marine ecology - clines and adaptations Flashcards
The salt in seawater
○ Seawater (ocean water) is 96.5% pure water
○ The partciulates that dissolve or are suspended in seawater come from many sources and include:
§ Particulate mineral matter
§ Inorganic salts (ions)
§ Dissolved gasses
§ Particulate organic matter (POM)
Dissolved organic matter (DOM)
Forchhammers prcnple
○ Forchhammers pricnple (princple of constant proportions: major salts tend to cocur in constant proportions even when salinity (amount of salt) differs
§ Mainly made of Cl-, then Na+, then SO4 2-, Mg 2+, Ca2+, and K+
§ The ratio of these ions will stay the same no matter what sewater it is but it can be more or less salty in some places
salinity
○ Salinity: concentration of dissolved inorganic salts (ions) in seawater
§ Usually expressed as % (parts per thousand, ppt or parts per mil, ppm) or psu (practical salinity unit):
□ #g of dissolved salts/ 1000g seawater
§ Averages 35% in open oceans (40% in red sea)
□ Density of water increases with salinity (salt makes water dense)
□ In areas where water is trapped water usuallu evaptotes and it become smuch more saltier
§ Add/removal of water: evaporation, precipattion, river input, freezin/thawing of sea ice
□ Can be abiotic or biotic removal and additions
Global variation in surface water salinity
§ Evaptortaion and precipattin over lattitude
§ Equator is low salinity due to high precipiation while arid regions (30 degree northa nd south) have high salinity bc of evaporation
§ Hadley cells impact salinity
□ Since precipation at equator, less salt
□ Moisture is absorbed by air moving from the 30 degrees back to equator causing the dried areas and tehrefore low precipattion, more evaporation and high salinity
§ Global variation in surface water salinity - atmospheric circulation
□ Hadley cell, mid latitude cell and polar cell
Vertical salnity gradient (south atlantic)
○ Salinity changes as u go down - halocline
○ Saltier at top then again once you go more deeper
○ Salt can change density of water - density is improtant for layering of water masses
Heat capcty
○ Cohesion gives water a relatvly high heat capcity
Resitant to phase changes - it takes more enegry to inc the temp of water
Ocean temp
○ Temp in the ocean ranges from -2 degrees celcius to 40 degrees
§ Deep oceans are 2-4 degrees
§ Latitudnal gradient
§ At euqator theres more idrect sinlight so more heat enegry absorbed
Types of clines
(changes in the ocenas characteristcS)
○ Thermocline - layer of water in which temp changes more rapdily with depth than it does in the layers above or below § (stratification: warmer, more variable saline water near surface; cooler, constant saline waters at depth bc more cold and more saline is more dense) ○ Halocline - analogous (similar) to a thermocline, salt content along a vertical gradinet § Peaks at 1000 m (water water with salt rmbr is below the cold freshwater of ice) ○ Pycnocline - vertical gradient of water density, or the layer in which water density increases rapdily with depth § Pressure always inc as u go down siimlar to hwo light always decreases as u go down ○ Stratifcation - when water fo diff densities form vertical layers in the water column Epipelagic - mixed layer
Vertical salinity gradient (artic)
□ The artic ocean has been called the upside down bc its starts less salty at top and then more at the bottom (the south atlantic was more salty at top bc of evaportaion)
□ Often called inverted ocean bc its opp of whats expected
□ The canada basin starts cold, then inc, then cold again (atlantic brings in warm water)
□ The canada basin starst less salty (low salinity) bc of ice melting and rbinging freshwater, then becomes more salty bc the atlantic water brings in the high salinity water and then it kind of decreases but not rlly after in the artic bottom water
The artic sea ice melts from the bottom creating that layer of low salinity water at the top
oceans water masses (artic)
§ Water mass: large volume of water with unique properties of temp, salinity and density that extends horizontally over thousnds of km
§ There is a polar mixed layer
§ Pacific halocline on the bering strait side for the canada basin
□ Used to bring in no water during ice age
§ There is an atlantic halocline from the fram straight that extend over the canada basin and the amunden basin
§ Then there is atlantic water from the fram straight going all over
§ And then tehre is the artic deep water all over
§ All oceans are structured by water masses § 3 water masses occur in canada basin of the artic ocean: □ Artic/polar water □ Atlantic water □ Artic bottom water § Frshwater input can have a major oceanographic and biological role in localised areas and this is changing Ex. Mckenzie water brings in freshwater
Osmoregulatoon
○ Homeostatis - maintain osmotic balance
§ Osmoconformers - make body fluids isotonic to seawater
§ Osmoregulators - actievly regulate the amount of salts or water in the body
§ Sharks are an example of osmoconfomers - sharks blood is isotonic (or slightly hypertonic (more saline)) to seawater § Osmoregulation: □ Marine mammals regulate osmotic balance via renal system (get most water from their diet) □ Fish and crustaceans are hypotonic, they excrete excess salt and take in water trhough gills (water leaves them bc they have less saline)
Elasmobranch (osmoocnfmers)
□ Type of shark
□ Osmoconformers - maintain body fluids that are isontinc to sea water
□ Urea - produced as a waste product, stored in blood to inc ionic conc closer to that of seawater
□ Trimethylamine N oxide (TMAO) - counters the destablizing efefct urea (and pressure) has on enzymes
□ Greenland shark (somniosus microcephalus):
® Longest lived vertebrate - 300-500 years (slow moving)
® Live in deep (2000+m) cool waters
® High concentration of trimethlamine oxide in msucle tissues
® Made into an icelandic dish - prepared by buring a cleaned shark carcass and letting it ferment for 6-12 weeks and then cutting it into strips and allowed to dry for months (high cocn makes meat toxic)
Teleosts (osmoregylators)
□ Bony fishes
□ Osmoregulators - maintain body fluids that are hypoonic to seawater (less salt in them)
□ Chlroide pumps in gills - actievly pump chlroide ions out against a conc gradient
□ Kidneys - excrete urea, retain water
□ Diadromous fish - move between the marine and freshwater envrinments
Their systems must be able to switch between the two
Osmolytes
□ Organic substitute for inorganic ions - allows regylation of cell volume and maintanece of inorgnaic ion conc
□ Free aa used by many invertebrates, basteria, hagfishes - use unchaged aa that have little effect on protein functions (ex. Taurine or glycine)
□ Urea used by sharks
□ Glycerol, mannitol, sucrose used by seaweeds, uncellular alage
Done when u don’t want to use salt for osmolatirtty
Birds and reptiles
□ Cells lining the salt gland atcievly transport NaCL out of the blodo and into the ducts where its secreted out of the nostrils or mouth (osmoregulatorn)
