salinity

Question 1

define salinity

Answer 1

• Defined
○ Salinity is g of inorganic solids/1000g sw (ppt or 0/00)
○ Major inorganic ratios are constant
Resident times can vary (e.g. short for N,S)

Question 2

how is salinity estimated / measured? open ocean usual?

Answer 2

g of inorganic solids/ 1000g sw (ppt or 0/00)
major inorganic ratios are constant
@ resident times can vary (e.g. short for N, S)
estimate from: Refractometer
Chlorinity - then X by 1.81
○ Can be measured with conductivity (temp corrected) will be seen as PSU or S measures relative to standard KCL sol. At 1 atm. Pressure and 15 degrees C
○ Open ocean is 33-37 psu

Question 3

why is salinity a challenge

Answer 3

• Osmotic balance is a major challenge to marine org - salinity affects this
Particularly Na+ and K+ for nerve and muscle, inorganics must be precisely regulated

Question 4

how do marine organisms regulate salinity

Answer 4

• Regulation by low permability to SW and localize salts (gills, excretory organs)
• Marine org. vary organic osmolytes (manipulate Carbon based molecules generated by cellular reactions)
○ e.g. protists - glycerol, mannitol, sucrose
○ Inverts hagfish, bacteria - generate amino acids to balance solute conc.
○ Elasmobranchs and oseichthyes - urea
• Some adapt to extreme conditions
Migrate to fresh water and produce osmolytes: