APES_Chapter_6_Aquatic_Biodiversity - Chapter 6 Chapter...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Chapter 6 Chapter Aquatic Biodiversity AP Environmental Science Edinburg North High School Chapter 6: Aquatic Biodiversity Chapter Focus Questions: • What are the basic types of aquatic life zones, and what factors influence the kinds of life they contain? • What are the major types of saltwater life zones, and how do human activities affect them? • What are the major types of freshwater life zones, and how do human activities affect them? Core Case Study: Core Why Should We Care about Coral Reefs? • Coral reefs – – – Warm coastal waters Marine equivalents of tropical rainforest (Fig. 6-1a) Polyps (jellyfish relative), CaCO3, symbiotic symbiotic zooxanthellae zooxanthellae – 0.1% of world’s ocean area • Ecological and economic services – – – – – – Moderate atmospheric temperature Natural barriers protective 15% of world’s coastline Provides habitats for marine organisms Produce one-tenth of global fish catch Building materials for poor countries • Conservation – 20% of the world’s coral reefs lost to coastal 20% development, pollution, overfishing, warmer oceans, and other stresses oceans, – Another 30% will be lost in next 20-40 yr – Coral bleaching, linked to warmer water and Coral silt from land (Fig. 6-1b) silt I. Aquatic Environments I. • The Water Planet: Saltwater and Freshwater – Oceans cover 71% earth’s surface, freshwater < 1% (Fig. 6-2) – Major types of organisms determined by salinity. Major salinity – Aquatic life zones classified into two major types: • Marine, or saltwater, iincludes estuaries, coastlines, coral reefs, or saltwater ncludes coastal marshes, mangrove swamps, and oceans. coastal • Freshwater, iincludes lakes, ponds, streams, rivers, and inland ncludes wetlands. wetlands. – Distribution of the worlds major saltwater oceans, coral Distribution reefs, mangroves and freshwater lakes and rivers reefs, (Fig. 6-3) – Play vital roles in ecosystems and human Play systems systems • • • • • • • Biological productivity Climate Biogeochemical cycles Biodiversity Fisheries: fish and shellfish Oil, natural gas, and minerals Recreation and transport routes • What kinds of organisms live in aquatic life What zones? zones? – Plankton • • • Phytoplankton Zooplankton Ultraplankton – Nekton – Benthos – Decomposers • Life in Layers – Three main layers: surface, middle, and bottom – Factors that determine the distribution and Factors abundance of organisms: abundance • Temperature, light, DO, nutrients – Photosynthesis confined to upper layer, or Photosynthesis euphotic zone. euphotic • Depth depends on water clarity. – Nutrients (nitrates, phosphates, iron, and others) Nutrients more limited in open ocean. more • Upwellings (see Suppl. 10) however has high NPP. – Most deep bottom organism depend on dead Most debris that falls to the bottom. debris II. Saltwater Life Zones II. • Why should we care about the oceans? – They provide many important ecological and They economic services (Fig. 6-4). economic – We know less about the oceans and We freshwater systems than we do about the surface of the moon. surface • Further study could yield immense ecological and Further economic benefits. economic • The Coastal Zone: Where Most of the Action is – Two major life zones: coastal and open ocean ( Fig. 6-5). – Extends from high tide mark to end of continental Extends shelf. shelf • Relatively shallow, nutrient-rich • Numerous interaction with land, so easily affected by Numerous human activities. human – Only 10% of the world’s ocean area, but contains Only 90% of marine species 90% – Site of most large commercial fisheries – High NPP because of ample nutrients and High sunlight. sunlight. • Estuaries and Coastal Wetlands: Centers of Estuaries Productivity Productivity – Estuary – area where rivers meet the sea • Seawater mixes with freshwater along with nutrients Seawater and pollutants (Fig. 6-6) and – Coastal wetlands – coastal land areas covered with water all or part of the year with • River mouths, inlets, bays, sounds, and salt marshes ( Fig. 6-7; iin temperate areas) and mangrove forests in n tropical zones (in tropical areas). tropical • Significant daily and seasonal changes in tidal and Significant river flows, and land runoff of sediment and other pollutants pollutants – Estuaries and coastal wetlands very productive – Mangrove forests are the tropical equivalents of Mangrove salt marshes. salt • 70 % of gently sloping sandy and silty coastlines in 70 tropical and subtropical regions. tropical • Mangrove trees can grow in saltwater (Fig. 6-8). • Systems provide important ecological and economic Systems services services – – – – Filter toxic pollutants, excess nutrients, and sediments. Reduce storm damage Provide food, habitats, and nursery sites Intact mangroves worth $200,000-$900,000/km2 • Based on sustainable fishing and fuel wood use; does Based not include ecological services. not • 10-45x more worth than when cleared for aquaculture • Protecting mangrove forest cost only $1000/km2 • More than a third of the world’s have been destroyed. – For shrimp farms, crops, and coastal development – Bangladesh and the Philippines have lost almost ¾ • Rocky and Sandy Shores: Living with the Rocky Tides Tides – Gravitational pull from the sun and the moon Gravitational causes tides to rise and fall every 6 hours (depending). (depending). – Intertidal zone – area of the shoreline between low and high tides. between – For an organism, lots of physical and For physiological stress. physiological • Crashing waves • High and low tides – periodic immersion and High emersion emersion • Changing levels of salinity – Rocky shores (Fig 6-9a) • Are pounded by waves • Numerous pools and other niches in the intertidal Numerous zone zone • Remarkable number of niches in response to daily Remarkable and seasonal changes in and – – – Temperature Water flow Salinity Salinity – Barrier beaches, or Sandy Shores (Fig. 6-9b) or Sandy • Gently sloping shores • Many critters burrow into the sand • Variety of shorebirds with specialized feeding niches Variety (Fig. 4-8) (Fig. – Barrier Islands (Fig. 6-10) • Low, narrow, sandy islands that form offshore from Low, a coastline. coastline. • Prime targets for development – Examples: Atlantic City, NJ; Palm Beach, FL; South Examples: Padre Island, TX Padre – Development prone to destruction from mother nature • Flooding, beach erosion, and hurricanes – According to climate models many of the world’s barrier According islands may be under water by end of century. islands • Undisturbed barrier islands – One or more rows of sand dunes – Dunes act as a line of defense against storm surges – Development disrupts these natural barrier island Development formations formations • “People inaccurately call these human-influenced People events ‘natural disasters’.” events • Threats to Coral Reefs: Increasing Stresses – Coral reefs found in clear,warm tropical and Coral subtropical waters subtropical • Thrive in clear, warm, fairly shallow water of constant Thrive salinity. salinity. • Temperature range (18–30 oC); bleaching can be 30 C); triggered with an increase of just one degree. triggered – One-fourth of all marine species (Fig. 6-11) • Biodiversity can be reduced by: – – – – Severe storms Freshwater floods Invasion of predatory fish Human activities (Fig. 6-12) – Loss of Coral Reefs • 20% are so damaged that they are unlikely to 20% recover recover • By 2050, 30-50% could be lost due to climate By change, habitat loss, pollution, and overfishing change, • Only 300 of 6000 reefs are protected (at least on Only paper) paper) – Ecology and Economy 21 • Worth an estimated $100,000-$600,000 km--2 y--1 from small-scale sustainable fishing, tourism, and pet trade. trade. – Does not include ecological services – If included, much cheaper to protect than to use them If unsustainably unsustainably – There is evidence that coral reefs can recover. • • protection by restricted fishing reducing inputs of nutrients and other pollutants • Biological Zone in the Open Ocean: Light Biological Rules Rules – Open sea – at edge of continental shelf. – Divided into three vertical zones depending on Divided light availability (Fig. 6-5) light – Euphotic zone – brightly lit upper zone • • • • Phytoplankton carry out photosynthesis Nutrients low except at upwellings DO high Populated with fast-swimming predatory fish – Bathyal zone – dimly lit middle zone • No photosynthesizers • Zooplankton and smaller fish – Migrate to surface to feed at night. – Abyssal zone – lowest zone, dark and very cold, and has little DO cold, • Contains enough nutrients to support a large Contains number of species number • Ocean floor is complex – Mid-Atlantic Ridge – Canyons – Trenches deeper than the height of Mt. Everest • Food rains from above, called marine snow Food marine – Deposit feeders – Filter feeders – Average productivity and NPP per unit area is Average low except at equatorial upwellings low • Absolute productivity is large because ocean Absolute covers large area. covers • Productivity increase as latitude increases. • Effect of Human Activities on Marine Effect Systems: Red Alert Systems: – Humans have an affinity for the coast – Ecological and economic services being Ecological degraded or destroyed (Fig. 6-13) degraded – In 2006, 45% of world’s pop. and more than In half in the US lived near the coast half – By 2010, 80% projected to live near the coast III. Freshwater Life Zones III. • Freshwater Systems – 1% of earth’s surface – Lentic, or standing: lakes, ponds, and inland or wetlands. wetlands. – Lotic, or flowing: streams and rivers – Ecological and economic services (Fig. 6-14) • Lakes: Water-Filled Depressions – Large natural standing bodies of standing Large freshwater formed from precipitation, runoff, and groundwater seepage. groundwater • Causes of depressions: – Glaciation, crustal displacement, and volcanic activity – Water supplied by rainfall, melting snow, and Water streams streams – Vary tremendously in size, shape and nutrient Vary availability availability – Four distinct zones defined by depth and Four distance from shore (Fig.6-15) distance • Littorral zone – Shallow, near shore to depth rooted plants cannot grow – Most productive zone – Biodiversity high: algae, rooted plants, turtles, frogs, Biodiversity crayfish, bass, perch, carp crayfish, • Limnetic zone – – – – Open sunlit layer away from shore Main photosynthetic body of the lake Primary organism: phyo- and zooplankton Large fish inhabit this zone, move into littoral zone to feed Large and reproduce and • Profundal zone – Open water where it is too dark for photosynthesis – Fish adapted to lakes cooler, darker and lower oxygen Fish levels levels • Benthic zone – Bottom of the lake – Decomposers, detritus feeders, and fish that move from one Decomposers, zone to another. zone – Nourished from limnetic and littoral, and sediments that Nourished wash in wash – Thermoclines form in winter ad summer, but mix Thermoclines in the fall and spring. in • These overturns mix the water equalizing These overturns temperature, taking oxygen to the bottom, and nutrients to the top. nutrients • Effects of Plant Nutrients on Lakes: Too Much of a Effects Good Thing Good – Lake classified according to their nutrient content and Lake primary productivity. primary • Oligotrophic – poorly nourished (Fig. 6-16a) – – – Newly formed, deep, steep banks Low NPP ⇒ clear water Low Small populations of phytoplankton and fish (e.g., smallmouth bass Small and trout) and • Eutrophic – well-nourished (Fig. 6-16b) – Excessive phosphates and nitrates ⇒ high NPP Excessive – Sediments, organic material, and inorganic nutrients have washed Sediments, in in – Plant growth and decomposition – Typically shallow, murky brown or green w/ poor visibility • Cultural eutrophication • Many lakes are mesotrophic Many mesotrophic • Freshwater Streams and Rivers: From Freshwater Mountains to the Oceans Mountains – Surface water – precipitation that does not Surface sink into the ground or evaporate. sink – Runoff – surface water that flows into streams – Watershed, or drainage basin – land area that Watershed, delivers runoff, sediment, and dissolved substances into a stream. substances – Most streams begin in elevated areas (e.g., Most mountains, hills) mountains, – Flow from a mountain can be divided in to three different Flow life zones (Fig. 6-17): life • Source zone (or headwaters) – Usu. Shallow, cold, clear, and swiftly moving ⇒ high O2 Usu. – Low production ⇐ lack of nutrients and phytoplankton Low – Nutrients mostly from once living material (leaves, branches, Nutrients insects) insects) – Plants, algae and mosses that attach to rock – Fish and other animals have compact or flattened bodies to live Fish under stones under • Others with streamlined, muscular bodies to swim in strong Others currents. currents. • Transition zone – – – – Merging of headwaters forming wider, deeper, and warmer streams Gentler slopes with fewer obstacles Higher turbidity, slower moving, less oxygen More phytoplankton, and cool and warm-water fishes with less More oxygen requirements. oxygen • Flood plain zone – Streams join into wider, deeper rivers that flow across broad, Streams flat valleys flat – Water usu. w/ higher temp and less DO – Support large populations of producers: algae, Support cyanobacteria, and rooted aquatics along the shore cyanobacteria, – Muddy and contains high concentration so suspended silt – Main channels support distinctive varieties of fish (e.g., carp Main and catfish) and – Backwaters support species similar to lakes – Mouth of river may be divided in to many channels as is Mouth flows through the delta flows • Sediments deposit here and in the coastal wetlands and Sediments estuaries. estuaries. – Coastal deltas, wetlands and inland floodplains Coastal are important parts of earth’s natural capital. are • Relatively high diversity and productivity • Absorb floodwater and protect against tropical storms Absorb and tsunamis and – Human activities have degraded or destroyed Human the natural protection of coastal surface formations formations • Hurricanes, typhoons and tsunamis become partially Hurricanes, unnatural disasters (see Case Study, p. 140) unnatural – Streams shape the land over which they pass. – Watershed must be the focus when we wish to Watershed protect streams and rivers from excessive inputs of nutrients and pollutants. of • Freshwater Inland Wetlands: Vital Sponges – Inland wetlands – lands covered with freshwater all or part of the time, excluding lakes, reservoirs, and streams, located away from coastal areas. and • • • • • Marshes Swamps (Fig. 6-18) Prairie potholes Floodplains Arctic tundra in summer – When a wetland is dry, a wetland may be When recognized by soil composition and certain plants. plants. – Highly productive – Habitats for game fish, muskrats, otters, Habitats beavers, migratory waterfowl, and other birds beavers, – Inland wetlands provide free ecological and Inland economic services. economic • Filter and degrade toxic wastes and pollutants – In US, worth at least $1.6 billion/yr • Reduce flooding and erosion by absorbing and Reduce releasing stormwater slowly, and by absorbing overflows from streams and lakes overflows – In US, worth $3-4 billion/yr • • • • Help replenish stream flows during dry periods Help recharge groundwater aquifers Help maintain biodiversity Supply valuable products such as fish and shellfish, Supply blueberries, cranberries, wild rice, and timber blueberries, • Provide recreation for birdwatchers, nature Provide photographers, boaters, anglers, and waterfowl hunters hunters • Impacts of Human Activities on Freshwater Impacts Systems Systems – Four major impacts • First, dams, diversions, or canals fragment about 40% dams, of world’s 237 large rivers. of • Second, flood control levees and dikes alter and flood destroy aquatic habitats. destroy • Third, cities and farmlands as pollutants and excess cities nutrients to watershed. nutrients • Fourth, draining or filling of inland wetlands to grow draining crops (Fig. 6-19) or have been converted with crops or concrete, asphalt, and buildings. concrete, • Case Study: Inland Wetland Losses in the United Case States (Science and Politics) States – In US 95% of wetlands are freshwater; remaining are In saltwater or coastal. saltwater – Alaska has more wetlands than the other 49. – More than half the inland wetlands in continental US More have been lost since the 1600s. have • 80% for crops • Rest for mining, forestry, oil and gas extraction, highways, and Rest urban development urban • Iowa has lost 99% – Loss of this natural capital has been an important factor Loss in increased flood and drought damage. in – Other countries too: France and Germany lost 80% A Healthy Coral Reef (Fig 6-1a) Healthy Back Bleaching in Coral Reefs (6-1b) Bleaching Back The Ocean Planet (Figure 6-2) The Back Distribution of Major Oceans, Coral Reefs, Mangroves, and Freshwater Lakes and Rivers (Figure 6-3) Freshwater Back (Fig. 6-4) (Fig. Back Major Ocean Life Zones (Fig. 6-5) Major Back Back to Op Sediment Plume at Mouth of Madagascar’s Betsiboka River (Fig. 6-6) Betsiboka Back Components and Interactions in a Temperate Salt Marsh Ecosystem (Fig. 6-7) Temperate Back Mangrove Forest in Daintree National Park In Queensland, Australia (Fig. 6-8) In Back Specialized Niches in a Rocky Shore (Fig. 6-9) Shore Back Specialized Niches in a Sandy Shore (Fig. 6-9b) Shore Back Typical Barrier Island Profile (Fig. 6-10) (Fig. Back Components and Interactions in a Coral Reef Ecosystem (Fig. 6-11) Coral Back Major Threats to Coral Reefs (Fig 6-12) Major Back Major Human Impacts on the World’s Marine Systems (Fig. 6-13) Marine Back Major Ecological and Economic Services (Fig. 6-14) (Fig. Back Life Zones in a Temperate Zone Lake (Fig. 6-15) Lake Back Oligotrophic Lake (Fig. 6-16a) Oligotrophic Back Eutrophic Lake (Fig. 6-16b) Eutrophic Back Three Zones in the Downhill Flow of Water (Fig. 6-17) (Fig. Back Cypress Swamp in Tennessee (Fig. 6-18) Cypress Back Prairie Pothole Wetland That Has Been Ditched and Drained for Cropland (Fig. 6Ditched 19) Back ...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online