Aquatic Biodiversity Chapter 8 8 1 What is

Aquatic Biodiversity Chapter 8

8. 1 What is the General Nature of Aquatic Systems?

Earth: The Watery Planet § 71% Earth covered by ocean • 2. 2% covered by freshwater

What are Earth’s Major Oceans?

What are Earth’s Major Oceans? § Pacific • Largest, deepest § Atlantic • Second largest § Indian • Mainly in Southern Hemisphere § Arctic • Smallest, shallowest, ice-covered

Average Ocean Depth

Why are the oceans important? 1. 2. • • 3. Influence weather Lungs of the planet Take CO 2 out of the atmosphere and replace it with O 2 Supply 70% O 2 humans breathe! Sustain life

Ocean life Smallest life Largest life Microscopic Bacteria Blue Whale

How do humans impact ocean life? § 80% of all Americans live within an hour’s drive from an ocean or the Great Lakes § 8 of the 10 largest cities are in coastal environments

Core Case Study: Why Should We Care about Coral Reefs? § Biodiversity § Important ecological and economic services • Natural barriers protecting coasts from erosion • Provide habitats • Support fishing and tourism businesses • Provide jobs • Studied and enjoyed

Core Case Study: Why Should We Care about Coral Reefs? § Degradation and decline • • Coastal development Pollution Overfishing Warmer ocean temperatures leading to coral bleaching • Increasing ocean acidity

Aquatic life zones § Saltwater: marine • • Oceans and estuaries Coastlands and shorelines Coral reefs Mangrove forests § Freshwater • Lakes • Rivers and streams • Inland wetlands

Distribution of the World’s Major Saltwater and Freshwater Sources

8. 2 Why Are Marine Aquatic Systems Important?

Oceans Provide Important Ecological and Economic Resources § Reservoirs of diversity in three major life zones • Coastal zone • Usually high NPP • Open sea • Ocean bottom

Estuaries and Coastal Wetlands Are Highly Productive § Estuaries and coastal wetlands • • • River mouths Inlets Bays Sounds Salt marshes Mangrove forests

Estuaries and Coastal Wetlands Are Highly Productive § Important ecological and economic services • Coastal aquatic systems maintain water quality by filtering • Toxic pollutants • Excess plant nutrients • Sediments • Absorb other pollutants • Provide food, timber, fuel, and habitats • Reduce storm damage and coast erosion

Estuaries and Coastal Wetlands Are Highly Productive § Seagrass Beds • Support a variety of marine species • Stabilize shorelines • Reduce wave impact

Some Components and Interactions in a Salt Marsh Ecosystem in a Temperate Area

Mangrove Forest in Daintree National Park in Queensland, Australia

Blue Planet Video Clip § Seasonal Seas 5: 00 -15: 00

Most Aquatic Species Live in Top, Middle, or Bottom Layers of Water § 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, or photic, zone

Pelagic Intertidal Abyssal Benthic

Zone: Intertidal § Area between high tide and low tide • Sometimes covered, sometimes exposed § Very tough habitat to live in! • • Subjected to drying and submersion Temperature extremes Pull of the waves Sea and land predators

Zone: Intertidal § Animals • Often burrow • Hard shells that can be sealed to prevent water loss § Plants • Cling to hard bottoms

Intertidal Creatures High Tide Low Tide

Video Clip § Blue Planet: Tidal Seas 5: 00 -18: 00

Zone: Pelagic § Open ocean zone • Sub-divided by depth or amount of sunlight

Zone: Pelagic § Epipelagic Zone • Photic zone • Plankton and photosy thesis • Shallowest zone § Mesopelagic zone • Little light (twilight) • Plants cannot grow § Deep-pelagic • Aphotic

Pelagic Creatures

Pelagic Creatures § Plankton (drifters) • Microscopic organisms • Weak swimmers (at mercy of currents) • Primary Producers § Nekton • Animals that can swim well • Mostly vertebrates

Plankton and Primary Production § Gross primary productivity (GPP) • Rate at which an ecosystem’s producers convert solar energy into chemical energy stored in their tissues § Net primary productivity (NPP) • Rate they create and store energy minus the energy they use for homeostasis • Ecosystems and life zones differ in their NPP = GPP - R

Zone: Abyssal § Midnight zone – no light penetrates § High pressure • Pressure at 10, 000 = weight of 5 jumbo airliners

Zone: Abyssal § Animal Adaptations • Withstand the dark, the cold (near freezing), and the tremendous pressure • Dark or nearly transparent in color • Bioluminescent • Don’t move much, and usually eat what falls from above

Zone: Benthic § Zone ranging from the deepest part of the ocean to the shore § Organism diversity • Plants, anemones, sponges, fish, skates and rays, octopus, mollusks, crabs, sea stars, corals and worms. • Most are scavengers.

Zone: Benthic

Intertidal Benthic Hydrothermal vent Coral Reef

Zone: Benthic § Hydrothermal Vents • Discovered in 1977 by submersible Alvin • Were gushing hot mineralrich water

Zone: Benthic § Hydrothermal Vents • Formed when cold sea water seeps into cracks in Earth’s crust • Superheated by the magma in the mantle. • Hot water with dissolved minerals from the magma rises and spews out like an undersea geyser

Zone: Benthic § Fantastic communities of organisms that live by chemosynthesis § Thrive around these “black smokers”, using energy from chemical reactions with minerals in the water to live.

Hydrothermal Vent Video Clip

Your Turn § Your Turn: Cartoon Guide to Aquatic Ecosystems

8. 3 How Have Human Activities Affected Marine Ecosystems?

Human Activities Are Disrupting and Degrading Marine Systems § Major threats to marine systems • Coastal development • Overfishing • Runoff of nonpoint source pollution • Point source pollution

Human Activities Are Disrupting and Degrading Marine Systems § Major threats to marine systems • Habitat destruction • Introduction of invasive species • Climate change from human activities • Pollution of coastal wetlands and estuaries

Video Clip § Case Study: Chesapeake bay – An Estuary in Trouble

Class Bacillariophyceae § Diatoms • Most abundant phytoplankton • Major oceanic primary producer • Cell walls composed of silica (glasslike) • Live alone or in chains • Centric or pennate shapes

Division Dinophyta § Dinoflagellates • Abundant in warm surface H 2 O (tropics) • Some symbiotic (zooxanthellae) • Live in coral, clams, urchins, anemones • Give carbohydrates & receive nutrients & shelter

Why Do Dinos. Produce Light? § Camouflage! § When it senses a predator (motion in H 2 O) • Attracts larger predators that consumes the would-be Dino predator

Red Tides (Dinoflagellate Bloom) § Mass development of dinoflagellates discolor water § Often caused by excess nutrients • Enter ocean from land (runoff) • Fertilizer, sewage

Red Tide Impacts § Toxic to marine life: accumulates in clams, mussels, scallops, fish, mammals • Death to some species; biomagnification § Human poisoning after consumption (30 min. ) • Symptoms: • Paralytic: paralysis, asthma, heartattack (rare) • Neurotoxic: tingling, paralysis, memory loss • Diarrhetic: cramps, vomiting, diarrhea

Red Tide Impacts

Measuring Primary Production § Satellites measure differences in sea surface color • Color = type of producer • Green color = chlorophyll pigments

Productivity Limitations

Eutrophication § Light Availability – depth, season, latitude • Little photosynthesis below 100 m (330 ft) • Phytoplankton productivity limited to photic zone

Eutrophication § Nutrient Availability – “Natural fertilizer” • Upwelling - aids primary production by bringing nutrients to surface • Nitrogen and Phosphorous • Caused by winds blowing either parallel or offshore along a coastline • Brings up cold nutrient-rich water

Eutrophication • Caused by winds blowing either parallel or offshore along a coastline • Brings up cold nutrient-rich water

Eutrophication § Nutrient Availability – “Natural fertilizer” • Zooplankton (fecal pellets, death) – leads to future phytoplankton blooms • Need bacteria to decompose waste

§ Water temperature - diatoms like cool H 2 O

Phytoplankton: Season & Latitude

Phytoplankton vs. Zooplankton

Your Turn! § Analyzing Plankton Data

8. 4 Why Are Freshwater Ecosystems Important?

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

Water Stands in Some Freshwater Systems and Flows in Others § Formation of lakes § Four zones based on depth and distance from shore • Littoral zone – top layer near the shore • Limnetic zone – open sunlit layer away from the shore; extends to depth penetrated by light • Profundal zone – deep open water; too dark for photosynthesis • Benthic zone – bottom of lake; mostly decomposers, detritus feeders and some fish

Stratification by depth/distance from shore

Distinct Zones of Life in a Fairly Deep Temperate Zone Lake

Stratification by temperature § Epilimnion § Hypolimnion

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

The Effect of Nutrient Enrichment on a Lake

Three aquatic life zones § Source zone • Headwaters and mountain streams swiflty flow • Increases DO levels • Lack nutrients; low productivity Rain and snow Lake Glacier Rapids Waterfall Source Zone

Three aquatic life zones § Transition zone • Headwater streams merge to form wider and warmer streams • Gentle slopes • High turbidity • Less DO • Moderate productivity Tributary Flood plain Transition Zone

Three aquatic life zones § Floodplain zone • • • Friction from water modifies land High temperatures Low DO High productivity Murky water Erosion Floodplain Zone Oxbow lake Salt marsh Delta Deposited sediment Ocean Sediment Water

Rain and snow Lake Glacier Rapids Waterfall Tributary Flood plain Oxbow lake Salt marsh Delta Deposited sediment Ocean Source Zone Transition Zone Floodplain Zone Water Sediment Stepped Art Fig. 8 -17, p. 176

Freshwater Inland Wetlands Are Vital Sponges § Marshes § Swamps § Prairie potholes § Floodplains § Arctic tundra in summer

Freshwater Inland Wetlands Are Vital Sponges § 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

Your Turn! § Draw a graph that depicts the changes in water temperature levels in a lake through the four seasons! • One color to represent epilimnion • One color to represent hypolimnion • Label lake overturn (upwelling events) § Draw a graph that depicts the changes in dissolved oxygen levels in a lake through the four seasons! • One color to represent epilimnion • One color to represent hypolimnion • Label lake overturn (upwelling events)

What is turbidity? § Measure of the degree to which the water looses its transparency • Due to the presence of suspended particulates

What is turbidity? § The more total suspended solids in the water, the murkier it seems and the higher the turbidity

What causes turbidity? § There are various parameters influencing the cloudiness of the water. Some of these are: • Phytoplankton • Sediments from erosion • Resuspended sediments from the bottom (frequently stir up by bottom feeders like carp) • Waste discharge • Algae growth • Urban runoff

What are the consequences of high turbidity? § Suspended particles absorb heat from the sunlight • Turbid waters become warmer • Reduce the concentration of oxygen in the water

What are the consequences of high turbidity? § The suspended particles scatter the light • Decrease the photosynthetic activity of plants and algae • Contributes to lowering the oxygen concentration even more