Discovering Past Climates Digging for Diatoms Discovering Past Climates

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

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

Plankton Nets

Just how tiny can they be? Femtoplankton- little known group, viroplankton fall here Piccoplankton 0 - 0.002 mm      Ultraplankton  0.002 - 0.0055 mm      Nannoplankton 0.005 - 0.06 mm      Microplankton  0.06 - 0.5 mm      Mesoplankton  0.5 - 1.0 mm      Macroplankton 1.0 mm - 1.0 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.

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

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

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

Photos of Diatoms

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

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.

Where and How to Core? Iqaluit Boothia Peninsula Lake JR01

Coring a Core… © Canadian Museum of Nature

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

Photos of Dinoflagellates Red tide

Bioluminescence

Bioluminescence

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

Photos of Coccolithophores

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

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.)

Photos of Temporary Zooplankton Squid larva Crab larva

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)

Photos of Copepods

Photos of Krill

Humpack Whales Feeding on Krill

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

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