Life in Water Flashcards
life began in water
stable temp, buoyancy (less structure), viscosity, density (large animals can fly), solvent
what is the limiting resource
oxygen
freshwater comes in two kinds:
lentic (still) and lotic (moving)
physical factors
light, temperature, water movement, salinity, oxygen, pressure
light compensation point
depth where rate of oxygen production and use are the same (less light, less photosynthesis in deep)
thermocline
a layer of water through which temperature changes dramatically
layers: thermal stratification
water cycling facts
driven by solar energy - wind, evaporation, clouds etc.
97% - oceans
2% polar icecaps
1% freshwater
the hydrological cycle
reservoirs - lakes, ocean, atmosphere etc.
enterning water: precipitation or sub/surface flow
exits: evaporation, flow
cycle turn over is 9 days in atmosphere and 3100 in oceans
how are currents formed? what do currents do?
wind blows
moderate climate, move nutrients, gene flow
gyres
circulation systems that under Coriolis move right in NH and left in SH
- cold water from poles to equator
- warm water from equator to poles
this moderates climate
upwelling
deep water moved to surface
oceans as an environment
largest continuous environment
littoral/intertidal zone
shallow shoreline, influenced by tides rising and falling
neurotic zone
from coast to shelf (200m)
oceanic zone
beyond continental zone
epipelagic (photic) zone
surface to 200m
mesopelagic zone
200-1000
bathypelagic zone
1000-4000
abyssal zone
4000-6000
hadal zone
deepest
benthic
habitants at bottom of aquatic environment
pelagic
habitants above the bottom
thermocline trends
permanent and drastic at tropics but weak at poles
thermohaline circulation
at poles water freezes, leaving salt behind. water gets saltier and denser and sinks, pulling up less salty water = upwelling
- threatened by freshwater melting (less salty)
- cycles nutrients
salinity
varies with evaporation and precipitation
oxygen
highest at surface and bottom
comparison of oceans
tropical seas are physically and chemically stable
temperature and high lat are more productive
highest productivity at coastlines
open ocean supports species and is important to O and CO2 budgets
fringing reef
shore of island or continent (shallow, photosynthesis, tropics and subtropics)
barrier reef
stands between open sea and lagoon (photosynthesis, shallow, tropics and subtropics)
atolls
dotting islands
kelp forests
photosynthesis, temperature regions
levels of intertidal zone
- oxygen
supra tidal (splash zone), high intertidal, middle intertidal, low intertidal, subtotal (always covered) - larger amount of oxygen
spring tides and neap tides
sun and moon pull together (big); sun and moon work opposite (small)
salt marshes, mangrove forests and estuaries
transition between freshwater and marine and marine and terrestrial
salt marshes have salt plans (evaporated water)
mangroves are tropical and subtropical
estuaries are dynamic
high productivity and many species in wetlands
rivers and streams
- riparian zone
- vertical divisions
O not limiting
riparian zone: transition between water and terrestrial
vertical divisions: water surface, water column, benthic zone, hypoheic zone (transition to ground water), phreatic zone
trees and turbidity on rivers and streams
limit light
flood pulse concept
periodic flooding brings nutrients to flood plains and wetlands
biochemical oxygen demand
some pollutants require a lot of oxygen to breakdown
zones of lakes
littoral (shore) and limnetic (open)
oligotrophic lake
well-mined, well oxygenated, low production
eutrophic lakes
high production, low oxygen
