Blue Planet - Intro To Marine Environments - Lecture notes - Notes 1 PDF

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BLUE PLANET INTRODUCTION LECTURE 1

29 FEB 2016

Assessment: 1. 30% 2000 word report 2. 20% 1 hour mid semester test  MONDAY 4TH APRIL 3. 50% 3 hour final exam Overarching themes: 1. Importance of scale (migration of whale, kilometres, time – months) 2. Physical environment driving biological processes Others: a. environmental gradients b. species distributions c. adaptation d. disturbance e. competition Why study the world’s oceans? A. Understand Climate Change B. Harvesting the sea We rely so much on the ocean for food: overfishing, illegal fishing, unrecorded ones. C. Oceans cover 71% of the Earth’s surface  Blue Planet Seawater on the Blue Planet:  97.5% = saltwater (1,365,000,000 km3)  2.5% = freshwater  0.3% = lakes and river storage  30.8% = groundwater, including soil moisture, swamp water and permafrost  68.9% = glaciers and permanent snow cover D. Evolution of LIFE on the blue planet a. 4200 mya – oceans formed b. 3600 mya – life first known (stromatolites) c. 2500 mya – oxygen levels start to rise in atmosphere d. 800 mya – water cycle reaches steady state e. 570 mya – ‘Cambrian explosion’ (the fossil Burgess shale found) f. 430 mya – first land plants g. 420 mya – first land animals E. Evolution of MARINE SCIENCE Marine exploration: 1. Captain James Cook (1768-71)  Challenger expedition (1874)  modern ships 2. Alexander the Great (circa 1445)  Trieste (1958-59)  Underwater submarine 3. John Lethbridge (circa 1710)  Jacques Cousteau (1940s)  scuba diving

F. Major Physical Properties & Processes a. Heat capacity: ability of substance to store heat energy

b. Temperature: related to heat capacity Temperature as a function of depth: Warm  Rapid cooling  Gradual decrease

Thermocline: layer in which temperature changes rapidly c. Salinity: measure how much salt in the water

Salt ion: mostly Na+ (sodium) and Cl- (chloride). 1 kg seawater: 35% salinity

Halocline: layer in which salinity changes rapidly

Halocline and Thermocline are important in determining density d. Density

Cold water has higher density than hot water thus sinks. Increase in salinity  increase in density (the saltier, the denser) e. Light Light wavelength: not distributed evenly through water i. e. objects look duller. Some penetrate very deep (like blue) some almost not at all (red).

Fate of light in aquatic system: 1. Reflection 2. Scattering 3. Absorption We have temperature gradients, salinity gradients, density gradients, light gradients. Why are deep sea organisms red in colour? (vampire squid, amphipod)  There is no red wavelength available to interact with the surface of these animals, no red light going into the deep sea, which makes it appear essentially black. It’s good for vampire squid because as prey, if there’s a little blue or green light, it’s gonna be invisible so other organisms can’t see. Red pigments are hard to make/produce, so these organisms need red pigmentation from diet to make coloration such as carotenoids. Physical drivers in combination Example: vertical distribution of phytoplankton

o Black lines are isotherms (lines joining up areas of similar elevation) – linking up water of SAME TEMPERATURES. o Colour represents CHLOROPHYLL – proxy for phytoplankton abundance. Red & yellow: lots of chlorophyll. Key drivers of phytoplankton distribution: vertical variation in light and nutrients. Patchy  not blue everywhere or red everywhere What is temperature doing? Cold water pushed up from the depth of the ocean coming up to the surface = UPWELLING EVENT.

NO UPWELLING: layer of surface water – nice and warm, low salinity. Below is cool high salinity – deep water. o Got density gradient (pycnocline) Lots of mixing going in the circles  mixing occurring in surface layer (wind) Negligible mixing in deep waters Animals & plants in the surface are sucking up all those nutrients and using them up so surface water is not available for further plankton growth. There is flux of nutrients between boundary layer. LIGHT: sufficient light for photosynthesis, then photosynthesis is not available UPWELLING: disrupt density gradients. There is a zone for maximum/optimum photosynthesis. Bringing nutrients and fertilising surface water. f. Flow: movement of waves. Extreme example: Tidal bore and Storm-generated waves. Movement of waves affects the productivity of organisms due to their exposure and swimming performance in comparison to the distribution of water movement. Flow as one of the physical properties of the ocean determines how species are distributed around the island/where organisms occur. Example of biological effects:  Wave exposure, distribution and swimming performance of fish. There is a fundamental difference in distribution of fish, between shallow, deep, sheltered waters. In sheltered: abundance of different species, in deep waters with big waves: only certain big individuals. g. Dissolved Oxygen Concentration is influenced by: 1. Physical properties 2. Biological processes (such as decomposition)

Decline quickly. Dissolved oxygen is important for distribution of organisms. Cooler  more oxygen. Ice: high oxygen level....