1. Discovering Past Climates
Digging for Diatoms
Discovering Past Climates

2. Carbon dioxide + water  sugar + oxygen
Phytoplankton
Microscopic plants that drift in the upper waters of the oceans
Use sunlight to produce their own food through the process of photosynthesis:
CO2 + H2O  C6H12O6 + O2
Carbon dioxide + water  sugar + oxygen

3. Phytoplankton, cont’d
Are critical to all life on earth because they are the basis of food webs and generate most of the atmospheric O2
When conditions are right (i.e., sufficient nutrients) they are capable of blooms – very rapid growth in numbers
Are collected in funnel-shaped plankton nets towed behind research vessels

4. Plankton Nets

5. Just how tiny can they be?
Femtoplankton- little known group, viroplankton fall here
Piccoplankton mm      Ultraplankton  mm      Nannoplankton mm      Microplankton  mm      Mesoplankton  mm      Macroplankton 1.0 mm cm      Megaloplankton greater than 1.0 cm
The last 4 groups are called net plankton as they can be caught with plankton nets. The first 3 groups are obtained through centrifugation, filtering, or settling of samples.

6. Types of Phytoplankton
There are 3 main types:
Diatoms
Dinoflagellates
Coccolithophores

8. Diatoms Are the most dominant and productive phytoplankton
Have beautifully ornate shells made of silica; unique to each species of diatom
Used in silver polish, toothpaste, and for filtering beers, wines, and juices

9. Centric Pennate Cyclotella Nitzschia
Although thousands of species exist, diatoms are usually divided in two groups: the pennates (pen-shaped) or the centric (rounded)
Centric
Pennate
Cyclotella
Nitzschia
© Canadian Museum of Nature

10. Photos of Diatoms

11. A Diatom by Any Other Name…
There may be up to 100,000 different species of diatoms (15,000 have been identified so far).
Each species requires certain ecological conditions in order to survive
Chemical
Physical
Nutrients pH
Salinity
Temperature
Light

12. Who Touched the Thermostat?
Because of their ecological eccentricities, and the fact that their glass shells remain long after they die, diatoms can provide scientists with a stunning insight into the environments and climates of the past!
By dating a soil sample and studying its diatom fossil content (number and type), we can estimate the climate of a given period.

13. Where and How to Core?
Iqaluit
Boothia Peninsula
Lake JR01

14. Coring a Core…
© Canadian Museum of Nature

15. Dinoflagellates Most have 2 flagella (whips)
Some are capable of bioluminescence (producing light)
Some cause “red tide” – they bloom so extensively that the water looks red
Some release a neurotoxin that is stored in certain shellfish and causes Paralytic Shellfish Poisoning (PSP) in humans when shellfish are eaten

16. Photos of Dinoflagellates
Red tide

17. Bioluminescence

18. Bioluminescence

19. Coccolithophores
Are covered with discs made of calcium carbonate (CaCO3)
White Cliffs of Dover are fossilized coccolith deposits – allowed the British to make many strategic tunnels during WWII
Can thrive in nutrient-poor waters where other phytoplankton cannot survive

20. Photos of Coccolithophores

21. Remember More diverse and abundant = Warmer Less diverse and scarcer =
Colder

22. Zooplankton
Microscopic (not all) animals that feed on diatoms, dinoflagellates, and other phytoplankton or on other zooplankton
Some members remain as zooplankton their whole life (copepods, krill, etc.) while others are just in their juvenile stage (crabs, sea stars, barnacles, lobsters, etc.)

23. Photos of Temporary Zooplankton
Squid larva
Crab larva

24. Zooplankton, cont’d Copepods make up more than 70% of the zooplankton
Krill are shrimp-like creatures about the size of your thumb yet have the largest biomass of any species on earth!
Krill are eaten in tremendous numbers by some of the largest marine animals (whale sharks and baleen whales)

25. Photos of Copepods

26. Photos of Krill

27. Humpack Whales Feeding on Krill

28. Adaptations of Plankton
Plankton cannot swim against an ocean current, yet it is important for each type of plankton to remain in the upper part of the water column
Their small size (microscopic) allow them to float and resist sinking

29. Adaptations of Plankton, cont’d
Phytoplankton must remain in the upper part of the water so that they have access to sunlight so that they can photosynthesize
Zooplankton must remain in the upper water column because that’s where their food is - the phytoplankton