Fitoplanctos.. Presentacion.. (1)

8/2/2019 Fitoplanctos.. Presentacion.. (1)

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Organisms

Plankton: organisms that weakly swim or go where thewater takes them

Phytoplankton

Periphyton: benthic algae

Epiphyton: algae growing on macrophytes


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Phytoplankton taxonomy

Was once based on morphology or pigments, now more

molecular. See Graham and Wilcox 2000 Algae for more information.

Usually grouped in Divisions (VARIABLE!)

Also often grouped by

Size

Mobility (motility) Flagella: movable filament that can be used to propel organism through the

water

Gas vacuoles


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Phytoplankton groupings, con't

Origin: Periphyton (benthic)

Tychoplankton (detach from benthos)

Meroplankton (part of life on sediments)

Euplankton/holoplankton (entire life in water column)

Potomoplankton (resuspended algae in lotic systems)


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Cyanobacteria ~1,350 species

Prokaryotes: lack plastids and distinct membranebound nucleus

Photosynthesize functionally like plants

Chloroplasts of other algae and plants originated fromcyanobacteria through endosymbiosis


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Cyanobacteria, con't

Often dominant, esp. eutrophiclakes

Some species fix N

(heterocysts)

Large cyanobacteria oftendominate due to

disproportionate losses of

other species

Allelopathy (toxic or inhibitory

effects on other species) Buoyant (gas vacuoles)

Anabaena 400x

heterocysts


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Cyanobacteria, con't

Resting stages: thick-walled resting cells (cysts)

called akinetes (Anabaena &

Aphanizomenon)

Vegetative resting stage

(Mycrocystis)

linkage between benthos and

pelagic


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Chlorophyta: Green algae ~2,400 species

Eukaryotes

Includes unicellular flagellated and nonflagellated cells,

colonies and filaments and macroalgae (Chara)

Represent 40-60% species with high biomasscontribution in eutrophic and hypereutrophic lakes

Often dominate benthic algae


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Volvox

Chlamydomonas 400xCladophora40x

Spirogyra 200x

Hydrodictyon 40xChlorophyta


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Chlorophyta

Scenedesmus 600x

Assorted desmids


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Euglenophyta ~1,020 species

Small to medium sizedflagellated species

Often abundant in well-mixed

eutrophic ponds and littoral

areas

www.mib.uga.edu/.../mibo3000/ eukaryotic/01232001.html

Euglena

bio.rutgers.edu/euglena/ mainpage.htm
http://www.mib.uga.edu/microlabs/lectures_mibo3000/mibo3000/eukaryotic/01232001.htmlhttp://bio.rutgers.edu/euglena/mainpage.htmhttp://bio.rutgers.edu/euglena/mainpage.htmhttp://www.mib.uga.edu/microlabs/lectures_mibo3000/mibo3000/eukaryotic/01232001.html


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Bacillariophyta - diatoms ~5,000 species

Wide range in size: 2um - 2mm Require silica (Si) to build frustules

abundant during mixing when Si abundant

when lake stratifies, diatoms sink to bottom & remove Si from epilimnion

Heavy & no flagella: sink after stratification & formresting stage on sediments: viable after 100's years

Two groups:

pennate: bilaterally symmetrical

centric: radially symmetrical


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Diatoms

www.mib.uga.edu/.../mibo3000/ eukaryotic/diatoms.jpg

www.cnas.smsu.edu/labimages/ Biology/Bio122/week1.htm
http://www.cnas.smsu.edu/labimages/Biology/Bio122/week1.htmhttp://www.cnas.smsu.edu/labimages/Biology/Bio122/week1.htm


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Chrysophyta ~450 species

Small single-celledflagellates and flagellated

colonies

Common in oligotrophic clear

lakes and humic lakes Often codominate with

cryptophytes

Diatoms are often grouped

under chrysophyta

Synura, http://microbes.limnology.wisc.edu/outreach/majorgroups.ph


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Cryptophyta ~100 species

Small or medium-sizedflagellates

Common in oligotrophic

lakes

Single-cell cryptophytes,chrysophytes, dinoflagellates

main food of rotifers and

crustacean zooplankton (next

week!) Mixotrophic (more than one

more of nutrition): eat

bacteria & smallest algae

http://protist.i.hosei.ac.jp/taxonomy/Phytomastigophora/Cryptophyta/Cryptomonadaceae.html


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Pyrophyta - dinoflagellates ~ 220 species

Motile (flagellates) Have resting cysts

Some do not have

chlorophyll

Red tide in the ocean Peridinium

Ceratium

www.cnas.smsu.edu/labimages/ Biology/Bio122/week1.htm
http://www.cnas.smsu.edu/labimages/Biology/Bio122/week1.htmhttp://www.cnas.smsu.edu/labimages/Biology/Bio122/week1.htm


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Sizeinfluences

- growth rate

- energy paths (consumption)

- sinking time


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Size

Picoplankton (0.2-2 m dia)

Nanoplankton (2-30 m dia)

Microplankton (30-200 m

dia)

< 30 m = edible algae

A bacterium

E Daphniahead(e - eye) (large zooplankton)

B Cryptomonas(Cryptomonad)

D Keratella(small zooplankton)

C Scenedesmus(green)


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Influences of size

Pico- and nanoplankton: high rates of production Large surface to volume ratio (exchange of nutrients)

Very slow sinking rates

Nanoplankton are tasty

Microplankton Sink faster

Grow slower

Not tasty


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Photosynthesis

Photosynthesis= fixing carbonnCO2 + nH2O ------> (CH2O)n + nO2 (n=# molecules)

Change in population biomass = growth - consumption -sinking

Growth=photosynthesis


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Compensation point

Compensation point:

photosynthesis = respiration

Maximize the amount of time spent above the

compensation point (in the light)


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Ways to stay in light

Mixing sink slow enough to stay in mixed epilimnion

Mobility flagella

gas vacuoles

Change sinking rate change shape or density


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modifications

Muscilaginous cover around Staurastrumspecies (green)- reduce sinking (to a point)

- reduce consumption (or digestion)


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Effects of light & temperature on

photosynthesis

Maximumphotosynthesis

LightLimited(photo-

chemicalrxns)

LightSaturated(enzymaticrxns limitedby temp) Photo-

inhibited

Photo

synthesisrate

(mgC)

Available light


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Photosynthesis distribution=

specific primary production * light

climate * algae biomass

Mesotrophic epilimnion (well mixed)

Eutrophic with surface bloom

Oligotrophic with max. biomass atmetalimnion

Shallow transparent lakes with max.

biomass on bottom

Depth

PhotosynthesisBiomass


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Depth distribution of photosynthesis

Trophogenic zone ~euphotic zone

Note that phytoplankton on the surface of

hypereutrophic lakes shade out the

water column


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Factors influencing seasonal

distribution

Physical Temperature

Light

Limiting nutrients silica

nitrogen phosphorus

Biological competition

resources, sinking

Biological grazing

parasitism


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Seasonal distribution in a temperate, dimictic lake

(green)

(diatoms)


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1. Light limited: small, often motile (but productive)2. Light increasing,still ice cover, no mixing (dynoflagellates can

swim up towards light)


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3. Spring mixing: high nutrients, low grazing, increasinglight, diatoms dominate


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4. Initial stratification: diatoms settle & die, loss of Si to

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Fitoplanctos.. Presentacion.. (1)