Lecture 8 Flashcards
Humans and other mammals can tolerate how much dehydradtion
~12-14%
Most organisms are what percent in water?
50-90%
Water budgets - aquatic organisms
Water (internal) = Water gain (drinking) - Water loss (secretion) + or - Water (osmosis)
Salinity in aquatic systems
Freshwater - 5 ppt
Estuaries - 10-25 ppt
Oceans - 35 ppt
Lakes - 1-400 ppt
What’s Diffusion
movement of soluble salts or water due to random movement of particles (down a concentration gradient)
What’s Osmosis
Similar to diffusion but involves movement across a semipermeable membrane
What’s Hypoosmotic
low solute concentration, high water concentration
- prefix relates to [solute]
What’s Hyperosmotic
High solute concentration, low water concentration
- prefix relates to [solute]
What’s Isosmotic
same solute and water concentration
- prefix relates to [solute]
- iso means equal
- most marine fish and invertebrates
Osmolarity
Refers amount of solute/water in an organism in relation to its environment
Hypoosmotic (some) marine organisms
- internal [salt] is lower and [water] is higher compared to environment
- risk dehydration and surplus salt intake through gills, therefore drink constantly, low urination rates, excess salt excreted through specialized chloride cells
Most Freshwater organisms are hyperosmotic
- internal [salt] is higher and [water] is lower compared to environment
- risk is too much water enters organism
- solution: produce high amounts of dilute (minimize salt loss) urine
Relationship between [salt] and [water]
- inverse relationship, if water is moving in, salt is moving out and vice versa
- high salt conc. equals low water conc. and vice versa
What’s Acclimation
It’s a reversible physical change due to an organism being placed in a new environment
What’s Anadromous
- Fish born in fresh water, spend most of its life in the sea, returns to freshwater to spawn
- i.e. salmon, striped bass