Aquatic Ecology Aquatic Biomes There are two types of aquatic biomes: Marine biomes include estuaries, coastal wetlands, coral reefs, the oceanic zone, and polar ecosystems Freshwater biomes include lakes/ponds, rivers/streams, and inland wetlands Aquatic Organisms Both freshwater and marine ecosystems share major types of organisms: – plankton are free-floating organisms which have such weak swimming ability that they are at the mercy of the prevailing water movement • phytoplankton are capable of photosynthesis while zooplankton are animals – nekton are organisms capable of sustained locomotion against the prevailing water movement – benthos are bottom-dwelling organisms without the need for swimming Limiting Factors The types and numbers of organisms in aquatic environments depend on temperature, access to sunlight, dissolved oxygen, and availability of nutrients such as carbon (CO2), nitrogen (NO3-), and phosphorus (PO43-) Marine Biomes Saltwater oceans cover about 71% of the earth’s surface. The oceans are essential for regulating global temperature and climate. There are about 250,000 known species of marine plants and animals. There are two major marine zones: – the neritic zone extends to the edge of the continental shelf and contains 90% of all marine species – the oceanic zone includes all waters Bluefin Tuna Thunnus thynnus beyond the continental shelf. Estuaries An estuary is a partially enclosed area of coastal water where seawater mixes with freshwater. – Constant water movement from tides and currents provide for a nutrient- rich environment with a wide range of temperature and salinity Coastal Wetlands Coastal wetlands are areas of coastal land that are covered with saltwater all or part of the year Wetlands are incredibly important because they filter water, protect shorelines from erosion, and provide feeding and breeding grounds for many organisms Types of Coastal Wetlands marshes are freshwater or estuarine wetlands dominated by grasses bogs are inland freshwater wetlands dominated by mosses swamps are freshwater, estuarine, or marine wetlands dominated by trees mangrove swamps are tropical communities dominated by halophytic (adapted to grow in saline conditions) trees Coral Reefs Coral reefs are massive colonies of coral polyps living in a secreted skeleton of calcium carbonate (limestone - CaCO3). – most coral (phylum Cnidaria) is in a mutualistic symbiosis with zooxanthellae, which are single- cell algae. Coral reefs are among the oldest and most productive ecosystems in the world, but grow at only one-half centimeter per year. Coral Reefs The biggest threat to coral reefs is the deposition of eroded soil. This is the primary cause of bleaching, in which the coral becomes stressed and expels the zooxanthellae. Other stresses to coral include increased UV radiation, global warming, and runoff of pesticides, fertilizers, and industrial chemicals The Oceanic Zone Divisions of the oceanic zone: – epipelagic: 0-200 m, this the photic zone (lighted) – mesopelagic: 200-1,000m – bathypelagic: 1,000-2,000 to 4,000 m, 10oC to 4oC (benthic zone is the bathyal zone) – abyssalpelagic: to a depth of 6,000 m, overlying the plains of the major ocean basins (benthic zone is the abyssal zone) – hadalpelagic: 6,000-10,000 m, includes the open water of deep trenches (benthic zone is the hadal zone) While polar bears, Ursus maritimus, do not eat plankton, the largest The Oceanic Zone part of their diet is fish which do The Oceanic Zone is one of the least productive of all ecosystems, because light penetrates only the surface waters. Polar Ecosystems Polar Caps are considered marine ecosystems because the primary food source is plankton – the Arctic Ocean is rich in nutrients from surrounding land masses – the Antarctic is not as rich in nutrients, lacking the Whale Shark, Tiburon ballena surrounding land masses Freshwater Biomes Freshwater life zones occur where water with a salinity of less than 1 ppt accumulates on or flows through the surfaces of terrestrial biomes. – lentic systems are standing, such as lakes, ponds, and inland wetlands – flowing systems are moving, such as streams and rivers. Lakes and Ponds Lakes are large bodies of standing fresh water, formed when precipitation, runoff, or groundwater seepage fills depressions in the earth’s surface. Lakes normally consist of four major zones: – the littoral zone is the shallow area near the shore to the depth at which rooted plants stop growing – the limnetic zone is the open, sunlit water surface layer away from the shore that extends to the depth penetrated by sunlight – the profundal zone is the deep, open water where it is too dark for photosynthesis – the benthic zone is the bottom of the lake Lakes and Ponds Seasonal changes occur in temperate lakes, causing an overturn of the water column. During the summer and winter, the water becomes stratified into different temperature layers, separated by a thermocline. In the fall and spring, the waters at all layers mix in overturns that equalize the temperatures at all depths. Streams and Rivers The entire land area, which delivers water, sediment, and dissolved substances to a stream or river is called a watershed, or a drainage basin. A river system is a series of different ecosystems because of different environmental conditions in each of three zones: – The source zone contains the headwaters of the river. This zone typically has cold, clear, highly oxygenated water. – In the transition zone, the headwater streams merge to form wider, deeper streams. The warmer and slower moving water supports more biodiversity, particularly phytoplankton. – The flood plain zone joins streams into wider and deeper rivers that meander across broad, flat valleys. This area supports the greatest number of both plant and animal species. Inland Wetlands Inland wetlands include marshes, swamps and bogs along with seasonal wetlands (ex.floodplain wetlands, prairie potholes). These are important for three main reasons: – provide food and habitat for fish, migratory waterfowl, and other wildlife – filter, dilute, and degrade toxic wastes, excess nutrients, sediments, and other pollutants from runoff – reduce flooding and erosion by absorbing overflows of streams and lakes Water Cycle The overall amount of water on the Earth stays about the same. The water cycle is a process of water movement between the Earth’s surface and the atmosphere. The sun provides the energy that drives the water cycle. Heat from the sun evaporates water from the ocean, lakes, rivers, soil, plant leaves, and body of organisms. Water vapor cools in the atmosphere it condenses and forms droplets in clouds. When clouds meet cold air the water returns to the Earth as precipitation. Precipitation is rain, sleet, and snow. Where does most precipitation fall? Ocean – Earth is 71% Ocean. Water which falls on land and soaks into the soil and rocks until it reaches a layer of rock or clay where it can’t go down any further. This layer of water is called groundwater. How much water is on the Earth? 71% of the Earth is covered with water. The problem is 97% of the water on Earth is salt water and only 3% is fresh water. Of the 3% fresh water about 77% is frozen in the polar icecaps. Water we use for our everyday needs comes from surface water and groundwater. Surface Water All fresh water that is above ground is called surface water like ponds, lakes, streams, and rivers. The area of land that is drained by a river is called its watershed. Groundwater The water that seeps underground is called groundwater. Water percolates through the soil and to the rock below. Large areas of groundwater found in underground rock formations called aquifers. It takes millions of years to form an aquifer. Porosity Porosity is the amount of space between the particles that make up a rock. Rocks which allow water to flow through it are called permeable. The recharge zone is the area of land where the groundwater originates to form an aquifer. The problem is people are pumping water out of the aquifer faster than it can be replaced naturally. Ogallala Aquifer The largest aquifer in the United States is the Ogallala Aquifer which is losing water very quickly and some communities which have used this water are now using other sources. A hole which is drilled or dug to reach groundwater is a well. Water Use and Management Most water must be treated to make it safe to drink or potable. Pathogens are disease causing organisms which can be found in water. Chlorine is added to drinking water to prevent bacteria from growing. Industry uses 19% of water in the world. To manufacture goods, dispose of waste, and generate power. Who uses the water? Highest % of industrial water use occurs in Europe and North America. Agriculture uses 67% of the water in the world. by irrigation. Water management projects bring water to dry habitats for recreation, drinking, or for electricity. Conflicts over control of water has been a problem all over the world and as our need for fresh water increases so will the problem of water rights. Solutions to Water Shortages We need to develop new sources of fresh water. We need to practice conservation. Low flow shower heads and toilets. Xeriscaping is landscape designing that requires minimal water use. Problems The problem with desalinization today it is very expensive. Another possible solution is the towing of water from one place to another. Saudi Arabia is conducting experiments on towing icebergs. Problem with towing icebergs they are hard to tow, melt rapidly, and are difficult to transport on land. The removal of large amounts of ice will disrupt the polar ecosystem.
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