marine bio 2

• Every water molecule has areas of partial charge, partial negative charge near oxygen, each hydrogen has a partial positive charge, this is called polarity (polar molecule)
• Hydrogen Bonds = weak attractions between water molecules 

  • They cause cohesion, high surface tension, high specific heat, high boiling point, stratification (layers based on density) so floating ice insulates the water below allowing it to remain a liquid habitat
• Specific Heat – amount of energy required to raise one gram by one degree Celsius
• thermocline: a steep temperature gradient in a body of water such as a lake, marked by a layer above and below which the water is at different temperatures.

  1. Surface layer (aka mixed layer) is warmer because of the sun
  2. Intermediate layer (permanent thermocline is the slope on the line in this layer)
  3. Bottom layer/deep layer is steady and cold with little changes in temperature (3-4ºC)

  There is a temporary thermocline that occurs typically in the summer at the surface called a seasonal thermocline
• Solvent = liquid that can dissolve other stuff

  • Water is called the “universal solvent” because it is good at dissolving charged solutes
  • Salts, nutrients, and dissolved gasses
• Salinity = the total amount of salt dissolved in seawater (all salts together)

  • Units are parts per thousand or %o
  • Average ocean salinity, globally = 35 %o

  A region's salinity: depends on precipitation and evaporation, is quite stable in open ocean
• Photic zone = the surface zone where sunlight is bright enough to support photosynthesis (varies from few m -> 100 m)

  Aphotic zone = the zone where it is too dim to be used for photosynthesis (can still have some light)
• Gas exchange is when gas diffuses into a place where it is less abundant, such as the ocean
• Dissolved O2:

  • Only enters the ocean at or near the surface
  • Produced by photosynthesis in water
  • Used by aerobic organisms throughout the ocean
  • O2 has low solubility in water, making it scarce in seawater, typically around 5-10 ppm (parts per million)
  • Deeper water obtains O2 only from shallower water, resulting in very low O2 levels at deeper depths
• Dissolved CO2:

  • Inputs include gas exchange and produced by respiration in water
  • Output: Used by photosynthetic organisms in water
  • CO2 is highly soluble in water, making it plentiful in seawater and always available when needed
• A light intensity decreases exponentially with water depth (not linear)

  • Light intensity diminishes by ~ half every ten meters
  • Water can be clear or cloudy (“turbid”) which changes how much light can pass through
• Water absorbs red light very quickly (~ top 10 m) -> appear gray-ish under water

  Blue light is the last color to be absorbed

  • Ocean water looks blue in color when it is relatively clean or pure, it is a sign of low phytoplankton populations
• Waves

  Created by wind in a localized area that pushes on the sea surface (e.g. storm at sea)

  Swells = rounded waves

  Surf = waves that collide with the shoreline

  Waves don’t move the water, just pass through

  • Waves move water in a circular motion 
  • Contributes to mixing in the surface layer

  Waves become breaking surf when the wave’s bottom drags against the seafloor and slows
• Surface Currents

  Caused by wind, driven mainly by global wind patterns 

  Currents travel to the right of the wind direction (northern hemisphere) due to the rotation of the earth

  Currents travel to the left in the southern hemisphere

  Gyre = a roughly circular pattern of surface currents around the edges of an ocean basin 
• 4 surface currents of the north pacific gyre

  1. North equatorial current (blows from east to west across the pacific and is started from the trade winds) 
  2. Kuroshio current (carries warm water)
  3. North pacific current (hits north america and bends to the right)
  4. California current (towards the equator)

  Trash gets pushed into the middle (garbage patches)
• Importance of Surface Currents

  1. Mixing of surface layer (top 200m)
  2. Carry heat -> big effect on regional ocean temperature
  3. -> and on regions air temperature, and global climate
  4. Dispersal of plankton and larvae
• Upwelling is an upward current of deep water rising to the ocean surface
• Upwelling occurs when surface water is displaced
• Benefits of upwelling for local ecosystems:

  • Deeper water has more dissolved nutrients
  • Nutrient-rich water is brought to the photic zone, acting as fertilizer for phytoplankton
• Upwelling can happen along the equator and along certain coastlines (coastal upwelling)
• Coastal upwelling occurs when:

  • Coastal wind pushes surface water offshore
  • Deeper water rises to replace the surface water
  • Often happens on west coasts where the wind must be parallel to the shore
  • Example: NW wind along the CA coast results in surface water being pushed offshore (90 degrees to the right of the wind) and deeper water rising to the surface along the coast, increasing primary production in the photic zone
• • Downwelling currents = a downward current of water, sinking from current -> greater depths
  • Depends on density, occurs when surface water becomes more dense
  • in/near polar seas, cold dense water downwells
  • Water circulation that brings oxygen from sea surface to deeper water
  • The “Great Ocean Conveyor” circulates oxygen throughout the deep ocean
• • El Niño is one half of a cycle known as “The Southern Oscillation”
  • = a seesaw of atmospheric and oceanic conditions across the South Pacific ocean
  •  occurs every 3-7 years
  • Unusually low atmospheric pressure in eastern pacific
  • Unusually warm water in equatorial Pacific and near South America
  • Atmosphere -> trade winds weaken wind -> disturbance in ocean currents -> ocean temperature
• Local Effects of El Niño

  1. NP High Pressure System is weakened
  2. NW coastal wind is weakened or absent 
  3. Coastal upwelling weakened or  absent
  4. Coastal water warmer
  5. Low primary productivity - water is nutrient poor and unproductive
  6. Fisheries disrupted (low numbers of fish/migration)
  7. More rain, severe storms 
• La Niña

  • Roughly opposite effects of El Niño
  • Locally: NPHPS is higher, upwelling is strong
• Coastal upwelling occurs seasonally in spring and summer
• The steadiest wind, the northwest wind, leads to coastal upwelling
• Coastal upwelling is generated by the North Pacific High Pressure System over the eastern Pacific ocean
• The North Pacific High Pressure System generates winds that are responsible for seasonal changes in coastal California
• In spring and summer, the North Pacific High near central CA causes a steady northwest wind, leading to coastal upwelling, colder water, and nutrients
• The North Pacific High shields California from storms, making spring and summer dry seasons
• In fall and winter, the North Pacific High moves south near Mexico, resulting in no consistent coastal wind and no coastal upwelling
• eyepiece magnification: 10x

  low power objective lens: 4x

  high power objective lens: 40x

  total magnification under low power = 40x

  total magnification under high power = 400x
• What are the 4 surface currents that make the North Pacific Gyre?

  North equatorial current, Kuroshio current, North pacific current, California current