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Feedback Loops Ch 5, pgs 109-122 Earth’s environmental systems • Our planet’s environment consists of complex networks of interlinked systems - Matter and molecules - Organisms, populations, interacting species - Nonliving things (rocks, air, water, etc.) • A systems approaches assesses questions as a whole - Helping address complex, multifaceted issues - But systems can show behavior that is hard to understand and predict Systems show several defining properties • System = a network of relationships among parts, elements, or components - They interact with and influence one another - They exchange energy, matter, or information • Systems receive inputs of energy, matter, or information - They process these inputs and produce outputs • Feedback loop = a circular process in which a system’s output serves as input to that same system • Negative and positive feedback loops do not mean bad and good Negative feedback loop • Negative feedback loop = output from a system moving in one direction acts as input - That moves the system in the other direction • Input and output neutralize one another - Stabilizes the system - Example: predator – prey interactions • Most systems in nature Positive feedback loop • Positive feedback loop = instead of stabilizing a system, it drives it further toward one extreme or another - Exponential growth in human population, erosion, melting sea ice • Rare in nature - But is common in natural systems altered by humans Systems are active • Dynamic equilibrium = system processes move in opposing directions - Balancing their effects • Homeostasis = a system maintains constant (stable) internal conditions • Emergent properties = system characteristics are not evident in the components alone - The whole is more than the sum of the parts It is hard to fully understand systems; they connect to other systems and do not have sharp boundaries Eutrophication: a systems perspective • Fertilizer from Midwestern farms adds nutrients to the Mississippi River, which causes… - Phytoplankton to grow, then… - Bacteria eat dead phytoplankton and wastes - Explosions of bacteria deplete oxygen, causing… - Fish and other aquatic organisms to suffocate • Sources of nitrogen and phosphorus include: - Agricultural sources, nitrogen-fixing crops - Livestock manure, sewage treatment plants, street runoff, industrial and vehicle emissions Eutrophication • The process of nutrient over-enrichment leads to: - Blooms of algae - Increased production of organic matter - Decomposition and lack of oxygen in the water Central Case: The Gulf of Mexico’s “Dead Zone” • The Gulf of Mexico brings in a billion pounds/year of shrimp, fish, and shellfish • Gulf “dead zone” = a region of water so depleted of oxygen - That marine organisms are killed or driven away • Hypoxia = low concentrations of dissolved oxygen in water - From fertilizer, fossil fuel emissions, runoff, sewage Worldwide marine dead zones • Over 400 dead zones occur globally - Most are off the coasts of Europe and the U.S. - Mostly due to farm, city and industrial pollution - Some are seasonal, others are permanent • Fisheries and ecosystems are devastated - Causing over $2 billion/year in lost harvests Systems are perceived in various ways • Categorizing environmental systems helps make Earth’s complexity comprehensible • For example, the Earth consists of structural spheres - Lithosphere = rock and sediment - Atmosphere = the air surrounding our planet - Hydrosphere = liquid, solid or vapor water - Biosphere = the planet’s living organisms and the abiotic (nonliving) portions of the environment • Boundaries overlap, so the systems interact Major Components of Systems - Abiotic = nonliving components; physical and chemical factors - water, air, nutrients, solar energy - Biotic = living or once living components Ecosystems • Ecosystem = all organisms and nonliving objects that occur and interact in a particular area at the same time - It includes abiotic and biotic components • Biological entities are tightly intertwined with chemical and physical entities through interactions and feedback loops • Ecosystems receive, process and transform inputs of energy while cycling and recycling matter - Outputs produced include heat, water, wastes Systems of interacting entities in ecosystems • Energy from the sun flows in one direction - Arriving as radiation and leaving as heat • Matter is recycled within ecosystem - Through food-web relationships and decomposition Ecosystems interact spatially • Ecosystems vary greatly in size - From a puddle of water to a bay, lake or forest • Adjacent ecosystems may share components and interact - ex. prairie and forests interact where they converge • Ecotones = transitional zones between two ecosystems - Elements of each ecosystem mix • Patches = form the landscape - Example: forested patches within an agricultural landscape - Widely spaced patches endanger organisms Productivity • The amount of photosynthesis that takes place is one indicator of an ecosystem’s productivity • Primary productivity: amount of biomass produced by photosynthetic organisms - Net Primary Productivity (NPP): the left-over remains of biomass available to use as food for other consumers after the producer has used some for their own respiration • Secondary productivity: amount of biomass produced by organisms that eat photosynthetic organisms NPP (net primary productivity) • NPP can be considered the rate at which energy for use by consumers is stored in new biomass (cells, leaves, roots, and stems) - Most productive ecosystems - 1. algal beds and reefs - 2. tropical rain forests - 3. swamps and marshes - Least productive ecosystems - 1. desert - 2. open ocean - 3. tundra Numbers equal biomass Net primary productivity of ecosystems High net primary productivity = ecosystems whose plants rapidly convert solar energy to biomass NPP variation causes global geographic patterns NPP increases with temperature and precipitation on land, and with light and nutrients in aquatic ecosystems NPP as a limiting factor • Since producers are the source of all food in an ecosystem, NPP is ultimately a limiting factor - Humans now use, waste, or destroy about 27% of the earth’s total potential NPP, and 40% of the NPP of the planet’s terrestrial ecosystems Biodiversity Ch 11 pgs 181-296 Levels of biological diversity (biodiversity) • Humans are reducing Earth’s diversity of life • Biodiversity = variety of life at all levels of organization - Species diversity - Genetic diversity - Population and community diversity Species diversity • Species = a set of individuals that share certain characteristics and can interbreed - Producing fertile offspring • Species diversity = the number or variety of species in a particular region - Richness = the number of species - Evenness (relative abundance) = the similarity in numbers between species • Speciation adds to species richness - Extinction reduces species richness Species diversity and evenness Compared with the boxed area at the top: Which area has greater species richness? Why? Which has reduced richness? Why? Genetic diversity • Encompasses the differences in DNA among individuals • The raw material for adaptation to local conditions • Populations with higher genetic diversity can survive - They can cope with environmental change • Populations with low genetic diversity are vulnerable to environmental change or disease • Inbreeding depression = genetically similar parents mate and produce inferior offspring - Cheetahs, bison, elephant seals Ecosystem diversity • Ecosystem diversity = the number and variety of ecosystems - Including different communities and habitats in an area • May include habitats, communities, or ecosystems at the landscape level - Sizes, shapes, and connections among patches - Beaches, cliffs, coral reefs, ocean waters • An area with a variety of vegetation holds more biodiversity than the same size area with one plant type Some groups have more species than others • Species are not evenly distributed among taxonomic groups - Insects predominate over all other life-forms - 40% of insects are beetles • Groups accumulate species by: - Adapting to local conditions - Geographic speciation - Low rates of extinction Insects outnumber all other species Measuring biodiversity is not easy • Out of the estimated 3–100 million species on Earth, 1.8 million species have been identified and described • Most widely accepted estimate of the number of species? - 14 million • It is very difficult to know how many species exist - Small organisms are easily overlooked - Many species look identical until thoroughly examined - Many remote spots on Earth remain unexplored • Entomologist Terry Erwin found 163 beetle species living on one tree species Biodiversity is unevenly distributed • Living things are not distributed evenly on Earth • Latitudinal gradient = species richness increases toward the equator Canada has 30–100 species of breeding birds, while Costa Rica has more than 600 species Latitudinal gradient has many causes • Climate stability, high plant productivity, no glaciation - More specialized habitats, species coexistence • Diverse habitats increase species diversity and evenness - Tropical rainforests and drylands, ecotones • Human disturbance can increase habitat diversity, which leads to species diversity - But only at the local level Biodiversity loss and species extinction • Extinction = occurs when the last member of a species dies and the species ceases to exist • Extirpation = the disappearance of a population from a given area, but not the entire species globally - Can lead to extinction • Extinction is a natural process - 99% of all species that ever lived are now extinct • Background rate of extinction = natural extinctions - For mammal or marine species: each year 1 species out of every 1–10 million goes extinct Earth has had five mass extinctions • Earth has had five mass extinctions in the past 440 million years - Each event eliminated at least 50% of all species • Humans are causing this sixth extinction event - We will suffer as a result People have hunted species to extinction Extinctions followed human arrival on islands and continents Current extinction rates are higher than normal • The current extinction rate is 100 to 1,000 times greater than the background rate • This rate will increase tenfold in future decades - Human population growth and resource consumption • The Red List = species facing high risks of extinction - Mammal species (21%), bird species (12%) - 17–74% of all other species • In the U.S., in the last 500 years, 237 animal and 30 plant species have been confirmed extinct - Actual numbers are undoubtedly higher Biodiversity loss has many causes • Reasons for biodiversity losses are complex and hard to determine - Multiple factors interact in causing losses • Four primary causes of population decline are: - Habitat alteration - Invasive species - Pollution - Overharvesting • Global climate change now is the fifth cause Habitat alteration causes biodiversity loss • The greatest cause of biodiversity loss • Habitats are destroyed, fragmented, and degraded - Farming simplifies communities - Grazing modifies grassland structure and composition - Clearing forests removes resources organisms need - Hydroelectric dams turn rivers into reservoirs - Suburban sprawl replaces natural communities A few species (e.g., pigeons, rats) benefit from changing habitats Habitat fragmentation • Habitat fragmentation = gradual, piecemeal degradation of habitat - Farming, roads, logging, etc. • Continuous habitats are broken into patches - Species needing that habitat disappear • Landscape-level strategies try to optimize areas to be preserved Habitat loss occurs in every biome • Habitat loss is responsible for declines for 83% of mammals and 85% of birds • 99% of U.S. prairies have been converted to agriculture - Grassland birds have declined 82–99% Pollution causes biodiversity loss • Pollution harms organisms in many ways - Air pollution degrades forest ecosystems - Water pollution impairs fish and amphibians - Agricultural runoff harms terrestrial and aquatic species - Toxins, garbage, oil, and chemicals impact organisms • Damage to wildlife and ecosystems caused by pollution can be severe - But it is less than the damage caused by habitat alteration or invasive species Overharvesting causes biodiversity loss • Vulnerable species - Large, few in number, longlived, and have few young • The Siberian tiger is hunted without rules and regulations - Powerful economic incentives increase poaching • Many other species are affected - Whales, sharks, gorillas - The oceans contain only 10% of the large animals they once did Invasive species cause biodiversity loss • Introduction of non-native species to new areas - Accidental: zebra mussels, weeds - Intentional: food crops, exotic pets, ornamental plants • Island species are especially vulnerable Invaders cost billions of • Invaders lack natural predators, competitors, or dollars in damage each year parasites Climate change causes biodiversity loss • Human manipulation of Earth’s climate system has global impacts on biodiversity • Emission of greenhouse gases warms temperatures - Modifying global weather patterns • The frequency of extreme weather events increases - Droughts, etc. • Increased stress forces organisms to shift their geographic ranges - Most animals and plants will not be able to adapt - 20–30% of species are at increased risk of extinction Warming has been the greatest in the Arctic Because of melting ice, polar bears can’t hunt seals, so they were added to the endangered species list in 2008 Endangered Species Ch 11, pgs 296-310 Biodiversity provides free ecosystem services • Provides food, fuel, fiber, and shelter • Purifies air and water and detoxifies wastes • Stabilizes climate, moderates floods, droughts, wind, temperature • Cycles nutrients, renews soil fertility • Pollinates plants and controls pests and disease • Maintains genetic resources • Provides cultural and aesthetic benefits • Allows us to adapt to change The value of 17 ecosystem services = $46 trillion per year Biodiversity helps maintain ecosystem function • It increases stability and resilience of natural systems • Decreased biodiversity reduces a system’s ability to function and provide services to our society • The loss of a species affects ecosystems differently - If the species can be functionally replaced by others, it may make little difference - Loss of key species and top predators causes other species to decline or disappear Biodiversity enhances food security • Industrial agriculture has narrowed our diet - Wild and rare species can improve food security • New potential food crops are waiting to be used - Serendipity berry is 3,000 times sweeter than sugar • Genetic diversity within crops is enormously valuable - Turkey’s wheat crops received $50 billion worth of disease resistance from wild wheat • Wild strains provide disease resistance - Many grow back year after year without being replanted Organisms provide drugs and medicines • Wild species produce $150 billion/year of drugs • Taxol comes from the Pacific yew tree - Treats cancer • Every species that goes extinct is a lost opportunity to cure disease Biodiversity generates economic benefits • Biodiversity generates income through tourism - Especially in developing countries - Costa Rica: rainforests - Australia: Great Barrier Reef - Belize: reefs, caves, and rainforests - Tanzania: savanna wildlife • A powerful incentive to preserve natural areas - Reduce impacts on the landscape and species • But too many visitors to natural areas can degrade the outdoor experience and disturb wildlife Conservation biology: the search for solutions • Conservation biology = studies the factors behind the loss, protection, and restoration of biodiversity - Scientists became alarmed at the degradation of natural systems • An applied and goal-oriented science • Conservation biologists integrate evolution, extinction, ecology, and environmental systems - Design, test, and enact ways to decrease our impacts Conservation biology: the search for solutions • Conservation geneticists = study genetic attributes of organisms to infer the status of their populations • Minimum viable population size = how small a population can become before it runs into problems - Small populations are most vulnerable to extinction and need special attention Conservation focuses on endangered species • Endangered Species Act (ESA) (1973) = the primary U.S. legislation for protecting biodiversity • It forbids the government and citizens from taking actions that destroy endangered species or their habitats - Or trading in products made from endangered species • The ESA’s goal is to prevent extinction - Stabilize declining populations - Enable populations to recover • In 2010, the U.S. had 1,010 species listed as endangered and 314 listed as threatened The ESA has been successful • Intensive management has saved or stabilized species - 40% of declining populations are now stable • These successes occur despite problems - Underfunding of the U.S. Fish and Wildlife Service and the National Marine Fisheries Service - Recent political forces have tried to weaken the ESA Peregrine falcons, brown pelicans, bald eagles, and others have recovered and are no longer listed The ESA is controversial • Many Americans support protecting endangered species • Opponents feel that the ESA values endangered organisms more than the livelihood of people - Protection will restrict land use and cost jobs - “Shoot, shovel, and shut up” = landowners conceal the presence of endangered species on their land - But the ESA has stopped few development projects • Habitat conservation plans and safe harbor agreements - Landowners can harm species if they improve habitat for the species in other places Species protection can be controversial • Protecting the northern spotted owl slowed logging in old-growth rainforests • Loggers feared for their jobs - Landowners feared restrictions International conservation efforts • UN Convention on International Trade in Endangered Species of Wild Fauna and Flora (1973) - CITES protects endangered species by banning international transport of their body parts • Convention on Biological Diversity (1992) - Seeks to conserve biodiversity - Use biodiversity in a sustainable manner - Ensure the fair distribution of biodiversity’s benefits • By 2010, 193 nations had signed on to the Convention - Only Andorra, the Vatican, and the U.S. did not join The Convention on Biological Diversity • The Convention aims to: - Provide incentives to conserve biodiversity - Manage access to and use of genetic resources - Transfer technology (including biotechnology) - Promote scientific cooperation - Assess human effects on biodiversity - Promote biodiversity education and awareness - Provide funding for critical activities - Encourage nations to report on conservation efforts • Despite some successes, biodiversity is still being lost Protecting biodiversity: captive breeding • Captive breeding = individuals are bred and raised so they can be reintroduced into the wild - 65 plant and animal species exist only in captivity • Reintroductions can be controversial - Ranchers opposed reintroducing wolves to Yellowstone National Park - Fragmented habitat must be improved before releasing animals Biologists have raised condor chicks in captivity with the help of hand puppets that look like the heads of adult condors Protecting biodiversity: cloning • Cloning creates more individuals and saves species from extinction - DNA from an endangered species is inserted into an egg without a nucleus - The egg is inserted into a closely related species • Several mammal species have been cloned - But these efforts are not enough to recreate lost biodiversity • Without ample habitat and protection in the wild, having cloned animals in a zoo does little good Forensics protects threatened species • Forensic science (forensics) = analyzes evidence to identify or answer questions relating to a crime • Conservation scientists use forensics to protect species - Researchers use DNA to identify a species or subspecies and its geographic origin • Detecting illegal activity helps enforce laws protecting wildlife - For example, whale meat is analyzed in Asian markets - DNA from killed elephants shows many more were killed than the Zambian government admitted Umbrella species protect others • Conservation biologists use particular species as tools to conserve communities and ecosystems • Umbrella species = species that, when protected, also help protect other, less charismatic species - Often large species that need large amounts of habitat - Protecting their habitat automatically protects others - Ex: Northern spotted owls. Molluscs and salamanders are within the protective boundaries of the northern spotted owl. • Flagship species = large and charismatic species used as spearheads for biodiversity conservation - The World Wildlife Fund’s panda bear • Some organizations are moving beyond the singlespecies approach to focus on whole landscapes Parks and protected areas • Setting aside land in parks and preserves conserves habitats, communities, ecosystems, and landscapes - 12% of the world’s area is in parks, wilderness, reserves, etc. • But these areas are not all managed for biodiversity - They are used for recreation, water protection, etc. - They are also illegally logged, etc. - Many are not large enough to preserve whole systems Biodiversity hotspots • Biodiversity hotspots = prioritizes regions most important globally for biodiversity - Support a great number of endemic species = species found nowhere else in the world • The area must have at least 1,500 endemic plant species (0.5% of the world total) - It must have lost 70% of its habitat due to humans Focusing on hotspots protects the greatest number of species per unit effort There are 34 global biodiversity hotspots 2.3% of the planet’s land surface contains 50% of the world’s plant species and 42% of all terrestrial vertebrate species Using innovative economic strategies • Debt-for-nature swap = a conservation organization pays off a portion of a developing country’s international debt • In exchange, the country promises to set aside reserves to: - Fund environmental education and - Better manage protected areas • The U.S.’s Tropical Forest Conservation Act - Paid $218 million in debt payments to 13 developing countries for conservation efforts • Conservation concession = conservation organizations pay nations to conserve, and not sell, resources We can restore degraded ecosystems • The best way to safeguard biodiversity and natural systems? - Protect natural areas before they become degraded • Ecological restoration = restores degraded areas to some semblance of their former condition • Restoration ecology = restoring damaged systems to bring back species and reestablish ecological processes - Filter pollutants, clean water and air, build soil, etc. Restoring Iraq’s wetlands • Southern Iraq’s wetlands were drained in the 1970s and 1980s under Saddam Hussein, devastating the area • After the 2003 U.S. invasion, a multi-million dollar international restoration effort began - Although successful, 2010’s drought caused Turkey and Syria to divert water from the rivers Drainage and Restoration Community-based conservation • Developing nations often do not support conservationists from developed nations trying to preserve areas • Community-based conservation = conservation biologists engage local people to protect land and wildlife - It offers education, health care, and development aid • Conservation efforts help local people - People are retrained and income is supplemented - Poaching is reduced • It ensures that local resources can be sustainably used Biogeochemical Cycles Ch 5, pgs 122-132 Nutrients circulate through ecosystems • Matter is continually circulated in ecosystems • Nutrient (biogeochemical) cycles = the movement of nutrients through ecosystems - Atmosphere, hydrosphere, lithosphere, and biosphere • Pools (reservoirs) = where nutrients reside for varying amounts of time - Flux = the rate at which materials move between pools - Can change over time - Is influenced by human activities Main components of a biogeochemical cycle • Source = a pool that releases more nutrients than it accepts • Sinks = a pool that accepts more nutrients than it releases The hydrologic cycle • Water is essential for biochemical reactions - It is involved in nearly every environmental system • Hydrologic cycle = summarizes how liquid, gaseous and solid water flows through the environment - Oceans are the main reservoir • Evaporation = water moves from aquatic and land systems into the atmosphere • Transpiration = release of water vapor by plants • Precipitation, runoff, and surface water = water returns to Earth as rain or snow and flows into streams, oceans, etc. Transpiration Groundwater • Aquifers = underground reservoirs of sponge-like regions of rock and soil that hold… - Groundwater = water found underground beneath layers of soil • Water table = the upper limit of groundwater in an aquifer - Water may be ancient (thousands of years old) • Groundwater becomes exposed to the air where the water table reaches the surface - Exposed water runs off to the ocean or evaporates The hydrologic cycle Human impacts on the hydrologic cycle • Removing forests and vegetation increases runoff and erosion, reduces transpiration and lowers water tables • Irrigating agricultural fields depletes rivers, lakes and streams and increases evaporation • Damming rivers increases evaporation and infiltration • Emitting pollutants changes the nature of precipitation • The most threatening impact: overdrawing groundwater for drinking, irrigation, and industrial use - Water shortages create worldwide conflicts The carbon cycle • Carbon is found in carbohydrates, fats, proteins, bones, cartilage and shells • Carbon cycle = describes the route of carbon atoms through the environment • Photosynthesis by plants, algae and cyanobacteria - Removes carbon dioxide from air and water - Produces oxygen and carbohydrates - Plants are a major reservoir of carbon • Respiration returns carbon to the air and oceans - Plants, consumers and decomposers Sediment storage of carbon • Decomposition returns carbon to the sediment - The largest reservoir of carbon - May be trapped for hundreds of millions of years • Aquatic organisms die and settle in the sediment - Older layers are buried deeply and undergo high pressure - Ultimately, it may be converted into fossil fuels • Oceans are the second largest reservoir of carbon The carbon cycle Humans affect the carbon cycle • Burning fossil fuels moves carbon from the ground to the air • Cutting forests and burning fields moves carbon from vegetation to the air • Today’s atmospheric carbon dioxide reservoir is the largest in the past 800,000 years - It is the driving force behind climate change • The missing carbon sink: 1-2 billion metric tons of carbon are unaccounted for - It may be taken up by plants or soils of northern temperate and boreal forests The phosphorus cycle • Phosphorus (P) is a key component of cell membranes, DNA, RNA, ATP and ADP • Phosphorus cycle = describes the routes that phosphorus atoms take through the environment - Phosphorous is NOT found in the atmosphere (NO GAS STAGE!), but instead in sedimentary rocks and does not depend on action of bacteria. - It is released by weathering of rocks • With naturally low environmental concentrations - Phosphorus is a limiting factor for plant growth The phosphorus cycle Humans affect the phosphorus cycle • Mining rocks for fertilizer moves phosphorus from the soil to water systems • Wastewater discharge also releases phosphorus • Runoff containing phosphorus causes eutrophication of aquatic systems - Produces murkier waters - Alters the structure and function of aquatic systems - Do not buy detergents that contain phosphate Sulfur Cycles • Most sulfur is found in underground rocks and deep oceanic deposits • Natural release comes from weathering of rock and gases released from seafloor vents and volcanic eruptions, and decomposition of dead organisms • Human activities affect the sulfur cycle - Burn sulfur-containing coal and oil - Refine sulfur-containing petroleum - Convert sulfur-containing metallic mineral ores (smelting) - Produce lare amounts of sulfur dioxide (SO2) and hydrogen sulfide gases (H2S) The nitrogen cycle • Nitrogen comprises 78% of our atmosphere - It is contained in proteins, DNA and RNA • Nitrogen cycle = describes the routes that nitrogen atoms take through the environment - Nitrogen gas in the atmosphere (N2) cannot be used by organisms - Has to be in the form of ammonia (NH3) or nitrates (NO3-) Steps • 1. Nitrogen fixation = lightning or nitrogen-fixing bacteria combine (fix) nitrogen with hydrogen - Change N2 to ammonium ions NH4+ - These are then used by plants • 2. Nitrification = soil bacteria converts ammonium NH4+ to nitrites (NO2- ) and then nitrates (NO3- ) • 3. Assimilation = Plants absorb ammonium (NH3), ammonia ions (NH4+ ), and nitrate ions (NO3-)through their roots. Other organisms gain this energy when they consume the plants Nitrogen Cycle Continued • 4. Ammonification = decomposing bacteria convert dead organism and other waste to ammonia (NH3) or ammonium (NH4+ ) which can be reused by plants • 5. Denitrification = Specialized bacteria convert ammonia (NH3) back into nitrites (NO2- ) and nitrates (NO3- ) and then back into nitrogen gas (N2)and nitrous oxide gas (N2O), releasing them back into the air The nitrogen cycle Humans affect the nitrogen cycle • Haber-Bosch process = production of fertilizers by combining nitrogen and hydrogen to synthesize ammonia - Humans overcame the limits on crop productivity • Fixing atmospheric nitrogen with fertilizers - Increases emissions of greenhouse gases and smog - Washes calcium and potassium out of soil - Acidifies water and soils - Moves nitrogen into terrestrial systems and oceans - Reduces diversity of plants adapted to low-nitrogen soils - Changed estuaries and coastal ecosystems and fisheries Humans put nitrogen into the environment Fully half of nitrogen entering the environment is of human origin Solutions to the dead zone • The Harmful Algal Bloom and Hypoxia Research and Control Act (1998) - Called for an assessment of hypoxia in the dead zone • Solutions outlined included: - Reduce nitrogen fertilizer use in Midwestern farms - Apply fertilizer at times which minimize runoff - Use alternative crops and manage manure better - Restore wetlands and create artificial ones - Improve sewage treatment technologies - Evaluate these approaches Decreasing pollution • Scientists, farmers and policymakers are encouraged to - Decrease fertilizer use while safeguarding agriculture • Offering insurance and incentives • Using new farming methods • Planting cover crops • Maintaining wetlands • There have been some successes despite a lack of funding