LEC 7: Salinity and Temperature

true or false: salinity and temperature have an effect on density

true or false: salinity and temperature have an effect on density

true!

define cohesion vs adhesion

cohesion = water attracted to water

adhesion = water attracted to other things

why is water often called the “universal solvent”?

since it can dissolve more substances than any other liquid

• dissolves polar and ionic substances (salts)

when a water molecules dissolves salt (NaCl) what is created

a solution is created that then forms hydration shells where:

• Cl- is surrounded by the “H+” of H2O

  • Na+ is surrounded by the “O-” of H2O

what is the percentage of pure water in sea water

a. ~50%

b. ~10%

c. ~95%

d. ~25%

c

what particulates dissolve in or are suspended in sea water

• inorganic salts

• dissolved gasses (N2, O2, CO2)

• Particulate organic matter (POM)

• Dissolved organic matter (DOM) (fats, carbs, vitamins proteins, DNA and larger bits)

  • particulate mineral matter (sand, sediments)

where are particulates that dissolve in or are suspended in seawater come from?

atmosphere

runoff/erosion

volcanic eruptions

organisms in the ocean - living or decaying

precipitation

what is the major ion composing the “salt” of saltwater

a. Na+

b. Cl-

c. K+

d. Ca+

b

true or false: sulfate is the bioavailable form of sulphur

true

what is forchhammer’s principle called and describe it

principle of constant proportions = major salts tend to occur in constant proportions, even when salinity differs

so in saltier environments, we still have the same proportion of the major salt components of saltwater

how was the principle of constant proprotions determined?

forchhammer (with the help of naval and civilian collaborators) collected many samples of seawater from Atlantic and Arctic ocean

• did this to determine the salinity variations in different areas of the ocean

• found the proportions of the major salts in seawater stay about the same everywhere

who is credited with defining “salinity” to mean the concentration of major salts in seawater

forchhammer

how does salinity level vary in seawater?

due to the addition or removal of fresh water rather than differing amounts of salt minerals in the water

define salinity

concentration of dissolved inorganic salts (ions) in seawater

o   # of g of dissolved salts / 1000 g seawater

what is the average salinity percentage of open oceans?

a. 10%

b. 25%

c. 35%

d. 60%

c

true or false: density of water decreases with salinity

false: density of water increases with salinity

true or false: an increased density in seawater means there is a higher concentration of salt and therefore causing more buoyancy

true

true or false the salinity of the average open ocean is higher then that of the red sea?

false: on average the open sea is 35% and the red sea is 40%

what is possibly occurring in areas that are of higher salt concentrations that are causing this to occur?

• evaporation (takes away water, leaves salt)

if more precipitation is occuring in seawater what does this mean in terms of salinity

salinity concentration will decrease and the area will be more dilute and less salty

true or false: evaporation and precipitation which affects salinity of saltwater is affected by latitude

true!

salinity of surface water varies over latitudes

why does the equator have low salinity?

due to high precipitation

at 30 degrees N and S do we find

a. salinity levels similar to the equator

b. high salinity levels

c. more precipitation

d. little evaporation

b

what is the name of the three atmospheric circulations that cause for the variation in salinity globally

• hadley cell

• mid-latitude cell

• polar cell

what atmospheric circulation is affecting the equator and how?

hadley cell cause warm moist air to converge near the equator and cause heavy precipitation

true or false: hadley cells determine precipitation regimes on a latitudinal basis

true

describe how hadley cells are causing more precipitation on the equator

• Wet equator, as air warms (due to concentration of sunlight on the equator) it rises, as it rises it absorbs a bunch of water vapor, as it goes up it precipitates, as it gets cold it dumps all that collected water onto the equatorial region

  • As it moves north and south the dry cold air begins to descend since it is now denser at these high-pressure zones (30 degrees N and S) and as it comes down its dries, so as it gets pushed towards or away from the equator it brings as much moisture as it can back to the equator where it repeats the cycle and dumps the water on the equator

at what point in depth of the ocean (south atlantic) is it the least salty?

a. 1000m

b. 2000m

c. 3000m

a

after 1000m it gets more salty

after 1000m depth of the south Atlantic, does the halocline increase or decrease?

increases

it gets saltier with depth

true or false: as thermocline decreases the halocline decreases in the south Atlantic

false

it does up up until the 1000m depth but below that thermocline continues to decline while halocline increases

at what temperature is water most dense?

4 degrees

at what temperature is salt water the most dense?

-2 degrees

true or false: at surface level of the south atlantic the halocline level is very high

true

at surface level of the south atlantic what is the salinity? what is the temperature?

salinity = 36g/kg

temp = 20 degrees

true or false: in south atlantic salinity will increase the deeper you go

true

why does salinity increase as you increase depth?

• b/c as pressure increases we increase the solubility of salt

• increased pressure means increased ability for dissolved gasses and salts to dissolve

why does salinity increase in depths?

thermohaline circulation!

• salt brines generated in arctic

why does it take a lot of energy to increase water temperature?

• takes lots of energy to break bonds

  • it is resistant to phase changes

define heat capacity

energy needed to increase 1g by 1 degree

define heat of fusion

energy needed to chnage 1g from solid to liquid

define heat of vaporization

energy needed to change 1g from liquid to gas

true or false: the larger the amount of water, the more energy needed to heat it up

true

why is the stability of temperature in the ocean important for aquatic organisms

• dont need to deal with fluctuating temperatures

• dont need to adapt to drastic changes in temperature

what is the range of temperature in the ocean

-2 to 40 degrees

what is the temperature range in the deep ocean

2-4 degrees

what factors are changing across latitudes

salinity (through precipitation/evaporation)

temperature

true or false: mid atlantic and mid pacific oceans will have low concetration of salt and low temperatures

false: high temp and high concentration of salt

define the thermocline

the layer of water that temperature is rapidly changing with depth than it does at layers above or below it

at surface level, we can find warm waters and high salt concentrations… true or false?

true

true or false: if the water has a higher salt concentration, it is more dense… same as if the water is colder it is more dense

true

define halocline

analogous to a thermocline, salt content along a vertical gradient

define pycnocline

vertical gradient of water density or the layer in which water density increases rapidly with depth

water more dense the deeper we go!!!!

• SO saltier water descends and colder water descends

what is occuring in the epipelagic layer of the ocean?

this is the “mixed layer”

not super stratified

why has the arctic ocean been called upside down?

• high latitude!

• we see the opposite effect of the halocline at the poles

  • we START with a less salty surface, see a rapid increase in salinity then gradual decline in salinity again

describe how the halocline is different in low vs high latitudes

low = warm water sits on top, as we descend it gets colder … salt concentration rapidly declines and gets saltier again as we descend

high = WEIRD… less salinity up top and warm water on BOTTOM!

where is the highest input of water, into the arctic ocean coming from?

a. bering strait

b. Atlantic ocean

c. fram strait

d. Barents sea

b

true or false: the cold salty Atlantic water enters from the fram strait and banks to the right, makes its way around the arctic ocean, and then exits either through the frame strait again or through the bearing strait

false: warm salty water is coming in from atlantic!

everything else is true

when sea ice in the arctic ocean melts, how is salinity at the surface affected?

• it decreases!!

• sea ice has expelled all salt through brine channels so when it melts it is releasing freshwater into the system and diluting the salt

• sea ice melts and forms a COLD, FRESHWATER LID on top of the arctic ocean

true or false: when sea ice melts, salinity will increase and create a cold salty lid ontop of the warm freshwater

FALSE: when sea ice melts, it forms a cold freshwater lid that sits on top of warm salty waters of the arctic ocean (b/c warm salty water is more dense, so it will sit below the newly melted sea ice that is cold freshwater)

true or false: a less dense cold freswater lid sits on top of a more dense warm salty water

true

explain why there is less salty waters seen on the surface of the arctic oceans (i.e. higher latitudes)

since melting sea ice releases cold, freshwater onto the surface, the salinity at the surface of the arctic ocean is lower, it then gradually increases due to the warm salty current that sits below this “lid” of cold freshwater, and then gradually increases with depth

define atlantification

• this is due to climate change

• we would see the arctic ocean slowly having the conditions of the Atlantic Ocean

• we’d see a shift from low salt concentrations at the surface to high concentrations at the surface

• we’d see a shift from cold surface temp to warm surface temp

• adapts conditions of Atlantic thermocline and halocline!!!!!

we can think of the arctic sea ice and melting from the top… true or false

false: think of melting sea ice from bottom up

how many major river system inputs are there into the arctic ocean?

6

• 4 from russia

• 2 from canada

define osmoconformers vs osmoregulators

osmoconformers = makes body fluids isotonic to seawater

osmoregulators = actively regulate the amount of salts or water in the body

define osmosis

water and salt moving from high to low concentrations

how do sharks maintain homeostasis with salt water

sharks blood is isotonic (slightly hypertonic) go sea water

how do marine mammals maintain homeostasis with salt water?

through their renal system

how do fish and crustaceans maintain homeostasis with salt water?

they are hypotonic with water

they excrete excess salt and take in water through gills

how do sharks maintain salt concentrations similar to that of water?

through urea!

urea is produced as a waste product, its stored in blood to increase ionic concentration closer to that of seawater

why cant marine mammals maintain homeostasis in the same way as sharks?

becasue sharks used urea thats stored in blood to increase the ionic concentration to make it closer to seawater, urea is toxic to mammals, and cannot be maintained in the body

what is the purpose of trimethylamine N-oxide (TMAO)?

it counters the destabilizing effect urea has on enzymes in sharks

what makes the meat of the greenland shark toxic?

the high concentration of trimethylamine oxide in muscle tissues

why is there such a high concentration of trimethylamine N-oxide in the muscle tissue of greenland sharks?

• b/c they live in the deep, with high salt concentrations

• soooo they need higher urea concentration in blood

how do teleosts osmoregulate their system in salt water

they maintain body fluids that are hypotonic to seawater

what methods do teleosts use to mantain osmoregulation

chloride pumps in gills - actively pump chlorine ions out against a concentration gradient

kidenys - excrete urea, retain water

describe the process of osmoregulation in teleosts

• they drink seawater

• it gets pumped through gills for countercurrent exchange

• chloride pump in gills pumps chloride ions out against the concentration gradient

• their kidney systems will excrete urea and retain water (which is what makes them hypotonic(?))

define a diadromous fish

fish moving between freshwater and marine environments

true or false: all teleosts are diadromous fish

false

what are osmolytes

organic substitute for inorganic ions - allows regulation of cell volume and maintenance of inorganic ion concentrations

true or false: instead of using sodium and chlorides to maintain osmoregulation, free amino acids are used by osmolytes

true

seaweed, sharks, and hagfish are all which type of osmoregulators

osmolytes

what is the method of osmoregulation for birds and reptiles?

the cells lining the salt gland actively transport NaCl out of the blood and into the ducts, where it is secreted out of the nostrils or mouth

why do birds and reptiles need osmoregulation if they dont spend lots of time in the ocean systems

they consumer fish!

define poikiloherms

organisms whose body temperature adjusts depending on environments

define homeotherms

organisms that have a constant body temp

define ectotherms

organisms that gain heat through the environment

they can regulate heat by actively moving to different strata (depths) or currents

define endotherms

organisms that generate heat via internal bodily functions

true or false: ectotherms can sometimes be endotherms and endotherms can sometimes be ectotherms

true! it is a spectrum, not binary

how does a homeothermic ectotherm behave?

wants to maintain an internal temperature but it seeks out environments/areas that will maintain that temp for them

how does a homeothermic endotherms behave?

organism with a constant body temp and generates internal heat to maintain that internal temp

what is an example of a homeothermic endotherm

birds & mammals

what is an example of a homeothermic ectotherm

snakes - seek out specific habitats with specific temperatures that maintains the internal temp that they desire

true or false: only homeotherms can be endotherms

false!

true or false: just becasue you are trying to maintain a specific internal temperature (homeotherm), does not mean you have to be an endotherm to do that

true! homeotherms can be endotherms or ectotherms

which category do most fish fall into?

a. homeothermic ectotherm

b. homeothermic endotherm

c. poikilothermic endotherm

d. poikilothermic ectotherm

d

which of these is hardest to find

a. homeothermic endotherms

b. poikilothermic ectotherms

c. homeothermic ectotherms

d. poikilothermic endotherms

b

marine mammals are:

a. homeothermic endotherms

b. poikilothermic ectotherms

c. homeothermic ectotherms

d. poikilothermic endotherms

a

they generate their own heat!

define trade-off

endotherms can travel through a wider variety of environmental temperatures, but use more energy to maintain their internal body temp

which of these uses more energy:

a. homeothermic endotherms

b. poikilothermic ectotherms

c. homeothermic ectotherms

d. poikilothermic endotherms

a