Rutgers University Chapter 12 News on Fresh Water Ocean Under Sea Paper Each week students will find a news story (local, regional, or international) that

Rutgers University Chapter 12 News on Fresh Water Ocean Under Sea Paper Each week students will find a news story (local, regional, or international) that relates to the topics (Chapters) covered that week. A ONE paragraph summary of the news story news story and a link to the news story. Essential Environment: The Science Behind the Stories
Sixth Edition
Chapter 12
Fresh Water, Oceans,
and Coasts
Lecture Presentations prepared by
James Dauray
College of Lake County
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This lecture will help you understand:
• Water’s importance to people and ecosystems
• Distribution of fresh water on Earth
• The freshwater, marine, and coastal portions of the aquatic
system
• Human use and alteration of aquatic systems
• Water supply problems and solutions
• Classes of water pollution and solutions
• Drinking water and wastewater treatment
• Ocean fisheries
• Marine protected areas
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Central Case Study: Starving the Louisiana
Coast (1 of 3)
• Louisiana is losing 75 km2 of
coastal wetlands each year
due to a loss of sediments
entering the Mississippi River
delta.
Figure 12.1 Human modifications along the
Mississippi River affect coastal wetlands at the
river’s mouth.
• The primary cause of this loss
is the roughly 2000 dams
throughout the Mississippi
River basin as well as levees
that prevent flooding.
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Central Case Study: Starving the Louisiana
Coast (2 of 3)
• The salt marshes in the delta
normally compact over time, but
this is offset by inputs of
sediments from the river.
– The dams prevent
sediments from reaching the
delta; they are instead
deposited in reservoirs.
– The levees prevent normal
flooding, instead directing
water directly out to the Gulf,
where the sediments are
deposited instead.
[Figure 12.1 Continued]
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Central Case Study: Starving the Louisiana
Coast (3 of 3)
• One proposed solution is to divert water from the river into
coastal wetlands.
– The Atchafalaya River delta has benefited from this
change and is now gaining land mass.
• The Tourist Opportunities and Revived Economies of the
Gulf Coast States Act (RESTORE Act), passed following
the Deepwater Horizon oil spill, created a comprehensive
restoration plan.
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Freshwater Systems (1 of 3)
• The majority (97.5%) of Earth’s water resides in the
oceans and is too salty to drink or use for irrigation.
– Only 2.5% is considered fresh water, water that is
relatively pure and free from salts.
Figure 12.2 Only 2.5% of Earth’s water is fresh water.
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Freshwater Systems (2 of 3)
• Water is renewed and recycled as it passes through the
water cycle.
– Precipitation falling from the sky sinks into the ground
or acts as runoff to surface water bodies.
– Rivers interact with ponds, wetlands, and coastal
aquatic ecosystems.
– Underground aquifers exchange water with surface
waters.
• These interactions create a web of interconnected
freshwater and marine aquatic ecosystems.
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Freshwater Systems (3 of 3)
• What happens in one system affects others, even those far away.
Figure 12.3 Water flows through freshwater systems and marine and coastal aquatic systems that
interact extensively with one another.
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Groundwater plays key roles in the hydrologic cycle
(1 of 3)
• Surface water is located atop Earth’s surface, such as in a
river or lake.
• Groundwater is water beneath the surface that resides
within pores in soil or rock.
– Any water that does not evaporate, flow into
waterways, or get taken up by organisms will infiltrate
into groundwater.
– Groundwater can remain underground for thousands of
years at a time.
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Groundwater plays key roles in the hydrologic cycle
(2 of 3)
• Groundwater is contained within aquifers: porous, spongelike
formations of rock or sand.
– The upper border of the layer completely filled with water is
the water table.
Figure 12.4 Groundwater occurs in
unconfined aquifers above or in confined
aquifers between impermeable layers.
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Groundwater plays key roles in the hydrologic cycle
(3 of 3)
• Any area where water
can infiltrate through
the surface and reach
the aquifer is a
recharge zone.
Figure 12.4 Groundwater occurs in unconfined
aquifers above or in confined aquifers between
impermeable layers.
• Confined aquifers
are trapped between
impermeable clay,
while unconfined
aquifers are not.
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Surface water converges in river and stream
ecosystems (1 of 2)
• Surface water becomes groundwater by infiltration.
• Groundwater becomes surface water through springs,
keeping rivers flowing and wetlands moist even in dry
conditions.
• Water that falls from the sky or melts from snow or a
glacier that flows over a land surface is called runoff.
– Runoff converges in low-lying areas, forming streams,
which can merge into rivers, which eventually reach a
lake or ocean.
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Surface water converges in river and stream
ecosystems (2 of 2)
• The area of land drained by a river system and all of its
tributaries makes up that river’s drainage basin or
watershed.
• Over thousands or millions of years, the shifting course of
a meandering river can carve out a flat valley.
• Areas near a river’s course that are flooded periodically
are within the river’s floodplain.
– Frequent flooding and deposition of soil makes
floodplain soils especially fertile.
– Agriculture thrives in flood plains, and riparian forests
near riversides are especially rich in species.
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Lakes and ponds are ecologically diverse systems (1 of 3)
• Lakes and ponds are bodies of standing surface water.
– The shallow area along the edges where aquatic plants
can grow is called the littoral zone.
– The benthic zone extends along the bottom.
– The limnetic zone is the upper layer of water that is
shallow enough to receive sunlight and allow
photosynthesis by phytoplankton.
– The profundal zone is between the benthic and limnetic
zones and lacks photosynthesis.
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Lakes and ponds are ecologically diverse systems (2 of 3)
Figure 12.5 Lakes and ponds are composed of distinct zones.
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Lakes and ponds are ecologically diverse systems (3 of 3)
• Ponds and lakes can change over time as rivers and
streams bring them nutrients.
• Oligotrophic lakes and ponds are low in nutrients and
high in oxygen.
• Over time, the addition of nutrients can transition the lake
or pond to eutrophic—high-nutrient, low-oxygen—
conditions.
– Given enough plant growth, the water body may
eventually fill in completely.
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Freshwater wetlands include marshes, swamps, bogs,
and vernal pools (1 of 2)
• Wetlands are systems
where the soil is saturated
with water, often
containing standing
shallow water.
Figure 12.6 Freshwater wetlands, such as this bald cypress
swamp in Louisiana, support biologically diverse and
productive ecosystems.
• Freshwater marshes
consist of cattails and
bulrushes that grow above
the water’s surface.
• Swamps also contain
standing water but are in
forested areas.
• Bogs are ponds covered in
thick floating mats of
vegetation.
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Freshwater wetlands include marshes, swamps, bogs,
and vernal pools (2 of 2)
• Wetlands can be seasonal, such as vernal pools that form
in the snowmelt of early spring and dry up later in the
summer.
• Wetlands provide many water-related ecosystem services
including slowing runoff, reducing flooding, recharging
aquifers, and filtering pollutants.
• Wetlands have been heavily impacted by human activities,
including draining and filling for agriculture, withdrawing
water for irrigation, and construction of dams.
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The Oceans
• The world’s five oceans are all connected, making a single
body of water that covers 71% of Earth’s surface.
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The physical makeup of the ocean is complex (1 of 5)
• Ocean water contains approximately 96.5% water by
mass, with the rest consisting of ions from dissolved salts.
– The salts arise from runoff that carries salts and
sediments from continents into the oceans.
• Sunlight does not penetrate ocean water deeply, so
temperatures tend to decrease with depth.
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The physical makeup of the ocean is complex (2 of 5)
• Vast, riverlike flows of water called currents are driven by
differences in density, heating, cooling, gravity, and wind.
Figure 12.7 The upper waters of the oceans flow in surface currents—long-lasting and predictable
global patterns of water movement.
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The physical makeup of the ocean is complex (3 of 5)
• Surface winds and heating also create vertical currents in
seawater.
• Upwelling pulls cold, deep, nutrient-rich water to the
surface.
• Surface currents that converge create downwellings,
which transport warm surface water to deeper waters,
providing an influx of dissolved oxygen and “burying”
carbon dioxide from the atmosphere.
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The physical makeup of the ocean is complex (4 of 5)
• Many parts of the ocean floor are rugged and complex.
– Underwater volcanoes can build islands above sea level.
– The Mid-Atlantic Ridge is an underwater mountain range that runs
the length of the Atlantic Ocean.
Figure 12.8 A stylized bathymetric profile shows key geologic features of the submarine
environment.
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The physical makeup of the ocean is complex (5 of 5)
• Continental shelves sit below the shallow waters bordering
the continents.
– These shelves drop off at the shelf-slope break.
– The continental slope angles steeply downward toward
the deep ocean basin.
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Ocean currents affect Earth’s climate (1 of 5)
• The thermohaline circulation is a worldwide current
system in which warmer, lower-salinity water moves along
the surface and colder, saltier (denser) water moves
horizontally below the surface.
– This moves warm water in the Gulf Stream to the
Atlantic Ocean near Europe, where heat is released
and the cooler water sinks.
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Ocean currents affect Earth’s climate (2 of 5)
• The region of downwelling near Western Europe is called the
North Atlantic Deep Water (NADW).
– Scientists are concerned that an influx in fresh water from
melting glaciers in Greenland could disrupt this flow.
Figure 12.9 As part of the oceans’ thermohaline circulation, warm surface currents carry heat
from equatorial waters northward toward Europe, where they warm the atmosphere.
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Ocean currents affect Earth’s climate (3 of 5)
• The El Niño–Southern
Oscillation (ENSO) is a
systematic shift in atmospheric
pressure, sea surface
temperature, and ocean
circulation in the tropical Pacific
Ocean.
Figure 12.10 El Niño conditions occur every 2 to 8
years, causing marked changes in weather patterns.
• Under normal conditions,
prevailing winds blow from east
to west along the equator,
forming a large convective loop
in the atmosphere.
– This causes a “pile-up” of
warm water to form near
Indonesia, fueling storms
in that region.
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Ocean currents affect Earth’s climate (4 of 5)
• El Niño conditions are
triggered when air pressure
decreases in the eastern
Pacific and increases in the
western Pacific, weakening
the equatorial winds,
allowing warm water to flow
eastward, and suppressing
upwelling along the Pacific
coast of the Americas.
– This can create storm
activity in normally arid
regions like California
and drier conditions in
Indonesia.
[Figure 12.10 Continued]
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Ocean currents affect Earth’s climate (5 of 5)
• La Niña events are the opposite of El Niño events;
unusually cold waters rise to the surface and extend
westward, causing winds blowing to the west to
strengthen.
• ENSO cycles occur every 2–8 years.
– Scientists are studying whether changes in air and sea
temperatures are increasing the frequency and
strength of these cycles.
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Marine and Coastal Ecosystems
• Regions of ocean water differ greatly, with certain zones
supporting more life than others depending on
characteristics such as:
– Topography
– Temperature
– Salinity
– Nutrients
– Sunlight
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Intertidal zones undergo constant change (1 of 2)
• Intertidal ecosystems spread between the uppermost reach
of the high tide and lowest limit of the low tide.
Figure 12.11 The rocky intertidal zone stretches along rocky shorelines between the lowest and
highest reaches of the tides.
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Intertidal zones undergo constant change (2 of 2)
• Tides are the periodic rising and falling of the ocean’s
height at a given location due to the gravitational pull of the
sun and moon.
– Intertidal organisms are exposed to sun part of the day,
and covered in water the rest of the day.
• Rocky intertidal zones are highly diverse because
environmental conditions such as temperature, salinity,
and moisture change dramatically from the high to low
reaches.
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Fresh water meets saltwater in estuaries
• Estuaries are bodies of water where rivers flow into the
ocean, mixing saltwater with fresh water.
– Salinity fluctuates daily due to the tides and changes in
river flow.
– Estuaries are sheltered from the heavy waves of the
ocean and provide habitat for many plants, which
provide food for shellfish, birds, and fish.
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Salt marshes line temperate shorelines
• Salt marshes occur where the tides wash over gently sloping sandy or silty
substrates.
– Water from rising and falling tides flows in and out of salt marshes through
channels called tidal creeks.
– Salt marshes provide biodiversity, filter pollutants, and stabilize shorelines.
Figure 12.12 Salt marshes occur
in temperate intertidal zones
where the substrate is muddy.
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Mangrove forests line coasts in the tropics and
subtropics
• Mangroves are trees that are salt tolerant, with roots that grow upward
to gather oxygen and others that grow down to support the tree like stilts.
– Fish, shellfish, snakes, and other organisms thrive among the roots
in the water, while many birds feed and nest in the tree foliage.
Figure 12.13 Mangrove
forests line tropical and
subtropical coastlines.
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Kelp forests harbor many organisms
• Along many temperate coasts, large brown algae called kelp grow
from the floor of the continental shelves, reaching toward the sunlit
surface.
– Dense stands form underwater “forests,” which provide food and
shelter for many animals.
Figure 12.14 “Forests” of tall
brown algae known as kelp
grow from the floor of the
continental shelf.
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Coral reefs are treasure troves of biodiversity (1 of 3)
• A coral reef is a mass of calcium carbonate composed of
the shells of tiny animals called corals.
• Coral reefs may be found in three areas:
– Extensions of a shoreline.
– A barrier island paralleling a shoreline.
– A ring around a submerged island called an atoll.
• Coral are related to jellyfish and can capture passing food
with their tentacles.
– They also form symbiotic relationships with algae
called zooxanthellae, which produce food through
photosynthesis.
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Coral reefs are treasure troves of biodiversity (2 of 3)
• Most corals are colonial and the surface of a reef will contain millions
of densely packed individuals.
• Coral reefs host tremendous biodiversity because they provide shelter
from waves and their complex physical structure produces many
habitats.
Figure 12.15 Coral reefs provide food
and shelter for a tremendous diversity
of fish and other creatures.
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Coral reefs are treasure troves of biodiversity (3 of 3)
• Many coral reefs have fallen victim to “coral bleaching,” a process that
occurs when zooxanthellae lose color and die, depriving the coral of
nutrition.
– Occurs when coral are stressed by increased water temperatures
and elevated pollution levels.
[Figure 12.15 Continued]
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Open-ocean ecosystems vary in their biodiversity
• In the open ocean, most primary productivity occurs in the top layer,
called the photic zone.
– Microscopic phytoplankton constitute the base of the food chain.
• Pelagic habitats are found between the ocean surface
and floor.
• Benthic habitats occur on the ocean floor.
Figure 12.16 The uppermost reaches of ocean
water contain billions upon billions of
phytoplankton—tiny photosynthetic algae,
protists, and bacteria that form the base of
the marine food chain.
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Human Activities Affect Waterways
• Water is one of our most precious resources and is
renewable.
• People are withdrawing water at unsustainable levels and
depleting many sources of surface water and groundwater.
• The construction of engineered waterways like dams and
canals has altered an estimated 60% of the world’s largest
rivers.
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Fresh water and human populations are unevenly
distributed around Earth (1 of 2)
• Climate differences and other factors have created varying amounts of
groundwater, surface water, and precipitation across the Earth.
Figure 12.17 Nations vary tremendously in the amount of fresh water per capita available to their
citizens.
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Fresh water and human populations are unevenly
distributed around Earth (2 of 2)
• The distribution of the human population does not match
the distribution of water, creating areas that do not have
adequate local water supply.
Figure 12.17 Nations vary tremendously in the amount of fresh water per capita available to their
citizens.
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Water supplies households, industry, and agriculture
• The majority of our freshwater use (about 70%) is for
agriculture.
– Industry accounts for about 20%.
– Residential use accounts for about 10%.
• The increased demand for i…
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