Life in the Ocean Pt. 2

Used to link nucleic acids Used in molecules that carry energy Phosphorus Used to link nucleic acids Used in molecules that carry energy Calcium phosphate -> formation of bones, teeth, & some shells

Silica Marine organisms – including diatoms & radiolarians – make skeletons from silica (silicon dioxide)

Both cycles are simple: Phosphorus & Silica Both cycles are simple: Taken from rivers & precipitation and taken up by organisms near ocean’s surface.

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Phosphorus & Silica Phosphorus -> released in organic form when organisms decompose Silica in shells -> released back to the water when organisms die – available to be reused back to the environment

Factors Affecting Marine Life Physical factors: any aspect of the physical environment that affects living organisms. Conditions are usually milder & less variable Biological factors: biologically generated aspects of the environment.

Physical Factor: Light Photosynthesis may occur below sea surface Sunlight coming in at a low angle reflects off the surface

Physical Factor: Light Selectively absorbed: Blue light travels further Red light is absorbed at the surface Light absorbed by water becomes heat

Physical Factor: Light Depth light travels depends on number & characteristics of particles: Scatter & absorb light High concentration quickly absorb most blue & ultraviolet light Add the reflection of green light by chlorophyll in producers -> changes color of productive coastal waters to green.

Physical Factor: Light Photic Zone: uppermost layer lit by sun Coastal regions: 330 ft Mid-latitude: 500 ft Record: 1,935 ft -> tropical pacific Photosynthesis occurs slowly at levels with little light

Physical Factor: Light Aphotic zone: permanently dark layer; extends down to seabed

Physical Factor: Light Euphotic Zone: upper part of photic zone where most of the biological productivity occurs Generally 230 ft – mid-latitudes Water in this zone accounts for ~1% of all seawater volume, yet nearly all marine life depends on it

Physical Factor: Light Disphotic zone: STILL in photic zone; photosynthesis is difficult