Water. Earth’s Hydrosphere Hydrosphere = all the parts of the earth that are made up of water –Oceans, Lakes, Rivers –Underground water, clouds.

Water

Earth’s Hydrosphere• Hydrosphere = all the parts of the earth

that are made up of water – Oceans, Lakes, Rivers– Underground water, clouds

The Hydrosphere• More than 70% of

Earth’s surface is covered by water.

• > 97% of the

hydrosphere is salt water – Oceans– Salt Lakes (Great Salt

Lake in Utah)

• Salt water = Water that contains dissolved salts – 35 g of salt/liter of ocean

water

Fresh Water• Less dissolved salt

than salt water

• Lakes, ponds, streams & underground water

• <3% of the hydrosphere – >2/3 = frozen glaciers

and ice caps

Fresh Water• Surface water = water in lakes, streams, and

rain runoff• Ground water = found beneath the surface of the

earth – Moves more easily through rock layers that are

porous – Aquifer = an underground layer of porous rock that

contains water

Aquifers• Sometimes flow between two

layers of rock that water cannot seep through

• Pressure accumulates – Water pressure – Weight of rock layer above

water

• Artesian Wells = wells in which water flows to the surface due to high pressure

• Water contained in aquifers is replenished very slowly

Aquatic Biomes

Aquatic Biomes• Water covers more than 70% of earth. • Aquatic Habitat = a habitat in which

organisms live in or on water.

Aquatic Biomes• Not grouped

geographically the way that terrestrial biomes are

• Aquatic biomes are: – Scattered– Determined by

depth rather than location

Abiotic Factors

• Abiotic factors which determine aquatic biomes and terrestrial biomes are not the same

• Abiotic factors in terrestrial biomes: – Temperature – Rainfall

Abiotic Factors: Aquatic Biomes• Amount of dissolved salts in the water• Depth of the water • Rate of water flow• Amount of dissolved oxygen in the water

Salinity• Aquatic biomes can be divided into two main groups

based on the amount of dissolved minerals in the water. – Saltwater– Freshwater

• All water contains some dissolved salts and other minerals. – Saltwater contains more than freshwater.

Salinity

• Salinity = the amount of dissolved salts in a sample of water.

– Measured in parts per

thousand or parts per million (ppm)

– Ocean water = 30 parts per thousand

– Freshwater = < .5 parts per thousand

Salinity

• Brackish Water = water that is more saline than freshwater but less saline than ocean water.

– Common in river

deltas and coastal marshes

– Where fresh water meets the ocean

Ex: Where the Mississippi River meets the Gulf of Mexico

Freshwater Salinity• Lakes, Ponds,

Rivers

• Exceptions = hypersaline (more saline than the ocean!) lakes – Great Salt Lake in

Utah, Mono Lake in California

– 40 parts per thousand

Salinity vs. Density

• Saltwater is denser than fresh water:

– Salinity is tested using a hydrometer

– Measures buoyancy (how much mass can float on the water)

Temperature vs. Density • Warm water is

less dense than cooler water

– Water temperatures decrease & density increases at lower water depth zones

Depth• Ecosystem is greatly influenced by the

amount of sunlight that penetrates to the bottom. – Determines the type of plants that grow– Remember: producers (includes plants) form

the base of the food web!

Depth Zones• Photic Zone = the top

layer of water, which receives enough sunlight for photosynthesis to occur– Depth of the photic

zone depends upon the turbidity of the water

– Open ocean - photic zone = up to 200 m deep

Depth Zones• Aphotic Zone = below the photic zone,

sunlight never reaches the aphotic zone– Only found in the ocean and deep lakes

Depth Zones• Benthic Zone = The floor of a body of water

– Ocean = supports microscopic decomposers & scavengers

– Shallow freshwater = sunlight allows insect larvae, snails, catfish and turtles to survive