Marine Biology

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Marine Biology

• Plankton

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General Info

• Plankton comes from the Greek word planktos
  which means drifter.

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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.

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Two Types of Plankton

• Phytoplankton- which are autotrophs (plank-like)
• Zooplankton- which are heterotrohs (animal-like)

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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.

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Location Epipelagic region of the ocean (cont)

• Shallowest part of the pelagic realm
• The pelagic realm is the vast open ocean away
  from the bottom and the shore

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Location Epipelagic region of the ocean (cont)

• Coastal/neritic are waters that lie over the
  continental shelf (small portion of the
  epipelagic)
• Oceanic are surface waters beyond the
  continental shelf.

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Location Epipelagic region of the ocean (cont)

• This area lacks deposit feeders since there is NO
  bottom
• Suspended feeders are therefore ABUNDANT
• None of these deposit feeders!

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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)

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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

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Plankton have trouble remaining afloat (cont)

• Coping strategies (cont)
• 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

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Vertical Migration

• Predators abound the epipelagic. Therefore, some
  zooplankton sink where there is little light
  during the day and rise to feed at night

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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

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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

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Phytoplankton (cont)

• 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

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Phytoplankton (cont)

• Diatoms (cont)
• 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)

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Phytoplankton (cont)

• Diatoms (cont)
• Reproduce rapidly when conditions are good. Other
  species are depend on this and it influences the
  success of some fish species.

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Phytoplankton (cont)

• 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

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Phytoplankton (cont)

• Dinoflagellates (cont)
• 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

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Phytoplankton (cont)

• Dinoflagellates (cont)
• 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

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Phytoplankton (cont)

• Dinoflagellates (cont)
• 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.

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Phytoplankton (cont)

• Nanoplankton
• Very small and hard to catch
• Still important in ocean primary production
• Two types
• Cyanobacteria
• Coccolithophorids

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Phytoplankton (cont)

• Nanoplankton (cont)
• 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

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Phytoplankton (cont)

• Nanoplankton (cont)
• Coccolithophorids
• Covered with rounds calcium carbonate paltes

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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

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Zooplankton (cont)

• 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

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Zooplankton (cont)

• Holoplankton (cont)
• Krill
• Shrimp-like crustaceans
• Prefer colder waters
• Filter feeders, eat diatoms, detritus, and
  zooplankton

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Zooplankton (cont)

• Holoplankton (cont)
• 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

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Zooplankton (cont)

• 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