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The Open Ocean. AKA EPIPELAGIC. OPEN OCEAN / EPIPELAGIC ZONE. From surface to 100-200 m (300-600 ft) Beyond shelf break Similar to photic zone – layer from surface to the depth where light limits photosynthesis Phytoplankton main primary producers (where nutrients are available)
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The Open Ocean AKA EPIPELAGIC
OPEN OCEAN / EPIPELAGIC ZONE • From surface to 100-200 m (300-600 ft) • Beyond shelf break • Similar to photic zone – layer from surface to the depth where light limits photosynthesis • Phytoplankton main primary producers (where nutrients are available) • Copepods most abundant zooplankton • Almost all nekton carnivorous predators
ABIOTIC FACTORS • Light • Limited nutrients • Organic particles sink before they can be released by bacteria, surface waters poor in nutrients, phytoplankton growth nutrient-limited • Nitrogen limiting nutrient in ocean • Iron limiting in Southern & equatorial Pacific oceans • At high latitudes winter overturn & mixing bring nutrient-rich deep water to surface
BIOTIC FACTORS • Staying afloat • Cells & tissues denser than water • Shells & skeletons more dense • Finding food and avoid being eaten
ADAPTATIONS • Staying afloat • Increased water resistance to sink slower • More surface area, more drag, slower sinking • Increase buoyancy • Storing lipids, gas-filled floats/swim bladders
ADAPTATIONS • Finding food and avoid being eaten • highly developed sense organs • Vision – well developed eyes • Lateral line – sense vibrations in the water • Hearing • Echolocation – built in SONAR in cetaceans • Coloration & camouflage • Countershading (dark top & light bottom) • Excellent swimmers • Streamlined • Well-developed & efficient muscles • High, narrow tails