Physical + Chemical Oceanography

Physical + Chemical Oceanography

1. Abiotic factors that shape marine ecology + physiology

   • Chlorophyll a = measure of photosynthetic biomass
   • Water = the universal solvent

2. Salinity

   • Nitrates + phosphates in their inorganic forms from river run-off, rain + snow
     • SRP = soluble reactive phosphate
     • Fuller et al (2005): seasonal patterns of concentration changes
   • Chlorides + sulphides from hydrothermal vents
   • 6 ions make up ~99% of dissolved salts in the ocean
     • Na + Cl make up 85%
   • PSU = practical salinity units
   • Higher salinities in middle of the ocean
   • Fe important: triggers enzyme activity + key in ETC

3. Gases

   • CO2 more soluble in water than in air (80%)
   • Between 0-8ml/l of O2 in seawater
     • Dissolves more easily in colder waters
     • Oxygen minimum zone

4. Temperature

   • High at ocean surface
   • Thermocline

5. Density

   • In autumn, surface water cools + becomes denser
     • Sinks = downwelling
     • Displaces deeper water = overturn

6. Light

   • Secchi disc used in freshwater systems
   • Quantum sensors with photocells used in oceans
   • Blue light penetrates the furthest
   • Turbidity

7. Circulation patterns

   • Coriolis effect
     • Deflected to right in N hemisphere
     • Deflected to left in S hemisphere
   • Gyres: large circular systems
   • Tropical organisms prefer west coasts + extend to higher latitudes
   • Kelps prefer old waters + occupy eastern shores
   • Ekman spiral: net effect of water moving at right angles to the wind direction
   • Wind induced upwelling eg Peruvian upwelling