Ecology and Marine Communities

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Ecology and Marine Communities
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McGehees 6 questions of Biological Oceanography

• What species of organisms are found in the ocean?
• How do these organisms make a living?
• How are they distributed in the ocean, both
  vertically and horizontally
• What factors govern the patterns of distribution?
• What are the communities of organisms?
• What factors govern community structure?

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Basic definitions in Ecology

• Community a group of organisms that share a
  common living space
• Population Number of individuals of a given
  species living in a community
• Ecology The scientific study of the factors and
  interactions that determine the distribution and
  abundance of organisms

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Biological Factors Affecting Distribution and
Abundance of Organisms

• Food supply
• Predation
• Competition
• Intraspecific competition
• Interspecific competition
• Symbiosis
• Mutualism
• Commensalism
• Parasitism

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Garden eels are distributed uniformly on the
seafloor due to their inclination to defend
fiercely the space around their burrows
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Biodiversity

• Refers to 2 things
• Number of species present in a community
• Relative abundance of those organisms
• Example 1
• Forest A has 5 types of tree pine, oak, poplar,
  juniper, and sycamore
• Forest B has 2 types pine and juniper
• ? Forest A has more biodiversity
• Example 2 Forests A and B each have 5 types of
  tree
• A has 100 pines, 2 oaks, 1 poplar, 1 juniper, 1
  sycamore
• B has 40 pines, 30 oaks, 10 poplar, 10 juniper,
  10 sycamore
• ? Forest B has more biodiversity

Biodiversity is generally considered to be a good
thing. Why?
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The Deep Scattering Layer
The dark red layers are strong reflectors
(scatterers) of sound. These rise toward the
surface at dusk. Layers are composed of plankton
and nekton from many phyla.
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Myctophid fish a large group of bioluminescent
mesopelagic fish
In the dark
In the light
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Anglerfish Example of a Mesopelagic Predator
Uses a bioluminescent light at the end of an
antenna to attract prey
When he finds her, tiny male attaches to large
female, connects to her circulatory system
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Rocky Intertidal Community
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Coral reef environments provide many of the same
advantages as the rocky intertidal zone1) water
motion brings in new food and dissolved gases2)
lots of holes to hide in, and attack from
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Organisms living on the deep seafloor are good at
finding food
This tripod fish is thought to be able to detect
vibrations from great distance
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Organisms living on the deep seafloor are good at
finding food
Fish bait placed on the deep seafloor in an
experiment lasted less than 16 hours
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Tube worms at hydrothermal vents host
chemosynthetic bacteria on their outside skins.
They absorb carbohydrate produced by bacteria
through their skin, meaning their digestive
systems are outside their bodies!