Primary Productivity Flashcards
Light scattered, reflected and absorbed by clouds and atmosphere
45-50%
Light reflected from surface ocean
4-5%
Light absorbed by ocean (total surface radiation)
45-50%. ~50% infrared and ultraviolet- scattered and absorbed near surface. ~50% visible spectrum/ photosynthetically active radiation (PAR), decreasing with depth
Photic zone
Well lit- photosynthesis can occur
Dysphotic zone
Twilight, poorly-lit, no photosynthesis or growing plants
Aphotic zone
No light, chemosynthesis only
Nutrient concentrations
Highest in the deep ocean due to decay of otganic matter sinking through the water column
Upwelling of nutrients
Nutrients are supplied to surface ocean biota by upwelling and vertical mixing of water masses. High primary production
Areas highest in upwelling
Along the equator, continental margins and the Southern Ocean
Density
A function of salinity and temperature
Shallow stable mixed layer
Phytoplankton kept in a well-lit environment favourable for growth
Deep mixed layer
phytoplankton mixed over greater depth range and range of light conditions –> less favourable for growth–> low growth rates –> low primary productivity
Plankton
Derived from the Greek for ‘wandering’- they wander because they cannot control their motion against the current
Phytoplankton
Single-celled plants, bacteria , protists. All photosynthesis. Dominant primary producers of the pelagic realm. Present througout the photic zone
Importance of phytoplankton
Base of ocean food chains and food webs . Convert inorganic nutrients (C,N,P) into organic matter and provide food for consumers in higher trophic levels. Major O2 producers
Pigments contained within chloroplasts
Chlorophyll a= dominant. Chlorophyll b, c, and d. Accessory pigments e.g. phycoerythrin
Metabolism
All chemical reactions occurring in living organisms; allow organisms to grow and reproduce, maintain structures, respond to the environment
Intermediary metabolism
Conversion of energy in food to energy available for cellular processes; conversion of food into building blocks for proteins, lipids, nucleic acids and some carbohydrates; elimination of metabolic wastes
Respiration
A set of metabolic reactions that break down organic matter and release large amounts of energy- this energy supports other metabolic processes of all cells
Vital processes carried out by cells needing energy
Cell division, movement, maintaining body temperature, building/synthesising molecules
Food
The source of chemical energy for most living things; fats contain more than twice as much energy/gram as carbohydrates and proteins, which each contain similar amounts of energy
Major groups of phytoplankton
Diatoms, Coccolithophores, Dinoflagellates
Diatoms
Glass cell walls (“frustules”) formed by taking up dissolved silica from sea water. Two valves made of silica (SiO2) 20-200um in length
Diatoms- key features
Inhabit all aquatic environments but dominant in high nutrient areas. Produce 20-50% of Earth’s oxygen/ year. Substantial contribution to total ocean OM. Large and widespread deposits on the ocean floor.
