Water• Properties

– Surface Tension

– Viscosity

– Changes in State

Temperature

• High Specific heat of water allows it to absorb or lose lots of heat without changing temperature much

• Most important factor governing life processes and the distribution of organisms

Temperature

• SST (Sea Surface Temperature) varies with latitude and ranges between -1.9 º - 40 º C

Temperature

• Surface Mixed Layer (Redish Color): water layer of almost uniform temperature caused by mixing from wind and waves

• Thermocline (Green): area where temperature changes rapidly with depth

• Deep Ocean (Blue): gradual temperature change (water temp between 0 - 4 º C)

Temperature

• Depth profile of temperature from South to North in Atlantic Ocean

Temperature

• SST can be used to designate biogeographic zones• Organisms adapted to specific temp ranges

– Ectotherm– Endotherm

Salinity• Weight (grams) of inorganic salts dissolved in 1 kg of

water– Units are ‰ or psu (Practical Salinity Units)

Salinity• Where do Salts come from?

Salinity

Salinity

• What impacts salinity in the oceans?

• Ocean Salinity ranges between 32 - 38 psu (34.7 psu average)

Salinity

Salinity Profile of the Atlantic Ocean

Salinity• Why do we care about salinity as biologists?

– Salinity will impact the salt content inside organisms bodies

– Affects the buoyancy of pelagic organisms

– Partly impacts the density of water

Salinity

Diffusion: molecules tend to migrate away from regions of higher concentrations to areas of lower concentrations

Salinity

Osmosis: movement of water across a selectively permeable membrane from areas of low salt content to areas ofhigh salt content

• Osmoconformer• Osmoregulator

Salinity