estuary

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AQUATIC ECOSYSTEMS CHAPTER 7
freshwater
ocean
saltwater
plankton
nekton
benthos
upwelling
swamps
wetland
littoral zone
benthic zone
estuary
lake
algal bloom
river
salt marsh
B a r r i e r I s l a n d
eutrophication
coral reef
salinity
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Freshwater Ecosystems
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...determine where Org livesin the water.

• Temp
• Sunlight
• O2
• Nutrients

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TYPES of ORGS

• Plankton (phyto - zoo -)
• Float near surface
• Principal food source in aquatic ecosystems
• Nekton
• Free-swimming orgs fish, turtles, whales...
• Benthos
• Bottom-dwellers mussels, worms, barnacles...

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TYPES of FW Ecosystems

• Lakes
• Ponds
• Wetlands
• Rivers
• Streams

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LIFE in a LAKE...

• LITTORAL ZONE
• Near shore
• Nutrient-rich
• Abundant/diverse life due to sunlight
  (photosynthesis)

• BENTHIC ZONE
• Lake bottom no light for photosynthesis
• Dead decaying orgs
• Decomposers, insect larvae, clams...carp.

...depends on the amount of sunlight available!
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Eutrophication

• Increase in amount of nutrients in aquatic
  ecosystem.
• Nutrients cause plants algae to increase...
• Bacteria increase as dead plant matter
  grows...bacteria use up dissolved O2...
• O2 - loving organisms die off.
• Lakes naturally become eutrophic over time....

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...but the process can be accelerated by sewer
system or agricultural runoff that places
fertilizer (and I use the term loosely!) into
lakes ponds.
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FW WETLANDS

• Areas of land periodically covered with water.
• MARSHES contain non-woody plants (cattails,
  reeds, rushes)
• SWAMPS woody plants (trees, shrubs)

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Marshes

• Characterized by low, flat land...little water
  movement...some brackish, some saltier.
• Flat-billed fowl (ducks, grebes) adapted for
  skimming insects off surface those with
  spear-like beaks (herons) suited to grasping
  small fish digging for buried frogs.
• Florida Everglades largest freshwater wetland in
  U.S.

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Swamps

• Flat, poorly drained land woody shrubs or
  water-loving trees.
• Snakes...bullfrogs...alligators!

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Freshwater WETLANDS provide important
environmental functions

• Act as filters or sponges to absorb remove
  pollutants from groundwater improve water
  quality of lakes/reservoirs downstream.
• Control flooding by absorbing extra water from
  rivers hurricane storm surges...saving
  urban/residential areas from damage.
• Habitat for migratory waterfowl...spawning
  grounds for game fish...cranberries!
• Buffer zones to protect against shoreline
  erosion.

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...they used to be wastelands...

• For decades, it was believed they were just
  breeding grounds for mosquitoes...
• Millions of acres were recovered via drainage,
  filling in, clearing...
• Now (thanks to envi sci!) they are protected by
  government...their destruction is prohibited.

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Rivers

• Rivers have been long used as free water sources
  for industry (and dumping grounds...)
• Toxins have killed off much river life and made
  river fish inedible...city farm runoff put
  pesticides other poisons in rivers.
• Dams alter ecosystems in and around rivers.

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Marine Ecosystems
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Estuaries

• Freshwater source (river) mixes with saltwater
  source (ocean).
• Currents cause nutrient trap to form _at_ bottom.
  Sunlight penetrates shallow waters.
• Rich nutrients/photosynthesis make estuaries some
  of the most biologically productive ecosystems on
  the planet.
• Protected from waves by peninsula/barrier
  islands.

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Estuary Life

• Plants plankton fish dolphins, manatees,
  seals et al...abundant food web.
• Oysters, barnacles, clams (filter feeders)
• Orgs are able to tolerate varying salinity
• Humans love estuaries too...

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Threats to Estuaries

• Of the 10 largest urban areas on the planet, 6
  are built on estuaries
• Tokyo
• New York City
• Shanghai
• Buenos Aires
• Rio de Janeiro
• Bombay

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Threats to Estuaries

• California estuaries filled in with waste used
  as building sites.
• Rivers carry pollutants downstream to estuary
  (sewage, ag waste, pesticides, toxic chemicals)

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Chesapeake Bay
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Barrier Islands

• Formed by rising sea levels (over the past 15,000
  years)
• Long, narrow sand ridges parallel to coastline, 3
  to 30 km out.
• Protect mainland coastal wetlands from storms
  waves.
• ...dont spend a lot of buying a home on em...

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Sanibel Island
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Southern Rhode Island
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Coral Reefs

• Limestone ridges built by photosynthetic algae
  skeletons of coral polyps.
• Found only in clear, warm, shallow saltwater.
• Among the most diverse ecosystems on planet
  (thousands of species).
• Convoluted shape provides habitats for fish,
  snails, clams, sponges...

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Coral Reefs

• 27 of worlds coral reefs in danger...
• Oil spills...sewage...pesticides...silt
  runoff...overfishing...
• If water gets too warm/too cold...
• If fresh water drains onto reef...
• If water gets too muddy/polluted...
• Reefs are fragile, they grow too slowly to repair
  themselves in time...

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Great Barrier Reef
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Oceans

• Usable sunlight penetrates to only 100 m
  depth...
• ...most ocean life thus located in shallow
  coastal areas, not in open oceans.
• Seaweed, algae, plankton...inverts fish that
  feed on them are concentrated near-shore.
• Many different minisystems exist...
• Open oceans are possibly the least productive of
  all ecosystems.

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UPWELLING

• _at_ coastlines surface currents carry water away
  from shore...
• Deeper, nutrient rich bottom water wells upto
  fill in...
• Phytoplankton love it...fish come for
  phytoplankton...humans come for fish...its all
  good?

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Threats to Oceans

• Fertilizer runoff from shore causes algal
  bloom...some are poisonous!
• Industrial waste sewage coastal pollution.
• Overfishing is destroying some fish
  populations...
• Stupid fishing methods are murdering innocent
  creatures...