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Ch 16 Marine and Coastal Systems: Resources, Impacts, and Conservation Part 2: Environmental Issues the Search for Solutions PowerPoint® Slides prepared by Jay Withgott and Heidi Marcum Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings This lecture will help you understand: • The marine environment • Major marine ecosystems • Human uses of marine resources • Human impacts on the marine environment • The state of ocean fisheries • Marine protected areas and reserves Schooling Marine fish Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Central Case: collapse of the cod fisheries • No fish has more impact on human civilization than the Atlantic cod • Eastern Canadians and U.S. fishermen have fished for cod for centuries since in early 1500s • Large ships and technology have destroyed the cod fishery (Trawling in particular) • Even protected stocks are not recovering Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Massachusetts cod fishermen haul in a dwindling catch Cod are groundfish • They live or feed along the bottom - Halibut, pollock, flounder • Cod eat small fish and invertebrates • They grow to 60-70 cm long and can live 20 years • Inhabit cool waters on both sides of the Atlantic Dwindles in 1980s - Trawling (p459) destroyed underground habitats Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings There are 24 stocks (populations) of cod Oceans cover most of the Earth’s surface • The oceans influence global climate, team with biodiversity, facilitate transportation and commerce, and provide resources for us • They cover 71% of Earth’s surface and contain 97% of Earth’s surface water – Major Hydrosphere • Oceans influence the atmosphere, lithosphere, and biosphere Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The oceans contain more than water • Ocean water is 96.5% water - Plus, ions of dissolved salts • Evaporation removes pure water and leaves a higher concentration of salt • Nutrients (nitrogen and phosphorus) • Dissolved gas: Oxygen is added by plants, bacteria, and atmospheric diffusion Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Ocean water is vertically structured • Temperature declines with depth • Heavier (colder & saltier) water sinks - Light (warmer & less salty) water remains near the surface • Temperatures are more stable than land temperatures - Water’s much higher heat capacity than land or air It takes much more heat to warm water than air (~4x ) (i.e., larger specific heat: 1 cal/(oC g)=4.184J/(K g) ) • Oceans regulate the earth’s climate - They absorb and release heat - Ocean’s surface circulation Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The ocean has several layers • Surface zone (~150 m): ~2% - Warmed by sunlight and stirred by wind, Consistent water density • Pycnocline(~1,000m): ~18% below the surface zone - Density increases rapidly with depth • Deep Zone: ~ 80% below the pycnocline - Dense, sluggish water - Unaffected by winds, storms, Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Ocean water flows horizontally in currents Convection • Currents: the ocean is composed of vast riverlike flows - Driven by density differences, heating and cooling, gravity (Tide), and wind - Influence global climate - Transport heat, nutrients, pollution, and the larvae of many marine species • Some currents such as the Gulf Stream are rapid and powerful - The warm water moderates Europe’s climate Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Ocean Currents : A Big Picture Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The upper waters of the oceans flow in currents Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Surface winds and heating create vertical currents • Upwelling: where surface current diverge, the vertical flow of cold, deep water towards the surface - Rich in nutrient from bottom, thus giving high primary productivity and lucrative fisheries - Also occurs where strong winds blow away from, or parallel to, coastlines • Downwellings: where surface currents come together (converge), oxygen-rich surface water sinks - transport warm water rich in gas (O2) for deep-water life. Start (11/20/08) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Seafloor topography can be rugged and complex • The seafloor consists of… - Underwater volcanoes - Steep canyons, trenches - Mountain range - The planet’s longest range is under water - Mounds of debris Diverging Mid-Atlantic Ridge: N/S Amarican Plate and African Plate (Cf. p200) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings - Some flat areas Profile of the ocean Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Regions of ocean differ greatly • Some zones support more life than others • Photic Zone: well-lighted top layer that supports high primary productivity (~ limnetic zone of a lake) • Pelagic Zone : habitats and ecosystems occurring between the ocean’s surface and floor (~ profundal zone of a lake) • Benthic Zone : habitats and ecosystems occurring on the ocean floor Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Open ocean systems vary in biodiversity • Microscopic phytoplankton constitute the base of the marine food chain in the pelagic zone: Producers - Algae, cyanobacteria and protists • These organisms feed zooplankton (Primary Consumer) - Which then feeds fish, jellyfish, whales, etc. (Secondary Consumers) • Predators at higher trophic levels include larger fish, sea turtles, sharks, and fish-eating birds (Tertiary Consumer) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Marine Ecosystems: • Kelp Forest Ecosystem : • Deep Ocean Ecosystem : • Coral Reef Ecosystem : Coastal Ecosystems: • Intertidal (Littoral) Ecosystem : • Salt Marsh Ecosystem : • Mangrove Forest Ecosystem : • Estuary Ecosystem : Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Kelp forests: Underwater Forests harbor many organisms: • Kelp: (~60 m) large, dense, brown algae growing from the floor of continental shelves (Cf.: Giant Sequoia ~ 80m) • Dense strands form kelp forests along temperate coasts • Shelter and food for organisms • Absorbs wave energy and protects shorelines from erosion • Eaten by people • Alginates serve as thickeners in cosmetics, paints, paper, and soaps → The Keystone species ? Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Deep Ocean Ecosystem: • Animals adapt to extreme water pressure and the absence of light - Scavenge carcasses or organic detritus - Some are predators, while others have mutualistic relationships with bacteria - Some species carry bacteria that produce light chemically by bioluminescence (What’s the common example in land?) Anglerfish lures prey with a glowing organ • Hydrothermal vents support tubeworms, shrimp, and other chemosynthetic species Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings (The Black Smoker, p104, Fig. 4.18) Coral reefs are treasure troves of biodiversity • Located in shallow subtropical and tropical waters needs warm, clean pollution free, O2 rich water • Corals: tiny colonial marine organisms (animal) - Related to sea anemones and jellyfish - Remain attached to rock or existing reef and capture passing food with stinging tentacles - Derive nourishment from symbiotic photosynthetic brown algae, zooxanthallae - Extract CO2 ( in a form of CO32-) from sea water to build reef limestone (CaCO3) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Coral reefs are treasure troves of biodiversity • Corals: tiny colonial marine organisms (animal) - Related to sea anemones and jellyfish - Remain attached to rock or existing reef and capture passing food with stinging tentacles Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Coral reefs consist of millions of corals • Coral reef: a mass of calcium carbonate composed of the skeletons of corals - Consists of millions of densely packed individuals - Protect shorelines by absorbing waves - Innumerable invertebrates and fish species find food and shelter in reef nooks and crannies Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Coral reefs are in worldwide decline • Coral bleaching: occurs when zooxanthellae leave the coral - Coral lose their color and die, leaving white patches - From climate change, pollution, or unknown natural causes • Nutrient pollution causes algal growth, which covers coral • Divers damage reefs by using cyanide to capture fish • Acidification of oceans deprives corals of necessary carbonate ions for their structural parts • Limestone becomes part of lithosphere storage of C (or CO2 ) • Destruction of coral will cause more CO2 in the atmosphere End (11/20/08) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Intertidal Zones Ecosystem undergo constant change • Intertidal (littoral) ecosystems : where the ocean meets the land - between the uppermost reach of the high tide and the lowest limit of the low tide • Tides: periodic rising and falling of the ocean’s height due to the gravitational pull of the sun and moon - Intertidal organisms spend part of their time submerged in water and part of their time exposed to sun and wind Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A typical intertidal zone Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Intertidal zones are a tough place to live • But they have remarkable diversity - Rocky shorelines, crevices, pools of water (tide pools) - Anemones, mussels, crabs barnacles, urchins, sea slugs, and, starfish • Temperature, salinity, and moisture change dramatically from high to low tide - Sandy intertidal zones have slightly less biodiversity Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Salt Marsh Ecosystems occur widely • Salt marsh: occur along coasts at temperate latitude - Tides wash over gently sloping, sandy, silty substrates - High primary productivity - Critical habitat for birds and commercial fish and shellfish species - Like any wetlands, Filter pollution - Stabilize shorelines against storm surges Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings People have changed and destroyed salt marshes for development - We lose key ecosystem service - Flooding worsens Tidal Creeks and Benches Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Mangrove Forests Ecosystem: line coasts • In tropical and subtropical altitudes, these tropical evergreen replace salt marshes along sandy coasts • Mangroves: trees w/ unique roots - Curve upwards for O2 - Curve downwards for support • Nurseries for commercial fish and shellfish • Nesting areas for birds • Food, medicine, tools, construction materials Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Mangrove forests have been destroyed • Development for residential, commercial, and recreational uses • Shrimp farming • Half the world’s mangrove forests are gone • Once destroyed, coastal areas no longer - Slow runoff - Filter pollutants - Retain soil - Protect communities against storm surges • We are protecting only 1% of remaining mangroves Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Estuary Ecosystems: where fresh and salt water meet • Estuaries: water bodies where rivers flow into the ocean - Wide fluctuations in salinity • Critical habitat for shorebirds and shellfish • Transitional zone for anadromous (spawn in freshwater, mature in salt water) fishes (example?) • Affected by development, pollution, habitat alteration, and overfishing Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Oceans provide transportation routes • Humans have interacted with oceans for thousands of years - Moving people and products over vast distances - Accelerated global reach of cultures • Has substantial impact on the environment - Moves resources around the world - Ballast water transplants organisms, which may become invasive Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings We extract minerals from oceans • Minerals such as sand, gravel, sulfur, calcium carbonate, and silica • Rich deposits of copper, zinc, silver, and gold • Magnesium: dissolved (Mg2+ , third most ions) H2O(l) + CaO(s) → Ca2+(aq) + 2OH-(aq) Mg2+(aq) + 2OH-(aq) → Mg(OH)2(s) Mg(OH)2(s) +2HCl(aq) → MgCl2(aq) + 2H2O(l) MgCl2(aq) → MgCl2(s) → MgCl2(l) → Mg(s) + Cl2(g) evaporate H2O melt Electrolyze • Manganese nodules are scattered along the ocean’s floor - But, they are too hard to currently mine Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Marine pollution threatens resources • Even into the mid-20th century, coastal U.S. cities dumped trash and untreated sewage along their shores • Oil, plastic, chemicals, excess nutrients make their way from land into oceans • Raw sewage and trash from cruise ships • Abandoned fishing gear from fishing boats In 2006, 359,000 Ocean Conservancy volunteers from 66 nations picked up 3.2 million kg (7 million lbs.) of trash Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Nets and plastic debris endangers marine life • Plastic items dumped into the sea harm or kill wildlife • Plastic is non-biodegradable - Drifts for decades - Washes up on beaches - Wildlife eat it or get entangled and die • Marine debris affects people - Equipment damage • The 2006 Marine Debris Research, Prevention and Reduction Act Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Oil pollution comes from spills of all sizes causing serious environmental problems • Major oils spills make headlines 1989 March 24, 1989; 11 M gal the Exxon Valdez hit a reef 2010, April 20th : 200 M gal the BP Offshore Station Explode • Most pollution comes from small sources, such as Boat leakage & runoff from land Naturally occurring leaks from the seabed • Oil spills coat & poison wildlife Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Oil pollution has decreased • Governments have implemented more stringent regulations • The U.S. Oil Pollution Act of 1990 - Creates a $1 billion prevention and cleanup fund - Requires all ships have double hulls by 2015 • Recently, oil spills have decreased - The oil industry resists such safeguards Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Toxic pollutants contaminate seafood • Mercury contamination - From coal combustion and other sources - Bioaccumulates and biomagnifies - Dangerous to young children and pregnant or nursing mothers - Avoid eating swordfish, shark, and albacore tuna - Eat seafood low in mercury (catfish, salmon, canned light tuna) • Avoid seafood from areas where health advisories have been issued Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Emptying the oceans • We are placing unprecedented pressure on marine resources - Half the world’s marine fish populations are fully exploited - 25% of fish population are overexploited and heading to extinction • Total fisheries catch leveled off after 1998, despite increased fishing effort - It is predicted that populations of all ocean species we fish for today will collapse by the year 2048 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The total global fisheries catch has increased Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings We have long overfished • People began depleting sea life centuries ago • Some species hunted to extinction: Steller’s sea cow, Atlantic gray whale, Caribbean monk seal • Overharvesting of Chesapeake Bay oyster beds led to the collapse of its fishery, eutrophication, and hypoxia • Decreased sea turtle populations causes overgrowth of sea grass and can cause sea grass wasting disease • People never imagined that groundfish could be depleted - New approaches or technologies increased catch rates Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fishing has industrialized Factory Fishing : highly industrialized, huge vessels use powerful technologies to capture fish in huge volumes - process and freeze their catches while at sea • Driftnets for schools of herring, sardines, mackerel, sharks • Longline fishing for tuna and swordfish • Trawling for pelagic fish and groundfish →devastate deep ocean ecosystem Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fishing practices kill nontarget animals • By-catch: the accidental capture of animals • Driftnetting drowns dolphins, turtles, and seals - Fish die from air exposure on deck - Banned or restricted by many nations • Longline fishing kills turtles, sharks, and albatrosses - 300,000 seabirds die each year • Bottom-trawling destroys communities - Likened to clear-cutting and strip mining Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Modern fishing fleets deplete marine life rapidly • Grand Banks (p444) cod have been fished for centuries • Catches more than doubled with immense industrial trawlers - Record-high catches lasted only 10 years Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Industrialized fishing depletes populations • Catch rates drop precipitously with industrialized fishing - 90% of large-bodied fish and sharks are eliminated within 10 years - Populations stabilize at 10% of their former levels • Marine communities may have been very different before industrial fishing - Removing animals at higher trophic levels allows prey to proliferate and change communities Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Oceans today contain only one-tenth of the large-bodied animals they once did Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings We are “fishing down the food chain” • Figures on total global catch do not relate the species, age, and size of fish harvested • As fishing increases, the size and age of fish caught decline - 10-year-old cod, once common, are now rare • As species become too rare to fish, fleets target other species - Shifting from large, desirable species to smaller, less desirable ones - Entails catching species at lower trophic levels Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Consumer choices influence fishing practices • Buy ecolabeled seafood - Dolphin-safe tuna • Consumers don’t know how their seafood was caught - Nonprofit organizations have devised guides for consumers - Best choices: farmed catfish and caviar, sardines, Canadian snow crab - Avoid: Atlantic cod, wild-caught caviar, sharks, farmed salmon Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings We can protect areas in the ocean • Marine protected areas (MPAs) : established along the coastlines of developed countries - Still allow fishing or other extractive activities • Marine reserves : areas where fishing is prohibited - Leave ecosystems intact, without human interference - Improve fisheries, because young fish will disperse into surrounding areas • Many commercial, recreation fishers, and businesses do not support reserves Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Conclusion • Oceans cover most of our planet and contain diverse topography and ecosystems • We are learning about the oceans and coastal environments, intensifying our use their resources and causing severe impacts • Setting aside protected areas of the ocean can serve to maintain natural systems and enhance fisheries • We may once again attain the ecological systems that once flourished in our waters Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review An “upwelling” is defined as…. a) The vertical flow of cold, deep water towards the surface b) The vertical flow of warm, deep water towards the surface c) The vertical flow of cold, shallow water towards the bottom d) The vertical flow of warm, deep water towards the bottom Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review The area of an ocean that contains open water that receives sunlight is called the _______zone. a) b) c) d) Littoral Photic Pelagic Benthic Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review _____ is defined as “large, dense, brown algae growing from the floor of continental shelves.” a) b) c) d) Coral Red tide Bottomfish Kelp Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review Coral bleaching occurs when …. a) b) c) d) Corals reproduce Fish move into coral reefs Zooxanthellae leave the coral Coral reefs expand their range Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review An area where rivers flow into the ocean is called a(n) …? a) b) c) d) Estuary Mangrove swamp Salt marsh Coral reef Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review Which of the following does not mask the decline of fisheries? a) b) c) d) Fishing fleets travel longer distances Fishing fleets spend more time fishing Fishing fleets use traditional methods of fishing Data supplied to monitoring agencies may be false Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review Marine reserves have all the following benefits except: a) b) c) d) Fishing increases in the reserve The size of fish increases Larvae can “seed” areas outside the reserve Decreased mortality and habitat destruction Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Interpreting Graphs and Data What does this graph show about the future of global fisheries catch? a) China will be a major player in applying fishing pressure b) China will be player a smaller role in applying fishing pressure c) The world will decrease its fishing pressure d) The U.S. is not included in this graph Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Interpreting Graphs and Data Which conclusion can you draw from this graph? a) Oceans today contain far fewer fish b) Oceans today contain far more fish c) It is easier to find fish today d) There is little correlation between fishing and fish stocks Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Viewpoints If a developer wants to build a community on an estuary, providing jobs but eliminating the marsh, what should be done? a) Let the developer build; we need the jobs b) Let the developer build, but make him/her pay for any damage from storms c) Let the surrounding landowners vote whether to let the developer build d) Prevent the development; the potential damage is too great Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Viewpoints Do you plan to alter your decisions about eating seafood? a) Yes; I will be more selective about what I eat b) No; I will continue to eat the same type and amount of seafood as always Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings