IPS Resilient Planet Mission 3

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Transcript IPS Resilient Planet Mission 3

IPS Resilient Planet Mission 3Paradise Lost
A Fragile Environmental Recovery
Welcome to the Chesapeake Bay
• The Chesapeake Bay
is the largest and
most productive
estuarine ecosystem
in the United States
Welcome to the Chesapeake Bay
• An estuary is a large body of water that opens
to an ocean, where salt water and fresh water
All the land that drains water into the Bay is
the estuary's watershed.
• The wetlands that border the Bay are
transitional ecosystems.
• They have characteristics of both land and
aquatic habitats and include tidal saltwater
marshes, freshwater marshes, brackish
marshes, and mudflats
• Like other wetlands, estuaries are highly
productive environments that support diverse
communities on land and in water.
• The sediment falls to the bottom of the Bay,
making it an important natural sink for many
elements and compounds.
• The Bay's nutrient-rich
waters support a
significant community
of primary producers.
Coastal forests,
marshlands, shore
grasses, and submerged
aquatic vegetation
(SAV) provide food and
shelter for animals.
• The Bay is home to nearly 300 species of fish.
Globally, the productivity of estuaries has
declined in recent years as human populations
have increased along their shores.
• Estuaries across the
globe have similar
characteristics. They lie
between land and
ocean, contain a mixture
of salt water and fresh
water, and accumulate
large amounts of
sediment and organic
• http://pmm.nasa.gov/education/videos/nasareal-world-nasa-and-chesapeake-bay
• SAV—Submerged Aquatic Vegetation These
plants are sources of food and habitat for
many shellfish, finfish, birds, amphibians,
reptiles, invertebrates, and mammals
The high primary productivity in the wetlands
fuels food webs
Filter Feeders
These organisms filter
suspended particles to obtain
food by straining the water.
Anything not eaten is bound
with mucus and discarded
• http://www.youtube.com/
• Pit Stops for Migratory Birds
The North American migratory
flyways describe the routes
followed by migratory birds
• Habitats for Endangered Species like sea
turtles and manatees.
• Natural, Economic, and Aesthetic Values –
Recreation and coastal industries
• One reason the Bay is so productive is because
it is shallow.
• Aquatic plants receive plenty of sunlight—even
those that live on the bottom. Aquatic plants are
grouped into three categories based on the way
they grow - floating, emergent (rooted at the
water's edge, but their stems and leaves grow
above the surface of the water. Cattails,
cordgrass, and rushes are examples) , and
Submerged aquatic vegetation (SAV) which is
critical in the recycling of nitrogen and
phosphorous that would otherwise dissolve in
the water which controls the population of algae.
• Fresh water from land mixes with salt water
from the Atlantic Ocean to create brackish
• Salinity is the amount of dissolved salts in the
water and is an important abiotic factor in
determining what plants and animals can exist
in any part of the estuary. practical salinity
• The salinity increases as you go deeper into
the water. A zone where salinity changes
rapidly with depth is called a halocline.
• Temperature is another important abiotic
factor in the Chesapeake Bay. a zone can form
where temperature rapidly changes with
depth, called a thermocline.
• Changes in sea level When the tide is high,
large expanses of sand and mud may be
covered by water. When the tide goes out,
that land becomes exposed to air. This pattern
of immersion and exposure creates a very
stressful environment. Known as the intertidal
• Dead Zones
• Runoff from land carries
sediment and nutrients into
the Bay.
• Sometimes the runoff contains
high levels of fertilizers
washed from farms, suburban
lawns, golf courses, and
sewage plants.
• Dead Zones
• Fertilizers contain large amounts of nitrogen
and phosphorous, that can cause a sudden
population explosion called an algal bloom.
can survive.
• Dead Zones
• Any increase in
these nutrients is
• Dead Zones
• The algae begin to die and sink to the bottom.
decomposers use up all the oxygen. Oxygen is
an important limiting factor. Without it, the
ecosystem collapses and the area becomes a
dead zone where very few organisms can
• Development Pressures As the human
population increased, critical habitats in the
watershed were destroyed and the
competition for the resources in the Bay
became overwhelming.
• The Chesapeake Bay ecosystem degraded.
• Scientists use the term population density to
describe the concentration of a species.
• Improperly treated sewage, excessive runoff,
increased animal manure, soil erosion, and
heavy use of fertilizers.
• a single known source, it is considered a point
• When the pollution does not come from a
single known source, it is a non-point source.
• Riparian forest occur when
trees line a riverbank, their
roots bind the soil and reduce
erosion. Riparian trees and
wetland plants filter about
80% of the phosphorous and
about 90% of the nitrogen
from the water. By slowing
water flow, the plants also
trap sediment.
• Filter feeders, such
as oysters and clams,
filter food particles
from the water. The
oyster filters and
absorbs the nutrients
but treats the abiotic
sediment as waste
which are heavy
enough to sink to the
bottom of the bay
making the water
less turbid.
• Today, however, the population of oysters is
less than 1% of its former size. The loss of
oysters due to overfishing, diseases, loss of
habitat, and low oxygen has significantly
affected water quality.
One way to help wild oysters and other aquatic populations to
recover is to "farm" seafood. Farming aquatic organisms underwater
is called aquaculture