1. Aquatic Biodiversity
APES CHAPTER 8

2. CORE CASE STUDY –CORAL REEFS
What coral reefs require?
Dissolved oxygen, light & nutrients
What threatens coral reefs? (3)
Chemical pollution, global warming, extra UV ozone hole, excess sediment from rivers (soil erosion), human contact

3. Coral Reefs
What percent of reefs is estimated to be destroyed by human intervention?
10 percent
What about estuaries and wetlands?
About 50%(US) through filling, sewage, runoff pollution, and diversion

4. 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.

5. 8-1 What Is the General Nature of Aquatic Systems?
Aquatic life zones cover almost three-fourths of the earth’s surface
Saltwater: marine
Estuaries
Coastal wetlands
Coral reefs
Mangrove forests
Open Ocean
Freshwater
Lakes
Rivers and streams
Inland wetlands

6. Most Aquatic Species Live in Top, Middle, or Bottom Layers of Water
Aquatic systems contain floating, drifting, swimming, bottom-dwelling, and decomposer organisms.
Plankton: important group of weakly swimming, free-floating organisms
Phytoplankton (plant), Zooplankton (animal), Ultraplankton (photosynthetic bacteria)
Necton: fish, turtles, whales
Benthos: bottom dwellers (barnacles, oysters)
Decomposers: breakdown organic compounds (mostly bacteria)

7. Most Aquatic Species Live in Top, Middle, or Bottom Layers of Water
Types and numbers of organism found depend on:
Temperature
Access to sunlight for photosynthesis
Dissolved oxygen content
Nutrient availability
These characteristics vary with depth.
Euphotic zone (“well lit” in Greek)
The upper layer through which sunlight can penetrate.

8. 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.

9. 8-2 Why Are Marine Aquatic Systems Important?
The oceans that occupy most of Earth’s surface provide many ecological & economic services.
Scientists estimate marine systems provide $12 trillion in goods/services/ year – 70% more than terrestrial ecosystems.

10. Estuaries and Coastal Wetlands Are Highly Productive
The coastal zone: the warm, nutrient-rich, shallow water that extends from the shoreline to the 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.
Subject to human disturbance because of high populations along ocean coastlines.

11. Estuaries and Coastal Wetlands Are Highly Productive
Estuaries are where fresh water rivers empty into the salt water oceans.
The fresh water is less dense so it floats on top of the more dense salt water.
Estuaries include river mouths, bays, salt marshes, and mangrove forests.

12. Estuary – Madagascar’s Betsiboka River
Satellite pix
Sediment plume(turbidity by runoff) mouth as flow thru estuary into Mozambique Channel.
Topography, heavy rains, deforestation, Madagascar is world’s most eroded country.
Fig. 7.7, p. 157

13. Estuaries and Coastal Wetlands Are Highly Productive
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 and habitats for many aquatic species.

14. Rocky and Sandy Shores Host Different Types of Organisms
Intertidal Zone: the area of a shoreline between low and high tides.
Organisms living in the intertidal zone have evolved a number of ways to survive under harsh and changing conditions. They must deal with daily changes in temperature, salinity, wave action, and being left “high and dry”.

15. Coral Reefs Are Amazing Centers of Biodiversity
Coral reefs form in clear, warm coastal waters of the tropics and subtropics.
Very important that they have consistently warm water
They are home to a huge amount of biodiversity
25% of all marine species
“Rain Forest of the Ocean”

16. Core Case Study: Why Should We Care about Coral Reefs?
Biodiversity
Important ecological and economic services:
Moderate atmospheric temperatures
Act as natural barriers protecting coasts from erosion
Provide habitats
Support fishing and tourism businesses
Provide jobs and building materials
Studied and enjoyed

17. Core Case Study: Why Should We Care about Coral Reefs?
Degradation and decline:
Pollution
Overfishing
Warmer ocean temperatures
Causing coral bleaching
Increasing ocean acidity
Dissolving coral (calcium carbonate)

18. The Open Sea and Ocean Floor Host a Variety of Species
Euphotic zone: brightly lit surface layer
Nutrient levels low, dissolved O2 high, plenty of photosynthetic activity.
Bathyal zone: dimly lit middle layer
No photosynthetic activity, zooplankton and fish live there and migrate to euphotic zone to feed.
Abyssal zone: dark bottom layer
Very cold, little dissolved O2.
High nutrient levels – filter down from the layers above
Upwelling – nutrients are brought to the surface by currents

19. Major Life Zones and Vertical Zones in an Ocean

20. 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.

21. 8-3 How Have Human Activities Affected Marine Ecosystems?
Major threats to marine systems:
Coastal development
Overfishing
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

22. 8-4 Why Are Freshwater Ecosystems Important?
Concept 8-4 Freshwater ecosystems provide major ecological and economic services and are irreplaceable reservoirs of biodiversity.

23. 8-4 Why Are Freshwater Ecosystems Important?
Freshwater life zones include:
Standing (lentic) water
lakes, ponds, and inland wetlands
Flowing (lotic) systems
streams and rivers

24. Water Stands in Some Freshwater Systems and Flows in Others
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, sun-lit)
Profundal zone (deep, open water, too dark for photosynthesis)
Benthic zone (bottom of lake, nourished by dead matter)

25. Distinct Zones of Life in a Fairly Deep Temperate Zone Lake

26. Turnover in a Lake
During the summer and winter, lakes become stratified into temperature layers.
In the spring and fall, the temperature equalizes and the lakes “overturn”.
Oxygen is brought from the surface to the lake bottom and nutrients from the bottom are brought to the top.

27. Some Lakes Have More Nutrients Than Others
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.
Mesotrophic (medium nourished) lake: most lakes are in between
Eutrophic (well nourished) lake: Over time, sediment, organic material, and inorganic nutrients wash into lakes causing excessive plant growth.

28. Some Lakes Have More Nutrients Than Others
Cultural eutrophication:
Human inputs of nutrients from the atmosphere and urban and agricultural areas can accelerate the eutrophication process.

29. Freshwater Streams and Rivers Carry Water from the Mountains to the Oceans
Water flowing from mountains to the sea creates different aquatic conditions and habitats.

30. Freshwater Streams and Rivers Carry Water from the Mountains to the Oceans
Watershed
or drainage basin
the land area that delivers runoff, sediment, and dissolved substance to a stream or river.
The larger the watershed, the larger the river it feeds into.

31. Freshwater Inland Wetlands Are Vital Sponges
Inland wetlands act like natural sponges that absorb and store excess water from storms and provide a variety of wildlife habitats.

32. Freshwater Inland Wetlands Are 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.

33. 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.

34. 8-5 How Have Human Activities Affected Freshwater Ecosystems?
Human activities are disrupting the freshwater ecosystems in many ways:
Construction of dams and canals on 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.