Marine biology

How much of the planets surface that seas cover

71%

How much of the Southern hemisphere that si covered by seas

80%

How much of the Northern hemisphere that is covered by seas

61%

How many percent of the oceans that are deeper than 2000m

84%

Greatest depth of the oceans and where it is

11000 meters in Marianas trench

Two examples of marginal seas

The Gulf of Mexico and the Mediterranean Sea

Marginal seas are strongly affected by

Regional climate, precipitation-evaporation balance, rever input of freshwater and dissolved solids, limited exchange with the open ocean, geological history

Topographic structures of the ocean

Continental shelf, marginal sea, volcanic islands, trench, mid-oceanic ridge, seamount, continental slope, continental rise, abyssal plain, submarine canyons

The continental shelfs slope

About 1°

The continental slopes slope

About 2.9°

How deep is continental shelfs are

200-400 meters

How deep the abyssal plain is

4000-6000 meters

How deep the trenches are

5500-11000 meters

How deep the mid-oceanic ridges are

2500-3000m above surrounding abyss

How much of the sea surface the continental shelf take up

About 8%

How much of the sea surface the abyssal plain take up

About 40%

How much of the sea surface the mid-oceanic ridges take up

About 30%

Plate boundaries include

Two plates moving towards each other; trenches, two plates moving away from each other; ridges, two plates moving past each other; faults.

Where the oceanic crust is formed

At mid-oceanic ridges.

How trenches are formed

By crusts moving laterally and being destroyed by subduction.

Subduction

When one tectorial plate is forced beneath another.

Terrigeneous sediments are made of

Silt, sand and/or clay

Pelagic sediments

Sediments that settle slowly through the open ocean column.

Biological pelagic sediments

Calcium ooze like coccolithofores and dinoflagellates and siliceous ooze like diatoms.

Inorganic pelagic sediments

Red deep-sea clay and chemical precipitates like mangan nodules.

Properties of water

High heat capacity, high energy of evaporation, high dissolving power and high transparency.

Latitudinal temperature gradient

Water temperature in the world oceans is lowest at the poles (70° N/S) and highest at the equator (0°).

The vertical temperature gradient in the summer

Water temperature in the world oceans is highest at the surface and declines slowly as it approaches 1000 meters depth and then fast til we reach about 2°C.

The vertical temperature gradient in the winter

Steady at about 2°C no matter the depth

How cold deep ocean is

2 - 4°C

Oceanic temperature range

-1.9 - 40°C

Terrestrial temperature range

-68.5 - 58°C

Influxes of heat in the ocean

Latitudinal gradient of solar heating, geothermal heating, internal friction, water vapor condensation

Losses of heat in the ocean

Back radiation of surface, convection to atmosphere, evaporation.

Practical salinity unit (psu) is measured by

Conductivity

Salinity

amount (g) of dissolved salts per kg seawater (‰)

Salinity is controlled by

Increases with evaporation and sea-ice formation. Decreases with precipitation and river runoff and melting of sea-ice.

Salinity in the open ocean

32 - 38‰

Major elements definition and examples

>100ppm. Chlorine, sodium, magnesium, sulfur, calcium, potassium.

Minor elements definition and examples

1-100ppm. Bromine, carbon, strontium, boron, silicone, fluorine.

Trace elements definition and examples

< 1ppm. Nitrogen, phosphorus, iron.

Forchhammer’s principle

Ratios between many major elements are constant all over the ocean, even though salinity varies. Residence time of elements with constant ratios is much greater than time to mix them evenly throughout ocean by water currents.

Residence time

The time a substance spends in water before its lost to sediments.

Latitudinal salinity gradient

Salinity is lowest at the poles and at the equator while highest at mid-latitudes due to evaporation and precipitation.

How salinity is measured

By chemical titration, conductivity and index of refraction.

Why chlorinity is used to measure salinity

Chlorine is essentially constant in open-oceans.

Seawater density is influenced by

Salinity and temperature

Maximum density of seawater

None.

Eastward velocity at 60° N

830 km/h

Eastward velocity at 30° N

1440 km/h

Eastward velocity at the equator

1670 km/h

The Coriolis effect

Because the Earth rotates on its axis, circulating air is deflected toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere.

Ekman spiral

The impact of winds and the Coriolis effect has on surface water. Winds will push surface water and the Coriolis effect will deflect it 45°, deeper water will be more deflected due to friction, causing the net deflection to be 90°.

Upwelling

When wind is moving along side a shore, water is pushed away from shore due to the Coriolis effect and causes deep, nutrient-rich water to move upwards.

Wind-driven circulation

Water is circulated due to air being heated by the equator and moves to higher latitudes where it gets cooled down and moved back down to the equator. The movement of hot/cold air causes winds to circulate water in specific ways.

Thermo-haline circulation

Water is moved due to its own temperature and salinity, causing currents to move certain ways.

Estuaries

Coastal bodies of water where the open sea mixes with fresh water from a river.

Highly stratified estuary

The river flow is big and tidal mixing is weak between the fresh- and seawater causing them to not mix and being two separate layers.

Moderately stratified estuary

The river flow is less dominant and there is moderade tidal mixing causing a salinity gradient where the water get more saline with increasing depth.

Vertically homogeneous estuary

Low river input and strong tidal mixing causes there to be no difference in salinity based on depth but rather with distance from the shore.

Reynold’s number, Re

A measure of the relative importance of adhesion and inertial forces in a fluid.

Adhesion forces

Internal resistance of the fluid to flow due to its viscosity

Viscosity

Molecular “stickiness”

Inertial forces

The tendency of a fluid to keep flowing

What happens with Re in sea water with increasing size and velocity

It increases

Re < 1

Viscous forces dominate, the flow is smooth and laminar.

Re > 1000

Inertial forces dominate, the flow is turbulent and chaotic.

What does Re tell us about small animals?

They live in a viscous medium, meaning that they will stop moving with stopped swimming - they need to move constantly.

What does Re tell us about large animals?

They live in a inertial medium, meaning that they can generate high speed - they can “coast” without swimming.

What is the relationship between viscosity and temperature?

Kinematic viscosity decreases with increasing temperature

Laminar flow

Streamlines are all parallel, flow is very regular.

Turbulent flow

Streamlines irregular to chaotic

When does laminar flow change into turbulent flow in a pipe?

Increasing diameter, increasing velocity and increasing fluid density beyond a certain point.

No-slip condition

Velocity is zero

Bernoulli’s principle

In places where less water can travel, it must travel faster to maintain the same amount flowing out, this causes pressure in that part to decrease.

What does Bernoulli’s principle mean for fishes?

They get lifted up due to less pressure on the top side of the fins.

Three components of drag

Frictional, pressure and wave drag.

Frictional drag Df

Drag that is caused by friction created when fluid moves against the surface of an object that is moving through it.

Pressure drag, Dp

Drag, or resistance, experiences by a body moving through a fluid due to the fluid pushing back and slowing it down which comes from the pressure of hitting the front of the object.

What is the relationship between drag and body shape?

A streamlined fish has the least pressure drag but the most frictional drag and the opposite for disc shaped fish.

Periodic swimmers

Tuna and mackerel, steady and wave-like body movements to swim efficiently for long periods. Caudal fin is specially shaped to maximise thrust with minimal drag. Frictional drag dominates.

Caudal fin

The tail fin

Transient swimmers

Grouper and pike, quick accelerations, tight turns, lie still until burst.

Solutions to drag on sessile forms

Flexibility - sway with current, grow straight into the current, strengthen body.

Two types of asexual reproduction

Clone - offspring are genetically identical. Colonies - genetically identical individuals that are connected and live together, first formed from a zygote and then asexual budding.

Two types of sexual reproduction

Gonochoristic - separate sexes. Hermaphroditic - same individual can be functional female and male.

Protandrous

Hermaphrodite that starts out as male and later turns into a female.

Protogynous

Hermaphrodite that starts out as a female and later turns into a male.

Three types of hermaphrodity

Simultaneous - female and male at the same time. Sequential - first male/female and later female/male.

Example of simultaneous hermaphrodites

Acorn barnacles

Protoandry - size advantage model

Eggs are costly, more efficient to be female when individual is larger

Protogyny - size advantage model

Aggression is important for mating success, more efficient to be male when individual is larger.

Sneaky tactict

A way for the less aggressive male polymorphs to obtain mates

Examples of dwarf males

Symbion pandora, Bonellia viridis, Scalpellum vulgare

Epidemic spawning

Known in bivalves, stimulus from one spawner causes others to shed their gamets

Mass spawning

Known in coral species, spawn on one single night.

Dispersal

Undirected “migration”

Migration

Leaving an area in a directed way e.g., from spawning area to nursery area.

Types of migration

Anadromous, catadromous, diadromous and oceanic.

Anadromous migration

Spawn in freshwater and move to sea as adults. More common at higher latitudes. E.g., salmon.