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Biological Productivity. Conditions for Life in the Sea Consider the main biochemical reaction for life in the sea, and on earth in general: 6H 2 O +

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Presentation on theme: "Biological Productivity. Conditions for Life in the Sea Consider the main biochemical reaction for life in the sea, and on earth in general: 6H 2 O +"— Presentation transcript:

1 Biological Productivity

2 Conditions for Life in the Sea Consider the main biochemical reaction for life in the sea, and on earth in general: 6H 2 O + 6CO 2 + energy + nutrients = C 6 H 12 O 6 + 6O 2 Focus on left side of equation What is in short supply in the sea and thus limits the amount of life in the ocean??

3 Absorbing Nutrients 6H 2 O + 6CO 2 + energy + nutrients = C 6 H 12 O 6 + 6O 2  Phytoplankton are base of the food chain  Most important primary producers of complex sugars and oxygen Lauderia sp.

4 Open Ocean Food Webs Barrie Kovish Vicki Fabry Pacific Salmon Copepods Coccolithophores Pteropods

5 Sinking Organic Debris Present Ocean Food Web – Complex ecosystem interactions based on a low CO 2 ocean MicrobialRemineralization Primary Producers Zooplankton Food Web Upper Trophic Levels Seafloor community Provided by James Barry MBARI Ocean Food Web

6 Absorbing Nutrients  Nutrients absorbed by plants through diffusion across a semi-permeable membrane Lauderia sp.

7 Diffusion: molecules move from high to low concentrations

8 Which Nutrients are in Short Supply?  Nitrogen (N) as Nitrate NO 3 (-2)  Phosphorus (P) as Phosphate PO 4 (-2)  Silicon (Si) as Silicate SiO 4 (-2)

9 Phosphate and Nitrate in the Pacific

10 Silicate in the Pacific

11 Biolimiting Nutrients  N, P, and Si are exhausted first in Eq. surface waters during photosynthesis  Essential to the growth of phytoplankton  If these biolimiting nutrients increase in sea water, life increases  If these biolimiting nutrients decrease in sea water, life decreases  Where would you expect to find the highest biomass in the Pacific??

12 CZCS Global Primary Production

13  O 2 is high in the surface and mixed layer  O 2 decreases to a minimum at base of thermocline  O 2 then steadily increases with depth How Does Nutrient Distribution Compare w/ Dissolved Oxygen? 6H 2 O + 6CO 2 + energy + nutrients = C 6 H 12 O 6 + 6O 2

14 Dissolved O 2 Reverse of Nutrients

15 Why is the Concentration of Oxygen High in the Mixed Layer?? Hint #1: How and where is oxygen produced in the sea??? 6H 2 O + 6CO 2 + energy + nutrients = C 6 H 12 O 6 + 6O 2 Hint #2: How can oxygen be mixed downward from the atmosphere into the ocean?

16 How is Oxygen Removed from the Thermocline & Slightly Below??

17 Dead and decaying organic matter sinks downward from surface waters  Rate of sinking decreases as it encounters the cold, dense water of the thermocline  Material decays (oxidizes) at the thermocline, which strips O 2 out of the water and returns nutrients to the sea  Cold, nutrient-rich water of the thermocline is returned to sunlit surface waters by way of upwelling

18 CZCS Global Primary Production

19 Marine Ecology

20 Basic Ecology  physical and chemical parameters affecting distribution and abundance  An ecosystem includes both the living (biotic) and non-living (abiotic) portions of the environment. –Examples include: salt marshes, estuaries, coral reefs, the North Pacific Gyre.

21 Classification of Organisms by Environment  horizontal: neritic | oceanic  vertical: –epipelagic (top) / euphotic (good) –mesopelagic (middle) / disphotic (low) –bathypelagic (deep) / aphotic (without) –abyssopelagic (“bottomless”)

22 Divisions of the Marine Environment Figure 9-1

23 Classification of Organisms by Lifestyle  Scientists have established another classification scheme to categorize biota on the basis of lifestyle. The major groups are: –plankton (floaters) –nekton (swimmers) –benthos (bottom dwellers)

24 Plankton  weak swimmers, drifters, unable to counteract currents. –Phytoplankton (plants) –Zooplankton (animals)

25 Nekton  active swimmers capable of counteracting currents. –Fish –Squids –Reptiles –Birds –Mammals

26 Distribution of Marine Lifestyles  16.7% of Earth’s animals are marine  2% inhabit pelagic environment (most of the oceans are cold and dark)  98% are benthic!

27 Benthos  Epiflora or epifauna live on the sea bottom.  Infauna live in the sea bottom.  Benthic plants - restricted to shallow waters (light)  Benthic animals occur everywhere from shallow depths to the deep sea.

28 Research Video Clips: “Live fast, die young...”

29 Hydrostatic Pressure  Pressure caused by the height of water.  Function of water height and water density  Pressure generally increases at a rate of 1 atm per 10 m of water. ( or 16 psi per 10 m depth)

30 Think You’re Under Pressure Now?

31 Hydrostatic Pressure (Cont.)  enormous in the deep sea yet animals live there.  Animals do not contain gases.  However, mesopelagic fish which have gas-filled swim bladders to help maintain neutral buoyancy –unable to move rapidly between depths –pressure change could cause bladder explode.


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