diversity and role of micro algae in marine ecosystems Flashcards
Liebig’s law
yield of plants are limited by the nutrient that is present in the environment in the least quantity relative to its demands
temperature effects on algal growth
growth rate increases with temperature
What controls MLD in autumn - winter
Surface cooling increases density, makes water column unstable and expands MLD 5-1000 m
What controls MLD in spring
Surface heating isolates the surface from deeper colder waters (stratification) 5-70 m
Big MLD phytoplankton often in
dark
small MLD phytoplankton often in
light
In winter, nutrients are
mixed in the surface, high concentrations
In Spring, nutrients are
used by algae, and exported to depth (sinking, higher trophic levels)
in summer, nutrients are
at a minimum at the surface. Limited access to deep nutrients, regeneration.
Not all nutrients come from the deep, some come from
volcano eruptions, dust storms
Critical depth theory
Spring shallowing of MLD increases light availability for phytoplankton growth
Coupling/decoupling theory
Increased mixed layer depth separates grazers / algae which results in lower encounter rates, so growth rate goes up. Spring bloom starts in winter.
blooms in polar
intense, short blooms in summer
Blooms in temperate area
Intense spring bloom, summer time nutrient limitation, fall bloom
Blooms in tropical area
low intensity bloom. maximal productivity in fall/winter
Subtropical gyre
slowly circulating pools of warm, nutrient poor waters because of downwelling
Equatorial upwelling zone
Trade winds bring nutrient rich waters to the surface, fueling productivity
DCM
Deep chlorophyll maximum
CPR
Continuous plankton recorder
what did CPR find?
decline in Atlantic diatoms, dinoflagellate abundance
AMO
Atlantic Multidecadal Oscillation
explain NAO positive phase
.
Explain NAO negative phase
small high and low pressure area, storms are blocked from coming through. Subpolar gyre remains small, so subtropical gyre can flow towards Europe.
AMOC
Gulf Stream
