Life in the Ocean

1. Life in the Ocean All living things grow, metabolize, react to the external environment and reproduce Organisms need energy and ingredients Energy: the ability to do work Metabolism: process by which organisms gain energy from the external environment. The ingredients: Biomolecules Carbohydrates, Proteins, Lipids, Nucleic Acids

3. Photosynthesis and Respiration

4. Nutrients • Materials needed to make biomolecules. • Raw materials are nutrients, and they include minerals, vitamins, and other inorganic compounds • Nitrogen and Phosphorus are usually the most important nutrients in the marine environment. • Often called limiting nutrients because without them they limit productivity. • Nitrate (NO3-1), the most important form of nitrogen, is used in making proteins and nucleic acids • Phosphate (PO4-3), the most important form of phosphorus, is used in making phospholipids, ATP and DNA.

5. Primary Production • Sugars produced by photosynthesis are raw material for the other organic compounds, such as lipids, proteins and nucleic acids. • When autotrophs produce more organic matter than they use, there is an overall gain in organic matter. • This net increase is called primary production, and it is this primary production that supplies all the heterotrophs, i.e. animals, with food.

6. Challenges of Life in the Ocean • Lack of substrate • They are at constant risk of sinking • They are constantly being thrashed around by mixing.

7. Challenges of Life in the Ocean • Transparency of seawater • Adequate light for photosynthesis only exists in the upper part of the ocean, in a region known as the euphotic zone, • ranges from 10-200m in depth. • The euphotic depth is the depth at which light levels are 1% of surface light, which is considered to be when light becomes limiting for photosynthesis.

10. Challenges of Life in the Ocean • Lack of Nutrients • Most of the nutrients in the ocean are below the euphotic zone. • Where there is enough light, there often aren’t enough nutrients for primary production

11. Temp, O2, Nitrate Profiles

12. Global Nitrate Profiles

13. Global Primary Productivity

15. Phytoplankton • Phytoplankton (plant-wanderer) are the primary producers in the open ocean • They range in size from 1 - 100m (there are 1000 m in a mm) • The smaller you are, the less you sink. • When you are that small, you can be thrown around by breaking waves and it doesn’t affect you at all. • When you’re that small you have a higher surface-to-volume(S/V)ratio, which increases your ability to pick up nutrients, which may be in very low concentrations. • The larger the organism, the smaller the S/V ratio, the smaller the organism, the larger the S/V ratio. • Being that small you tend to reproduce quickly, so that your numbers can increase rapidly under the right circumstances. • During a phytoplankton bloom, some cells will divide as much as 3 times per day.

16. It’s Good to be Small • The smaller you are, the less you sink. • When you are that small, you can be thrown around by breaking waves and it doesn’t affect you at all. • When you’re that small you have a higher surface-to-volume(S/V)ratio, which increases your ability to pick up nutrients, which may be in very low concentrations.

17. Phytoplankton Reproduce Exponentially • Being that small you tend to reproduce quickly, so that your numbers can increase rapidly under the right circumstances. • During a phytoplankton bloom, some cells will divide as much as 3 times per day.

18. Plankton • Greek for Wanderer or Drifter • Organisms that can’t swim against a current • Usually small • Picoplankton: 0.2-2 μm • Netplankton: >20 μm • Types • Phytoplankton • Zooplankton • Protists

19. Phytoplankton • Greek for Plant Drifter • Vary in size from 1-100 μm • Grow very fast • Cells divide as much as 3 times/day • Make own food but need • Light, Nitrogen, Phosphorus • Examples • Diatoms, Dinoflagellates

21. Dinoflagellates

23. Diatoms

32. Zooplankton • Animal Wanderer • Holoplankton: plankton their entire lives • Ex: Copepods • Meroplankton: planktonic part of their lives • Ex: Fish, crabs, lobster, barnacles • Need to eat other things • Examples • Copepods, Protozoans, Pteropods, Jellies

33. Copepods

34. Protozoans

35. Pteropods

36. Jellies