estuaries
where rivers meet oceans and the fresh/salt water mixes, salinity is therefore varied
challenge: salinity is inconsistent
benefit: for fish who don’t rely on consistent salinity to survive
average salinity of the ocean
35%o (parts per thousand)
high tide
most land-water coverage
intertidal zone
between high and low tide
low tide
least land-water coverage
pelagic zone
open ocean
mesopelagic zone
mid-depth
bathypelagic zone
very deep
abysopelagic zone
even deeper
hadal zone
so deep that it refers to hades, hell
benthic zone
all of the above zones
seamount
mountain on the ocean floor, volcanic origin
mid-ocean ridge
mountain chain
trench
the continental plate that goes underneath, very deep, rocky bottom
volcanic island
the volcanic plate above
plankton
organisms that can’t swim/move against a current
larva of larger creatures
can be plants
very small, microscopic
nekton
organisms that can swim against a current
most fish
benthic
epifauna
epi- “on top of” the surface of the ocean floor
snails
infauna
live buried in the ocean floor
clams
interstitial
microscopic organisms, usually food for small fish (worms, etc.)
demersal
associated with the bottom, but can swim
rays
flounder
often covered in sand
microorganisms
smaller than 0.063 mm
meiofauna
between 0.063 mm and 5 mm
macrofauna
larger than 5mm
megafauna
pretty much everything else thats visible
How is salinity controlled?
+
evaporation, sea-ice formation
-
precipitation, river runoff
conductivity
ability to conduct an electrical current, varies with temp
refractometer
refractive index, how much light bends when traveling through a liquid
why is circulation important?
migration
feeding
mating/rearing young
circulation patterns can affect…
water temp, coastal climates
gyres
large ocean circulation/currents
western side of oceans/eastern side of continents tend to be warmer.
upwelling
wind blows along the coast
surface water is pushed away from the coast
bottom water moves up
results of upwelling
bottom water is
cold
full of nutrients
nutrients → photosynthesis → food→ lots of fish!
el niño
winds shift
water moves toward shore
no upwelling
results of el niño
no upwelling → no nutrients → less photosynthesis → less food → fewer fish.