1. Chapter 7
Aquatic Biodiversity

2. Euphotic zone- layer of water where sunlight can penetrate
What is the concentration of dissolved O2 at the surface ? at 1000 m ?
What is the concentration of dissolved CO2 at the surface? at 1000 m ?
Explain why dissolved O2 levels are so high near the surface.
Explain why dissolved CO2 levels are so low near the surface.
Explain why the O2 becomes less concentrated and the CO2 becomes more concentrated in deeper waters.
How would you expect this graph to change at night ? Why ?
How should the pH change with depth during the day ? Explain.
Graph page 146

3. Aquatic Life Zones Saltwater or Marine · Estuaries Freshwater
· Coastlines
· Coral reefs
· Coastal marshes
· Mangrove swamps
· Ocean
Freshwater
· Lakes and ponds
· Streams and
rivers
· Inland wetlands

4. Core Case Study: Why Should We Care About Coral Reefs?
Coral reefs form in clear, warm coastal waters of the tropics and subtropics.
Formed by massive colonies of polyps.
Figure 6-1

5. Natural capital: a healthy coral reef in the Red Sea covered by colorful algae These diverse and productive ecosystems are being damaged and destroyed at an alarming rate.
Figure 6.1
Natural capital: 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 too warm temperatures). With the 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.
Fig. 6-1a, p. 126

6. Bleached Coral Reef
That has lost most of its algae because of changes in the environment (such
as cloudy water or too warm temperatures).
With the 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.
Figure 6.1
Natural capital: 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 too warm temperatures). With the 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.
Fig. 6-1b, p. 126

7. Coral Reefs-built from accumulated layers of calcium carbonate, CaCO3 laid down by relatives of sea anemones.
1. Most of these organism require
warm shallow water
2. Many live in a symbiotic relationship
with green algae known as
zooxanthellae
3. A very diverse marine environment
4. The Great Barrier Reef off the coast
of Australia is one of the largest

8. Value of coral reefs Provide valuable habitat
Provide humans with seafood
Pharmaceuticals
Recreation/tourism dollars

9. Human Impacts Covered with silt from inland logging
In 1980’s coral bleaching occurred stressed corals expelled zooxanthellae algae
Thought to be related to warming of the seas.
Corals can recover because
1. Hold a secret reserve of algae
2. Can take on other algae species when one
species leaves
3. Seasonally lose up to 75% of algae
Diving and snorkeling Overfishing
Agricultural and industrial pollutants in runoff.

10. Core Case Study: Why Should We Care About Coral Reefs?
Help moderate atmospheric temperature by removing CO2 from the atmosphere.
Act as natural barriers that help protect 14% of the world’s coastlines from erosion by battering waves and storms.
Provide habitats for a variety of marine organisms.

11. Natural capital: the ocean planet
Natural capital: the ocean planet. The salty oceans cover 71% of the earth’s surface. About 97% of the earth’s water is in the interconnected oceans, which cover 90% of the planet’s mostly ocean hemisphere (left)
Figure 6.2
Natural capital: the ocean planet. The salty oceans cover 71% of the earth’s surface. About 97% of the earth’s water is in the interconnected oceans, which cover 90% of the planet’s mostly ocean hemisphere (left) and 50% of its land–ocean hemisphere (right). Freshwater systems cover less than 1% of the earth’s surface.
Ocean hemisphere
Land–ocean hemisphere
and 50% of its land–ocean hemisphere (right). Freshwater systems cover less than 1% of the earth’s surface.
Fig. 6-2, p. 127

12. AQUATIC ENVIRONMENTS
Figure 6-3

13. Life in Layers
Life in most aquatic systems is found in surface, middle, and bottom layers.
Temperature, access to sunlight for photosynthesis, dissolved oxygen content, nutrient availability changes with depth.
Euphotic zone (upper layer in deep water habitats): sunlight can penetrate.

14. The Coastal Zone The Open Ocean Life Zones Euphotic Zone 1.Light
2. Dissolved Oxygen
3. Nutrients
upwellings
4.Organisms
Bathyal Zone
2. Organisms
Abyssal Zone
2.Oxygen
3. Nutrient levels
Figure 6-5

15. Marine Ecosystems
Scientists estimate that marine systems provide $21 trillion in goods and services per year – 70% more than terrestrial ecosystems.
Figure 6-4

16. Major Human Impacts Salt Marshes, Mangrove Forests, Sea-grass Meadows-
Filled in for coastal development
Aquaculture of shrimp
Beaches-
Erosion
Benthic Habitat-
Bottom trawlers
Coral Reefs-
Ocean warming, pH changes associated with global warming.

17. Estuaries and Coastal Wetlands: Centers of Productivity
Estuaries include river mouths, inlets, bays, sounds, salt marshes in temperate zones and mangrove forests in tropical zones.
Figure 6-7

18. Estuaries &Associated Coastal Wetlands
Located at the mouth of rivers and streams
Fresh and salt water mix
Highest NPP of any ecosystem because
· 1. Nutrient runoff from land
· 2. Tides circulate nutrients and remove wastes
· 3. Light penetrates the shallow water
· 4.Plant carry out photosynthesis and trap detritus
Organisms must deal with daily changes in temperature and salinity.

19. Saltwater marshes Found associated with temperate estuaries
Dominated by salt tolerant grasses
Important services
· 1. Habitat
· 2. Sediment and pollution trapping
· 3. Storm buffering
Most are being covered over for coastal development

20. Mangrove Forests
Are found along about 70% of gently sloping sandy and silty coastlines in tropical and subtropical regions.
Figure 6-8

21. Mangrove Forests-tropical equivalent of saltwater marsh
Network of roots of the mangrove trees are important nurseries of many commercially important fish and shellfish (shrimp)
Branches of mangrove trees provide important habitat for nesting birds: pelicans, herons, egrets.
Roots stabilize submerged soil preventing coastal erosion
Storm buffer
Being harmed by:
Logging
Coastal development
· Aquaculture

22. Intertidal Zone- between high and low tide
· Organisms must contend with changing levels of water
In rocky shoreline habitat, most organisms are anchored in some way and have a
way to seal off their bodies to prevent moisture loss when the tide goes out.
Most sandy beach organisms either burrow in the sand or travel in and out with the tide.

23. The importance of sea grass
High NPP make them important producers in shallow water
Roots stabilize sediments reducing erosion
Provide food and habitat for many marine species, sea turtles, manatees, ducks and geese
Chinook salmon
and eelgrass

24. Kelps Beds Formed from species of marine algae
Many are anchored to the bottom and have air filled bags to allow the upper part of the plant to float to the top
equivalent to the forest biome on the land
Kelp beds or forests provide habitat and food for many species

25. 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.

26. Barrier Islands
Low, narrow, sandy islands that form offshore from a coastline.
Primary and secondary dunes on gently sloping sandy barrier beaches protect land from erosion by the sea.
Figure 6-10

27. 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.

28. FRESHWATER LIFE ZONES Freshwater life zones include:
Standing (lentic) water such as lakes, ponds, and inland wetlands.
Flowing (lotic) systems such as streams and rivers.
Ponds are generally shallow and have only one zone-light reaches to the bottom
Figure 6-14

29. 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).

30. 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.
What causes this overturning?

31. Sunlight Painted turtle Green frog Blue-winged teal Muskrat Pond snail
Littoral zone
Limnetic zone
Figure 6.15
Natural capital: distinct zones of life in a fairly deep temperate zone lake.
Diving beetle
Plankton
Profundal zone
Benthic zone
Northern pike
Yellow perch
Bloodworms
Fig. 6-15, p. 137

32. 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.
Figure 6-16

33. 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.

34. 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.

35. Physical Properties of water
Approaches maximum density at 4oC
At temperatures cooler than 4oC water becomes less dense and it floats
and freezes as temperatures drop to 0oC
At temperatures greater than 4oC water becomes less dense and it floats

36. Seasonal Overturn in Lakes
Spring Overturn-
Surface waters
warm to 4oC and
descend through
the colder less
dense waters
beneath.
Fall Overturn-
Surface waters
cool to 4oC (39oF)
and descend to
the bottom
Nutrients
Oxygen levels

37. Freshwater Streams and Rivers: From the Mountains to the Oceans
Water flowing from mountains to the sea creates different aquatic conditions and habitats.
Figure 6-17

38. Oxbow lake Deposited sediment
Rain and snow
Glacier
Lake
Rapids
Waterfall
Tributary
Flood plain
Oxbow lake
Salt marsh
Deposited sediment
Delta
Ocean
Source Zone
Transition Zone
Figure 6.17
Natural capital: 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.
Water
Sediment
Floodplain Zone
Fig. 6-17, p. 139

39. Case Study: Dams, Wetlands, Hurricanes, and New Orleans
Dams and levees have been built to control water flows in New Orleans.
Reduction in natural flow has destroyed natural wetlands.
Causes city to lie below sea-level (up to 3 meters).
Global sea levels have risen almost 0.3 meters since 1900.

40. 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.
Figure 6-18

41. 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.

42. Impacts of Human Activities on Freshwater Systems
Dams, cities, farmlands, and filled-in wetlands alter and degrade freshwater habitats.
Dams, diversions and canals have fragmented about 40% of the world’s 237 large rivers.
Flood control levees and dikes alter and destroy aquatic habitats.
Cities and farmlands add pollutants and excess plant nutrients to streams and rivers.
Many inland wetlands have been drained or filled for agriculture or (sub)urban development.

43. Impacts of Human Activities on Freshwater Systems
These wetlands have been ditched and drained for cropland conversion.
Figure 6-19