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

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