Marine Ecology

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Marine Ecology
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Introduction

• We will spend the next several lectures looking
  at connections between environments.
• Youll hear words like habitat and ecology often.
  
• Marine ecology puts all the stuff weve discussed
  until now into larger perspective.

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Organization

• Communities are often looked at as being biotic
  (living) or abiotic (not-living). Notice I
  didnt say dead. Why is this significant?
• Organisms interact with each component in unique
  ways.
• Adaptation, is one of the most significant
  interactions an organism can undertake to
  ultimately succeed in its environment.

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Adaptation to differing light regimes.
Turbinaria spp. change growth patterns according
to available light. The animals on the left
live in a higher photic zone than the ones on the
right. Which one likely contains more
chlorophyll??
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What happens when adaptive ability is good?
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Or lack of predation??
With sufficient resources (nutrients, shelter)
sea urchins can take over! Over time they may
exceed the carrying capacity of their habitat.
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Carrying Capacity max population.
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Sometimes limiting resources cause intense
competition between (inter), or within (intra)
species groups.
These Hermit Crabs are engaged in
intraspecific competition. If one bests the
other and establishes a territory then
competitive exclusion has taken place. What
happens in an extreme case of comp. exclusion?
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Resource partitioning may play a role.
At one time, whale sharks may have contained huge
teeth! To avoid competition for food, they became
specialists on plankton? Has this solved their
dilemma entirely??
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Other animals take the opposite extreme.
Purple cone snails (Conus purpurascens) may have
been effective algae eaters.
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Sometimes behavior is modified in different ways
to avoid competition.
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Predator vs. Prey

• If you eat someone else, youre a predator.
• If you are eaten, prey.
• Most predators or prey fall into simple
  categories of carnivores (meat) or herbivores
  (plant).
• Omnivors are out there too, but given the choice
  they will usually choose to be either a carn. or
  herb.
• Detritivores arent considered predatory.
  (Imagine having a piece of decaying material
  suddenly defend itself!!)

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What if you just take up space??
Barnacles, just sit around. As long as they
dont harm the host, they arent a nuisance, but
how do we classify them??
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Living together in a chaotic world.

• Symbiosis living together for a common benefit.
  (Symbiont smaller, host larger).
• Commensalism one animal lives on another, but
  doesnt harm it.
• Parasitism one does benefit (host doesnt).

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Ecosystem Organization
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Marine environment is divided by distance from
land, depth and the type of organisms living
there.
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Food chains, the linkage between food webs,
are fairly easy to determine when animals are
specialists. In this three step chain, whales
are the top predator existing ultimately on krill
(which exist on phytoplankton). Each step in
the chain is known as a trophic level. How many
trophic levels are present here?
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Multiple food chains at multiple trophic
levels result in a food web. As you can observe,
many interactions are possible. Energy can be
transferred from one level to the other in
amazing ways.
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• Here is another
• way of looking
• at it.
• Killer whales
• are the top predators.
• Each part of the trophic
• level could be viewed as
• a factory for converting
• one thing to another!
• How many factories
• does it take to convert
• diatoms into
• killer whale??

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Trophic Pyramids Heat conversion
In a trophic pyramid plants and animals all are
assigned a caloric value. As we travel up the
trophic pyramid, heat is lost. By the time we
reach the uppermost level many calories have been
used, and much heat produced to make a pound of
blue or right whale.
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How much is being produced?
By measuring the rates of p-synth.
Ecologists are often able to determine how much
carbon is fixed by plants (gross primary
productivity) This is yet another method to
measure system productivity and its
efficiency. Units gC/m2/day
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Earths Primary Production
Ocean Production Red high, blue low Land
Production Green high, yellow low
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Carbon Cycle
Essentially, the oceans are a gigantic carbon
sinkhole. In which form is the
carbon contained? As more carbon cycles between
stages, we see that imbalances might be
detrimental to the health of many parts of the
ecosystem or to the entire thing! Which section
makes the largest contribution to carbon
circulation?
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Nitrogen Cycle
In a similar fashion, the nitrogen cycle shows
us where this element comes from and where it
goes. Like carbon, elemental nitrogen may
circulate between sections in several form.
Much of the cycling of nitrogen occurs as a
result of bacterial activities. Where is the
greatest impact on this cycle noticable?
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Phosphorus Cycle
Phosphorus is different! Unlike elemental carbon
and nitrogen, phosphorus is a mineral, in other
words...its a rock! As such it generally goes
downhill. While cycling does occur within the
ocean, much of the phosphorus ends up in the
sediments. Where is the largest contribution of
phosphorus to the marine ecosystem?