BIOL 361: Marine Science

Aristotle

Birth of natural history observation

Linnaeus

-first systemic classification

-Devsied naming scheme (genus and species)

Georges Cuvier

-proposed system of phyla - organized living and fossil species into groups

-Also helped establish first system of describing benthic habitats by biology

Earliest record of navigation

Polynesian explorers who used stars and currents

earliest map?

Made by Ptolemy (150 AD)

Latitiude

- North to South

- 1 degree latitude = 60 minutes = 60 nautical miles

- 1 minute = 60 seconds = 1 nautical mile

-DETERMINE: sighting of sun or stars - 1 degree latitiude = 60 miunutes

Longitude

-around

-DETERMINE: accurate knowledge of time travlled- 1/2 degree longitude = 2 minutes

-difficult because you need to have accurate knowledge of time travelled

navigation using a sextant

-sextant gives the angle of the sun above the horizon; use the almanacs known position of stars to find your latitude

Edward Forbes (1815-1854)

-naturlaist

-developed the Azoic theory : "no life deeper than 300 fathoms" (600m)

-***first major marine scientific hypothesis

Michael Sars (1850)

-Marine biologist

-DISPROVED Azoic theory

- described specimens he dredged from deeper than 300 fathoms in Norways fjords

Charles Darwin

-theory of coral reef subsidence

-pictured reefs as a balance of growth of reef and sinking of seafloor

H.M.S Challenger

1872-1876 expedition

-4 year circumnavigation of the globe, to all seas but the Arctic

-gatehred data on ocean temp, currents, marine life,

-discovered marianas trench (deepest ocean at 8200m)

-had 300km of hemp rope for sounding

-refuted Haeckels Bathybius theory

Haeckels Bathybius theory

"life arose from a primordial slime in the oceans"

Changes in Technology (old-new)

1. Vessels (ships)

2. Submersibles (up to 2200ft)

3. Aquarius underwater sea lab (6 wk underwater stay)

4. Autonomous underwater vehicles (AUV)

5. Cabled Undersea Observatory (van island) (Ocean networks canada)

what is ocean networks canada

a cabled unsersea observatory off the coast of vancouver island

oceans cover xx% of the earths surface

70%

84% of the ocean is deeper than xxx, with the deepest part being

2000m

marianas trench ; 11000m

who 1st reached Marianas trench

james Cameron- 2012

marginal sea

semi-enclosed regions affected by local climate

ie: salish sea on van island; connects to pacific ocean

marginal seas affected strongly by. .

- regional climate

-precip-evap balance

-river input of fresh water + dissolved solids

-limited exchange with open ocean

-geological history

evidence for continental drift

1. fossils of simialr fauan are foudn on diff continents

2. seafloor mapping & radiometric dating (found seafloor younger than the continental crust)

3. Magnetic anomolies (stripes on the ocean floor near spreading ridges show movement of the oceanic crust

water properties

1. excellent solvent - bc of polarity

2. High heat capacity - large thermal buffer capactiy and acts as climate buffer.

3. High heat of vaporizaion (amount of heat required to change liquid to vapour)

4. High heat of fusion (amount of heat required to change water from a solid to liquid at 0 degrees)

thermocline

gradient in temperature

-ina body of water where the temp declines rapidly between surface layer and deep water

Salinity

the grams of dissolved inorganic solids per 1000g of seawater

salinity controlled by: increased evaporation, sea-ice formation. Decresased precipitation, rivier runoff.

chlorinity

grams of chlorine per liter of seawater

salinity=1.81 x chlorinity (twice)

-measured by: chemical titration, conductivity (more chlorine = more conductivity), index of refraction.

CTD

Conductivity - Temperature - Depth (the instrument used typically)

-tests hwo conductivity varies with temp and depth

-conductivity is a measure of salts in the water

Ratios between many major elements are constant all over the ocean, even though xxxx varies

salinity

- the ocean is well mixed, relative to inpur or removal

excess of xxx over precipitation in mid latitiudes

evaporation.

AND vice versa at equator

density of seawater affected by

salt and temp

-more salt=more dense = lower

-colder water= more dense = lower

salinity changes largley through addition/loss of

freshwater

saltwater freezes at a xxx temp than freshwater

colder

regions of the ocean

-continental shelf

-canyons

-abyssal plain

-mid-oceanic ridges

the ocean floor is made up of xxx that are constantly moving

plates

magnetic stripes show ....

polar reversals

xxx found on different continents suggest they were once united

fossils

water is polar due to ...

asymmetry of hydrogen atoms

polarity makes water..

an excellent solvent, gives it a high heat capacity, heat of fusion, and heat of vaporization

vertical temperature and salinity gradients =

thermoclines, haloclines

cold saline water is,...

dense and sinks

salinity varies by latitude due to ...

evaporation and precipitation (more locally by sea ice formation and river input)

elemets make saltwater...

conductive - measure salinity by conductivity

boundary currents

very large ocean currents that run along a continent

Gyres

massive circular or spiraling circulation patterns thousands of kilometers in diameter that are bordered by permanent boundary currents

Eddies

similar circular pockets of water that break off from a Boundary current

-temporary

-can be warm or cold

-important for dispersal of animals and plankton

what causes ocean currents?

1. wind driven circulation

2. Thermohaline circualtion

3 mechanisms of wind driven circulation

1. heat imbalance (heating by the sun)

2. Earths rotation (Coriolis effect)

3. Continents

what cells give rise to an Atmospheric circulation pattern ?

Hadley, Ferrel, Polar

coriolis effect

in the northern hemisphere, this apparent force deflects moving objects to the right, and to the left in southern hemisphere

-winds go from high to low pressure bc of this

what 2 things cause coriolis effect?

1. earths rotation: object at equator move faster than objects at the poles

2. Gravity: objects are pulled towards earth by gravity

energy is transferred from winds to the upper layer of the ocean through xxx between the ocean and the atmosphere at the sea-surface

friction

Ekman Transport

-the deflection of water at 90 degrees

-to the right in the N hemi, to the left in the S hemi

-due to coriolis efect causing each successive ice sheet of water to defelct relative to the sheet above

western boundary currents carry xxx water

warm

eastern boundary currents carry xxx water

cold

Upwelling

nutrient-rich water (deeper) move to the surface to replace the water transported offshore

-upwelling areas very productive (more nutrients like silica, N, P; phytoplankton blooms; sunshine in shallower areas with nutrients cause phytoplankton blooms which can support huge fish abundancies)

El nino Southern Oscillation (ENSO)

- a periodic chnage in the strength of the equitorial current in winter

-can result in 1m difference in sea level on east or west Pacific

-shallow thermocline - stratification

- no upwelling

-equatorial current 'slackens'

-poor fisheries

La Nina

warm water moves westward

-steep thermocline ; cold deep water is brought to the surface

-strong upwelling off peru

-good fisheries

ENSO events cause ...

chnage in strength of equatorial current leadign to stratification and loss of upwellings in eastern pacific

Thermohaline Circulation

-high latitude surface waters have high salinity and low temp = low density

-dense water sinks and moves to lower latitudes

-this generates a massive ocean river from Arctic to Atlantic and back

-called the GLOBAL CONVEYOR BELT

-Slow: takes ~ 1000 years tor travel the full distance

-oxygenated surface water is brought in the deep sea at high latitudes

waves form by..

friction with air

-energy from wind is transferred to waves by friction

-begin with ripples to swell to waves

-how far the wave moves and what the wave form is like depends on wind strength, distance wind can travel, depth of water, how long the winds been blowing

wave motion (4)

1. only energy moves (little mvmt of net water)

2. water particles move in circular orbits

3. orbit diameter decreases with distance form the bottom (seafloor)

4. waves reflect from objects with no energy loss

wave dimensions

1. crest (highest point)

2. trough (lowest point of wave surface)

3. wave length (from crest to crest

4. Height (from trough to crest)

5. Period (time of passage of successive crests)

6. velocity (= L/t for waves)

7. depth of a wave (half of the length)

wave action

-In deep water- wave action diminishes the deeper you go

-in shallow water - wave action doesnt diminish, the wave energy reflects off the bottom

final wave height is determined by... (3)

1. Average velocity of the wind

2. length of time the wind blows

3. Fetch: the distance over which the wind blows

two types of wind waves

1. Local seas: short period, irregular, driven by local wind

2. Swell: long period, regular, independent of local winds, driven by distant weather conditions

when does a wave break ?

in shallow water, when the wave gets too high it breaks; if the ratio of Height to Length is greater than 1/7 the wave is unstable and collapses

-when the water depth is less than half the length (d < L/2)), the wave becomes elliptical and particles are displaced

Rogue waves

-unusually huge waves that come without warning

-from interaction of storms with currents

Tsunamis (harbour wave)

-caused by undersea earthquakes

-can move 800km/h

-long wave lengths, lose very little energy

Internal waves

-occur where LOW DENSITY water lies over higher density water

-generates a wave in-between the two water bodies

-influenced by tides in shallower water

Tides

change in sea level DUE TO the gravitational pull of the sun and moon

Tide types vary depending on..

time of year, time of day, local geography, weather

types of tides

1. Diurnal (once a day)

2. Semi-diurnal (twice a day; 2 highs/2 lows each day)

3. Mixed semi-diurnal (different highs and lows during the day)

spring tides

greatest vertical tidal range, highest high, lowest low

-moon is in line with the sun and moon horizontally

Neap tides

smallest vertical tidal range

-the minimum change in height when moon is perpendicular to the sun

gravitational effect of the moon is x times greater that of the sun

6 times greater

tides : earth- moon-sun system

1. moons rotation around the earth gives a monthly cycle (spring and neap tides)

2. Earths rotation gives a daily cycle

3. earths orbit of the sun gives an annual cycle

Tide cycles

1. Twice daily: 12 hr 25 min; caused by the rotation of earth

2.Biweekly: 14 days; caused by rotation of the moon around the earth

3. Half yearly: 6 months; caused by the rotation of the earth around the sun and the tilt of earths axis

tide cycles in different locations are a function of ...

basin shape, basin size, latitude

tidal patterns are affected by..

ocean shape (depth), size, and coastal effects (narrowing of channels can amplify or damp tides or cause tidal bores and seiches)

weather patterns can..

accentuate or disrupt tidal patterns

tidal bore vs seiche

tidal bore: tide moving up a channel against the retreating water

seiche: a standing wave caused by the wave reflecting off shorelines

how do weather patterns affect tides

atmospheric pressure: low pressure can cause storm surge or storm tides (eg Hurricane Irma)

Phytoplankton

microscopic algae that use chlorophyll to photosynthesize, using sunlight and nutrients to make protein, fat, carbs

-live in upper part of ocean where sunlight reaches

-drive productivity in the ocean

Zooplankton

microscopic to macroscopic animals that graze on phytoplankton

where do plankton occur?

plankton occur in spatially discontinuous PATCHES, sometimes concentrated at interfaces between water bodies

Causes of patterns of productivity (plankton)

-Turbulence or mixing is the main cause for productivity

a) currents and wind cause spreading and mixing

b) currents converging cause Langmuir circulation

c) currents and coastlines cause eddies

Temporal patterns in plankton abundance

-seasonal patterns differ depending on latitude

-caused by...

- turbulence/mixing

-light/temp/salinity

-grazing by zooplankton

-reproduction

Mixing depth in winter vs spring

winter: storms mix water to a greater depth, less light, light doesnt reach as deep

spring: water is mixed less, more light, light penetrates further

Compensation depth

-where photosynthesis = respiration

-above this depth phytoplankton photosynthesize

mixing depth

-depth above which all water is thoroughly mixed, due to wind

-determines the critical depth

Critical depth

-depth above which TOTAL oxygen produced in the water column equals total oxygen consumed

if the mixing depth is shallower than the critical depth, you will get a...

bloom (and vice versa, mixing depth deeper than CD, you get no bloom)

Why do we need to know critical depth?

to understand productivity and the ability of an ecosystem to sustain fisheries

How does a spring plankton bloom occur?

-winter mixing brings nutrients to surface

-spring sun heats water less mixing by wind, thermocline develops

-phytoplankton cells are now in nutrient rich calmer water, results in a bloom

Phyotoplankton use xxx to photosyntheisze

nutrients

What nutrients are needed by phytoplankton for growth

-mainly: nitrogen, phosphorous, silicon, iron

-also: trace elements (Mn, Zn, Mo, Co, Cu) and organic trace substances (ie vitamins)

Nitrogen (for phytoplankton)

-used for making proteins

-occurs in 3 forms: ammonium (taken up the fastest/most easily), Nitrate (most abundant) and Nitrite (less common form)

-ammonium is from 'regenerated nitrogen"- excreted from plankton or from benthic communities like mussel beds or sponge reefs/coral reefs

Phosphorous (for phytoplankton)

-used for ATP and cell reactions, comes from land/rivers (available most close to land or river output)

-most available in dissolved from (phosphate)

Redfield ratios

constant rate of N:P in the oceans at 16:1

-slightly lower Nitrogen in open ocean due to nitrogen fixation of coastal plankton

Silicon (for phytoplankton)

-comes from the land (rocks) by weathering

-therefore limited to most available near the land

-limiting for diatoms (major plankton)

**Fe and Si often enter the ocean by wind as 'dust'

Iron (for phytoplankton)

-A cofactor required in oxygen production during photosynthesis

-iron crucial in parts of ocean where Nitrogen appears not limited; these areas are called HNLP areas (High nutrient/low productivity)

**Fe and Si often enter the ocean by wind as 'dust'