Chapter 8 Miller and Spoolman (2010) Aquatic Biodiversity Chapter 8 Miller and Spoolman (2010)

Core Why Should We Care about Coral Reefs? Coral reefs form in clear, warm coastal waters of the tropics and subtropics. Among the oldest, most diverse, and most productive ecosystems. Formed by massive colonies of tiny animals called polyps. Secrete crust of limestone (CaCO3) around their soft bodies. Elaborate network of crevices, ledges, and holes. Symbiosis with Zooxanthellae, which live in the tissues of polyps.

Degradation and decline Coral reefs occupy only 0.2% of the ocean floor, but provide important ecological and economic services. Moderate atmospheric temperatures Act as natural barriers protecting coasts from erosion (protect 15% of world’s coastline) Provide habitats Support fishing and tourism businesses Provide jobs and building materials Studied and enjoyed Degradation and decline 15% of coral reefs destroyed Another 20% damaged by coastal development, pollution, overfishing, warmer oceans Coral bleaching Increasing ocean acidity Decline of coral reefs should serve as a warning about threats to the health of the oceans, which provide crucial ecological and economic sevices.

Figure 8.1 A healthy coral reef in the Red Sea covered by colorful algae (left) and a bleached coral reef that has lost most of its algae (right) because of changes in the environment (such as cloudy water or high water temperatures). With the colorful algae gone, the white limestone of the coral skeleton becomes visible. If the environmental stress is not removed and no other alga species fill the abandoned niche, the corals die. These diverse and productive ecosystems are being damaged and destroyed at an alarming rate.

8-1 What Is the General Nature of Aquatic Systems? Concept 8-1A Saltwater and freshwater aquatic life zones cover almost three-fourths of the earth’s surface with oceans dominating the planet. Concept 8-1B The key factors determining biodiversity in aquatic systems are temperature, dissolved oxygen content, availability of food and availability of light and nutrients necessary for photosynthesis.

Figure 8. 2 The ocean planet Figure 8.2 The ocean planet. The salty oceans cover 71% of the earth’s surface. Almost all of the earth’s water is in the interconnected oceans, which cover 90% of the planet’s mostly ocean hemisphere (left) and half of its land–ocean hemisphere (right). Freshwater systems cover less than 2.2% of the earth’s surface (Concept 8-1A).

Most of the Earth Is Covered with Water Global ocean is single continuous body of water divided into four large areas. Atlantic Pacific Arctic Indian Freshwater makes up less than 2.2% of earth’s surface.

Aquatic equivalents of biomes are called aquatic life zones. Distribution of many aquatic organisms is determined in large part by the water’s salinity.  aquatic life zones are classified into two major types: Saltwater, or marine (oceans, estuaries, coastal wetlands, shorelines, coral reefs, and mangrove forests) Freshwater (lakes, rivers, streams, and inland wetlands) Aquatic systems play vital roles in the earth’s biological productivity, climate, biogeochemical cycles, and biodiversity, and they provide us with fish, shellfish, minerals, recreation, transportation routes, and many other economically important goods and services.

Figure 8.3 Natural capital: distribution of the world’s major salt water oceans, coral reefs, mangroves, and freshwater lakes and rivers. Question: Why do you think most coral reefs lie in the southern hemisphere?

Most Aquatic Species Live in Top, Middle, or Bottom Layers of Water Major types of aquatic organisms Plankton – drifters Phytoplankton Zooplankton Ultraplankton Photosynthetic bacteria may be responsible 70% of PP near ocean surface Nekton – swimmers Benthos – bottom dwellers Decomposers

Key factors that determine the distribution of organisms in an aquatic life zone Temperature Dissolved oxygen content Availability of food Availability of light and nutrients needed for photosynthesis in the euphotic, or photic, zone Depth of euphotic zone in lakes and oceans can be reduced by turbidity – cloudiness caused by algal blooms or excessive silt. Excessive nutrient loading – cultural eutrophication Clearing land causes erosion and silt with runoff In shallow systems: open streams, lake edges, and ocean shorelines, nutrients are usually available In most areas of open ocean, nitrates, phosphates, iron, and other nutrients are in short supply  limits NPP.

8-2 Why Are Marine Aquatic Systems Important? Concept 8-2 Saltwater ecosystems are irreplaceable reservoirs of biodiversity and provide major ecological and economic services.

Oceans Provide Important Ecological and Economic Resources Enormously valuable ecological and economic services: estimated at $12 trillion annually (Figure 8-4) Oceans still poorly understood. Huge reservoirs of biodiversity Many ecosystem types Variety of species, genes, and biological and chemical processes Important for sustaining life. Marine life is found in three major life zones: coastal, open sea, and ocean bottom (Figure 8-5).

Figure 8.4 Major ecological and economic services provided by marine systems (Concept 8-2). Question: Which two ecological services and which two economic services do you think are the most important? Why?

Figure 8.5 Natural capital: major life zones and vertical zones (not drawn to scale) in an ocean. Actual depths of zones may vary. Available light determines the euphotic, bathyal and abyssal zones. Temperature zones also vary with depth, shown here by the red curve. Question: How is an ocean like a rain forest? (Hint: see Figure 7-17, p. 156.)

Coastal zone Warm, nutrient rich, shallow water that extends from the high-tide mark on land to the gently sloping, shallow edge of the continental shelf. < 10% of world’s ocean area but contains 90% of marine species Most commercial fisheries Most ecosystems—estuaries, coastal wetlands, mangrove forests, and coral reefs—have high NPP.  ample supplies of sunlight and plant nutrients, which come from land.

Estuaries and Coastal Wetlands Are Highly Productive Life in these coastal ecosystems is harsh Significant daily and seasonal changes in Tidal and river flows, temperature, salinity and runoff of pollutants such as eroded sediments and chemicals form land. May be composed of only a few plant species that can withstand rapidly changing environmental factors, athough such species are highly productive. Estuaries Where rivers meet the sea Partially enclosed bodies of water where sea water mixes with freshwater as well as nutrients and pollutants from streams, rivers, and runoff from land (Figure 8-6).

Figure 8. 6 View of an estuary from space Figure 8.6 View of an estuary from space. The photo shows the sediment plume (turbidity caused by runoff) at the mouth of Madagascar’s Betsiboka River as it flows through the estuary and into the Mozambique Channel. Because of its topography, heavy rainfall, and the clearing of forests for agriculture, Madagascar is the world’s most eroded country.

Coastal wetlands Seagrass beds Coastal land areas covered with water all or part of the year River mouths, inlets, bays, sounds, salt marshes (Figure 8-7) in temperate zones, and mangrove forests in tropical zones. Some of the earth’s most productive ecosystems  high nutrient inputs, rapid circulation from tidal flows, and ample sunlight penetrates shallow water. Seagrass beds Another component of coastal marine biodiversity. 60 species of plants that grow in shallow marine and estuarine areas along most continental shorelines. Support a variety of species Stabilize shorelines and reduce wave impacts.

Figure 8.7 Some components and interactions in a salt marsh ecosystem in a temperate area such as the United States. and decomposers. The photo shows a salt marsh in Peru.

Mangrove forests Magroves—69 tree species that can grow in salt water (Figure 8-8) Tropical equivalent of salt marshes. 70% of gently sloping, sandy and silty coastlines in tropical and subtropical regions. Provide important ecological and economic services Maintain water quality Food, habitat, and nursery sites for aquatic and terrestrial species Reduce storm damage and coastal erosion Historically, sustainably supplied timber and fuelwood to coastal communities Between 1980 and 2005, and estimated 20% of mangrove forests were lost mostly due to coastal development.  polluted drinking water, salt water intrusion  reduced protection from storms  reduced biodiversity

Figure 8.8 Mangrove forest in Daintree National Park in Queensland, Australia. The tangled roots and dense vegetation in these coastal forests act like shock absorbers to reduce damage from storms and tsunamis. They also provide a highly complex habitat for a diversity of invertebrates and fishes.

Rocky and Sandy Shores Host Different Types or Organisms Moon and sun cause ocean tides that rise and fall every 6 hours Intertidal zone – the area of shoreline between low and high tides. Organisms here are adapted to extreme conditions: waves, varying water levels, varying salinity Organism hold on to something, dig in, and/or hide in protective shells Rocky shores (Figure 8-9, top) Pounded by waves Organisms occupy different niches in response to daily and seasonal changes in temperature, water flows, and salinity.

Figure 8. 9, Top Living between the tides Figure 8.9, Top Living between the tides. Some organisms with specialized niches found in various zones on rocky shore beaches.

Sandy shores or barrier beaches (Figure 8-9, bottom) Support other types of organisms; most survive by burrowing, digging, and tunneling in sand Shorebirds have specialized feeding niches (Figure 4- 13, p. 93) Barrier Islands (Figure 8-10) – low, narrow, sandy islands that form offshore, parallel to some coastlines. South Padre Island Undisturbed barrier beaches generally have one or more rows of natural sand dunes in which the sand is held in place by plant roots. First line of defense against storm surges and heavy wave action from storms. Such areas are valuable for real estate development.

Figure 8. 9, Bottom Living between the tides Figure 8.9, Bottom Living between the tides. Some organisms with specialized niches found in various zones on barrier or sandy beaches.

Figure 8.10 Primary and secondary dunes on gently sloping sandy barrier beaches help protect land from erosion by the sea. The roots of grasses that colonize the dunes hold the sand in place. Ideally, construction is allowed only behind the second strip of dunes, and walkways to the ocean beach are built so as not to damage the dunes. This helps to preserve barrier beaches and to protect buildings from damage by wind, high tides, beach erosion, and flooding from storm surges. Such protection is rare in some coastal areas because the short-term economic value of oceanfront land is considered much higher than its long-term ecological value. Rising sea levels from global warming may put many barrier beaches under water by the end of this century. Question: Do you think that the long and short-term ecological values of oceanfront dunes outweigh the short-term economic value of removing them for coastal development? Explain.

Coral Reefs Are Amazing Centers of Biodiversity Marine equivalent of tropical rain forests Habitats for one-fourth of all marine species Figure 8.11 Natural capital: some components and interactions in a coral reef ecosystem.

The Open Sea and Ocean Floor Host a Variety of Species Open sea is marked by a sharp increase in depth at the edge of the continental shelf. Divided into three vertical zones based on light penetration and temperature (Figure 8-5). Euphotic zone Brightly lit upper zone where phytoplankton carry out some 40% of the world’s photosynthesis. Nutrient levels are low, except at upwellings. DO levels are high Large fast-swimming predatory fish: swordfish, sharks, and bluefin tuna.

Bathyal zone Abyssal zone Dimly lit middle zone does not contain photosynthesizing producers. Zooplankton and smaller fishes which migrate to feed at the surface at night. Abyssal zone Dark and very cold, with little DO Abundant with life even though there is no photosynthesis to support it. Marine snow Deposit feeders such as worms Filter feeders such as clams and sponges Avg. NPP per unit area is low, but make larger overall contribution to earth’s overall NPP. NPP, higher at upwellings

8-3 How Have Human Activities Affected Marine Ecosystems? Concept 8-3 Human activities threaten aquatic biodiversity and disrupt ecological and economic services provided by saltwater systems.

Human Activities Are Disrupting and Degrading Marine Systems A four year study by U.S. National Center for Ecological Analysis and Synthesis Examined 17 different human activities 41% of the world’s oceans, heavily affected No area left completely untouched In 2006, 45% of world’s population lives near the coast.  destruction and degradation of natural resources and services (Figure 8-4). Projected to be 80% in 2040

Major threats to marine systems Coastal development Runoff of non-point source pollution: fertilizers, pesticides and livestock waste Point source pollution such as sewage from cruise ships and oil tanker spills Habitat destruction from coastal development and trawler fishing Overfishing Invasive species Human enhanced climate change causing sea level rise: destroys coastal habitats, coastal cities and coral reefs Climate change: warming oceans and decreasing pH Pollution and degradation of coastal wetlands and estuaries

Case Study: The Chesapeake Bay— an Estuary in Trouble Figure 8.13 Chesapeake Bay, the largest estuary in the United States, is severely degraded as a result of water pollution from point and nonpoint sources in six states and from the atmospheric deposition of air pollutants.

Case Study: The Chesapeake Bay— an Estuary in Trouble Largest estuary in the US Polluted since 1960  Population increased significantly to 16.6 million in 2007 The estuary receives wastes from point and nonpoint sources Bay has become a huge pollution sink; only 1% of waste is flushed to the Atlantic Ocean Phosphate and nitrate levels too high  Large algal blooms and oxygen depletion 60% of phosphates come from point sources 60% of nitrates come from non-point sources

Overfishing of oysters, crabs, and important fishes Combined with pollution and disease, has caused populations to fall since 1960. 1983, U.S. Implemented the Chesapeake Bay Program Integrated coastal management, including citizens’ groups, communities, state legislatures, and federal government Land-use regulations in six states to reduce ag and urban runoff Banned phosphate detergents Closely monitoring industrial discharges Restoration of wetlands and sea grasses

Chesapeake Bay Program has achieved some success Native oyster problem Chesapeake Bay Program has achieved some success Between 1985 and 2000 Phosphorus, -27% Nitrogen, -16% Sea grasses coming back There has been a drop in federal funding

8-4 Why Are Freshwater Ecosystems Important? Concept 8-4 Freshwater ecosystems provide major ecological and economic services and are irreplaceable reservoirs of biodiversity.

Water Stands in Some Freshwater Systems and Flows in Others Standing (lentic) bodies of freshwater Lakes Ponds Inland wetlands Flowing (lotic) systems of freshwater Streams Rivers Cover only 2.2% of earth’s surface but provide important ecological and economic

Figure 8.14 Major ecological and economic services provided by freshwater systems (Concept 8-4). Question: Which two ecological services and which two economic services do you think are the most important? Why?

Four zones based on depth and distance from shore Formation of lakes Large natural bodies of standing freshwater formed when precipitation, runoff, streams or groundwater fills depressions in the earth’s surface. Four zones based on depth and distance from shore Littoral zone Limnetic zone Profundal zone Benthic zone

Figure 8.15 Distinct zones of life in a fairly deep temperate zone lake. Question: How are deep lakes like tropical rain forests? (Hint: See Figure 7-17, p. 156)

Some Lakes Have More Nutrients Than Others Figure 8.16 The effect of nutrient enrichment on a lake. Crater Lake in the U.S. state of Oregon (left) is an example of an oligotrophic lake that is low in nutrients. Because of the low density of plankton, its water is quite clear. The lake on the right, found in western New York State, is a eutrophic lake. Because of an excess of plant nutrients, its surface is covered with mats of algae and cyanobacteria.

Some Lakes Have More Nutrients Than Others Oligotrophic lakes Low levels of nutrients and low NPP Eutrophic lakes High levels of nutrients and high NPP Mesotrophic lakes Cultural eutrophication leads to hypereutrophic lakes

Freshwater Streams and Rivers Carry Water from the Mountains to the Oceans Surface water Runoff Watershed, or drainage basin – the land area that delivers runoff, sediment, and dissolved substances to a stream, Three aquatic life zones in the downhill flow of water Source zone Transition zone Floodplain zone

Figure 8.17 Three zones in the downhill flow of water: source zone containing mountain (headwater) streams; transition zone containing wider, lower-elevation streams; and floodplain zone containing rivers, which empty into the ocean.

Source zone Transition Zone Shallow, cold, clear, and swiftly flowing Large amounts of DO Lack nutrients, not very productive Nutrients come from organic matter that falls into the river. Fauna: cold-water fishes and other animals adapted for fast moving water. Flora: algae and mosses attached to rocks Transition Zone Headwater streams merge to form wider, deeper, and warmer streams Slower flowing, less DO, and can be turbid Cool- and warm-water fishes, and more producers.

Flood Plain Zone Steams join into wider and deeper rivers that flow across broad flat valleys. Water higher in temp, less DO Producers such as algae, cyanobacteria, and rooted aquatic plants along the shores. Water, muddy and high concentration of suspended particulate matter (silt). Main channels support distinct fishes (carp, catfish), backwaters support fish similar to lakes At mouth of river, may divide into many channels as it flows through the delta, built up by deposits of silt, and coastal wetlands and estuaries.

Case Study: Dams, Deltas, Wetlands, Hurricanes, and New Orleans Figure 8.18 Much of the U.S. city of New Orleans, Louisiana, was flooded by the storm surge that accompanied Hurricane Katrina, which made landfall just east of the city on August 29, 2005. When the surging water rushed through the Mississippi River Gulf Outlet, a dredged waterway on the edge of the city, it breached a floodwall, and parts of New Orleans were flooded with 2 meters (6.5 feet) of water within a few minutes. Within a day, floodwaters reached a depth of 6 meters (nearly 20 feet) in some places; 80% of the city was under water at one point. The hurricane killed more than 1,800 people, and caused more than $100 billion in damages, making it the costliest and deadliest hurricane in the U.S. history. In addition, a variety of toxic chemicals from flooded industrial and hazardous waste sites, as well as oil and gasoline from more than 350,000 ruined cars and other vehicles, were released into the stagnant floodwaters. After the water receded, parts of New Orleans were covered with a thick oily sludge. Figure 8.18 Much of the U.S. city of New Orleans, Louisiana, was flooded by the storm surge that accompanied Hurricane Katrina, which made landfall just east of the city on August 29, 2005. When the surging water rushed through the Mississippi River Gulf Outlet, a dredged waterway on the edge of the city, it breached a floodwall, and parts of New Orleans were flooded with 2 meters (6.5 feet) of water within a few minutes. Within a day, floodwaters reached a depth of 6 meters (nearly 20 feet) in some places; 80% of the city was under water at one point. The hurricane killed more than 1,800 people, and caused more than $100 billion in damages, making it the costliest and deadliest hurricane in the U.S. history. In addition, a variety of toxic chemicals from flooded industrial and hazardous waste sites, as well as oil and gasoline from more than 350,000 ruined cars and other vehicles, were released into the stagnant floodwaters. After the water receded, parts of New Orleans were covered with a thick oily sludge.

Case Study: Dams, Deltas, Wetlands, Hurricanes, and New Orleans Coastal deltas, mangrove forests, and coastal wetlands: natural protection against storms Dams and levees reduce sediments in deltas: significance? New Orleans, Louisiana, and Hurricane Katrina: August 29, 2005 Global warming, sea rise, and New Orleans Figure 8.18 Much of the U.S. city of New Orleans, Louisiana, was flooded by the storm surge that accompanied Hurricane Katrina, which made landfall just east of the city on August 29, 2005. When the surging water rushed through the Mississippi River Gulf Outlet, a dredged waterway on the edge of the city, it breached a floodwall, and parts of New Orleans were flooded with 2 meters (6.5 feet) of water within a few minutes. Within a day, floodwaters reached a depth of 6 meters (nearly 20 feet) in some places; 80% of the city was under water at one point. The hurricane killed more than 1,800 people, and caused more than $100 billion in damages, making it the costliest and deadliest hurricane in the U.S. history. In addition, a variety of toxic chemicals from flooded industrial and hazardous waste sites, as well as oil and gasoline from more than 350,000 ruined cars and other vehicles, were released into the stagnant floodwaters. After the water receded, parts of New Orleans were covered with a thick oily sludge.

Figure 8. 19 Projection of how a 1-meter (3 Figure 8.19 Projection of how a 1-meter (3.3-foot) rise in sea level from global warming by the end of this century would put New Orleans and much of Louisiana’s current coast under water. (Used by permission from Jonathan Overpeck and Jeremy Weiss, University of Arizona)

Freshwater Inland Wetlands Are Vital Sponges Inland wetlands are lands covered with freshwater all or part of the time (excluding lakes, reservoirs, and streams). Marshes, dominated by grasses and reeds Swamps, dominated by trees and shrubs Prairie potholes, carved out by ancient glaciers Floodplains Actic tundra

Some wetlands are permanent, some are seasonal Wetlands are highly productive Habitat for game fishes, muskrats, otters, beavers, migratory waterfowl, and many other birds species. Ecological and economic services Filter and degrade toxic wastes Reduce flooding and erosion Help to replenish streams and recharge groundwater aquifers Biodiversity Food and timber Recreation areas

8-5 How Have Human Activities Affected Freshwater Ecosystems? Concept 8-5 Human activities threaten biodiversity and disrupt ecological and economic services provided by freshwater lakes, rivers, and wetlands.

Human Activities Are Disrupting and Degrading Freshwater Systems Human activities affect freshwater ecosystems in four major ways: Dams and canals Alter and destroy terrestrial and aquatic habitats Reduce water flow and sedimentation in coastal deltas and estuaries. Flood control levees and dikes Disconnect rivers from their floodplains Destroy aquatic habitats Alter or reduce the function of wetlands Cities and farms add pollutants and excess nutrients to streams and lakes Cultural eutrophication Draining or filling in wetlands

Case Study: Inland Wetland Losses in the United States More than half of inland wetlands in continental U.S. lost since 1600s 80% destroyed to grow crops 20% lost to mining, forestry, oil and gas extraction, highways and urban development. Has caused increased flood and drought damage in the U.S. Other countries too For example, 80% of all wetlands in Germany and France have been destroyed.