Dale A. Holen

Associate professor of Biology

PSU Worthington-Scranton

“Animals” that Photosynthesize

and “Plants” that Eat

Aquatic Food Web

Primary

Producers

(phytoplankton)

Primary

consumers

(zooplankton)

Secondary

consumers

Tertiary

consumers

Terrestrial food chain Aquatic food chain

Classification of Living Things

Viruses, Prions, Viroids

Prokaryotes

Eukaryotes

- protists

- fungi

- plants (autotrophic/phototrophic)

- animals (heterotrophic/phagotrophic)

Pitcher Plant Sundew

Exceptions to the Rule

Carnivorous Plants

Elysia chlorotica

Vaucheria litoria

Bacterial Grazing by Planktonic Lake Algae

David F. Bird and Jacob Kalff

Science 31 January 1986: 493-495.

Ecological Significance of Mixotrophy

chloroplasts

beads

Flynn KJ, Stoecker DK, Mitra A, Raven JA, GlibertPM, Hansen PJ, Granéli E,

Burkholder JM (2013) Misuse of the phytoplankton–zooplankton dichotomy: the need to assign organisms as mixotrophs within plankton functional types. Journal of Plankton Research 35, 3–11

Classical misrepresentation of the functional classification of planktonic protists

Functional classification of planktonic protists contributing to primary and/or secondary production

Spectrum of nutritional capabilities for representative

Chrysophytes

Strict phototrophy Mallamonas, Synura

Mixotrophy:

Obligate phototrophy and facultative Dinobyron divergens

phagotrophy Dinobryon cylindricum

Obligate phototrophy and obligate Uroglena americana

phagotrophy Ochromonas spp.

Chrysamoeba

Facultative phototrophy and facultative Ochromonas danica

phagotrophy Poterioochromonas

malhamensis

Strict phagotrophy Spumella

Paraphysomonas

Ochromonas vallesciaca

Holen, 1995. Chrysophyte Algae, Cambridge Univ. Press

Paramecium bursaria photosynthetic animal

http://protist.i.hosei.ac.jp/PDB/images/Ciliophora/Paramecium/bursaria/sample_4.jpg

http://content8.eol.org/content/2008/12/10/21/98465_large.jpg

With Chlorella Without Chlorella

Endosymbiotic

Chlorella

Mesodinium (Myrionecta) rubrum photosynthetic animal

http://www.smhi.se/oceanografi/oce_info_data/plankton_

checklist/others/mesodinium_rubrum.gif

Crytptomonad endosymbionts

Obligate phototroph

Strombidium viride photosynthetic animal

http://protist.i.hosei.ac.jp/PDB/Images/Ciliophora/Strombidium/sp_4.jpg

http://www.dr-ralfwagner.de/Bilder/Strombidium_viride-15.jpg

Kleptoplastidy

Ochromonas (Chrysophyte) Phagotrophic algae

• single-celled, naked

• 4-12 mm diameter

• two unequal flagella (one w/mastigonemes)

• 1-2 chloroplasts

• raptorial feeders

• nutritionally diverse

• statospores (species-specific)

• 80 species?

http://4.bp.blogspot.com/_VA6LePZ6KNY/R60qdxEFAoI/AAAAAAAAAYE/h6UTegWfhZs/s320/Ochromonas.jpg

Which came first, photosynthesis

or phagotrophy?

You’re probably wondering….

Did you know that there are phagotrophic algae Lucy?

Who Cares ?

Traditional grazing chain

Mixotrophs in the Microbial Food Web

Traditional grazing chain

Mixotrophs in the Microbial Food Web

≈30% What is the fate of all this OM?

Mixotrophs in the Microbial Food Web

Mixotrophs in the Microbial Food Web

Phagotrophic

algae

Photosynthetic

protists

Chrysolepidomonas dendrolepidota

• strict phototroph?

• ≈ 6 µm diameter

• cells solitary and free swimming

• heterokont, longer flagellum with

mastigonemes

• single parietal chloroplast and distinct

stigma

• unique scales cover cell body

• stomatocyst

• distribution?

Peters, M. C. and Andresen, R. A. (1993), THE FINE STRUCTURE AND SCALE FORMATION OF CHRYSOLEPIDOMONAS DENDROLEPIDOTA

GEN. ET. SP. NOV.(CHRYSOLEPIDOMONADACEAE FAM. NOV., CHRYSOPHYCEAE). Journal of Phycology, 29: 469–475.

Collecting a water sample

Are they phagotrophic?

fluorescent beads

1 2 3

4 5 6

7 8 9

Time (h)

0 20 40 60 80 100 120 140

FLB ingestion f

lagellate

-1

0.0

0.2

0.4

0.6

0.8

1.0

Mean FLB ingested vs. time for Chrysolepidomonas cultured at 20 µE m-2 s-2. Each data point is the mean of 3 replicate samples with 100 flagellates counted / sample. Mean ingestion rate = 0.72 bacteria flagellate-1 h-1.

r2 = 0.78 y = 0.003x + 0.30

What is the bacterial ingestion rate of Chrysolepidomonas?

Beads or FLB?

Time (h)

0 50 100 150 200 250 300 350

Fla

gellate

concentr

ation (

ml-1

)

0

50x103

100x103

150x103

200x103

250x103

300x103

Without added bacteria

With added bacteria

µ = 0.027, dt = 26.1 h

µ = 0.019, dt = 36.1h

Growth of Chrysolepidomonas on DYV inorganic medium at 20o

C at a light intensity of 240 µE m-2 s-1 on a 12:12 light/dark cycle.

How does phototrophic growth compare to mixotrophic growth?

Time (h)

0 20 40 60 80 100 120 140 160

Fla

gellate

Concentr

ation (

ml-1

)

0

20x103

40x103

60x103

80x103

100x103

120x103

140x103

Without added bacteria

With added bacteria

Growth of Chrysolepidomonas on DYV inorganic medium minus N & P at 20o C at a light intensity of 240 µE m-2 s -1 on a 12:12 light/ dark cycle.

Can Chrysolepidomonas use bacteria as a source of mineral (N and P) nutrients?

µ = 0.017, dt = 40.5 h

µ = 0.009, dt = 73.7 h

Bacterial concentration (ml-1

)

0 5x106 10x106 15x106 20x106 25x106 30x106

Chry

sole

pid

om

onas

(h

-1)

0.010

0.015

0.020

0.025

0.030

Growth rate of Chrysolepidomonas as a function of initial bacterial concentration. All cultures were incubated on DYV inorganic medium at 20o C and 240 µE m-2 s-1 on a 12:12 light/dark cycle. P. aeruginosa was used as the particulate food source.

Time (h)

0 20 40 60 80 100 120 140 160

Fla

gellate

Concentr

ation (

ml-1

)

0

2000

4000

6000

8000

10000

12000

Growth of Chrysolepidomonas on a small (≈ 2 µm) green alga at 200 C and a light intensity of 240 µE m-2 s-1.

How flexible is Chrysolepidomonas relative to the food it consumes? (Is there food selectivity/discrimination?)

The effects on Chl a (cell-specific and total)

in P. malhamensis during growth on bacteria

in the light and the dark.

Lacawac Sanctuary

Dissolved Oxygen (mg L-1

)

0 2 4 6 8 10D

ep

th (

M)

0

2

4

6

8

10

12

Temp ( oC)

0 5 10 15 20 25 30

Dep

th (

M)

0

2

4

6

8

10

12

Illumintion ( E m -2

s -1

)

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Dep

th (

M)

0

2

4

6

8

10

12

Prorodon

Van Dorn Bottle

YSI DO and temp.

meter

Light sensor

and meter

Thermocline

Prorodon concentration (ciliates L-1

)

0 2000 4000 6000 8000 10000 12000 14000

Depth

(M

)

0

2

4

6

8

10

12

Prorodon concentration (ciliates L-1

)

0 2000 4000 6000 8000 10000 12000 14000

Depth

(M

)

0

2

4

6

8

10

12

Dissolved Oxygen (mg L-1

)

0 2 4 6 8 10D

ep

th (

M)

0

2

4

6

8

10

12

Temp ( oC)

0 5 10 15 20 25 30

Dep

th (

M)

0

2

4

6

8

10

12

Illumintion ( E m -2

s -1

)

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Dep

th (

M)

0

2

4

6

8

10

12

D.O. ≈ 1.0 mg L -1

Light = 6 µE m-2 s-1

Homo sapiens chlorotica

Thank You !