final exam Flashcards
Why are phytoplankton so important on Earth?
They fix about half of the total carbon fixed by photosynthesis on Earth, influence atmospheric chemistry and biogeochemical nutrient cycling, form the base of aquatic food chains, and contribute to oil, siliceous, and limestone deposits.
What is the biological carbon pump?
CO₂ is fixed by photosynthesis into organic matter, which passes to consumers and can sink to deeper waters, while respiration and bacterial decomposition return CO₂ to seawater, with some carbon eventually sequestered in sediments.
Define biomass in the context of phytoplankton.
Biomass is the total amount of phytoplankton at a given time (e.g., g Chl a/L).
Define primary productivity in phytoplankton.
Primary productivity is the rate at which phytoplankton produce organic matter (e.g., g C/m²/day).
How can phytoplankton biomass be measured?
Biomass can be measured via chlorophyll a (in vivo, in vitro, satellite).
How can primary productivity be measured?
Productivity can be measured via O₂ production, isotope incubation, and fluorescence tools.
Why is size relevant in phytoplankton eco-physiology?
Size determines surface area-to-volume ratio (SA/V), affecting nutrient uptake and growth rates.
How does SA/V vary with algal size?
SA/V decreases as cell size increases, especially if spherical; flattened or colonial forms help maintain higher SA/V.
Is SA/V related to growth rate?
Yes, higher SA/V in small cells enables faster nutrient uptake, resulting in faster growth; lower SA/V in large cells leads to slower growth.
How does size affect sinking in phytoplankton?
Larger cells sink faster; small cells are more buoyant, with adaptations like vacuoles, colony formation, and altered shapes helping reduce sinking.
Why are spatial and temporal scales important in phytoplankton ecology?
Ecological processes occur on different time and space scales, requiring matching the scale of observation to the process for accurate measurement.
Define gross and net growth rates.
Gross (µ) = growth or reproduction rate; Net (r) = µ - loss rate (λ).
How to calculate growth rate, doubling time, and divisions per time?
Exponential growth: r = µ - λ; N = N0 e^(rt); Doubling time: td = ln2/r = 0.69/r; Divisions per day = 1/td.
Define gross and net primary production.
Gross PP (Pg) = total photosynthesis; Net PP (Pn) = Pg - respiration (R).
