Marine Sciences Test 1

1. Differentiate between benthic, pelagic, neritic, and oceanic zones, and explain why life varies across these zones.

• benthic—seafloor

• pelagic—open water (contains neritic and oceanic)

• neritic—costal

• oceanic—open ocean

Life varies across these zones because of different levels of sunlight and nutrients. The neritic zone has much more life because the water is shallower and thus the sunlight can reach further, allowing for more opportunities for marine vegetation.

Outgassing theory

• Theory of where oceans water came from

• water condensed from a thick early atmosphere

  • volcanic activity releases water vapor

Extraterrestrial explanation for where oceans water came from

• meteorites and comets contain lots of water/ice

  • however contribution is likely small and the composition of their water is different (“heavy”) from our oceans

How are ocean biomes defined?

• salinity

• light

• depth

• temperature

• pressure

• substrate characteristic

Sonar

Sound navigation and ranging

used to map the ocean floor

how to calculate seafloor depth

time difference between creating a sound and receiving its echo

Why do we refer to the oceans of the world as “one world ocean.”

• the oceans are continuous—the names are for our ID/understanding

What hemisphere and ocean region contain more water?

Pacific, Southern

What are the five major ocean regions?

• Epipelgaic

• Mesopelagic

• Bathypelagic

• Abyssalpelagic

• Hadapelgic

Understand the evidence of the Tectonics Plate Theory

• Ocean floor chemical and physical characteristics

  • chemical

    • When these crusts collide the denser oceanic subdues beneath the continental

  • physical

• Evidence that continents move

  • Continents seem to fit like puzzle pieces

  • using longitudinal records from different years—Wegner demonstrated that Washington and Paris moved from each other

  • the same fossil types were found on different continents

• How and where new seafloor is formed

  • sediment thickness is greatest at edges of continents—oceanic crust is sub-ducting

  • mid-ocean ridges—from volcanic activity (magma rises cools in the water and spreads laterally)

• Tectonic plate boundaries

  • earthquakes happen along boundaries especially the mid-ocean ridge

discuss the discoveries that consolidated the mechanisms of seafloor and continents formation

Crust: Continental crust vs oceanic crust

Crust is lightweight and thin, made of part of lithosphere

Continental—consists mostly of granite, less dense

Oceanic—consists mostly of basalt (volcanic), and is denser than continental

Lithosphere vs Asthenosphere

Lithosphere—cool and rigid outer layer, crust and part of mantle, floats on top of asthenosphere

Asthenosphere—thin, hot, and slowly floating, upper layer of mantle, deforms under stress (not a solid or a liquid)

mid-ocean ridge

where new seafloor is made, here seafloor is young and thin. It spreads out and ages and thickens.

convergent boundaries vs divergent boundaries vs transform boundaries

• when two plates of similar density collide and push up against each other, creating mountains OR when a denser plate subducts into the mantle, creating trenches, volcanic arcs, and earthquakes

• when continental plates separate, new crust forms between them and creates deep valleys in which fresh water lakes form

• where plates slide horizontally, strike-slip faults occur causing earthquakes and surface features like faults. Doesn’t create or destroy crust

9 0f the 17 lithospheric plates (1 not pictured)

• North American

• Eurasian

• African

• Austrailain

• Indo-Austrailian

• Indian

• South American

• Antarctic

• Pacific

specific heat

the heat required to raise the temp of the unit mass of a given substance by a given amount (usually one degree)

water has a high specific heat

absorbs a lot of heat before it warms

about 3.4 hydrogen bonds per water molecule

stabilizes ocean temps

surface tension

water has high surface tension

the surface of the water exposed to air is difficult to puncture because the water molecules at the surface are hydrogen bonded to other molecules below

cohesion and adhesion

cohesion—water sticks to itself

• caused by hydrogen bonds

  • bonds are loose in warm water, tight in cold water and complete in ice cold water

adhesion—water sticks to other things

water light transmission

slows the transmission of light

latent heat

the energy absorbed or released during a phase change

80 calories is the latent heat of melting

liquid water heats up at the rate of 1 degree celsius per 1 cal

takes 540 cals to break the hydrogen bonds of liquid water (520 cals is the latent heat of evaporation)

Sources of salt for the ocean

Runoff from the land, and openings in the seafloor

what ions constitute the vast majority of the oceans salinity (in order)

1. Chlorine

2. Sodium

3. Sulfate

4. Magnesium

5. Calcium

6. Potassium

salinity

concentration of dissolved ions in the water

Salinity categories and their values

average salinity of the ocean/range

1. Brine—50+ ppt

2. Saline—30-50ppt

   1. ocean 32-50, avg 35

3. Brackish—0.5-30ppt

4. Fresh—0-0.5 ppt

How is salinity measured?

parts per thousand (ppt) aka grams of salt per 1000 grams of water

salinity variation: coasts vs open ocean

Coast: proximity to/influence of rivers

salinity increases further from the coast

Open ocean: salinity is influenced by evaporation and precipitation

where are the highest salinities? Lowest? Moderate?

subtropics (20 degrees lat)—low precipitation, high evaporation

equator (0degrees lat)—high precipitation, low evaporation

temperate latitudes experience a lot of precipitation

saltiest ocean basins, why?

2 portions of the Atlantic, Red Sea, and a portion of the Indian ocean

high evaporation rates

Halocline

depth at which salinity rapidly changes

where is salinity at the surface highest during the summer, subtropics, equator or polar lats?

The subtropics

thermohaline circulation

important because it moves nutrients to different parts of the ocean

occurs because temp and saline determine different water densities, and the circulation is driven by differences in density

relationship between density and temp(water), why?

water density is higher in cooler waters

at colder temps water molecules move less and are tighter, which decreases volume thus increasing density

what phenomena is causing rising sea levels

thermal expansion—as water warms molecules move more and are looser which causes the volume to expand

Pycnocline

depth at which density rapidly changes

relationship between salinity and density

as salinity increases so does density

effects of increasing salinity on temp and density, subsequent effect on ocean

increasing salinity lowers the temperature of when maximum density occurs

thus the freezing temp of the ocean at 35ppt salinity is -1.9 degrees celsius compared to 3.98 for freshwater

why does salt lower the freezing temp?

salts interact with the charged ends of water molecules, interfering with the formation of hydrogen bonds

when is seawater densest?

At low temps and high salinity, which is deep in the ocean

thermocline

depth at which temp changes rapidly

When/where does the ocean freeze? What happens when it freezes?

Rarely, and if so it occurs at the poles or in shallow areas

When seawater freezes the salt is excluded so the ice is pure water, the leftover salt mixes with the water creating a brine which sinks beneath the ice

why is it important for life that ice floats?

insulates the water so organisms don’t die from extreme temperatures/freezing

albedo effect

enables ice to reflect large portion of sunlight, so the ice doesn’t melt

density increases with cooler temps and higher salinity, but what is the sole reason for its increase with depth?

pressure! As you get closer to earth’s core gravity exerts more pressure, water is compressible

speed of sound?

1500 m/s

Near the water surface, what factor effects the speed of sound the most?

Temperature—near the surface is where temp is changing radically so it has the moat significant effect

warm water produces more kinetic energy and thus the sound waves can transfer quicker

SOFAR channel

the depth (near the surface) at which the speed of sound declines because of the thermocline. Sound waves are refracted (redirected). Sound Fixing and Ranging Channel. Speed of sound is reduced but its transmission is very effective. Where whales do long distance communication.

SOSUS oceanic uses

Sound surveillance system

• measure the speed and direction of deep ocean currents

• study volcanic eruptions and earthquakes as well as marine mammal vocalizations

• measure large-scale ocean temperature variability

As oceans get warmer how will this impact sound in the ocean?

The speed of sound will be quicker near the surface, so noises from boats and things will travel quicker

the SOFAR will become deeper, interfering with the established communication for long distance

Air density is influenced by what 4 factors?

• Elevation/altitude

• temp

• pressure

• humidity

where is air more dense, high or low elevations?

its denser at lower elevations

air density relationship with temp

• warm air expands (particles have more kinetic energy and thus are less tight, so volume increases), thus density decreases, and so the warm air rises to an altitude where its surrounded by air of the same density

• as air cools its density increases and it sinks until its surrounded by air of the same density

air pressure relationship with temp

areas of high pressure are cold, ares of low pressure are hot

Where is more energy absorbed? Outgoing? What causes this imbalance? What is the impact on circulation?

tropics and subtropics

increases as attitudes become lower because sunlight becomes more direct

Higher latitudes have more outgoing energy than absorbed energy, especially the poles because ice reflects the suns energy

the earth is a sphere and it is titled. The rays have to travel through a further distance of atmosphere to the poles so the energy is less concentrated. This is because the shape of the earth at the poles is rounder and thus there are more angles which means the rays are hitting the poles at a shallow angle, rather than head on like at the equator

This difference in temperature drives atmospheric circulation

What absorbs most of the sun’s energy?

the ocean

Latitudinal heat pump

term for the system of global convection cells

These cells circulate air because of differences in temp. Warm air rises and loses heat as it does so (getting further from the surface where heat is coming from), thus eventually sinking and warming near the surface

Model of circulation without the influence of the earth rotating or oceans

In this model each hemisphere is one cell. Cold air from the poles sinks and is warmed at the equator, warmed air rises and is cooled at the poles

Why are there 3 types of convection cells?

there is an unequal distribution of land, and also the speed of earth’s rotation

the three cell types, what drives them

Polar Cells

• between 60 and 90 degrees N or S

• forms the polar easterlies

  • dry and cold, forms high pressure areas

• differences in air temp

• smallest

Ferrel cell

• 30 and 60 N or S

• forms westerlies

• eddies from surrounding fast jet streams

• flows in the opposite direction of the other cells

Hadley Cells

• 0 and 30 degrees N or S

• form northeast and southeast trade winds (El Niño and Nina)

• at 0 degrees is the intertropical convergence zone (ITCZ)/doldrums

  • no Coriolis effect, poor wind

• differences in air temp

• largest

polar vortex and polar jet stream

a large scale, high-altitude band of winds that encircles the Arctic/Antarctic which traps cold air at the poles. Occurs in the winter. In the stratosphere.

a fast moving “river” of air located in the lower atmosphere (troposphere), separating cold polar air from warmer air. It acts as a boundary that keeps the polar vortex in place

polar vortex disruption

the polar vortex weakens dramatically every other year, and move away from the poles it may even split into 2. This pushes the polar jet stream further south, and warm air gets pulled up north. Thus, why lower latitudes get hit with cold temps sometimes.

Coriolis effect

The earth is a sphere and so the equator (the widest point) must rotate at a higher speed to ensure everything is aligned. Conversely, the poles rotate at a slower speed.

As air moves towards the equator it lags behind the faster moving surface and thus is deflected to the west. Air moving towards the poles is moving much faster than the surface and is thus deflected to the east.

which deflects more: slow winds from the poles, or fast winds from the equator? What about high latitude vs at the equator?

fast winds deflect more, and winds at higher latitudes deflect more than at the equator

seasonal differences in pressure over land and the ocean

The ocean has a higher heat capacity than land. So, during the summer, the land absorbs more heat than the ocean. Thus, there is low pressure over the land and high pressure over the ocean. But, during the winter the land loses its heat readily and the ocean loses it at a much slower pace. Thus, there is high pressure over the land and low pressure over the ocean.