Chapter 13

Chapter 13 - Intro to Oceanography Chapter 13 I What is...

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Intro to Oceanography: Chapter 13 I. What is Primary Productivity? a. Primary productivity – rate at which energy is stored by organisms through the formation of organic matter using energy derived from solar radiation (photosynthesis) or chemical reactions (chemosynthesis) b. Photosynthetic Productivity i. Gross primary production – total amount of organic carbon produced by photosynthesis per unit of time ii. Net primary production – gross primary production minus cellular respiration and is manifested as growth and reproduction products iii. New productions results from nutrients brought in from outside the local ecosystem by processes such as upwelling iv. Regenerated production results from nutrients that are recycles within the ecosystem c. Measurement of Primary Productivity i. Plankton nets – fine mesh nets, which resemble windsocks at airports, filter plankton from the ocean as they are towed at a specific depth by research vessels ii. SeaWiFS measure ocean color by the amount of chlorophyll d. Factors Affecting Primary Productivity i. Availability of nutrients 1. Runoff also dissolves and transports substances such as nitrates and phosphates, which are basic nutrients for phytoplankton 2. Continents are major source of nutrients, so the greatest concentrations of marine life are found along the continental margins 3. Production is high only in regions of shallow water downcurrent from islands or landmasses where a significant amount of iron from rocks and sediments is dissolved in water ii. Availability of Solar Radiation 1. Compensation depth for photosynthesis – the depth at which net photosynthesis becomes zero e. Why Are the Margins of the Oceans So Rich in Life? 1. Organisms adapted to live under harsh conditions 2. Upwelling and Nutrient Supply f. Light Transmission in Ocean Water i. Visible light – most solar energy falls in this range of wavelengths ii. The Electromagnetic Spectrum 1. Humans can only perceive visible light which contain different wavelengths of violet, blue, green, yellow, orange, and red energy levels 2. Short wavelengths (left of visible light) such as X-rays and gamma rays damage tissue in large doses 3. Long wavelengths (right of visible light) such as infrared and microwaves are used for communication and heat transfer
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iii. The Color of Objects 1. Objects absorb and reflect different wavelengths of light 2. Secchi disk – used to measure water transparency, and based on that, the depth of light penetration can be estimated (water clarity) iv. Water Color and Life in the Oceans 1. Ocean color is influenced by a. The amount of turbidity from runoff b. The amount of photosynthetic pigment, which increases with increasing biological production c. Water molecules disperse solar radiation so that the wavelength for blue light is scattered the most. d.
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Chapter 13 - Intro to Oceanography Chapter 13 I What is...

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