Lecture 1- Introduction

Question 1

How much of the total water is in the oceans?

Answer 1

97.5% but overall there isn’t that much water on Earth

Question 2

How much of the total water is fresh water and what is it composed of?

Answer 2

-2.5% = out of those 68.7% is in glaciers =groundwater= 30.1% =permafrost= 0.8% =surface and atmospheric water= 0.4% and out of the surface and atmospheric water= 67.4% freshwater lakes, soil residues 12.2%, Atmosphere 9.5%, other wetlands 8.5%,rivers 1.6%, plants and animals 0.3%

Question 3

Why do we know so little about the deep oceans? (less than about the surface of the moon)

Answer 3

-very hard to get deep under water, highly dependent on technological advances -we’ve only been able to explore it in the last few decades -first scuba dive= 1943 -first manned submersible= 1946

Question 4

How long ago did the first oceans form?

Answer 4

4000 MYA

Question 5

How long ago did the first known life evolve?

Answer 5

3600 MYA (in the oceans)

Question 6

How long ago did the ocean and the atmosphere achieve a steady state?

Answer 6

1000 MYA

Question 7

When did the first land plants evolved?

Answer 7

430 MYA

Question 8

How did Earth get water?

Answer 8

-as planet cooled= clouds= rain (for thousand of years= about half of today’s water gotten that way -comets= full of water bombarded the planet

Question 9

What is the significance of heat capacity of water in the sea?

Answer 9

-oceans have an amazing amount of heat capacity= defines how much energy is required to heat 1 g of water by 1C -oceans can absorb lot of energy without heating, once it’s heated up it takes lot of time and to cool down -so oceans really important in regulating temperature globally

Question 10

How does the temperature change with depth in seawater?

Answer 10

as you move deeper it gets much colder, as hetaing happens at the surface -temperature is at the maximum on the surface most of the time( can be continental cooling in witer so the lower layer is slightly warmer) -region in the ocean where temp changes quickly with depth= thermocline= big chnages over quite small differences -deep oceans quite stable temp= cold

Question 11

Why are the oceans salty?

Answer 11

-They get water from rivers and those bring in broken down minerals (Na, Cl etc.) and those collect in the sea. The salts remain in solution for a long time as water evaporates and rains again but slat doesn’t so it collects and the sea gets saltier over time

Question 12

What is the salt composition of the sea?

Answer 12

-Na 30.6% -Cl 55.5% -SO4 2 7.7% -Mg2+ 3.7% -Ca2+ 1.2% -K+ 1.1% -minor constituents= 0.7% (Sr2+, Br-, C)

Question 13

How does salinity change with depth in seawater?

Answer 13

-sailinity varies strongly with depth, on the surface it is the salinity minimum, than the change bit= halocline -in the deep ocean= more salty

Question 14

How does density vary in the sea?

Answer 14

-density of seawater changes as a function of how much salt dissolved, = colder water more dense than warm water, pycnocline= rapid change in density

Question 15

How does light availability change with depth in seawater?

Answer 15

as you move deeper, light changes with depth, (total short wavelengths= UV, visual; blue shorter than red,infrared long) -there is particulate matter in the ocean, as the light comes in the light is bounced off the particlas, long wavelength bounces more and get absorbed really quickly (that is why infrared only penetrates only few hunderd meters) -so less light and fewer wavelengths available as you go deeper

Question 16

Why are many of deep water prey species red?

Answer 16

-in the very deep water there are no red wavelengths so the animal will appear as black= invisible to predators -black pigment is very hard to make so they cheat and are red

Question 17

What determines the vertical distribution of phytoplankton?

Answer 17

-the main determinants are the availability of light and nutrients (nitrates) -there is lot of light on close to the surface but not many nutrients, deeper there isn’t light and there are many nutrients so they strike a balance in the area where they get both light and some nutrients but not optimal for either, this area is usually around the pycnocline -density of the sea water is important for plankton = if water really dense than they won’t sink –how much chlorophyl in water column= strong correlation with how much phytoplankton so measure the chlorophyl and estimate plankton

Question 18

Why is flow a challenge for sea life?

Answer 18

-sea water is relatively dense as opposed to air, when water moves= quite lot of momentum so stress on organisms in water, mechanical stress, constrains on where organisms can live

Question 19

What is the ability of fish to swim in flowing water dependent upon?

Answer 19

-morphology of the fish ie. the shape and size

Question 20

What were the observed differences in shape of fish in sheltered and unsheltered coastal areas?

Answer 20

-surveys on more shletered and less sheltered, looked at differences in abundance, very different species in either environment, some in both= generalists but some only found in sheltered areas or only in exposed, only few can handle exposed shallow areas -in exposed shallow= bigger fish, less competing, specialised

Question 21

What is the problem with oxygen in seawater?

Answer 21

-water has lower affinity for oxygen than air, lot of oxygen at the surface and dramatically declines with depth, in areas where there is lot of phytoplankton and activity= almost no oxygen -global pic of oxygen, lot of variability, lot of upwelling= less oxygen as lot of life and phytoplankton

Question 22

What is upwelling?

Answer 22

-Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water. Thus the nutrients are closer to the surface= phytoplankton bloom and deplete oxygen= hypoxia= dead zone

Question 23

What are the differences in scale of life in marine and terrestrial environments?

Answer 23

-marine: biggest primary producers are small plants, very small, then herbivores are larger and invertebrates and vertebrates are largest, temporally faster to reproduce -terrestrial- biggest primary producers are big plants that are the largest in the terrestrial sphere, invertebrates are smallest and then vertebrates and herbivores in the middle, temporally slower life cycles

Question 24

What is the ecological scale for terrestrial processes?

Answer 24

-year to millenial timescales in terrestrial processes -from small to big spatially, can be global

Question 25

What is the ecological scale for marine processes?

Answer 25

-processes in marine are faster, here things even operate on day scale -spatially also up to global

Question 26

What is the space time scale from major features of atmospheric (terrestrial) systems?

Answer 26

-atmospheric which influence terrestrial= faster

Question 27

What is the space time scale from major features of marine systems?

Answer 27

-they also happen over large spatial scale but slower than terrestrial

Question 28

What are the effects of biophysical coupling?

Answer 28

-so agents of disturbance= terrestrial like storms etc fast -life in seas are much more influenced by the sea changes as they take so long and can effect evolution, the terrestrial are too fast to influence the organisms so much