Aquatic.pdf

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%.  The Hydrologic Cyc...

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%.  The Hydrologic Cycle Distribution of water is not static: ❖ Heat ❖ Evaporation ❖ Clouds ❖ Precipitation  The Hydrologic Cycle Turnover time is the time required for the entire volume of a reservoir to be renewed. ❖ Atmosphere 9 days ❖ Rivers 12-20 days ❖ Oceans 3,100 years  Freshwater Ecosystems Lotic Ecosystems (rivers and streams) ❖ flowing water ❖ greater interaction with surrounding terrestrial habitat Lentic Ecosystems ❖ still water (lakes and ponds) ❖ significant seasonal changes Dimensions of Stream Structure The River Continuum Concept (RCC) Lake Structure Seasonal Temperature Changes  Marine Ecosystems Marine Shores ❖ Intertidal Zone ❖ Coastal Wetlands Shallow Marine Waters ❖ Reefs and Kelp Beds Open Ocean ❖ Photic Zone ❖ Aphotic Zone  Marine Shores Intertidal Zone can be divided vertically: ❖ Supratidal Fringe: Splash zone. ❖ Upper Intertidal: Covered only during highest tides. ❖ Lower Intertidal: Uncovered during lowest tides. ❖ Subtidal: Covered by water even during lowest tides. Intertidal Zonation  Estuaries, Salt Marshes, and Mangrove Forests Estuaries are found where rivers meet the sea. Salt Marshes and Mangrove Forests are concentrated along low-lying coasts. ❖ All driven by ocean tides and river flow. ❖ Transport organisms, nutrients, oxygen, and remove wastes. Salt Marshes and Mangrove Forests  Shallow Marine Waters Reef Categories ❖ Fringing reefs: Hug shore of continents. ❖ Barrier reefs: Stands between open sea and lagoon. ❖ Coral atolls: Coral islets built up from submerged ocean island. Kelp Beds ❖ Structure similar to terrestrial forests. ❖ Canopy at water’s surface.  Shallow Marine Waters Reefs and kelp beds both grow in surface waters with sufficient light for photosynthesis. ❖ Both limited by temperature. Currents deliver oxygen and nutrients, and remove waste products. Reefs and kelp beds among most productive and diverse ecosystems. Coral Reefs - Types  Deep Blue Sea - Physical Conditions Light ❖ Approximately 80% of solar energy striking the ocean is absorbed in first 10 m. ▪ Very little, if any penetrates past 600 m. ▪ Leaves approximately 3,400 m of water without sunlight.  Deep Blue Sea - 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. Oceanic Circulation