The Plankton Community Flashcards
How does sonar work to find plankton in the ocean?
send sound signal into the ocean, and the sound scatters back from objects (eg plankton, fish) it hits
eg fish finders
What is the DSL seen with sonar?
DSL= deep scattering layer
a layer that scatters the sound
- it’s plankton!
- some of the DSL migrates daily
Plankton in the deep scattering layer undergo diel vertical migrations. What does this mean?
they go up in the night, down in the daytime
- this pattern is genetically entrenched in the plankton (like our circadian rhythm)
What are 3 hypotheses for plankton’s diel vertical migrations?
which one has the best evidence?
- predator avoidance- best evidence
- light makes plankton easier to see by predators –> remain deep during the day, surface at night to feed - Metabolic advantage: temperature and food
- conserve energy by feeding in warmer water @ surface at night, and moving deeper at the hotter times of day - Avoid UV damage
- surface waters have high UV light in the day which can damage tissues
t/f
the vertical migration of plankton mixes the upper layer of the ocean
true!
biologically generated turbulence
What’s the difference b/w plankton and nekton?
plankton= too small to be able to swim counter to typical ocean currents (can’t migrate great distances, just crawl/ drift w currents)
nekton= active swimmers, can follow plankton (DSL) and swim against currents
Plankton can be classified in which 2 ways?
- by source of energy
- by how much time spent in the water column
Planktons classified by source of energy:
- phytoplankton: photosynthetic (autotrophic)
- zooplankton: animals (heterotrophic)
- mixoplankton/ mixotrophic: can be photosynthetic but can also ingest other organisms (eg parasite fish)
Planktons classified by how much time they spend in the water column:
give examples for each
- holoplankton= permanent residents (eg krill)
- meroplankton= temporary residents (only spend larval or reproductive life in the plankton) (eg hydrozoan jellyfish)
- neuston= associated with slick (eg phalaropes) feed at tide lines/ laminar circulation
____ and ____ are the main 2 phytoplanktons
___ occur seasonally and _____ appear periodically in huge numbers
diatoms and dinoflagellates
cyanobacteria
coccolithophores
Diatoms:
- are a major type of ___ (in both fresh and marine waters)
- forms a ___ shell, consisting of 2 ____ symmetrical ___
- reproduce by ___ ___
- consumes much of the ___ in the ocean surface
- responsible for ___ of the world’s photosynthesis
algae
silica
radially
valves
binary fission
silica
45%
Dinoflagellates:
- __cellular flagellates
- have an organic shell made of ___
- have __ flagella
- ___ and ___ reproduction
- can be __ trophic and ___ trophic
unicellular
cellulose
2
asexual and sexual
heterotrophic and autotrophic
Which type of plankton cause red tides?
What are red tides?
dinoflagellates, eg noctiluca
Red tides:
- area of huge productivity
- such a huge plankton bloom that it turns the water red
- can be bioluminescent
- often toxic to animals
What are 3 types of green algae found in the ocean? explain each
- cyanobacteria
- abundant
- nitrogen fixation in surface waters - silicoflagellates
- unicellular, biflagellate
- internal skeleton of silica scales
- not coastal- usually found in antarctic and open ocean - coccolithophores
- unicellular nanoplankton
- covered w calcium carbonate plates (coccoliths)
what are coccoliths and where are they found?
What happens to them over time?
calcium carbonate plates (disk shape structure) on the surface of coccolithophores
Coccoliths are shed when they die and deposit on the seafloor
-Blooms are so massive that over time their coccoliths form massive deposits on the seafloor –> compose the white cliffs of dover!
