1. Phytoplankton
MARE 444
Lecture 2

2. Phytoplankton
the majority of the plants in the ocean are planktonic unicellular algae called phytoplankton.
some can be caught be nets, others can only be collected by filtering or centrifugation (e.g., nano- and picoplankton).

3. Phytoplankton Group Phycological Terminology
Diatoms Bacilliariophyceae
Dinoflagellates Dinophyceae
Microflagellates Haptophyta, Prymnesiophyta,
Chrysomonadales,
Cryptomonadales
Picoplankton Photoautotrophs < 2μm
Cyanobacteria Cyanophyta, photosynth bact.
Prochlorococcus Photosynth bacteria
Eukaryotic Pico Very small, struct. advanced

4. Phytoplankton Vital role in marine food chain
4000 species of phytoplankton have been described, new species are continually being described
At least 13 classes of marine phytoplankton are distinguished, representing a wide variety of organisms

5. Phytoplankton
Phytoplankton account for about half of global primary production

6. Types of Phytoplankton
Bacteria and cyanobacteria
Diatoms
Dinoflagellates
Others

7. Photosynthetic Bacteria and Cyanobacteria

8. Photosynthetic Bacteria
Prokaryotic (Kingdom Monera)
Contain bacterial chlorophyll (different from the other chlorophyll molecules)

9. Cyanobacteria Prokaryotic (Kingdom Monera)
Contain chlorophyll-a (like eukaryotic autotrophs)

10. Cyanobacteria Important primary producers
Small size (1-2μm)- large SAV ratio
Sink or rise very slowly
Maximize nutrient absorption
Reduces grazing loss

11. Cyanobacteria
Distribution

12. A cyanobacteria bloom

13. The Diatoms
Microalgae

14. Diatom Cellular Structure
(chrysolaminarin)
(chlorophyll a and c,
fucoxanthin, etc)

15. The Diatoms

16. Planktonic diatoms Silica shell and lack of flagella = sinking
diatoms evolved various strategies to counter sinking
chains
spines
oil droplets
ionic regulation - internal ion concentration is lower than external seawater = reduction in density

18. Diatoms with elaborate spines and processes
Functions:

19. The Dinoflagellates

20. Dinoflagellate Characteristics
Typically 2 flagella
Large nucleus (looks like a fingerprint)
Chlorophylls a and c
Accessory pigments (ß-carotene, peridinin, xanthophylls)
Food reserve is starch

21. Dinoflagellate Characteristics
Some have:

22. Dinoflagellate Characteristics
Some are autotrophic, others are auxotrophic, others are mixotrophic, others are heterotrophic

23. Dinoflagellate Taxonomy
Armored
plates (numbers, shapes)
Naked
size and shape
cingular position, displacement, and overhang
sulcal placement and intrusion
presence/shape of apical groove

24. Dinoflagellate Ecology
Dinos tend to occur in the summer and early fall when nutrients are more depleted and seas are calmer

25. Microflagellates
Some (e.g., coccolithophorids) are very common

26. Coccolithophores
Unicell containing a haptonema between two smooth flagella
Haptonema - a coiled appendage that is used for feeding and sensory purposes
Chlorophylls a, c1, and c2, carotenoids
Chrysolaminarin

27. Coccolithophores
Single regular calcareous plates

28. Prokaryotic Picoplankton
Prochlrophyta
Often most abundant phtoplankton in oligotrophic, tropical waters
Have traits in common with several taxonomic groups
bacteria, cyanobacteria, green algae

29. Eukaryotic Picoplankton
Typically green algae (Chlorophyta)
Contain chlorophylls a and b, carotenoids, xanthophylls
Starch is the food reserve
1, 2, 4, or 8 flagella