SALINITY & OSMOREGULATION

HOW DOES SALT IMPACT THE ORGANISMS THAT LIVE IN IT?

KL OCEANOGRAPHY

UNIT II: OCEAN PLANET

OCEAN SALINITY

SALINITY= # OF GRAMS OF A DISSOLVED SALT IN 1 KG OF OCEAN WATER

• MEASURED IN PARTS / THOUSAND OR PPT OR ‰

• AVERAGE SALINITY OF OCEAN WATER = 35‰

MAJOR TYPES:

• NACL (SODIUM CHLORIDE)

• KCL (POTASSIUM CHLORIDE)

• MGCL2(MAGNESIUM CHLORIDE)

OCEAN SALINITY

SOME SOURCES OF SALT:

• VOLCANIC ACTIVITY CHLORINE GAS AND SULFUR EMITTED CL- IONS

• EROSION & RUNOFF IN THE MOUNTAINS (WEATHERING) NA+, MG+, K+ IONS

• WAVES & EROSION ALONG THE COAST VARIOUS SALTS CREATED BY ERODING BASALT AND LIMESTONE

IS SALINITY CONSTANT? NO!

• WHERE RUNOFF ENTERS FRESH WATER (ESTUARIES) DILUTES IT (LOWER SALINITY)

• EVAPORATION (SHALLOW WATER BODIES) INCREASES SALINITY CONCENTRATES THE AMOUNT OF SALT

SOURCES OF SALT

WATER & CELL MEMBRANES

WATER FACILITATES CHEMICAL REACTIONS BOTH OUTSIDE OF AND WITHIN LIVING SYSTEMS

• THE JOB OF THE CELL MEMBRANE IS TO KEEP THE CONTENTS OF THE CELL SEPARATE FROM ITS ENVIRONMENT.

• CELL MEMBRANE IS MADE OF PHOSPHOLIPIDS THAT ARE POLAR MOLECULES

• HEADS ARE POSITIVE

• TAILS ARE NEGATIVE

WATER & CELL MEMBRANES• POLAR MOLECULES

ATTRACTED TO WATER ARE HYDROPHILIC(WATER LOVING).

• LIKE THE “HEADS

• EX>SPONGE

• NONPOLAR MOLECULES/SUBSTANCES THAT CANNOT ATTRACT WATER ARE HYDROPHOBIC (WATER FEARING).

• LIKE THE “TAILS”

• EX> WAX

Hydrophilic

Hydrophobic

OSMOREGULATION

• ISOTONIC SOLUTION- SOLUTIONS HAVE SAME CONCENTRATION OF SOLUTE

• HYPERTONIC SOLUTION- HIGHER CONCENTRATION OF SOLUTE (MORE MOLECULES)

• HYPOTONIC SOLUTION- LOWER CONCENTRATION OF SOLUTE (LESS

MOLECULES)

• OSMOREGULATION= REGULATING THE AMOUNT OF WATER IN THE CELL THROUGH OSMOSIS AS A CELL RESPONDS TO OTHER DISSOLVED SUBSTANCES IN ITS ENVIRONMENT (LIKE SALINITY FLUCTUATIONS).

• OSMOSIS= MOVEMENT OF WATER INTO AND OUT OF THE CELL MEMBRANE

ISOTONIC SOLUTION

ISOTONIC=SAME AMOUNT OF SOLUTE INSIDE THE CELL AS IS IN THE SOLUTION ITS IN

• HAVING EQUAL OSMOTIC PRESSURE AS THE COMPARISON SOLUTION.

• SAME AMOUNT OF WATER FLOWS INTO AS FLOWS OUT OF THE CELL

HYPOTONIC SOLUTION• HYPOTONIC= GREATER

CONCENTRATION OF SOLUTE INSIDE THE CELL, THAN OUTSIDE THE CELL

• CELL HAS A HIGHER OSMOTIC PRESSURE (INTERNALLY) THAN A COMPARISON SOLUTION

• OSMOTIC (TURGOR) PRESSURE- FORCE EXERTED ON THE MEMBRANE/WALL

• HIGH OSMOTIC PRESSURE CAN CAUSE CYTOLYSIS-WHICH IS THE BURSTING OF CELL MEMBRANES

HYPERTONIC SOLUTION

• HYPERTONIC= A GREATER CONCENTRATION OF SOLUTE OUTSIDE THE CELL, THAN INSIDE THE CELL.

• CELL HAS A LOWER OSMOTIC PRESSURE (INTERNALLY) THAN A COMPARISON SOLUTION

• LOW TURGOR PRESSURE CAUSES PLASMOLYSIS, WHICH IS “CELL SHRINKING”.

• CAUSES PLANTS TO WILT

OSMOREGULATION• ORGANISMS ARE EITHER:

• OSMOCONFORMERS- DO NOT HAVE ADAPTATIONS TO HELP REGULATE SALT

OR

• OSMOREGULATORS- HAVE SOME SORT OF ADAPTATION TO MAINTAIN OSMOTIC BALANCE

OSMOCONFORMERS

OSMOCONFORMERS= ANIMALS WHOSE INTERNAL OSMOTIC CONCENTRATION IS THE SAME AS THE SURROUNDING ENVIRONMENT.

• MOST MARINE INVERTEBRATES

• NEED TO STAY WHERE THE SALINITY OF THE WATER MATCHES THAT OF THEIR BODY FLUIDS, OR ELSE THEY COULD SWELL AND BURST (IF PLACED IN FRESHWATER).

OSMOREGULATORS

OSMOREGULATORS= ANIMALS THAT MAINTAIN AN OSMOTIC DIFFERENCE BETWEEN THEIR BODY FLUID AND THE SURROUNDING ENVIRONMENT.

• MARINE BONY FISH

• THEY HAVE SPECIALIZED KIDNEYS HELP THEM RETAIN WATER BY PRODUCING CONCENTRATED SALTY URINE.

• MARINE REPTILES

• DO INGEST SEA WATER FOR NUTRIENTS

• DO HAVE SALT GLANDS THAT EXCRETE THE EXCESS SALT

OSMOREGULATORS• MARINE MAMMALS

• DO NOT INGEST SEA WATER DUE TO DEHYDRATION.

• THEY DO HAVE HIGHLY EFFICIENT KIDNEYS THAT PRODUCE VERY SALTY, CONCENTRATED URINE.

• OBTAIN FRESH WATER FROM CELLULAR RESPIRATION AND FROM FEEDING ON FISH AND INVERTEBRATES.

• CARTILAGINOUS FISHES

• DO NOT HAVE SPECIALIZED KIDNEYS LIKE FISH

• DO PRODUCE A CHEMICAL CALLED UREA IN THEIR BLOOD THAT THEY REGULATE THE AMOUNT OF WATER IN THEIR CELLS.

• DO HAVE AN EXCRETORY GLAND CALLED THE RECTAL GLAND THAT ELIMINATES EXCESS SALT.

OSMOREGULATION IN SHARKS

OSMOREGULATION IN MARINE FISHES

OSMOREGULATION IN FRESH WATER FISHES