Primary Productivity 2 Flashcards
Coccolithophores
Unicellular phytoplankton.
External shell made of calcareous plates called coccoliths. 1-10 um
Why are coccolithophores important
Important contributors to ocean carbon uptake: Organic C +CaCO3
Morphology of coccolithophores
- Nucleus:DNA
- Chloroplasts: Photosynthesis
- Cytoplasm
- Cell membrane
- Mitochondria: generate ATP (chemical energy)
- Golgi body: packages and distributes macromolecules
- Storage vacuole: waste, harmful products, pH regulation, internal pressure: density reduction
Dinoflagellates
Unicellular phytoplankton. 10-250um.
Flagella - dinoflagellates
Used for motility- can ‘swim’ to stay in nutrient-rich patches
Autotrophic
Perform photosynthesis to obtain energy from the sun and fix carbon
Heterotrophic
Obtain energy from organic carbon by eating other organisms, detritus or DOM
Mixotrophic
Can perform photosynthesis to fix carbon and take up DOM
Features of dinoflagellate anatomy
–> Epitheca - thecal plates
–> Transverse flagellum
–> Hypotheca - sulcus and longitudinal flagellum
Dinoflagellate reproduction
Mostly asexual- mitosis
Red tides (harmful algal blooms)
Occur when certain types of algae, particularly dinoflagellates, rapidly multiply in water. These blooms can discolor the water, though not always red, and some produce toxins harmful to marine life and humans. When these algae die, they deplete oxygen in the water, harming ecosystems
Phylogeny
Evolutionary history and relationships among individuals or groups of organisms
Planktic Microfossils
Provide one of the most complete records of biodiversity through time
What do planktic microfossils help us track?
Tracks global changes in the climate-ocean system and influences biodiversity and productivity of higher trophic levels of the biosphere e.g. higher diversity during warmer climate epochs
% of marine biota dissapeared over the last 30 years?
30%
What does loss of biodiversity lead to?
Weakens ecosystem resilience and functional role
30x30 initiative
Plan to conserve 30% of nature by 2030
Light availability
Affects the distribution of phytoplankton at depth
Pigments- light
Transform solar energy into chemical energy
All pigments absorb light of wavelengths?
400-700nm
Maximum absorption of chlorophyll a
Red and blue-violet
Pigment in photic and twilight zones
Fucoxanthin- blue-green
Pigment in deep photic zone
Phycoerythrin- yellow
Gross Primary Productivity (GPP)
Total photosynthesis
Net Primary Productivity (NPP)
GPP- respiration
Photoinibition
Decrease in the photosynthetic rate at higher light intensities e.g. shrinkage of chloroplasts
Compensation Point
Respiration=Photosynthesis
Limiting nutrients for life
- Nitrate NO3-
- Phosphate PO43-
- Iron Fe
- Manganese Mn
Limits of phytoplankton (Primary productivity))
Light or nutrients
Seasonal patterns
Affect levels of primary productivity
Polar: light limited, summer phytoplankton bloom
Temperate: spring and autumn phytoplankton bloom
Tropics: nutrient-limited, low productivity all year round
Zooplankton grazing
Zooplankton graze on phytoplankton.
Zooplankton grazing plays a crucial role in marine ecosystems by controlling phytoplankton populations. By consuming phytoplankton, zooplankton regulate their abundance, preventing unchecked growth that could lead to harmful algal blooms and disrupt the balance of the ecosystem.
Problems with zooplankton overgrazing
- Disruption of the food web
- Harmful algal blooms
- Changes in nutrient cycling
Ocean gyres = anticyclonic
Clockwise in N Hemisphere and anticlockwise in S hemisphere
Convergence gyres
No upwelling. low productivity
Small cyclonic gyres
Divergence, upwelling and high productivity
Coastal divergence
Upwelling of nutrient-rich deeper waters
Ekman transport
Net flow of water to the right of the wind in N. hemisphere and to the left in S . hemisphere
