AQUATIC BIOMES

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AQUATIC BIOMES

• Water, water, everywhere

By Patti Nicoll with some help from Brian Kaestner
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TYPES OF AQUATIC ZONES

• Saltwater, aka Marine
• Freshwater

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Categories of organisms

• Plankton cannot swim against current
• Phytoplankton
• Bacterioplankton
• Zooplankton
• Nekton can swim against current
• Benthos live on the bottom
• Decomposers break down dead matter

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Benefits of living in water

• Buoyancy
• Fairly consistent temperature
• Nutrients are dissolved and readily available
• Toxic metabolic wastes are diluted and dispersed

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Limiting factors

• Temperature
• Access to sunlight
• Salinity
• Dissolved oxygen (3-5 ppm is the usual level of
  need)
• Enters through atmosphere and photosynthesis and
  is removed by aerobic respiration
• Dependent upon temperature, number of producers
  and consumers
• Dissolved CO2
• Also dependent upon number of producers and
  consumers

• Availability of nutrients
• Near shore vs. Open ocean
• Carbon
• Enters through CO2 from atmosphere and aerobic
  respiration
• Removed by photosynthesis important component
  of reducing the Greenhouse effect
• Long term storage of CO2
• Nitrogen
• Most limiting nutrient in saltwater ecosystems
• Phosphorus
• Most limiting nutrient in freshwater ecosystems

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EXAMPLES OF DO AND DCO2
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MARINE BIOMES
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IMPORTANCE OF THE OCEANS

• Covers 71 of the earth
• Distributes solar heat
• Plays a large role in hydrologic cycle
• Regulates climate (global warming too)
• Serves as a reservoir for CO2
• Provides habitat for 250,000 known species
• Food source - fisheries
• Largest contributor to the earths overall net
  primary productivity
• Source of iron, sand, gravel, phosphates,
  magnesium, oil, and natural gas

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DISTINGUISHING CHARACTERISTICS

• Much more uniform than terrestrial habitats
• organisms can move around much more freely
• Diversity is lower than on land
• individual niches are less diverse
• Water moderates temperatures

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Sea Surface Temperatures
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Surface Currents (example)
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TWO MAJOR LIFE ZONES

• BENTHIC
• bottom environments
• subneritic (nearshore) or suboceanic (bathyl,
  abyssal, hadal)

PELAGIC open ocean and coastal neritic,epipelagic
, mesopelagic, bathypelagic, abyssalpelagic
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OVERVIEW OF OCEAN ZONES
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PELAGIC (OPEN OCEAN)

• Coastal zone
• Neritic
• Shore to 200m depth
• Highly productive - why?
• Important economically

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PELAGIC contd

• Oceanic zone
• Euphotic zone
• epipelagic - surface to 200m characterized by
  non-mobile producers (very productive in sheer
  volume) and very mobile consumers

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PELAGIC CONTD

• Epipelagic zone - plankton productivity

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PELAGIC contd

• Oceanic zone contd
• Mesopelagic zone - 200-800m
• organisms frequently move vertically in the water
  column to feed
• bioluminescence often found in organisms (used in
  communication and to attract prey)

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PELAGIC contd

• Oceanic zones contd
• Bathypelagic
• 800m-1500m
• Abyssopelagic
• 1500m - bottom
• organisms adapted to virtually no light
• food scarce, so must be opportunistic (big
  mouths)

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BENTHIC HABITATS contd

• Neritic
• shore to 200m depth
• lots of light
• lots of nutrients
• lots of biodiversity
• Organisms must be able to avoid being swept away
  or crushed by waves, and being immersed at high
  tide and dry at low tide. To cope most either
  hang on, dig in or hide in shells.

• Rocky bottom
• Soft bottom

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PELAGIC contd

• Benthic zones contd
• Suboceanic
• Bathyl, Abyssal, and Hadal zones
• Organisms are either scavengers, deposit feeders,
  or filter feeders (98 of identified species are
  here)
• Must deal with extreme cold and pressure
• A great deal of the oceans nutrients originate
  here

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SPECIAL HABITATS

• Hydrothermal vents
• based on bacterial chemosynthesis
• extreme ranges in temperature
• pressures up to 3300 pounds per square inch

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SPECIAL HABITATS

• Coral Reefs one of the most diverse life zones
• narrow margin of temperature tolerance (75-85OF)
• Narrow margin of salinity (34 to 37 ppt)
• Need clear water for algae
• Very susceptible to change and so are good
  climate indicators

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Human Impacts to Coral Reefs

• Primary cause of damage to reefs is due to
  sedimentation of the water due to runoff from
  shore development.
• Estimates are that humans have caused the death
  of 10 of the worlds coral reefs. Another 30
  are critical, another 30 are threatened and only
  30 are stable.
• If current trends continue, another 60 could be
  gone in the next 20-40 years
• Protected reefs can often recover, but protection
  is difficult and expensive

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HUMAN IMPACTS

• Destruction of reef habitat and biodiversity

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MORE SPECIAL HABITATS

• Estuaries/Wetlands/Salt Marsh/Mangroves
• highly productive and economically important
• Organisms very adaptable temperature and
  salinity vary a great deal
• Breeding grounds for many marine species (game
  species) and birds
• Dilutes, filters and settle sediments, excess
  nutrients, and pollutants
• Buffers flooding and protects coastlines from
  erosion
• 2/3 of the US major commercial fisheries depend
  on coastal estuaries and marshes for nursery and
  spawning grounds

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More Special Habitats

• BARRIER ISLANDS
• Help protect the mainland by dispersing energy
  from storm waves
• Sediment is constantly shifting and moving from
  one area to another gentle waves build them up
  and storms wear them down. Many resort areas are
  damaged due to this inherent characteristic

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BEACH EROSION

• Estimated 70 of worlds beaches are experiencing
  serious erosion
• 30 of US is significant
• Caused mainly because sea level has been rising
  for the last 12,000 years
• Humans have impacted though by redirecting rivers
  and draining wetlands

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Methods to stop erosion

• All methods known are only temporary due to the
  dynamic nature of shorelines erosion and build
  up are natural processes
• Traditionally jetties, seawalls, groins, and
  breakwaters have been used
• Most coastal ecologist are against using these
  since, in the long run, they cause more damage
• Since 1965 governments, developers, and
  communities in the US have spent an estimated
  3.5 billion replenishing beaches
• Two new methods, a drainage system and beachsaver
  module, are being tested.

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Example of beach erosion on barrier islands
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Human Impacts on Coastal Zones

• Since 1900, the world has lost 1/2 of its
  coastland - primarily through development
• In the past 200 years nearly 55 of the estuaries
  and coastal wetlands in the US have been
  destroyed or damaged primarily through dredging
  and filling and contamination
• California alone has lost 91 of its original
  coastal wetlands. Florida, however, has lost the
  largest area.
• A 1994 study estimated that the economic benefits
  from what was left of the CA wetlands is over
  124 trillion.

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HUMAN IMPACT contd

• Coastal wetlands are vulnerable to toxic
  contamination since they trap pesticides, heavy
  metals, and other pollutants, concentrating them
  to high levels.
• On any given day, 37 of US coastal shellfish
  beds are closed to commercial or sport fishing,
  usually because of contamination from sewage
  treatment, septic tanks, and urban runoff (red
  tide as well)
• Since mid 1960s tropical coastlines have lost
  half or more of their mangrove forests because of
  industrial logging for timber and fuel wood,
  aquaculture, agriculture, and urban development
  (fastest rate in SE Asia)

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Just something to
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think about
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FRESHWATER LIFE
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What is freshwater?

• Water that has a dissolved salt concentration of
  less than 1 by volume which accumulates or flows
  through the surface of terrestrial biomes is
  considered to be fresh

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Why are freshwater systems important?

• Only 1 of the surface of the planet is covered
  by freshwater, but 41 of the fish species live
  there.
• Highly productive due to almost constant run-off
• Their health is closely connected to terrestrial
  biomes and are therefore good indicators of
  terrestrial health

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Two main types of systems

• Lentic
• Standing bodies of water

• Lotic
• Flowing systems

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Lentic Systems - lakes

• Lakes are defined as areas where precipitation,
  runoff, or groundwater seepage fills depressions
  in the earths surface
• Sources of water
• Rain
• Melting snow
• Streams that drain area

• These depressions can be caused by
• Glaciation
• Crustal displacement caused by or accompanied by
  earthquakes
• Volcanic activity

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Lentic zones

• Littoral zone shallow area near shore that
  extends to a depth where rooted plants stop
  growing
• Limnetic zone open, sunlit, surface layer
  (equivalent to euphotic), that is away from
  shore, and extends to a depth penetrated by
  sunlight (this can be variable depending upon the
  lake).

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Lentic zones contd

• Profundal zone deep, open water where it is too
  dark for photosynthesis. It is inhabited by fish
  adapted to cooler, darker water.
• Benthic zone the bottom which is mostly
  inhabited by decomposers, detritus-feeding clams,
  insect larvae, and catfish.

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Classification

• Lakes are classified according to their nutrient
  content and their primary productivity
• Three main classes
• Oligotrophic
• Eutrophic
• Mesotrophic

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Oligotrophic

• Newly formed lake with low nutrients
• Often deep with steep banks
• Usually has crystal-clear blue or green water
  because of low nutrients
• Small populations of phytoplankton and fish

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Eutrophic

• Large or excessive supply of nutrients and bottom
  sediments
• Shallow, murky brown or green water with poor
  visibility
• High nutrients and high net primary productivity
• Large populations of plankton and diverse
  populations of fish
• During the warm summer months, the bottom layer
  (profundal zone) can become depleted of dissolved
  oxygen

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Mesotrophic

• Most lakes fall in this zone as being somewhere
  in between

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Seasonal Changes in Temperate Lentic (lake)
systems

• Water is the most dense at a temperature of 4oC
  (39oF). This is unusual for substances, but is
  fortunate for aquatic organisms. Ice floats at
  0oC since it is less dense. If it were otherwise,
  lakes would freeze from the bottom up and kill
  everything
• Instead, thermal stratification occurs
• These lakes resist mixing since the sun keeps the
  surface warm in the summer, and less dense

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Thermal Stratification

• Epiliminon upper layer of warm water with high
  dissolved oxygen
• Hypoliminon lower colder water, usually with
  low dissolved oxygen
• Thermocline middle layer where the water
  temperature changes rapidly with increased depth.
  This acts as a barrier to the transfer of
  nutrients and dissolved oxygen from the two other
  layers

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Spring and Fall Overturn (only in temperate
lakes)

• In spring, as waters warm, the ice melts and
  becomes dense. This causes the water to sink,
  causing a mixing between the upper and lower
  layers
• In fall, as the waters cool, it become dense
  again and mixes for a second time
• This redistributes, oxygen, temperature, and
  nutrients throughout the lake

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Lotic (stream and river) Definitions

• Surface water that doesnt sink into the ground
  is called runoff this feeds streams and rivers
  and then the oceans, contributing to the
  hydrologic cycle
• The entire land area, which delivers water,
  sediment, and dissolved substances to small
  streams, and larger streams, or rivers, and
  ultimately to the ocean, is called a watershed.

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Three Lotic zones

• Source zone narrow headwater, or mountain
  stream of cold, clear water with high dissolved
  oxygen
• Transition zone merged streams, on gentler
  slopes, with warmer water, more producers, and
  slightly lower dissolved oxygen
• Flood plain zone streams join into wider and
  deeper rivers, with silty water, that meander
  across broad, flat valleys. Higher temperatures,
  lower DO, large producer populations, rooted
  plants along slopes, and distinct fish species
  are found here

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Human Impact in Flood Zone

• Often meandering rivers are straightened,
  widened, and deepened to
• Improve navigation and
• Help reduce flooding and bank erosion
• This stream channelization is controversial

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Geographic Impacts of Streams

• The power of moving water is great. Rocks and
  soils are removed from fast moving areas, with
  large slopes, and deposited as sediment in
  low-lying areas

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Nutrients

• NATURAL SOURCES
• Falling leaves
• Animal feces
• Insects and other biomass washed during heavy
  rain and melting snowTo protect from excessive
  nutrients and pollutants the entire watershed
  must be protected

• POLLUTANTS
• Fertilizer runoff
• Pesticide runoff
• Wastewater from sewage plants
• Wastewater from industry
• Spilled or dumped oil

To protect from excessive nutrients and
pollutants, the entire watershed must be protected
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Inland Wetlands

• Lands covered with freshwater all or part of the
  time (excluding lakes, reservoirs, and streams)
  and located away from coastal areas are called
  inland wetlands
• They can vary a great deal none are typical
• Some are covered year round, but others remain
  dry for long periods, sometimes years. In these
  cases the only indicators are plant species
  (cattails, bulrushes, red maple)

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Economic and Ecologic Roles of Inland Wetlands in
the US

• Provide food and habitats for fish, migratory
  waterfowl and other wildlife
• Improves water quality (just like marine
  wetlands, aka estuaries). Inland wetlands have
  been given the name, natures kidneys, because
  of this.Conservative estimates are that inland
  wetlands in US provide water quality protection
  worth at least 1.6 billion/year.
• Reduce flooding and erosion by absorbing
  stormwater and releasing it slowly and by
  absorbing overflows from streams and lakes.
  Without these, additional flood control costs
  would be 7.7 billion to 31 billion/year
• Replenish groundwater supplies, which are a
  source for 50 of Americans
• Plays a significant role in the carbon, nitrogen,
  sulfur, and water cycles
• Provides recreation and grows crops

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Human Impacts

• Many are drained, dredged, filled-in or covered
  over
• Each year 183mi2 are lost, 80 to agriculture
  and rest to mining, forestry, oil and gas, and
  urban development
• Canada has 24 of the worlds wetlands and has
  lost 14 mostly to agriculture
• A federal permit is now required to fill-in
  wetlands and this has cut loss by 75 since 1969
• Only 8 of the remaining inland wetlands in the
  US are under federal protection and local
  protection is very weak
• Mitigation banking is used but is not always
  successful. The new wetlands often have no
  resemblance to their natural counterparts and are
  expensive.
• Environmentalists call for prevention,
  comprehensive land-use planning, using mitigation
  only as a last resort, and creating and
  evaluation a wetland before another can be
  destroyed

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Opposition to Wetland Protection

• Developers and farmers have been pressuring
  members of Congress to revise the definition of
  wetlands under the Clean Water Act. Under this
  revision, according to the Army Corps of
  Engineers and the EPA, 60-75 of the existing
  wetlands would lose federal protection and become
  eligible for development

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Sustainability

• Each stream, river, and lake reflects the sum of
  all that occurs in the watersheds above it and
  the ocean is the ultimate receptacle of human
  activity. Many of the chemicals reaching aquatic
  systems are now being shown to come from the
  atmosphere (air pollution)
• Good new is that these system are constantly
  renewed water is purified, nutrients are cycled
  in and out and biological organisms can be
  replenished, given opportunity. This will only
  work as long as the system is not overloaded.

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Water is precious!