1. Chapter 8 Aquatic Biodiversity

2. A Healthy Coral Reef in the Red Sea
Figure 8.1: A healthy coral reef in the Red Sea is covered by colorful algae (left), while a bleached coral reef (right) has lost most of its algae because of changes in the environment (such as cloudy water or high water temperatures). With the algae gone, the white limestone of the coral skeleton becomes visible. If the environmental stress is not removed and no other algae fill the abandoned niche, the corals die. These diverse and productive ecosystems are being damaged and destroyed at an alarming rate.
Fig. 8-1, p. 168

3. 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.

4. Most of the Earth Is Covered with Water (1)
Saltwater: global ocean divided into 4 areas
Atlantic
Pacific:
Arctic
Indian
Freshwater

5. Earth’s Oceans
Sect
All of the oceans are joined in a single large interconnected body of water called the world ocean. The world ocean play important roles in the regulation of the planet’s environment.

6. Earth’s Ocean
The largest ocean on Earth is the Pacific Ocean with a surface area of about 165,640,000 km2.
The deepest point on the ocean floor, the Challenger Deep, is found in the Pacific Ocean.
The Challenger Deep is located east of the Philippine islands and the bottom of the Mariana Trench and is 11,033m below sea level which is deeper than Mount Everest is tall.

7. Earth’s Ocean
The second largest ocean on Earth is the Atlantic Ocean, and covers about half the area of the Pacific Ocean which is a surface area of about 81,630,000 km2.
The Indian Ocean is the third largest ocean on Earth with a surface area of 73,420,000 km2.
The smallest ocean is the Artic ocean which covers 14,350,000 km2

8. Most of the Earth Is Covered with Water (2)
Aquatic life zones
Saltwater life zones (marine life zones)
Oceans and estuaries
Coastlands and shorelines
Coral reefs
Mangrove forests
Freshwater life zones
Lakes
Rivers and streams
Inland wetlands

9. Aquatic Systems
Figure 8.3: Aquatic systems include (a) saltwater oceans and (b) bays, such as Trunk Bay at St. John in the U.S. Virgin Islands, (c) freshwater lakes such as Peyto Lake in Canada’s Banff National Park, and (d) wild freshwater mountain streams.
Fig. 8-3, p. 170

10. Most Aquatic Species Live in Top, Middle, or Bottom Layers of Water (1)
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

11. Most Aquatic Species Live in Top, Middle, or Bottom Layers of Water (2)
Nekton
Strong swimmers: fish, turtles, whales
Benthos
Bottom dwellers: oysters, sea stars, clams, lobsters, crabs
Decomposers
Mostly bacteria
PLANKTON. BENTHOS. NEKTON

12. Most Aquatic Species Live in Top, Middle, or Bottom Layers of Water (3)
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 (photic) zone
Turbidity: degree of cloudiness in water
Inhibits photosynthesis, often due to Algal blooms.

13. Four Types of Aquatic Life Forms
Figure 8.4: We can divide aquatic life forms into several major types: plankton, which include (a) phytoplankton, tiny drifting plants, and (b) zooplankton, drifting animals that feed on each other and on phytoplankton; one example is this jellyfish, which uses long tentacles with stinging cells to stun or kill its prey. Other major types of aquatic life are (c) nekton, or strongly swimming aquatic animals such as this right whale, and (d) benthos, or bottom dwellers such as this sea star attached to coral in the Red Sea.
Fig. 8-4, p. 171

14. 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.

15. Oceans Provide Vital Ecological and Economic Resources
Estimated $12 trillion per year in goods and services
Reservoirs of diversity in three major life zones
Coastal zone
Warm, nutrient rich, shallow
Shore to edge of continental shelf
Usually high NPP from ample sunlight and nutrients
Open sea
Ocean bottom

16. Natural Capital Marine Ecosystems Ecological Services
Economic Services
Climate moderation
Food
CO 2 absorption
Animal and pet feed
Nutrient cycling
Pharmaceuticals
Waste treatment
Harbors and transportation routes
Reduced storm impact (mangroves, barrier islands, coastal wetlands)
Coastal habitats for humans
Figure 8.5: Marine systems provide a number of important ecological and economic services (Concept 8-2). Questions: Which two ecological services and which two economic services do you think are the most important? Why?
Recreation
Habitats and nursery areas
Employment
Oil and natural gas
Genetic resources and biodiversity
Minerals
Building materials
Scientific information
Fig. 8-5, p. 172

17. Estuaries and Coastal Wetlands Are Highly Productive (1)
Where rivers meet the sea
Seawater mixes with freshwater
Very productive ecosystems: high nutrient levels
River mouths
Inlets
Bays
Sounds
Salt marshes
Mangrove forests

18. View of an Estuary from Space
Figure 8.7: This satellite photo shows a view of an estuary taken from space. A sediment plume (turbidity caused by runoff) forms 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 its forests for agriculture, Madagascar is the world’s most eroded country.
Fig. 8-7, p. 173

19. Estuaries and Coastal Wetlands Are Highly Productive (2)
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

20. See Grass Bed Organisms
Figure 8.9: Sea grass beds support a variety of marine species. Since 1980, about 29% of the world’s sea grass beds have been lost to pollution and other disturbances.
Fig. 8-9, p. 174

21. Mangrove Forest in Australia
Figure 8.10: This mangrove forest is 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 highly complex habitat for a diversity of invertebrates and fishes.
Fig. 8-10, p. 175

22. Estuaries and Coastal Wetlands Are Highly Productive (3)
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, fuelwood, and habitats
Reduce storm damage and coast erosion

23. Rocky and Sandy Shores Host Different Types of Organisms
Intertidal zone
Rocky shores
Sandy shores: barrier beaches
Organism adaptations necessary to deal with daily salinity and moisture changes
Importance of sand dunes

24. Coral Reefs Are Amazing Centers of Biodiversity
Marine equivalent of tropical rain forests
Habitats for one-fourth of all marine species

25. Life Zones in the Ocean
The oceans are vastly deep, and the depth of the ocean has an effect on the marine life that lives there.
1) Epipelagic Zone: Top zone of the ocean. This area is full of life because there is enough sunlight to sustain photosynthesis. This zone is also called the Euphotic Zone.
2) Mesopelagic Zone: This zone gets sunlight but not enough to sustain photosynthesis. This zone is also called the Disphotic Zone.

26. Life Zones in the Ocean
3) Bathypelagic Zone: This is the lowest level on the continental shelf. This layer is the first of the Aphotic Zone because it receives no light at all. This means there is no creature like plants to create food. All the food in this zone comes from dead material floating from the higher layers.

27. Life Zones in the Ocean
4) Abyssopelagic Zone (ABANDON ALL HOPE YE WHO ENTER HERE…): This is the largest layer of the ocean. It is completely dark, and the oxygen concentration is very low. Pressure in this zone is extreme. No light penetrates its depth, yet it supports some of the strangest creatures on earth. This is the deepest layer of the ocean, called the Aphotic Zone because it receives no light at all. Creatures that live in this environment cannot be brought to higher layers because they will die in the low pressure.

28. Life Zones in the Ocean
5) Hadalpelagic Zone: This is the zone in the Mariana Trench and other trenches. It shares the same characteristics as the Abyssal Zone except it is even deeper.

29. Ocean Zones Depths of Ocean Zones Epipelagic zone: Surface – 650 ft
Mesepelagic: 650 ft – 3300ft
Bathypelagic Zone: ft ft
Abyssal Zone: ft- ~20000ft
Hadopelagic: ft and below

30. Light and Life Zones

31. Temperature Zones
The surface of the ocean is warmed by the sun, while the depths of the ocean, where sunlight never reaches, are very cold, just above freezing.
Surface waters are stirred up by waves and currents so the warm surface zone may be as much as 350 m deep.
Below the surface zone is the thermocline, which is layer about 300 to 700 m deep where the temperature falls rapidly.

32. Temperature Zones
Section 3

33. The Open Sea and Ocean Floor Host a Variety of Species (1)
Three vertical zones of the open sea
Euphotic zone
Phytoplankton
Nutrient levels low
Dissolved oxygen levels high
Bathyal zone
Dimly lit
Zooplankton and smaller fishes

34. The Open Sea and Ocean Floor Host a Variety of Species (2)
Abyssal zone
Dark and cold
High levels of nutrients
Little dissolved oxygen
Deposit feeders
Filter feeders
Upwelling brings nutrients to euphotic zone
Primary productivity and NPP

35. 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.

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

37. 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
Fig. 8-14, p. 180

38. 8-4 Why Are Freshwater Ecosystems Important?
Concept 8-4 Freshwater ecosystems provide major ecological and economic services, and are irreplaceable reservoirs of biodiversity.

39. Water Stands in Some Freshwater Systems and Flows in Others (1)
Standing (lentic) bodies of freshwater
Lakes
Ponds
Inland wetlands
Flowing (lotic) systems of freshwater
Streams
Rivers

40. Water Stands in Some Freshwater Systems and Flows in Others (2)
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

41. Water Stands in Some Freshwater Systems and Flows in Others (3)
Profundal zone
Deep water too dark for photosynthesis
Low oxygen levels
Some fish
Benthic zone
Decomposers
Detritus feeders
Nourished primarily by dead matter

42. Some Lakes Have More Nutrients Than Others
Oligotrophic lakes
Low levels of nutrients and low NPP
Very clear water
Eutrophic lakes
High levels of nutrients and high NPP
Murky water with high turbidity
Mesotrophic lakes
Cultural eutrophication of lakes from human input of nutrients

43. The Effect of Nutrient Enrichment on a Lake
Figure 8.17: These photos show 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, which 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.
Fig. 8-17, p. 182

44. Freshwater Streams and Rivers Carry Water from the Mountains to the Oceans
Surface water
Runoff
Watershed, drainage basin
Three aquatic life zones
Source zone
Transition zone
Floodplain zone

45. Freshwater Inland Wetlands Are Vital Sponges (1)
Marshes
Swamps
Prairie potholes
Floodplains
Arctic tundra in summer

46. Freshwater Inland Wetlands Are Vital Sponges (2)
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

47. 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.

48. 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, and lakes
Impact of drained wetlands

49. Three Big Ideas
Saltwater and freshwater aquatic life zones cover almost three-fourths of the earth’s surface, and oceans dominate the planet.
The earth’s aquatic systems provide important ecological and economic services.
Human activities threaten biodiversity and disrupt ecological and economic services provided by aquatic systems.