Marine Ecology, April 2

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Marine Ecology, April 2 4, 2007

• Abiotic factors
• General and intertidal

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Its all about the water!

• Origin of water on earth
• Polarity of water
• Hydrogen bonds and associated properties
• Density-temperature relationship and its
  importance
• Water as the universal solvent

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What is the origin of water on earth?
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Water molecules

• Polarity
• Hydrogen bonds
• Cohesion surface tension

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Hydrogen bonds and temperature

• High heat capacity
• Much heat needed for state or temperature change
• Liquid over a wide temperature range
• High latent heat of melting
• High latent heat of evaporation
• Density Max at 4ºC

What are the consequences of this density maximum?
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Water as the universal solvent

• What makes water such a great solvent?
• Key Polarity!

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Other important abiotic aspects of seawater

• Salinity (list of solutes)
• Temperature (range, variability)
• Nutrients (types, why important)
• Dissolved gases
• pH (effects of respiration and photosynthesis)
• Light (importance)
• Pressure
• Water movement (major currents, upwelling)
• Substrate

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Dissolved ions/salinity

• Sources of dissolved ions
• Average salinity
• 33-37 ppt

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Many of these ions have important physiological
roles.
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Salinity and estuaries
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Temperature

• Range of 28-212F (-2-100C)
• Highest at hydrothermal vents
• Temperature and organisms
• Brief example coral reefs
• Surface water temperatures (global)

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Vertical profiles of temperature, salinity, and
density
Be sure you understand how temperature and
salinity affect density and layering!
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Nutrients

• Key dissolved nutrients
• Inorganic nitrogen (i.e. nitrate, ammonia)
• Inorganic phosphorous (i.e. phosphates)
• Inorganic silica (i.e. silicates)
• Iron (various compounds)
• Dissolved organic material (DOM)
• Major roles
• Primary production/biomolecule synthesis
• Excess nutrients may be problematic

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Distribution of primary production mirrors
nutrient distribution
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Dissolved gases

• Oxygen, carbon dioxide, nitrogen
• Ocean has 50 times the levels of CO2 as the
  atmosphere!
• Levels of O2 and CO2 affected by
• Exchange with atmosphere
• Photosynthesis
• Respiration
• Movement of water masses

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• Vertical distribution of O2

Know how and why O2 varies with depth!
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pH -log H

• Depends on dissolved elements molecules
• Seawater has pH of 7.6-8.6
• Generally stable in ocean waters
• Diffusion/water movement/carbonate buffering
  prevent drastic changes
• Addition of CO2 (i.e. respiration)? pH
• Decrease of CO2(i.e. photosynth.)? pH
• In closed aquaria build-up of organic acid
  waste products ? pH

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Light

• Primary energy source for producers (except at
  vents)
• Loss of light with depth
• Wavelength/color dependent
• Depends on particulates

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Pressure

• Increase of 1 atmosphere/ 10 m
• Various impacts on organisms
• Example impact on air spaces

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Ocean circulation

• Ocean currents are wind-driven
• Coriolis effect causes deflection
• Ekman spiral ?
• Ekman layer moves 90º to right from wind
  direction in N hemisphere 90º to left in S
  hemisphere

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Major surface currents

• Note major ocean gyres

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Sea surface temperature (SST) revisited

• Notice effects of cold vs. warm currents

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Upwelling West coast of North America
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Key global upwelling zones
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Great ocean conveyer

• Time scale 4000 year turnover
• Key salty, cold water sinks near Greenland
  Antarctica brings oxygen to depths
• Ice formation contributes to high salinity air
  temperatures are cold

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Waves

• Caused by wind become higher and shorter close
  to shore
• Shallow organisms most affected
• Particles move circularly within waves

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Substrate!

• Mud, rock, sand, etc
• Different survival strategies in different
  substrates

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What causes the tides?

• Moons gravity
• Pulls water toward it
• Rotation of earth/revolution of moon
• Centripetal force creates near-equal, opposite
  bulge

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Why are their usually two high tides and two low
tides each day?

• And why are they 50 minutes later each day?

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The suns effect spring tides and neap tides
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The tilt of the earth

• This causes the two high tides and two low tides
  each day to be of unequal height

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General patterns of zonation (Pacific)
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Upper intertidal submerged only on high-high,
spring tides.

• Upper intertidal

Ligia sp. (rock louse)
Littorina sp. (periwinkles)
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Middle intertidal (upper zone) exposed to air
more than water, but submerged at least 1x per day

• Middle intertidal (upper)

Pelvetia/Fucus (rockweed)
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Mid-intertidal Usually submerged 2x per day,
exposed 2x per day (generally submerged a bit
more than exposed)

• Middle intertidal (lower)

Mytilus californianus California mussel
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Low intertidal Submerged except during low-low,
spring tides.

• Lower intertidal

Strongylocentrotus franciscanus red urchin
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Physical factors affecting distribution of
organisms

• Extent of tidal exposure
• Amount of wave action
• Exposure to direct sunlight
• Temperature
• Substrate
• Other characteristics of water (see previous
  lecture)

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Adaptations to the physical environment

• Trapping water within

• Algae mucopolysaccharides

• Barnacles and snails Trap doors
• Called an operculum in snails

• Anemones and snails closing up

• Limpets and others clamping down

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Adaptations to the physical environment (cont.)

• Microhabitat refuges

• Physiological adaptations

Be able to provide specific examples for each!