CHAPTER 8 Aquatic Biodiversity

Aquatic life zones Saltwater life zones (marine life zones) Oceans and estuaries Coastlands and shorelines Coral reefs Mangrove forests

Aquatic life zones Freshwater life zones Lakes Rivers and streams Inland wetlands

Aquatic Lifeforms Plankton: free floating Phytoplankton Primary producers for most aquatic food webs Zooplankton Primary and secondary consumers Single-celled to large invertebrates like jellyfish Ultraplankton Tiny photosynthetic bacteria Nekton Strong swimmers: fish, turtles, whales Benthos Bottom dwellers: oysters, sea stars, clams, lobsters, crabs Decomposers Mostly bacteria

Aquatic life zones Key factors in the distribution of organisms Temperature Dissolved oxygen content Availability of food Availability of light and nutrients needed for photosynthesis in the euphotic zone

Turbidity inhibits photosynthesis; decreasing ecosystem productivity Aquatic life zones Turbidity Degree of cloudiness in water from dissolved sediments and nutrients. Turbidity inhibits photosynthesis; decreasing ecosystem productivity

Marine Ecosystems: 3-Major Lifezones Coastal zone Warm, nutrient rich, shallow Shore to edge of continental shelf Usually high NPP from ample sunlight and nutrients Open sea Ocean bottom Rio de Janeiro, Brazil Mumbai, India

Water temperature (°C) High tide Coastal Zone Open Sea Low tide Depth in meters Sea level Photosynthesis 50 Euphotic Zone Estuarine Zone 100 Continental shelf 200 500 Bathyal Zone Twilight 1,000 1,500 Water temperature drops rapidly between the euphotic zone and the abyssal zone in an area called the thermocline . Abyssal Zone 2,000 3,000 Figure 8.6: This diagram illustrates the 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 line. Question: How is an ocean like a rain forest? (Hint: see Figure 7-15, p. 162.) Darkness 4,000 5,000 10,000 5 10 15 20 25 30 Water temperature (°C)

Estuaries and Coastal Wetlands Are Highly Productive Where rivers meet the sea & seawater mixes with freshwater Very productive ecosystems: high nutrient levels Includes: river mouths, Inlets, Bays, Sounds, saltmarshes, mangrove forests Important ecological and economic services Coastal aquatic systems maintain water quality by filtering pollutants Excess plant nutrients Sediments Reduce storm damage and coast erosion Provide food and habitats

Estuaries and Coastal Wetlands Are Highly Productive Madagascar; heavy sediment load from soil erosion due to deforestation.

Estuaries and Coastal Wetlands Are Highly Productive Salt Marsh Coastal temperate climate; most productive ecosystems; often found in estuaries. Coastal Salt Marsh Ecosystem

Estuaries and Coastal Wetlands Are Highly Productive Seagrass Beds Grow underwater in shallow areas Support a variety of marine species Stabilize shorelines Reduce wave impact Mangrove forests Along tropical and subtropical coastlines 69 different tree species that grow in saltwater i.e. salt tolerant Protect coast from erosion Sheltered habitat for fish and shellfish

Mangrove Forest Ecosystem

Rocky Shore & Sandy Shores Ecology Intertidal zone Rocky shores Sandy shores: barrier beaches Living between the Tides Coastal ecosystems where organisms adaptations help them deal with daily salinity and moisture changes due to high and low tide and subsequent temperature changes.

Rocky Shore Beach Barrier Beach Sea star Hermit crab Shore crab High tide Periwinkle Sea urchin Anemone Mussel Low tide Sculpin Barnacles Kelp Sea lettuce Monterey flatworm Nudibranch Beach flea Peanut worm Tiger beetle Barrier Beach Blue crab Clam Dwarf olive High tide Sandpiper Ghost shrimp Silversides Low tide Mole shrimp White sand macoma Sand dollar Moon snail

Vulnerable because they grow slowly and are disrupted easily Coral Reefs Coral Reefs exist in the warm shallow waters just beyond shoreline; most diverse marine biome. Formation Result of mutualistic relationship between polyps and algae; algae provide polyp with food, color and oxygen through photosynthesis; algae get a home and some nutrients Formed by massive colonies of polyps that secrete limestone around their soft body. When polyps die their empty crusts remain as a platform for more reef growth. Vulnerable because they grow slowly and are disrupted easily

Coral Reefs Biodiversity Marine equivalent of tropical rain forests Habitats for one-fourth of all marine species Important ecological and economic services Sequester carbon dioxide i.e. carbon sink Moderate atmospheric temperatures Act as natural barriers protecting coasts from erosion (waves and storm surge) Provide habitats (plus, fish nurseries) Support fishing and tourism businesses Provide jobs and building materials

Green sea turtle Moray eel Gray reef shark Sea nettle Green sea turtle Blue tang Fairy basslet Parrot fish Brittle star Sergeant major Hard corals Algae Banded coral shrimp Phytoplankton Coney Symbiotic algae Figure 8.12: Natural capital. This diagram illustrates some of the components and interactions in a coral reef ecosystem. When these organisms die, decomposers break down their organic matter into minerals used by plants. Colored arrows indicate transfers of matter and energy between producers, primary consumers (herbivores), secondary or higher-level consumers (carnivores), and decomposers. Organisms are not drawn to scale. Zooplankton Blackcap basslet Sponges Moray eel Bacteria Producer to primary consumer Primary to secondary consumer Secondary to higher-level consumer All producers and consumers to decomposers

Coral Reefs: Degradation & Decline Coastal development & pollution Overfishing & destructive fishing practices Coral Bleaching: warmer ocean temperatures stress algae; they exit polyps leaving behind a white skeleton of calcium carbonate Ocean acidification: ocean absorbs atmospheric carbon dioxide; reacting with water to produce carbonic acid and excessive hydrogen ions that dissolve shells and inhibit formation of calcium carbonate.

Ocean acidification: decrease in the pH and increase in acidity of the oceans, caused by the uptake of anthropogenic carbon dioxide from the atmosphere. Atmospheric carbon dioxide dissolves in ocean water reacting with water to form carbonic acid; carbonic acid dissociates to yield bicarbonate ions and hydrogen ions; hydrogen ions then react with calcium carbonate of shells and coral skeletons to produce calcium ions and bicarbonate ions. Essentially, free hydrogen ions rip apart calcium carbonate; effectively dissolving and inhibiting the formation of shells and coral.

Interconnected Shoreline Ecosystems

Ridge-to-Reef Ecosystem Based Management In Fiji, researchers found that declining forest cover is associated with reduced numbers of freshwater fish species in rivers and streams. The clearing of forest ecosystems results in heavy soil erosion, and increased sediment loads, in rivers and streams. This coupled with agricultural activity that leads to excessive nutrient loads, from fertilizer, in coastal zones results in turbidity and lack of productivity in rivers, streams, sea-grass beds and coral reefs ecosystems.

Three Vertical Lifezones of the Open Sea Euphotic zone Phytoplankton Nutrient levels low Dissolved oxygen levels high Bathyal zone Dimly lit Zooplankton and smaller fishes Abyssal zone Dark and cold High levels of nutrients Little dissolved oxygen Deposit feeders Filter feeders Abyssal zone (cont.) Upwelling brings nutrients to euphotic zone Primary productivity and NPP

Water temperature (°C) High tide Coastal Zone Open Sea Low tide Depth in meters Sea level Photosynthesis 50 Euphotic Zone Estuarine Zone 100 Continental shelf 200 500 Bathyal Zone Twilight 1,000 1,500 Water temperature drops rapidly between the euphotic zone and the abyssal zone in an area called the thermocline . Abyssal Zone 2,000 3,000 Figure 8.6: This diagram illustrates the 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 line. Question: How is an ocean like a rain forest? (Hint: see Figure 7-15, p. 162.) Darkness 4,000 5,000 10,000 5 10 15 20 25 30 Water temperature (°C)

Marine Ecosystems Human Activities Are Disrupting and Degrading Marine Systems Major threats to marine systems Runoff of nonpoint source pollution Introduction of invasive species Climate change from human activities Pollution of coastal wetlands and estuaries Coastal development Overfishing Use of fishing trawlers Point source pollution Habitat destruction

Natural Capital Degradation Major Human Impacts on Marine Ecosystems and Coral Reefs Marine Ecosystems Coral Reefs Half of coastal wetlands lost to agriculture and urban development Ocean warming Figure 8.13: This diagram shows the major threats to marine ecosystems (left) and particularly coral reefs (right) (Core Case study) resulting from human activities (Concept 8-3). Questions: Which two of the threats to marine ecosystems do you think are the most serious? Why? Which two of the threats to coral reefs do you think are the most serious? Why? Rising ocean acidity Over one-fifth of mangrove forests lost to agriculture, development, and shrimp farms since 1980 Soil erosion Algae growth from fertilizer runoff Bleaching Beaches eroding because of coastal development and rising sea levels Rising sea levels Increased UV exposure Ocean bottom habitats degraded by dredging and trawler fishing Damage from anchors Damage from fishing and diving At least 20% of coral reefs severely damaged and 25–33% more threatened

Freshwater Ecosystems

Lentic; i.e. Standing bodies of freshwater

Lotic; i.e. Flowing systems of freshwater

Freshwater Ecosystems Four zones based on depth and distance from shore Littoral zone Near shore where rooted plants grow High biodiversity Turtles, frogs, crayfish, some fish Limnetic zone Open, sunlight area away from shore Main photosynthetic zone Some larger fish

Freshwater Ecosystems Four zones based on depth and distance from shore Profundal zone Deep water too dark for photosynthesis Low oxygen levels Some fish Benthic zone Decomposers Detritus feeders Nourished primarily by dead matter

Temperate Lake Littoral zone Limnetic zone Profundal zone Benthic zone Painted turtle Blue-winged teal Green frog Muskrat Pond snail Littoral zone Plankton Figure 8.16: This diagram illustrates the distinct zones of life in a fairly deep temperate-zone lake. See an animation based on this figure at CengageNOW. Question: How are deep lakes like tropical rain forests? (Hint: See Figure 7-15, p. 162) Limnetic zone Profundal zone Diving beetle Northern pike Benthic zone Yellow perch Bloodworms

Freshwater Ecosystems Some lakes have more nutrients than others Oligotrophic lakes Low levels of nutrients and low NPP Very clear water Mesotrophic lakes (meso means middle) Eutrophic lakes High levels of nutrients and high NPP due to algal blooms; i.e. growth of algae Murky water with high turbidity Eutrophication Excessive nutrient loads (nitrogen & phosphorous) in a lake or other body of water, due to runoff from the land; causes dense growth of algae and plant life; after plant die-offs, decomposing plant matter uses up oxygen causing fish death. Cultural eutrophication: eutrophication from human input of nutrients

Freshwater Inland Wetlands Freshwater inland wetlands are vital sponges Freshwater inland wetlands include: Marshes Swamps Prairie potholes  Floodplains Arctic tundra in summer Provide free 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

Freshwater Inland Wetlands Human activities are disrupting and degrading freshwater systems Impact of dams and canals on rivers Impact of flood control levees and dikes along rivers Impact of pollutants from cities and farms on streams, rivers, lakes Impact of drained wetlands

Freshwater Ecosystems Rivers & Streams Carry Water from Mountains to Oceans Surface water Surface runoff Watershed; i.e. drainage basin Three zones in the downhill flow of water; i.e. aquatic life zones Source zone Transition zone Floodplain zone

Waterfall Lake Glacier Rain and snow Rapids Source Zone Transition Zone Tributary Flood plain Oxbow lake Salt marsh Delta Deposited sediment Ocean Water Sediment Floodplain Zone

South Platte River Watershed

Mississippi River Drainage Basin

Estuaries and Coastal Wetlands Are Important and imperiled Figure 8.14: The Chesapeake Bay is the largest estuary in the United States. However, the bay is severely degraded as a result of water pollution from point and nonpoint sources in six states and the District of Columbia, and from the atmospheric deposition of air pollutants.

Dams, Deltas, Wetlands, Hurricanes, & New Orleans

Dams, Deltas, Wetlands, Hurricanes, & New Orleans Coastal deltas, mangrove forests, and coastal wetlands provide natural protection against storms; slow waves + vegetation and soil absorb water. Dams and levees reduce sediments in deltas. Sediment is deposited behind dam (upstream) rather than in the river delta; thus reducing size of river delta. Levees designed to reduce flooding in upstream communities channel water; increasing speed and reducing sediment deposition.

Dams, Deltas, Wetlands, Hurricanes, & New Orleans Without such natural protection many areas of the world (New Orleans, Bangladesh) experience much more severe hurricane impacts due to increased storm surge. Global warming, sea rise, and New Orleans Wetland restoration in New Orleans

The Chesapeake Bay—an Estuary in Trouble Largest estuary in the US; polluted since 1960 Human population increased Point and nonpoint sources raised pollution Phosphate and nitrate levels too high Excess sediments from runoff and decreased vegetation Oysters, a keystone species, greatly reduced 1983: Chesapeake Bay Program Integrated coastal management with local, state, federal governments and citizens’ groups 2008 update: 25 years and $6 billion Program met only 21% of goals Water quality “very poor”

Low concentrations of oxygen Drainage basin Figure 8.14: The Chesapeake Bay is the largest estuary in the United States. However, the bay is severely degraded as a result of water pollution from point and nonpoint sources in six states and the District of Columbia, and from the atmospheric deposition of air pollutants. No oxygen Low concentrations of oxygen