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					Marine Biology
    Plankton
General Info:
• Plankton comes from the Greek
 word “planktos” which means drifter.
Movement
• Most organisms move with the current.
 Some have the ability to move on their
 own. For example, copepods are the
 fastest animal for their size- they move
 more than 500 body lengths per second.
 Two Types of Plankton
• Phytoplankton-
  which are
  autotrophs (plank-
  like)
• Zooplankton-
  which are
  heterotrohs
  (animal-like)
Location- Epipelagic region of the ocean:
• This location is near the surface where the water
    is warmer and lighter.
•   The depth is from the surface to 200m or 650 ft.
•   It often corresponds with the photic zone, the
    is the region where light penetrates.
Location: Epipelagic region of the ocean (con’t)

• Shallowest part of the pelagic realm
• The pelagic realm is the vast open ocean
  away from the bottom and the shore
Location: Epipelagic region of the ocean (con’t)
• Coastal/neritic: are waters that lie over the
    continental shelf (small portion of the
    epipelagic)
•   Oceanic: are surface waters beyond the
    continental shelf.
Location: Epipelagic region of the ocean (con’t)

• This area lacks deposit feeders since there is NO
  bottom
• Suspended feeders are therefore ABUNDANT

• None of these deposit feeders!
All energy comes from the sun:
• Nearly all primary producers (photosynthesis) from the
    ocean occurs in the epipelagic zone
•   Food produced sinks or is carried by the currents to
    other parts of the ocean.
•   Autotrophs carry out photosynthesis by taking in carbon
    dioxide and converting it to organic food (glucose)
Plankton have trouble remaining afloat:
• Organisms and their shells are more dense than
    water and therefore should sink
•   Coping strategies:
    – Increase water resistance- the greater the surface
      area the more resistance
    – Being small is helpful
    – Flat shape also increases surface area, as do
      projections and spines
Plankton have trouble remaining afloat (con’t):
• Coping strategies (con’t)
  – Increase buoyancy
     • Some store lipids as vacuoles of oil (less
       dense than water)
     • Some use pockets of gas which is less
       dense than water
        – Regulating the amount of gas can
          move the organism up and down the
          water column
     • Exchange heavy ions for lighter ones
Vertical Migration
• Predators abound the epipelagic. Therefore,
  some zooplankton sink where there is little light
  during the day and rise to feed at night
Recent Research
• New methods to count and identify phytoplankton
    biodiversity
    – Flow cytometry is optical technique that can process hundreds
      of thousands per minute
• MIT researchers discovered tiny but abundant new
    species called prophlorophytes
•   DNA research to understand evolution and
    relationships among plankton
    Phytoplankton
• Photosynthetic Autotrophs
     – Greater than 95% of photosynthesis in the ocean
     – Produce nearly 50% of the oxygen in our atmosphere
     – Primary producer in the epipelagic- WHY?
•   Gouped by size
     – Picoplankton- too small to be caught in nets
     – Net plankton- (micro, meso, macro, nano), large
       enough to be caught in nets
 Phytoplankton (con’t)
• 2 Main Types
  – Diatoms
     • Kingdom Protista
     • Have characteristics of both plants and animals
     • Prefer temperate, polar, and nutrient-rich water
     • They are unicellular, although some gather in chains
       or clusters
     • Enclosed in a cell wall that is made out of silicon
       dioxide
Phytoplankton (con’t)
– Diatoms (con’t)
   • They have a glasslike frustules which is a shell with tight-
     fitting halves. There is a wide variety of beautiful frustules!
        – Some frustules have perforations and spines that allow
          light to pass through and gasses and nutrients to enter
          and leave
        – Frustules from dead diatoms accumulate on the ocean
          bottom and are called diatomaceous ooze
        – Fossilized sediments of the ooze found inland are mined as
          diatomaceous earth which is used for polishing
          (toothpaste), insulating, and filtering (swimming pools)
Phytoplankton (con’t)
 – Diatoms (con’t)
    • Reproduce rapidly when conditions are
     good. Other species are depend on this and
     it influences the success of some fish
     species.
 Phytoplankton (con’t)
• Second type
  – Dinoflagellates
     • Kingdom Protista
     • Most abundant phytoplankton in warm, tropical
       waters
     • Unicellular with a cell wall made of cellulose plates
     • Most outstanding characteristic: 2 unequal flagella
        – One wraps around the groove in the middle of the cell
        – One trails free
        – They both direct movement in practically any direction
Phytoplankton (con’t)
– Dinoflagellates (con’t)
   • Unique DNA remains coiled in chromosomes
     throughout life
   • Although autotrophic they also feed on other food
     particles
   • Reproduce by cell division
      – Huge surges of reproduction are called blooms
      – They produced the Red Tides which actually turned the water
        red to red-brown
Phytoplankton (con’t)
– Dinoflagellates (con’t)
      – 2 Problems with Red Tides
           Produce toxins which may cause fish to die or
            accumulate in the tissues of resistant organisms
            which can result in paralytic shellfish
            poisoning which can be fatal to humans
           As the bloom dies and decomposes, the bacteria
            deplete the dissolved oxygen form the water
            causing fish to die
Phytoplankton (con’t)
– Dinoflagellates (con’t)
   • Some species produce light by Bioluminescence which
     can be seen at night in the open ocean
   • Some species celled zooanthellae live in symbiotic
     relationships with other marine organisms such as
     coral. They release organic matter used by the coral and
     help in the formation of the coral skeleton.
Phytoplankton (con’t)
• Nanoplankton
 – Very small and hard to catch
 – Still important in ocean primary production
 – Two types
    • Cyanobacteria
    • Coccolithophorids
  Phytoplankton (con’t)
• Nanoplankton (con’t)
    • Cyanobacteria
       – Kingdom Monera, therefore prokaryotic
       – Contain chlorophyll (green pigment) and phycocyanin
         (blue pigment)
       – Most are microscopic, but can form long visible strands or
         mats
       – Likely the first photosynthetic organisms on Earth and
         contributed to the accumulation of oxygen in the
         atmosphere
       – Can also carry out nitrogen fixation- converting
         atmospheric nitrogen gas to usable from alike ammonia
Phytoplankton (con’t)
• Nanoplankton (con’t)
    • Coccolithophorids
       – Covered with rounds calcium carbonate paltes
Zooplankton
• Tiny planktonic animals
• A few species are a critical link in the food
  web- they are herbivores, meaning they
  eat autotrophs
• Most are carnivorous and feed on the
  herbivorous zooplankton
 Zooplankton (con’t)
• They are divided into two groups:
 Holoplankton and Meroplankton
  – Holoplankton: spend their entire lives a plankton
     • Copepods
       – Most abundant zooplankton (70% or more) and may be
         the most abundant animal on Earth
       – The are crustaceans
       – Most eat phytoplankton and zooplankton (use bristled
         antennae)
       – Move fast to escape predators
Zooplankton (con’t)
 – Holoplankton (con’t)
    • Krill
      – Shrimp-like crustaceans
      – Prefer colder waters
      – Filter feeders, eat diatoms, detritus, and
        zooplankton
Zooplankton (con’t)
– Holoplankton (con’t)
   • Other holoplankton
      – Salps- related to sea squirts
      – Larvaceans- also related to sea squirts and secrete a
        house of mucus
      – Pteropods- small snail-like creatures with modified foot to
        make wing-like projections
      – Arrow worms (chaetognaths)- feed on copepods
Zooplankton (con’t)
– Meroplankton: Only a portion of the lives are spent
  as plankton (larva of fish and invertebrates)
   • Veligers- mollusks
   • Ophiopluterus- brittle stars
   • Bipinnaria- sea stars
   • Trpchophore- polychaete worms and some mollusks
   • Nauplius- crustaceans

				
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posted:11/10/2011
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