Life In Water - Chapter 3 PDF

Life in Water Chapter 3 1  The Hydrologic Cycle Over 71% of the earth’s surface is covered by water: ❖ Oceans contain 97%. ❖ Polar ice caps and glaciers contain 2%. ❖ Freshwater in lakes, streams, and ground water make up less than 1...

Life in Water Chapter 3 1  The Hydrologic Cycle Over 71% of the earth’s surface is covered by water: ❖ Oceans contain 97%. ❖ Polar ice caps and glaciers contain 2%. ❖ Freshwater in lakes, streams, and ground water make up less than 1%. 2  Aquatic Life Zones Aquatic life zones are classified into two major types: Saltwater/Marine (>3.5% salts) ▪ Oceans ▪ Estuaries (Actually a mix of freshwater and saltwater – Known as Brackish) ▪ Coastal Wetlands ▪ Shorelines ▪ Coral Reefs ▪ Mangrove Forests 3  Freshwater – Less than 1% salt concentration ▪ Lakes ▪ Ponds ▪ Rivers ▪ Streams ▪ Inland Wetlands Aquatic biomes are often determined by nutrients, light, salinity and depth of the water, as opposed to precipitation and temperature (terrestrial/land biomes). 4  Limiting factors in Deep Marine water- Physical Conditions Light ❖ Approximately 80% of solar energy striking the ocean is absorbed in first 10 m. ▪ Very little, if any penetrates past 200 m. Leaves approximately 3,800 m of deep black water with only light produced by bioluminescence. 5  Deep Marine water- Physical Conditions Temperature ❖ Sunlight increases velocity of water. ▪ Rapid motion decreases density, thus warm water floats on top of cooler water. ❖ Thermocline: Layer of water through which temperature changes rapidly with depth. ▪ Creates thermal stratification. Block nutrients mixing from lower to upper layer of water…. Reduce productivity 6  Deep Marine water- Physical Conditions Water Movements ❖ Oceans are never still. ▪ Wind-driven surface currents across open ocean create gyres that move right in the Northern Hemisphere and left in the Southern Hemisphere. ▪ Deepwater currents cause upwelling. 7  Deep Marine water- Chemical Conditions Salinity ❖ In the open ocean, salinity varies from about 34 ppt to 36.5 ppt. ▪ Lowest salinity occurs near equator where precipitation exceeds evaporation. ▪ Highest salinity occurs in subtropics where evaporation exceeds precipitation. 8  Deep Marine water- Chemical Conditions Oxygen ❖ A liter of air contains about 200 ml of oxygen at sea level, while a liter of seawater contains a maximum of 9 ml of oxygen. ▪ Typically concentration is highest near ocean surface, and decreases with depth. Minimum usually < 1,000m. 9  Deep Marine water- Biology Photosynthetic organisms are limited to upper epipelagic zone (Photic zone). ❖ It has both phytoplankton and zooplankton. ❖ Due to size, oceans contribute ¼ of total photosynthesis in the biosphere. Plankton are microscopic algae, plants, and other organisms that float on the surface of water biomes. Chemosynthesis occurs near undersea hot springs. 10  Aquatic Biomes (marine and freshwater) Phytoplankton are important producers in water biomes. They are the first step in many aquatic food chains 11  Marine biomes Oceans ❖ Can be divided into 2 main life zones 1. Photic zone- sunlight penetrates 2. Aphotic zone- NO sunlight 12 13  Photic Zone- above 200m Made up of the euphotic Sunlight penetrates Plant life and animal life is abundant 14  Aphotic Zone- below 200m Sunlight DOES NOT penetrate There are no plants Animal life is highly specialized 15  Aphotic Zone- below 200m Many of the living organisms of the deep ocean have a special adaptation known as bioluminescence 16  Marine biomes Estuaries ❖ Area where a river meets an ocean ❖ Located near coastlines, border land ❖ Nutrient levels are higher than both salt and freshwater ❖ 17 18  Coral Reefs Coral reefs - limestone ridges found in tropical climates and composed of coral fragments that are deposited around organic remains Coral reefs among the most diverse ecosystems on Earth ❖ thousands of species of plants and animals live in the cracks and crevices of coral reefs Corals are predators that use stinging tentacles to capture small animals, such as zooplankton, that float or swim close to the reef 19 20  Coral Reefs Corals live only in clear, warm salt water where there is enough light for photosynthesis. 21  Saltwater Seashores ❖ Tides have a huge influence on life here ❖ INTERTIDAL ZONE- portion of the shoreline that is covered with water at high tide and exposed to the air at low tide. 22  Intertidal Zone Can be sandy or rocky Small fish, clams, crabs, other mussels are trapped in the TIDAL POOLS during low tide 23 Intertidal Zone 24  Freshwater Biomes Type of Standing Abiotic Factors Biotic Factors Water Ecosystem Lake Deepest; may have Floating algae; shoreline aphotic zone plants; complex food webs Pond Fed by rainfall; may be Plants/algae in benthic seasonal; photic & zone; simpler food web benthic zone (than lake) Marsh Shallow; saturated soil; Roots under water, leaves hypoxic (anaerobic); above water; benthic FW, SW, brackish; tidal animals; grasses & cattails Swamp Low drainage; hypoxic; Large trees/shrubs; saturated soil; flat Cyprus, Willow, dogwood 25  Freshwater Biomes Freshwater contains little or no salt, so it has a LOW salinity. ❖ Flowing freshwater = rivers and streams ❖ Still Freshwater = lakes and ponds Streams ❖ The faster a stream flows the greater the amount of dissolved oxygen in it. 26  Freshwater Biomes Rivers ❖ Water moves slower in a river and debris settles on the bottom. ❖ Because of this, rivers tend to have more nutrients and less dissolved oxygen. 27  Freshwater Ponds ❖ Small, shallow bodies of water ❖ Sunlight penetrates all the way to the bottom ❖ Most completely filled with plant material ❖ Very high amount of nutrients 28  Freshwater Ponds 29  Freshwater Lakes ❖ Larger and deeper than ponds ❖ Plant growth is limited to the shoreline ❖ Sunlight does NOT penetrate to the bottom= no plants after a certain depth! 30  Freshwater Lakes 31  Ponds/Lakes: Temperature Temperature varies seasonally in ponds and lakes, warmer in the summer colder in the winter. Surface water is generally warmer than deeper water. Between these two layers is the thermocline, an area of rapid temperature change. 32  Deep Blue Sea - Structure Littoral Zone (intertidal zone): Shallow shoreline. Neritic Zone: Coast to margin of continental shelf. 33  Deep Blue Sea - Structure Oceanic Zone: Beyond continental shelf. Pelagic: Habitat off the bottom of the ocean. ❖ Epipelagic 0 - 200 m ❖ Mesopelagic 200 - 1,000 m ❖ Bathypelagic 1,000 - 4,000 m ❖ Abyssal 4,000 - 6,000 m ❖ Hadal 6,000 + m Benthic: Habitat on bottom of ocean. 34 35 36