Marin Biology Week 1 - Oceanography
Origins of the Oceans:
Study of radioactive isotopes - Earth 4.6 Bn years old
Water has been abundant throughout Earth's history
Precambrian 3.3bn - Cyanobacteria fossils
Currently unique - only currently known planet with oceans of liquid water
Earth is a habitable distance from the sun
Where did the water come from?:
Volcanism released water vapour, CO2 and other gases
Made-up atmosphere. As the earth's crust cooled, water vapour
condensed into the oceans.
Comets and meteorites (0.5% water) colliding with early earth.
Pillow basalt rocks: 48bn years old - evidence for lava underwater
All water on Earth - only 0.023% of total mass
Basic Oceanography:
Important when considering the study of biological processes in the ocean
It is essential to know the basic principles of oceanography to understand
marine biology
Major physical processes drive circulation patterns in the oceans and
influence life contained within.
Oceans – the single largest repository of organisms on Earth.
Virtually all phyla of life.
Subjected to properties of seawater.
Adaptations of animals, microbes and plants.
Why do we study the Oceans?:
Vast amount of living spaces that we know little about - how these
organisms are adapted to and how they interact with their environment.
Oceanic influences on weather and climate (C02 absorption, hurricanes,
etc)
Wealth in undersea deposits (metals, minerals, oil)
Fisheries and pharmaceuticals - biotechnology
Past climate research through cores (paleoclimates).
Basics of water:
Covalent bonds between H+ and o- atoms; H20 is a polar molecule
Hydrogen bonds between water molecules, weak
Universal solvent - different bonding
Density freshwater: 1g/cm3; sea water 1.02g/cm3
Viscosity (resistance to deformation) - force necessary to separate
molecules.
Greater viscosity: lower temperature and/or higher salinity
High heat of vaporisation (H+ bonds)
High heat capacity - moderates the climate
H2O can dissociate into H+ and OH- ions.
, Relationships:
Water has a unique temperature-density relationship.
Water is unusual because its maximum density occurs as a liquid rather
than a solid.
Reason ice floats
Water Density, Circulation and Oceanic Life:
Water molecules move closer to one another at lower temperatures.
When molecules are closer together, the substance is said to have a
greater density.
Substances with higher density are heavier than those with lower density
when the same volume is present.
Cold water, therefore, sinks underneath warmer water.
Colder water also holds more oxygen than the same volume of water, a
crucial factor for organisms living on the ocean floor.
Conversely, ice is less dense than liquid water, so it floats and thus
provides a habitat for life in polar regions.
What would happen if ice stayed at the bottom?
Characteristics of Seawater:
Temperature and salinity are two of the most important physical
characteristics of seawater
They determine the density of seawater
critical to oceanic currents
cold, salty water heavier, so sinks
Thermohaline currents (haline = salty)
Salinity:
Seawater is a complex mixture of water and salts
Defined as the total amount of salt dissolved in water.
Salinity was previously expressed as parts per thousand (ppt).
Now PSU of practical salinity units (global salinity 34-37 PSU)
The salinity of seawater is normally around 35, 35 PSU = 35g of salt in
1000ml of water (3.5%), but it can vary by location.
Ocean water near a location where a river meets the sea can be 15-25.
Other areas can be higher if evaporation is high and no rivers are bringing
fresh water.
Salinity follows the rule of constant proportions - i.e. proportions of ions in
seawater remain constant to each other.
Salts in the Sea:
Solutes come from the weathering of rocks, hydrothermal vents, and
solutes that were delivered in rivers from land runoff.
Global Salinity:
High latitudes - low surface salinity - high precipitation and runoff, low
evaporation
Tropics - high surface salinity - high evaporation, low precipitation
Origins of the Oceans:
Study of radioactive isotopes - Earth 4.6 Bn years old
Water has been abundant throughout Earth's history
Precambrian 3.3bn - Cyanobacteria fossils
Currently unique - only currently known planet with oceans of liquid water
Earth is a habitable distance from the sun
Where did the water come from?:
Volcanism released water vapour, CO2 and other gases
Made-up atmosphere. As the earth's crust cooled, water vapour
condensed into the oceans.
Comets and meteorites (0.5% water) colliding with early earth.
Pillow basalt rocks: 48bn years old - evidence for lava underwater
All water on Earth - only 0.023% of total mass
Basic Oceanography:
Important when considering the study of biological processes in the ocean
It is essential to know the basic principles of oceanography to understand
marine biology
Major physical processes drive circulation patterns in the oceans and
influence life contained within.
Oceans – the single largest repository of organisms on Earth.
Virtually all phyla of life.
Subjected to properties of seawater.
Adaptations of animals, microbes and plants.
Why do we study the Oceans?:
Vast amount of living spaces that we know little about - how these
organisms are adapted to and how they interact with their environment.
Oceanic influences on weather and climate (C02 absorption, hurricanes,
etc)
Wealth in undersea deposits (metals, minerals, oil)
Fisheries and pharmaceuticals - biotechnology
Past climate research through cores (paleoclimates).
Basics of water:
Covalent bonds between H+ and o- atoms; H20 is a polar molecule
Hydrogen bonds between water molecules, weak
Universal solvent - different bonding
Density freshwater: 1g/cm3; sea water 1.02g/cm3
Viscosity (resistance to deformation) - force necessary to separate
molecules.
Greater viscosity: lower temperature and/or higher salinity
High heat of vaporisation (H+ bonds)
High heat capacity - moderates the climate
H2O can dissociate into H+ and OH- ions.
, Relationships:
Water has a unique temperature-density relationship.
Water is unusual because its maximum density occurs as a liquid rather
than a solid.
Reason ice floats
Water Density, Circulation and Oceanic Life:
Water molecules move closer to one another at lower temperatures.
When molecules are closer together, the substance is said to have a
greater density.
Substances with higher density are heavier than those with lower density
when the same volume is present.
Cold water, therefore, sinks underneath warmer water.
Colder water also holds more oxygen than the same volume of water, a
crucial factor for organisms living on the ocean floor.
Conversely, ice is less dense than liquid water, so it floats and thus
provides a habitat for life in polar regions.
What would happen if ice stayed at the bottom?
Characteristics of Seawater:
Temperature and salinity are two of the most important physical
characteristics of seawater
They determine the density of seawater
critical to oceanic currents
cold, salty water heavier, so sinks
Thermohaline currents (haline = salty)
Salinity:
Seawater is a complex mixture of water and salts
Defined as the total amount of salt dissolved in water.
Salinity was previously expressed as parts per thousand (ppt).
Now PSU of practical salinity units (global salinity 34-37 PSU)
The salinity of seawater is normally around 35, 35 PSU = 35g of salt in
1000ml of water (3.5%), but it can vary by location.
Ocean water near a location where a river meets the sea can be 15-25.
Other areas can be higher if evaporation is high and no rivers are bringing
fresh water.
Salinity follows the rule of constant proportions - i.e. proportions of ions in
seawater remain constant to each other.
Salts in the Sea:
Solutes come from the weathering of rocks, hydrothermal vents, and
solutes that were delivered in rivers from land runoff.
Global Salinity:
High latitudes - low surface salinity - high precipitation and runoff, low
evaporation
Tropics - high surface salinity - high evaporation, low precipitation
