Section 7-1 Aquatic Environments

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. Formed by massive colonies of polyps. Finding Nemo Finding Nemo Finding Nemo Finding Nemo Figure 6-1

Fig. 6-1a, p. 126

Fig. 6-1b, p. 126

Core Case Study: Why Should We Care About Coral Reefs?  Help moderate atmospheric temperature by removing CO 2 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.

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

AQUATIC ENVIRONMENTS Figure 6-3

WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL  Comparison of population sizes and shares of the world’s freshwater among the continents. Figure 14-2

Categorization of Aquatic Biomes  Physical characteristics Salinity Salinity Depth Depth Water flow Water flow  Temperature (not used for categorization)

Types of Biomes  Freshwater Streams Streams Rivers Rivers Lakes Lakes Wetlands Wetlands  Marine (saltwater) Estuaries Estuaries Coral Reefs Coral Reefs Open Ocean Open Ocean

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. Plankton: important group of weakly swimming, free-floating biota. Phytoplankton (plant), Zooplankton (animal), Ultraplankton (photosynthetic bacteria)Phytoplankton (plant), Zooplankton (animal), Ultraplankton (photosynthetic bacteria) Necton: fish, turtles, whales. Necton: fish, turtles, whales. Benthos: bottom dwellers (barnacles, oysters). Benthos: bottom dwellers (barnacles, oysters). Decomposers: breakdown organic compounds (mostly bacteria). Decomposers: breakdown organic compounds (mostly bacteria).

Phytoplankton  Description – small drifting plants  Niche – they are producers that support most aquatic food chains  Example – cyanobacteria & many types of algae

Zooplankton  Description – herbivores that feed on phytoplankton or other zooplankton  Niche – food stock for larger consumers  Example – krill; small crustaceans

Nekton  Description – larger, strong- swimming consumers  Niche – top consumers in the aquatic ecosystem  Example – fish, turtles, and whales

Benthos  Description – bottom-dwelling creatures  Niche – primary consumers, decomposers  Example – barnacles, oysters, and lobsters

 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. Euphotic zone (upper layer in deep water habitats): sunlight can penetrate. The Ocean The Ocean The Ocean The Ocean Life in Layers

Section 7-2 Saltwater Life Zones

SALTWATER LIFE ZONES  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

The Coastal Zone:  The coastal zone The warm, nutrient-rich, shallow water The warm, nutrient-rich, shallow water Extends from the high-tide mark on land to the gently sloping, shallow edge of the continental shelf. 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 Contains 90% of all marine species. Contains 90% of all marine species. Provides numerous ecological and economic services. Provides numerous ecological and economic services. Subject to human disturbance. Subject to human disturbance.

The Coastal Zone Figure 6-5

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

Estuaries and Coastal Wetlands:  Estuaries and coastal marshes provide ecological and economic services. Filter toxic pollutants, excess plant nutrients, sediments, and other pollutants. 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. 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. Provide food, habitats and nursery sites for many aquatic species.

Rocky and Sandy Shores:  Organisms experiencing daily low and high tides have a number of ways to survive under harsh and changing conditions. Gravitational pull by moon and sun causes tides. Gravitational pull by moon and sun causes tides. Intertidal Zone: area of shoreline between low and high tides. Intertidal Zone: area of shoreline between low and high tides.

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

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

Fig. 6-12, p. 135 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 Natural Capital Degradation Coral Reefs

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. Figure 6-13

Section 7-3 Freshwater Life Zones

FRESHWATER LIFE ZONES  Freshwater life zones include: Standing (lentic) water such as lakes, ponds, and inland wetlands. Standing (lentic) water such as lakes, ponds, and inland wetlands. Flowing (lotic) systems such as streams and rivers. Flowing (lotic) systems such as streams and rivers. Figure 6-14

Flowing Water Ecosystems Because of different environmental conditions in each zone, a river is a system of different ecosystems.

Fig , p. 267 Deliver nutrients to sea to help sustain coastal fisheries Deposit silt that maintains deltas Purify water Renew and renourish wetlands Provide habitats for wildlife Natural Capital Ecological Services of Rivers

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

Headwater Stream Characteristics  A narrow zone of cold, clear water that rushes over waterfalls and rapids. Large amounts of oxygen are present. Fish are also present. Ex. trout.

Downstream Characteristics  Slower-moving water, less oxygen, warmer temperatures, and lots of algae and cyanobacteria.

Energy Source  Gravity

Standing Water Ecosystems Lakes, ponds, etc.

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. Euphotic zone (upper layer in deep water habitats): sunlight can penetrate.

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). Littoral zone (near shore, shallow, with rooted plants). Limnetic zone (open, offshore area, sunlit). Limnetic zone (open, offshore area, sunlit). Profundal zone (deep, open water, too dark for photosynthesis). Profundal zone (deep, open water, too dark for photosynthesis). Benthic zone (bottom of lake, nourished by dead matter). Benthic zone (bottom of lake, nourished by dead matter).

Littoral Zone  A shallow area near the shore, to the depth at which rooted plants stop growing. Ex. frogs, snails, insects, fish, cattails, and water lilies.

Limnetic Zone  Open, sunlit water that extends to the depth penetrated by sunlight.

Profundal Zone  Deep, open water where it is too dark for photosynthesis.

Lakes: Water-Filled Depressions Figure 6-15

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. 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. Oxygen is brought from the surface to the lake bottom and nutrients from the bottom are brought to the top.  What causes this overturning?

Thermal Stratification  The temperature difference in deep lakes where there are warm summers and cold winters.

Causes of Thermal Stratification  During the summer, lakes become stratified into different temperature layers that resist mixing because summer sunlight warms surface waters, making them less dense.

Thermocline  The middle layer that acts as a barrier to the transfer of nutrients and dissolved oxygen.

Fall Turnover  As the temperatures begin to drop, the surface layer becomes more dense, and it sinks to the bottom. This mixing brings nutrients from the bottom up to the surface and sends oxygen to the bottom.

Spring Turnover  As top water warms and ice melts, it sinks through and below the cooler, less dense water, sending oxygen down and nutrients up.

Freshwater Wetlands

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

Freshwater Inland Wetlands: Vital Sponges Filter and degrade pollutants. Filter and degrade pollutants. Reduce flooding and erosion by absorbing slowly releasing overflows. Reduce flooding and erosion by absorbing slowly releasing overflows. Help replenish stream flows during dry periods. Help replenish stream flows during dry periods. Help recharge ground aquifers. Help recharge ground aquifers. Provide economic resources and recreation. Provide economic resources and recreation.

Marshes  An area of temporarily flooded, often silty land beside a river or lake.

Swamps  A lowland region permanently covered with water.

Prairie Potholes  These are depressions that hold water out on the prairie, especially up north in Canada. It is a very good duck habitat.

Peat Moss Bog  A wet area that over time fills in (the last stage of succession is peat moss). It can be very deep. In Ireland, they burn this for wood.

Importance of freshwater wetlands  They filter & purify water.  Habitat for many animals and plants.

Historical Aspects  Developers and farmers want Congress to revise the definition of wetlands. This would make 60-75% of all wetlands unavailable for protection.  The Audubon Society estimates that wetlands provide water quality protection worth $1.6 billion per year, and they say if that wetlands are destroyed, the U.S. would spend $7.7 billion to $31 billion per year in additional flood-control costs.

Estuaries

Estuary Definition  A partially enclosed area of coastal water where sea water mixes with freshwater.

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.

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.

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.

Overview Questions  What are the basic types of aquatic life zones and what factors influence the kinds of life they contain?  What are the major types of saltwater life zones, and how do human activities affect them?  What are the major types of freshwater life zones, and how do human activities affect them?