxanthin
Phycobilins
Accessory Pigments
• Chlorophylls (440,
670nm) – all algae
• Fucoxanthin (440-460nm)
- Diatoms/Dinoflagellates
• Phycobilins –
phycoerythrin(540nm) &
phycocyanin(620nm)
- Cyanobacteria
Most common phytoplankton pigments
= ug/L
Chl distribution in the GoM from satellite data
3. Some common and important
phytoplankton groups
Small cells
Flagellates
Dinoflagellates
Diatoms
Coccolithophores
LARGE
cells
Fan-Shaped Phylogenetic Tree
A.
Euglena
Flagellates
Flagellum
• 2 central + 9 axial
microtubules
• Single or paired
• Anterior, posterior
flagellum
• Smooth or “hairy”
• Basal body =
anchoring structure
Flagellum
• 2 central + 9 axial
microtubules
• Single or paired
• Anterior, posterior
flagellum
• Smooth or “hairy”
• Basal body =
anchoring structure
Flagellates
• Division Chlorophyta
• Class:
– Euglenophyceae
– Prasinophyceae
– Chlorophyceae Chlamydomonas
• Chl a + b
3 Classes of Green Flagellates
Prasinophyceae
Euglenophyceae
Chlorophyceae
Flagellates
• Division Chlorophyta
• Class:
– Euglenophyceae
– Prasinophyceae
– Chlorophyceae Chlamydomonas
•
•
•
• Chl a + b
•
Division Cryptophyta
Division Heterkontophyta
Class:
1. Chrysophyceae
2. Dictyochophyceae
3. Eustigmatophyceae
4. Pelagophyceae
5. Raphidophyceae
6. Xanthophyceae
Chl a + c; and accessory
pigments
• Very small cells (10-50um)
http://en.wikipedia.org/wiki/Cryptomonad
Diatoms
• Very small cells (8-50um)
Summary Flagellates
• Flagellates part of phytoplankton – often
picoplankton, poorly studied, don’t
preserve well, very small, hard to ID
• 2 groups – green pigments (Chlorophyta),
brown pigments (Cryptophyta /
Heterokontophyta)
• Some groups prone to blooms and HABs
B.
= coccolithophores
“shell” house
• Very small cells (2-20um)
• Calcified scales armor cell
Major group of open ocean phytoplankton
http://oceanography.tamu.edu/Quarterdeck/QD5.2/qdhome-5.2.html
Some Coccolithophores
Isochrysidales
Coccosphaerales
Prymnesiales
Pavlovales
Calcidiscus
Emiliania huxleyi
Pontosphaera
C.
Prorocentrum minimum
Very important base of food web
Ceratium
Desmokont cell
Dinokont cell
http://www.mnh.si.edu/highlight/sem/dinoflagellates.html
Protoperidinium
Dinophysis
These are motile “plants” that eat other
critters!!!
• Small-Large cells (20-500um)
• “Cellulose” plates armor cell
“wooden house”
About 60 species have toxins that
make humans sick!
Protoperidinium
Noctiluca
Noctiluca
Coral symbionts
Resting spore = cyst
D.
= “glass”
house
• Small-Large cells (20-500um)
• Siliceous shell armors cell
Frustule divided
When too small
undergo sex repdn
Range of size classes
Pleurosigma
BENTHIC CELLS – NEAR SHORE
OCEANIC CELLS – OFF SHORE
Diatoms are extremely important primary producers:
“grass of the sea”!
Or Centrales (=Biddulphiales)
• Centric diatoms – “planktonic”
• 3 suborders:
– Coscinodiscineae (8 families): Thalassiosira,
Skeletonema, Melosira, Coscinodiscus
– Rhizosoleniineae (1 family): Rhizosolenia,
Pseudosolenia
– Biddulphiineae (5 families): Chaetoceras,
Lithodesmium, Odontella
Melosira
Thalassiosira
Skeletonema
Cyclotella
Chaetoceras
Actinoptychus
Or Pennales (=Bacillariales)
• Pennate diatoms – “benthic”
• Raphe = fissure along apical axis. Used
for locomotion; cytoplasm acts as a belt
moving cell forward.
• 2 suborders:
– Fragilariineae – araphid (4 families): Striatella,
Fragilaria, Thalassionema, Thalassiothrix
– Bacillarineae – raphid (4 families): Navicula,
Bacillaria, Nitzschia, Pseudo-nitzschia
http://www.dnr.state.md.us/bay/cblife/algae/diatom/index.html
Pseudo-nitzschia
Raphoneis
Asterionellopsis
Cylindrotheca
Thalassionema
• Sullivan, MJ, CA Montcreiff, AE
Daehnick 1991. Primary Production
Dynamics of Epiphytic Algae in
Mississippi Seagrass Beds. MASGC91-009
• Sullivan, MJ, CA Montcreiff 1993.
Trophic Importance of Epiphytic Algae
in Mississippi Seagrass Beds.
MASGP-92-018
• Sullivan, MJ, DJ Wear 1996. Effects of
Water-Column Enrichment on the
Production Dynamics of 3 Seagrass
Species and their Epiphytic Algae.
MASGP-93-023
Cocco, Dino, Diatom Summary
• “Shell”, “Wood”, or “Glass” Houses armor
the cell and protect from predation/environ
• Coccos are small open ocean
• Dinos are warmer waters/summer
• Diatoms are cooler waters/winter
• Diatoms are the “grass of the sea and the
estuary”
4. Phytoplankton and sediments
• There are so many phytoplankton cells in the
ocean that not all are eaten. Dead cells sink to
the bottom of the ocean.
• Coccoliths (calcified) and Diatoms (siliceous)
armor plates accumulate on the seafloor in the
form of “oozes”.
• However, CaCO3 (calcium carbonate) dissolves
under pressure and pH, so not all places where
diatoms are abundant will you find calcerous
oozes! Areas deeper than about 4km don’t have
carbonate oozes because of this.
Carbonate Compensation Depth (CCD)
CaCO3 + H20 + CO2<====> Ca++ + 2HCO3-
Global Marine Sediments
Made by phytoplankton!
http://faculty.uaeu.ac.ae/fhowari/images/fares/presentations-classes/marine/Introductio8.htm
Overview
1.
2.
3.
4.
5.
6.
Euphotic zone, diel vertical migration
P’plankton sizes and sampling issues
Flagellates, Coccolithophores, Dinoflagellates, Diatoms
Carbonate Compensation Depth
Deep sea sediments (calcareous vs silicious oozes)
Global Oceanic primary productivity – patterns and
trends
7. Grazing of phytoplankton and foodwebs – why are
estuaries so productive? (bloom and bust cycles)
8. HABs and dead zones
6. Global Ocean Primary Production
Lots of chlorophyll here!
Northern hemisphere summer (July)
6. Global Ocean Primary Production
• Phytoplankton are abundant nearshore –
nutrient sources from the land.
• P’plankton are more abundant when it’s
spring/summer (temperature is important).
• P’plankton produce about 50% of global
oxygen. Some C-sequestration (biological
pump), could be enhanced with iron (Fe).
• P’plankton are basis of food web in water.
http://news.nationalgeographic.com/news/2004/06/0607_040607_phytoplankton.html
Seasonal Cycles
http://www.agu.org/revgeophys/chisho00/node2.html - enhance with iron addition?
Approx 30% of atmospheric CO2 annually
http://en.wikipedia.org/wiki/Carbon_dioxide_sink#Oceans
1. Grazing food web
2. Detrital recycling
Why phytoplankton not consistently
distributed in the ocean?
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•
•
•
•
•
Mixing processes – wind, currents, (tides)
Upwelling of nutrients
Diurnal Vertical Migration
Light-limitation
Nutrient-limitation
Grazing = Predation
Competition for nutrients
Other factors?
Circulation cells cause
convergence (downwelling)
and divergence (upwelling)
Cold core and warm core
eddies are additional
features influencing
phytoplankton distn
Storm events can also affect the
distribution of p’plankton in the ocean.
Hurricanes draw cooler, nutrient-rich
waters to surface – more p’plankton!
IronEx (Fe limiting?)
John Martin's iron hypothesis—fertilizing the sea with iron—was first put
to the test on the open ocean in 1993. According to Martin's iron
hypothesis, seeding the ocean surface with iron should make
microscopic marine organisms like diatoms multiply dramatically, which
might in turn cool the planet. The big question is: Should this type of
"global engineering" be done?
http://www.agu.org/revgeophys/chisho00/chisho00.html
http://www.palomar.edu/oceanography/iron.htm
Nutrient-limitation regulates
phytoplankton population size:
bottom-up control
• Require C, N, P, Si (Diatoms), and about 7
minor nutrients (e.g. Fe)
• Redfield Ratio (106C:16N:1P) – Redfield 1963
• Major Nutrients are “non-conservative”: turn
over rate very rapid (often biological mediated)
• Open ocean almost NO N or P – used
instantly, that is why ocean water = p’plankton
cell nutrient ratios described by Redfield!
• Upwelling is VERY important.
Grazing by zooplankton regulates
phytoplankton population size:
top-down control.
Abundance
Phytoplankton
Zoopl
Time
Note: about 10% conversion efficiency for each trophic step. 3 trophic steps
means 1 gram of fish comes from 1kg of phytoplankton!
Combination of bottom-up and topdown controls result in phytoplankton
“Bloom and Bust” Cycles
Plankton in estuarine and oceanic environments typically exhibit a "bloom and bust"
lifestyle. When conditions in the upper mixed layer (nutrients, light, low predation) are
favorable (e.g. at the start of spring) their fast growth rates allows them to quickly
dominate the plankton ("bloom"). As nutrients become limiting due to the high density
of p’plankton cells and because zooplankton grazers have become more abundant,
the bloom quickly dies-off, leaving the animals with nothing to eat (“bust”). In the open
ocean, the condition that typically causes diatom (spring) blooms to end is a lack of
silicon (Si).
Phytoplankton
Zoopl
Year 1
Year 2
Nearshore and Estuarine Productivity
• Nutrients from land fuel large populations of
p’plankton (103-106 cells/liter). Abundant
nutrients allow many species of p’plankton to coexist.
• Shallow waters are not light-limiting, vertical
mixing (from winds/tides) allows cells to have
access to nutrients from the sediments also.
• The abundance of p’plankton is the fuel for
secondary production nearshore. Upwelling
zones are especially productive.
http://www.nwfsc.noaa.gov/hab/habs_toxins/phytoplankton/images/AlgalGrowth_Revised2.swf
8. Harmful Algal Blooms (HAB)
• Blooms of marine algae which produce:
– Toxic effects to organisms (and humans)
– Physical impairment of fish/shellfish
– Nuisance conditions from odor, discoloration
– Severe oxygen depletion or benthic
overgrowth
• GEOHAB and ECOHAB programs
http://www.cop.noaa.gov/stressors/
extremeevents/hab/current/factecohab.html
Major HAB-related events in the
United States
Types of HAB events
• Neurotoxic Shellfish Poisoning (NSP)
caused by Gymnodinium breve = Karenia
brevis along GoM coasts
• Paralytic Shellfish Poisoning (PSP)
caused by Alexandrium spp in New
England, Pacific (northern CA – Canada,
Alaska)
• Amnesic shellfish poisoning (ASP) caused
by Pseudo-nitzschia (NW, Atl and GoM)
GoM K. brevis monitoring
September 12, 1995 at North Lido Beach
http://isurus.mote.org/~pederson/phyto_ecol.phtml
http://www.cop.noaa.gov/stressors/extremeevents/hab/welcome.html
http://www.ncddc.noaa.gov/habsos/Mapping/
Hypoxia and Dead Zones
• Phytoplankton blooms from pulses of excess
nutrients in coastal zone, inputs large amounts
of organic matter to sediments.
• Bacterial decay of dead cells uses up bottom
oxygen (hypoxia or anoxia). Oxygen less than
2mg/L is insufficient to support animal life – kills
benthic critters/fish if they can’t escape.
• Dead zone present west of Mississippi River
mouth in LA.
• Hypoxic area found in 2008 in large portions of
MS Sound from Dauphin Island to Chandeleur
Islands (Dillon and Gundersson, in prep).
Fueled mainly by
fertilizers used in Midwest
ag fields and brought
down MS river by spring
melt/rains.
6,000-7,000 square miles
Summary
• P’plankton vary in abundance in space
and time for a variety of reasons including
circulation, light, nutrients, grazers.
• P’plankton are taxonomically very
different, but ecologically do similar things
• Diatoms and dinoflagellates are important
groups, some of which cause human
health issues during blooms (HABs).
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