Chapter 7. Aquatic Ecology: Biodiversity in Aquatic Systems Miller – Living in the Environment 13th ed.
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Chapter 7. Aquatic Ecology: Biodiversity in Aquatic Systems Miller – Living in the Environment 13th ed. Who lives in a pineapple under the sea? Aquatic Life Zones 1) Saltwater or Marine • estuaries, coastlines, coastal marshes, mangrove swamps, and oceans 2) Freshwater • lakes and ponds, streams and rivers, inland wetlands Aquatic Environments • Saltwater and freshwater aquatic life zones cover almost three-fourths of the earth’s surface 90% 50% Lakes Rivers Coral reefs Mangroves Types of organisms • Phytoplankton – cyanobacteria and algae • Zooplankton – primary and secondary consumers • Nekton – Swimming consumers (fish, turtles, and whales) • Benthos – bottom dwellers • Barnacles and oysters • Worms • Lobsters and crabs • Decomposers – bacteria © 2004 Brooks/Cole – Thomson Learning Advantages Physical support from water buoyancy Fairly constant temperature Nourishment from dissolved nutrients Water availability Easy dispersal of organisms, larvae, and eggs Less exposure to harmful UV radiation Dilution and dispersion of pollutants Disadvantages Can tolerate a narrow range of temperatures Exposure to dissolved pollutants Fluctuating population size for many species Dispersion separates many aquatic offspring from parents Factors Limiting Life in Aquatic Life Zones 1) Temperature 2) Access to sunlight • Euphotic zone • 5 ppm • • Shallow water upwelling 3) Dissolved oxygen 4) Available nutrients 0 Limiting Factors 2,000 O2 1,000 CO2 Depth (feet) Depth (meters) 500 4,000 1,500 6,000 2,000 1.5 90 3.0 4.5 6.0 O2 7.5 94 98 102 106 110 Concentration of dissolved gas (parts per million by weight) CO2 © 2004 Brooks/Cole – Thomson Learning 0 Natural Capital Marine Ecosystems Ecological Services Economic Services Climate moderation Food CO2 absorption Animal and pet feed Nutrient cycling Waste treatment Reduced storm impact (mangroves, barrier islands, coastal wetlands) Habitats and nursery areas Pharmaceuticals Harbors and transportation routes Coastal habitats for humans Recreation Employment Genetic resources and biodiversity Oil and natural gas Scientific information Building materials Minerals The Coastal Zone: Where Most of the Action Is • The 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. • The coastal zone makes up less than 10% of the world’s ocean area but contains 90% of all marine species. – Provides numerous ecological and economic services. – Subject to human disturbance. Open Sea Sea level Estuarine Zone Continental shelf Sun Euphotic Zone Photosynthesis High tide Coastal Zone Low tide The Coastal Zone Abyssal Zone Darkness Bathyal Zone Fig. 6-5, p. 130 What are estuaries and coastal wetlands? Estuary • Coastal water where seawater mixes with fresh water and nutrients from rivers, streams, and runoff Coastal Wetlands • Land areas covered with water all or part of the year Coastal Wetlands • River mouths • Inlets • Bays • Sounds • Mangrove forest swamps • Salt marshes Salt Marsh Mangrove Forests • Are found along about 70% of gently sloping sandy and silty coastlines in tropical and subtropical regions. Estuaries and Coastal Wetlands: Centers of Productivity • Estuaries and coastal marshes provide ecological and economic services. – Filter toxic pollutants, excess plant nutrients, sediments, and other pollutants. – Reduce storm damage by absorbing waves and storing excess water produced by storms and tsunamis. – Provide food, habitats and nursery sites for many aquatic species. Peregrine falcon Herring gulls Producer to primary consumer Snowy egret Cordgrass Short-billed dowitcher Marsh periwinkle Phytoplankton Primary to secondary consumer Secondary to higher-level consumer Smelt Soft-shelled clam Zooplankton and small crustaceans Bacteria All producers and consumers to decomposers Clamworm Salt Marsh Ecosytem Rocky and Sandy Shores: Living with the Tides • Organisms experiencing daily low and high tides have evolved a number of ways to survive under harsh and changing conditions. – Gravitational pull by moon and sun causes tides. – Intertidal Zone: area of shoreline between low and high tides. Rocky Shore 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 Sandy beach Peanut worm Tiger beetle Blue crab Clam Dwarf olive High tide Sandpiper Silversides Low tide White sand macoma Sand dollar Moon snail Mole shrimp Ghost shrimp Barrier Islands Ocean Beach Intensive recreation, no building Primary Dune Trough Limited No direct passage recreation and or building walkways Grasses or shrubs Secondary Dune No direct passage or building Back Dune Bay or Lagoon Most suitable for development Intensive recreation Taller shrubs Bay shore No filling Taller shrubs and trees Long, thin, low off-shore islands that generally run parallel to the shore. • Polyps – Soft bodies – Calcium carbonate crust • Zooxanthellae – Algae • Color • Food • Oxygen Importance of coral reefs • Removing CO2 from atmosphere • Natural barrier – Waves and storms – Allows oceans to replenish beach sand • Supports marine life • Source of global fish catch • Provides food, jobs, and building materials for world’s poorest countries • Supports fishing and tourism • Scientific research Gray reef shark Sea nettle Green sea turtle Producer to primary consumer Fairy basslet Primary to secondary consumer Blue tangs Parrot fish Sergeant major Algae Hard corals Brittle star Banded coral shrimp Phytoplankton Coney Secondary to higher-level consumer Symbiotic algae Zooplankton Blackcap basslet Moray eel Sponges Bacteria All consumers and producers to decomposers Coral Reef coral bleaching caused by the loss of algae Ocean warming Soil erosion Algae growth from fertilizer runoff Mangrove destruction Coral reef bleaching Rising sea levels Increased UV exposure from ozone depletion Using cyanide and dynamite to harvest coral reef fish Coral removal for building material, aquariums, and jewelry Damage from anchors, ships, and tourist divers Biological Zones in the Open Sea: Light Rules • Euphotic zone: brightly lit surface layer. – Nutrient levels low, dissolved O2 high, photosynthetic activity. • Bathyal zone: dimly lit middle layer. – No photosynthetic activity, zooplankton and fish live there and migrate to euphotic zone to feed at night. • Abyssal zone: dark bottom layer. – Very cold, little dissolved O2. Open Sea Sea level Estuarine Zone Continental shelf Sun Euphotic Zone Photosynthesis High tide Coastal Zone Low tide The Coastal Zone Abyssal Zone Darkness Bathyal Zone Fig. 6-5, p. 130 Effects of Human Activities on Marine Systems: Red Alert • Human activities are destroying or degrading many ecological and economic services provided by the world’s coastal areas. Freshwater Life Zones • Salt concentration of less than 1% – Standing bodies (lakes, ponds, inland wetlands) – Flowing bodies (streams and rivers) Natural Capital Freshwater Systems Ecological Services Economic Services Climate moderation Food Nutrient cycling Drinking water Waste treatment Irrigation water Flood control Hydroelectricity Groundwater recharge Transportation corridors Habitats for many species Recreation Genetic resources and biodiversity Scientific information Employment Lakes: Water-Filled Depressions • Lakes are large natural bodies of standing freshwater formed from precipitation, runoff, and groundwater seepage consisting of: – Littoral zone (near shore, shallow, with rooted plants). – Limnetic zone (open, offshore area, sunlit). – Profundal zone (deep, open water, too dark for photosynthesis). – Benthic zone (bottom of lake, nourished by dead matter). Life Zones Found in Freshwater • Littoral zone – consists of shallow water near the shore to the depth at which rooted plants quite growing. • Limnetic zone – the open sunlite water surface away from the shore. The main photosynthetic body of the lake. • Profundal zone – deep, open water, too dark for photosynthesis. • Benthic zone – at the bottom of the lake. Cool temperatures and low oxygen levels. Sunlight Green frog Painted turtle Blue-winged teal Muskrat Pond snail Littoral zone Limnetic zone Diving beetle Plankton Profundal zone Yellow perch Bloodworms Benthic zone Northern pike Lakes: Water-Filled Depressions • During summer and winter in deep temperate zone lakes the become stratified into temperature layers and will overturn. – This equalizes the temperature at all depths. – Oxygen is brought from the surface to the lake bottom and – nutrients from the bottom are brought to the top. 22˚ 20˚ 18˚ 8˚ Epilimnion Hypolimnion Thermocline 4˚ 4˚ 6˚ 4˚ 4˚ Seasonal 4˚ 5˚ 4˚C 4˚C Summer Changes in Fall overturn Temperate Lakes 4˚ 4˚ 2˚ 0˚ 4˚ 4˚ 4˚ 4˚ 4˚C 4˚C Winter Dissolved O2 concentration Spring overturn High Medium Low 4˚ 4˚ Effects of Plant Nutrients on Lakes: Too Much of a Good Thing • Plant nutrients from a lake’s environment affect the types and numbers of organisms it can support. – Oligotrophic (poorly nourished) lake: Usually newly formed lake with small supply of plant nutrient input. – Eutrophic (well nourished) lake: Over time, sediment, organic material, and inorganic nutrients wash into lakes causing excessive plant growth. Effects of Plant Nutrients on Lakes: Too Much of a Good Thing • Cultural eutrophication: – Human inputs of nutrients from the atmosphere and urban and agricultural areas can accelerate the eutrophication process. Sunlight Narrow littoral zone Little shore vegetation Limnetic zone Profundal zone Low concentration of nutrients and plankton Sparse fish population deeply sloping shorelines Sand, gravel, rock bottom Oligotrophic lake oligo = little + trophic = nutrition Sunlight Wide littoral zone Much shore vegetation High concentration of nutrients and plankton Limnetic zone Profundal zone Dense fish population Gently sloping shorelines Silt, sand, clay bottom Eutrophic lake eu = truly + trophic = nutrition Water flows downhill • Surface water • Runoff • Watershed • Drainage basin • River basin Major Characteristics of Freshwater Streams and Rivers Rain and snow Lake Glacier Rapids Waterfall Tributary Flood plain Oxbow lake Salt marsh Ocean Delta Deposited sediment Source Zone Transition Zone Water Sediment Floodplain Zone Inland Wetlands Land covered with water all or part of the time 1) 2) 3) 4) 5) 6) Marshes Swamps Prairie potholes Floodplains Bogs and fens Wet arctic tundra Freshwater Inland Wetlands: Vital Sponges • Inland wetlands act like natural sponges that absorb and store excess water from storms and provide a variety of wildlife habitats. Freshwater Inland Wetlands: Vital Sponges • Filter and degrade pollutants. • Reduce flooding and erosion by absorbing slowly releasing overflows. • Help replenish stream flows during dry periods. • Help recharge ground aquifers. • Provide economic resources and recreation. Impact of human activities • Fragmentation by dams, diversions, or canals • Flood control levees and dikes – Alter or destroy aquatic habitats – Disconnect rivers and floodplains – Eliminate wetlands • Draining or filling of wetlands • Cities and farmlands add pollutants and excess plant nutrients to streams and rivers.