Week 1 Flashcards
What is primary production?
Primary production is the formation of chemical energy (organic compounds) by living organisms (autotrophy). It sustains the biosphere, shapes the planet, and sets the upper limit on energy available to the ecosystem.
Why are primary producers important?
Base of the food web.
Responsible for ~50% of global net primary production.
Sequester carbon in the ocean, affecting atmospheric CO₂ levels.
Produce climate-reactive gases like DMS, influencing the planetary energy budget.
What are the major groups of primary producers?
Bacteria and Archaea (e.g., cyanobacteria).
Algae (microscopic and macroscopic).
Higher plants (e.g., seagrass).
How do phytoplankton influence global biogeochemical cycles?
They drive the cycling of carbon, nutrients, and oxygen. For example, their carbon fixation strongly influences atmospheric CO₂ levels, while they produce gases like DMS and CH₃I.
What is the diversity of marine primary producers?
Range from single cells (<1 µm) to chains or colonies (>200 µm).
Include both prokaryotes and eukaryotes.
Examples: Picophytoplankton (<2 µm) to larger diatoms and dinoflagellates.
What is the significance of phytoplankton blooms?
Increase phytoplankton biomass and color the ocean.
Impact local ecosystems, often visible via satellite imagery.
Example: Western English Channel bloom observed in July 2002.
How do primary producers contribute to biomineralization?
Coccolithophores create chalk deposits.
Diatoms produce siliceous deposits, contributing to sedimentary records.
What is critical depth theory?
A theory explaining phytoplankton growth limits based on light availability. Growth is only sustainable if the depth-integrated photosynthesis exceeds respiration.
How does light influence phytoplankton?
Light drives photosynthesis. Variations in intensity, depth penetration, and duration affect productivity. Factors like turbidity and seasonality also play roles.
What are the effects of nutrients on phytoplankton growth?
Nutrient availability controls phytoplankton biomass and productivity.
Key nutrients: Nitrogen, phosphorus, and iron.
Nutrient limitations lead to shifts in species composition.
What is the microbial loop?
A process where dissolved organic matter (DOM) is consumed by microbes, recycling nutrients back into the food web, enhancing ecosystem efficiency.
How do phytoplankton act as climate indicators?
Sensitive to changes in temperature, nutrients, and light, their distribution and productivity patterns reflect global change and ocean health.
What is the importance of the L4 sampling site?
Located in the Western English Channel, sampled since 1988, it provides data on seasonal cycles of phytoplankton dynamics and environmental variability.
Diagram: Seasonal cycle of chlorophyll at L4
Shows fluctuations in chlorophyll concentrations, representing phytoplankton blooms and seasonal variations in productivity.
Diagram: Phytoplankton blooms and ocean color
Illustrates how blooms change the color of the ocean, detectable by satellite imagery, highlighting biomass increases.
What is the role of zooplankton in the food web?
Zooplankton consume phytoplankton and transfer energy up the food chain to higher trophic levels, including fish and marine mammals.
What is the deep chlorophyll maximum?
A subsurface layer where chlorophyll concentration is highest due to optimal light and nutrient conditions, typically found in stratified waters.
What is the impact of ocean fronts and eddies?
Enhance nutrient mixing, stimulating phytoplankton growth.
Create localized hotspots of biodiversity and productivity.
What is primary production’s role in clean energy?
Phytoplankton have potential in biofuel production, offering sustainable energy solutions using photosynthesis-derived organic carbon.
How do phytoplankton sequester carbon?
Through photosynthesis and subsequent sinking of biomass, phytoplankton transfer carbon to the deep ocean, reducing atmospheric CO₂.
What are Harmful Algal Blooms (HABs)?
Certain phytoplankton species (e.g., Karenia mikimotoi) can form blooms that produce toxins, harming marine life and ecosystems.
What are phytoplankton’s functions in biogeochemical cycles?
Shows the role of phytoplankton in cycling carbon, nitrogen, and oxygen, linking atmospheric, oceanic, and biological systems.
What is the significance of Emiliania huxleyi?
A coccolithophore that contributes to carbonate sedimentation and reflects light, influencing climate processes.
Examples of Phytoplankton biomineralization deposits
Highlights chalk from coccolithophores and siliceous sediments from diatoms, key contributors to geological records.
