Water is Essential to Life

1. Water is Essential to Life

2. Importance • Leonardo da Vinci said that “Water is the driver of nature.” Without water, the other nutrient cycles would not exist in their present forms, and current forms of life on earth could not exist.

3. Water’s Unique Properties • There are strong forces of attraction between molecules of water. • Water exists as a liquid over a wide temperature range. • Liquid water changes temperature slowly. • It takes a large amount of energy for water to evaporate. • Liquid water can dissolve a variety of compounds. • Water expands when it freezes.

4. Attraction Between Molecules • The strong forces of attraction between molecules of water. • Hydrogen bonds • Result in many distinctive properties

5. Liquid state Exists in liquid state over wide range of temperatures: 32° F to 212° F Without water’s high boiling point, oceans would have evaporated long ago

6. Heat Capacity • Water changes temp very slowly because it can store heat. This protects living organisms from the shock of abrupt temperature changes.

7. Heat Capacity • Also moderates earth’s climate • Water warms & cools slower than surrounding land

8. Universal Solvent: • Water can dissolve a many substances. • Carry nutrients • flush wastes • distribute particles • facilitate other cycles

9. Universal Solvent • Water can dissolve a wide variety of compounds. This means it can easily become polluted by water-soluble wastes.

10. Water Cycle Water moves through ecosystems transporting trash and other pollutants

11. Expansion When Frozen • Ice has a lower density than liquid water. Thus, ice floats on water.

12. Capillary action Long narrow columns of water rise through roots to leaves

13. Surface tension • Surface behaves like an elastic membrane

14. Chapter 6 Aquatic Biodiversity

15. Coral Reefs Among the oldest, most diverse, most productive ecosystems Marine equivalent to tropical rain forests • Coral reefs form in clear, warm coastal waters of the tropics and subtropics. • Formed by massive colonies of polyps and algae Figure 6-1

16. 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.

17. AQUATIC ENVIRONMENTS • Saltwater and freshwater aquatic life zones cover almost three-fourths of the earth’s surface Figure 6-2

18. AQUATIC ENVIRONMENTS Figure 6-3

19. Factors Affecting Aquatic Ecosystems • Abiotic (physical) factors are the influences of the non-living parts of the ecosystem. • Examples include pH, salinity, temperature, turbidity, nutrients, wind speed and direction, humidity, precipitation, water pressure, and light intensity and water quality. • Biotic factors are the influences of the living parts of the ecosystem. Producers and consumers interact as competitors, parasites, pathogens, symbionts, and predators.

20. What Kinds of Organisms Live in Aquatic Life Zones? • Aquatic systems contain floating, drifting, swimming, bottom-dwelling, and decomposer organisms. • Plankton: important group of weakly swimming, free-floating biota. • Phytoplankton (plant), Zooplankton (animal), Ultraplankton (photosynthetic bacteria) • Necton: fish, turtles, whales. • Benthos: bottom dwellers (barnacles, oysters). • Decomposers: breakdown organic compounds (mostly bacteria).

21. Phytoplankton & Zooplankton • Phytoplankton are an autotrophic group of weakly swimming, free-floating biota that are producers that support most aquatic food chains. These organisms provide much of the oxygen in the Earth’s atmosphere and include: • Phytoplankton (plant-like organisms and cyanobacteria Different types of phytoplankton • Zooplankton are herbivores that feed on plankton and are, in turn, the food stock for larger consumers like whales. These organisms include: • Krill and small crustaceans Krill are one of the most important organisms in aquatic food chains especially for whales.

22. Nekton and Benthos • Nekton are larger, actively swimming consumers usually the top consumers in the aquatic ecosystems and include: • Fish, whales and turtles • Benthos are bottom-dwelling creatures that may be primary consumers or decomposers. These highly diverse organisms may live in tide pools, shelves or the abyss and include: • Barnacles, oysters, lobsters and sea anemones Sharks and Turtles are nektonic species Benthos or “depths of the sea” are organisms that live on the ocean floor

23. 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 – photosynthesis.

24. Ocean Zones • Coastal and EuphoticZone: Lots of light. From 0 - 200 meters. Photosynthesis takes place here • Bathyal Zone: The dimly lit part of ocean. From 200 - 1500 meters. • Abyssal Zone: Completely dark. Extends to a depth of 4000 to 6000 meters (2.5 to 3.7 miles). Water here is very cold & has little dissolved oxygen. Abyssal Zone Benthic Zone (Ocean Floor): Bacteria are common & can survive down to 500 meters below ocean floor.

25. High tide Sun Open Sea Coastal Zone Sea level Low tide Photosynthesis Euphotic Zone Estuarine Zone Continental shelf Bathyal Zone Twilight Abyssal Zone Darkness Fig. 6-5, p. 130

26. Marine Ecosystems • The oceans that occupy most of the earth’s surface provide many ecological and economic services. • Scientists estimate that marine systems provide $21 trillion in goods and services per year – 70% more than terrestrial ecosystems. Figure 6-4

27. Natural Capital Marine Ecosystems Economic Services Ecological Services Climate moderation Food CO2 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 Recreation Habitats and nursery areas Employment Genetic resources and biodiversity Oil and natural gas Minerals Scientific information Building materials Fig. 6-4, p. 129

28. The Coastal Zone: Where Most of the Action Is • The coastal zone: the 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.

29. Reefs • Reefs: • Reefs are Marine Protected Areas like national parks and wildlife refuges and have significant economic value because of tourism. Calcium carbonate living systems in warm shallow water where light penetrates, reefs are the habitat for many species. • Loss of reefs removes habitats. Reefs are the food source for marine life, breeding grounds for fish and bird species, and shelter and hiding place for many species. • The loss of biodiversity or richness could cause the extinction or decrease in populations of marine organisms. • Reefs serve as a buffer and protection for coastal areas from waves and storms, which could lead to destruction of coastal habitats or the erosion of shoreline habitats. • Reefs are a major carbon sink in the ocean and this carbon storage would be lost.

30. Sea Grass and Kelp • Kelp (Seaweed): • Brown algae groups that provide habitats and food for many organisms. Overfishing leads to the degradation of kelp forests as the herbivores are released from the potential predators. (Sea otter and the urchin.) • Kelp is being considered as a renewable resource because it is fast growing and yields large amounts of methane. The fast growing algae has been the topic of renewable energy talks because of the lack of an irrigation requirement. • Seagrass: • Seagrass is highly adaptable and serves as a producer for many marine ecosystems. Seagrass can reduce erosion and increase sedimentation through roots that stabilize the seabed. • These coastal seagrass zones provide shelter for organisms, wave protections, oxygen production and carbon storage.

31. Estuaries

32. Estuaries: Definition • A partially enclosed area of coastal water where sea water mixes with freshwater.

33. 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

34. Estuaries • Estuaries are a partially enclosed area of coastal water where sea water mixes with freshwater and are constantly changing. • Salinity, temperature, suspended solids, storms (precipitation), and tidal cycles fluctuate with the time of year. • The organisms that live in this unique habitat must be able to tolerate these conditions. • Nutrients that are transported from rivers brings a high amount of nutrients. • This allows a place of breeding for many ocean species and thus makes estuaries highly productive and fertile supporting complex food webs.

35. Estuary Ecosystem Services • Estuaries serve as a carbon sink by absorbing large amounts of CO2 (sink) and they also serve as filters for pollutants by trapping sediments and pollutants. • They act as sponges as they absorb water recharging groundwater stores and controlling flooding by slowing flow of water. • Economically wetlands are important as well: • Provide employment and recreational income through fishing, recreation, and photography. • Allow for protected waterway passage between rivers and oceans. • Protect property by buffering shores form flow of water and erosion. • Treat sewage and storm water that would otherwise be paid for by the local community. • Coastal ecosystems can easily be affected by rising sea levels, storms, temperature change, and rate of water cycling.

36. 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.

37. Salt Marshes • The ground here is saturated with water and there is little oxygen, so decay takes place slowly. It has a surface inlet and outlet, and contains many invertebrates. It is also the breeding ground for many ocean animals. Ex. crabs and shellfish.

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

39. Mangrove Forests • These are along warm, tropical coasts where there is too much silt for coral reefs to grow. It is dominated by salt-tolerant trees called mangroves (55 different species exist). It also helps to protect the coastline from erosion and provides a breeding nursery for some 2000 species of fish, invertebrates, and plants.

40. Importance of Estuaries • Just one acre of estuary provides $75,000 worth of free waste treatment, and has a value of about $83,000 when recreation and fish for food are included. • Prime Kansas farmland has a top value of $1,200 and an annual production value of $600.

41. Mouth of river carrying erosion

42. Some mangrove species take in brackish water and excrete the salt through glands in the leaves. Seaweeds growing in the intertidal zone tolerate exposure to the drying air every 12 h. Ocean Margin Plants • Ocean margin plants, e.g. intertidal seaweeds and mangroves, must cope with high salt content in the water and changing tidal conditions. • Sea level rise may change these areas, leading to a loss in species. • Construction, building, roads and other residential, commercial, and industrial projects may have a negative impact. Mangrove pneumatophores

43. 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.

44. Rocky and Sandy Shores: Living with the Tides • Organisms in intertidal zone develop specialized niches to deal with daily changes in: • Temperature • Salinity • Wave action Figure 6-9

45. Rocky Shore Beach Hermit crab Sea star Shore crab High tide Periwinkle Sea urchin Anemone Mussel Low tide Sculpin Barnacles Kelp Sea lettuce Monterey flatworm Nudibranch Fig. 6-9, p. 132

46. Barrier Beach Beach flea Peanut worm Tiger Beetle Blue crab Clam Dwarf Olive High tide Sandpiper Ghost Shrimp Low tide Silversides Mole Shrimp White sand macoma Moon snail Sand dollar Fig. 6-9, p. 132

47. 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

48. 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.

49. Threats to Coral Reefs:Increasing Stresses • Biologically diverse and productive coral reefs are being stressed by human activities. Figure 6-11

50. Natural Capital Degradation Coral Reefs Ocean warming Soil erosion Algae growth from fertilizer runoff Mangrove destruction Bleaching Rising sea levels Increased UV exposure Damage from anchors Damage from fishing and diving Fig. 6-12, p. 135