Life in the Ocean

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Life in the Ocean

• All living things grow, metabolize, react to the
  external environment and reproduce
• Organisms need energy and ingredients
• Energy the ability to do work
• Metabolism process by which organisms gain
  energy from the external environment.
• The ingredients Biomolecules
• Carbohydrates, Proteins, Lipids, Nucleic Acids

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Photosynthesis and Respiration
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Nutrients

• Materials needed to make biomolecules.
• Raw materials are nutrients, and they include
  minerals, vitamins, and other inorganic compounds
• Nitrogen and Phosphorus are usually the most
  important nutrients in the marine environment.
• Often called limiting nutrients because without
  them they limit productivity.
• Nitrate (NO3-1), the most important form of
  nitrogen, is used in making proteins and nucleic
  acids
• Phosphate (PO4-3), the most important form of
  phosphorus, is used in making phospholipids, ATP
  and DNA.

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Primary Production

• Sugars produced by photosynthesis are raw
  material for the other organic compounds, such as
  lipids, proteins and nucleic acids.
• When autotrophs produce more organic matter than
  they use, there is an overall gain in organic
  matter.
• This net increase is called primary production,
  and it is this primary production that supplies
  all the heterotrophs, i.e. animals, with food.

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Challenges of Life in the Ocean

• Lack of substrate
• They are at constant risk of sinking
• They are constantly being thrashed around by
  mixing.

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Challenges of Life in the Ocean

• Transparency of seawater
• Adequate light for photosynthesis only exists in
  the upper part of the ocean, in a region known as
  the euphotic zone,
• ranges from 10-200m in depth.
• The euphotic depth is the depth at which light
  levels are 1 of surface light, which is
  considered to be when light becomes limiting for
  photosynthesis.

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Challenges of Life in the Ocean

• Lack of Nutrients
• Most of the nutrients in the ocean are below the
  euphotic zone.
• Where there is enough light, there often arent
  enough nutrients for primary production

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Temp, O2, Nitrate Profiles
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Global Nitrate Profiles
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Global Primary Productivity
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Phytoplankton

• Phytoplankton (plant-wanderer) are the primary
  producers in the open ocean
• They range in size from 1 - 100?m (there are 1000
  ?m in a mm)
• The smaller you are, the less you sink.
• When you are that small, you can be thrown around
  by breaking waves and it doesnt affect you at
  all.
• When youre that small you have a higher
  surface-to-volume (S/V) ratio, which increases
  your ability to pick up nutrients, which may be
  in very low concentrations.
• The larger the organism, the smaller the S/V
  ratio, the smaller the organism, the larger the
  S/V ratio.
• Being that small you tend to reproduce quickly,
  so that your numbers can increase rapidly under
  the right circumstances.
• During a phytoplankton bloom, some cells will
  divide as much as 3 times per day.

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Its Good to be Small

• The smaller you are, the less you sink.
• When you are that small, you can be thrown around
  by breaking waves and it doesnt affect you at
  all.
• When youre that small you have a higher
  surface-to-volume (S/V) ratio, which increases
  your ability to pick up nutrients, which may be
  in very low concentrations.

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Phytoplankton Reproduce Exponentially

• Being that small you tend to reproduce quickly,
  so that your numbers can increase rapidly under
  the right circumstances.
• During a phytoplankton bloom, some cells will
  divide as much as 3 times per day.

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Plankton

• Greek for Wanderer or Drifter
• Organisms that cant swim against a current
• Usually small
• Picoplankton 0.2-2 µm
• Netplankton gt20 µm
• Types
• Phytoplankton
• Zooplankton
• Protists

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Phytoplankton

• Greek for Plant Drifter
• Vary in size from 1-100 µm
• Grow very fast
• Cells divide as much as 3 times/day
• Make own food but need
• Light, Nitrogen, Phosphorus
• Examples
• Diatoms, Dinoflagellates

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Dinoflagellates
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Diatoms
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Zooplankton

• Animal Wanderer
• Holoplankton plankton their entire lives
• Ex Copepods
• Meroplankton planktonic part of their lives
• Ex Fish, crabs, lobster, barnacles
• Need to eat other things
• Examples
• Copepods, Protozoans, Pteropods, Jellies

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Copepods
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Protozoans
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Pteropods
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Jellies