Plankton and productivity Flashcards
What does autotrophy mean in the context of marine productivity?
“Self-nourishment” — organisms that produce their own food via photosynthesis, e.g., phytoplankton
What is heterotrophy?
“Other nourishment” — organisms that consume organic matter, plants, or animals for nutrition
What is mixotrophy?
A nutritional strategy where organisms combine autotrophy and heterotrophy, e.g., many dinoflagellates
What is the difference between holoplankton and meroplankton?
Holoplankton spend their entire life drifting (e.g., phytoplankton, copepods), while meroplankton drift only during part of their life (e.g., larval sea urchins)
Name the main groups of phytoplankton
- Diatoms
- Cyanobacteria
- Dinoflagellates
- Coccolithophores
What are zooplankton and what do they include?
Heterotrophic plankton, including foraminifera, radiolarians, cnidarians, copepods, molluscs, and heterotrophic dinoflagellates
What are foraminifera and why are they important in geology?
Single-celled organisms with calcium carbonate shells that fossilize and are used to date rock layers
How do radiolarians differ from foraminifera?
Radiolarians absorb silicon to build their exoskeletons and capture prey with pseudopodia
Why are copepods ecologically important?
They graze on phytoplankton and microzooplankton, produce sinking fecal pellets, and contribute to carbon cycling
What are microzooplankton and their role in the marine food web?
Small zooplankton (20–200 µm) like ciliates and dinoflagellates, key consumers of primary production and part of the microbial loop
What is the difference between constitutive and non-constitutive mixotrophs?
Constitutive mixotrophs have their own chloroplasts; non-constitutive steal chloroplasts from prey
Why is understanding mixotrophy important for climate studies?
It affects predictions of oceanic carbon absorption and productivity
How does productivity differ in subtropical vs. temperate oceans?
Subtropical: low nutrients, small phytoplankton, fast turnover, low export.
Temperate: more nutrients, large phytoplankton, more grazing, greater sinking/export
What seasonal pattern drives plankton productivity in temperate waters?
Winter nutrient build-up → spring light increase → phytoplankton bloom → zooplankton peak → decline → small autumn bloom
What causes ocean stratification and what does it prevent?
Temperature, salinity, and density gradients (esp. warm surface layers); it prevents nutrient mixing
What processes drive upwelling?
Wind, the Coriolis effect, Ekman transport, and ocean floor topography
How do satellites help monitor plankton productivity?
By measuring chlorophyll (primary productivity) and nitrate levels (nutrient upwelling)
What role do microbial food webs play in ocean ecosystems?
They regulate carbon flow and recycling; crucial for productivity and are studied through experiments and models
