07 Deep Sea Habitat

07 Deep Sea Habitat - The Deep Sea Vast and stable...

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The Deep Sea ± Vast and stable environments with diverse and bizarre fish faunas that include ~ 11% of known fishes ± Most extensive environments, but ‘stable’ is oversimplification ± Temperature ranges from -1.8 0 C at poles to +13 0 C in Mediterranean, 2 0 C is typical ± Pressure influences biochemistry and gas exchange The Deep Sea . .. ± Light is extinguished rapidly with depth 99% extinct at 40 m in Gulf of Maine 140 m in Sargasso Sea decreasing solar light and increasing significance of biological light Surface light still influences the lives of organisms long after it has ceased to support photosynthesis ± Fishes visually competent down to a depth of 1200-1300 m (man to 950 m) The Deep Sea . .. ± Salinity relatively constant as far as organisms are concerned, but fractions of 1% are significant oceanographically in driving currents that affect the boundaries of species distributions, reproductive patterns, and food availability ± Oxygen can be critical Deepsea environments ± Below the well-lighted, well-mixed epipelagic zone, conditions change rapidly ± Photosynthetic algae disappear ± Below 200 m (Mesopelagic Zone) light fades to extinction at about 1000m ± Temperature falls through a more or less permanent thermocline to 4 to 8 0 C ± Nutrients, [DO], and circulation decline ± Pressure increases Deepsea environments . .. ± Below 1000 m (Bathypelagic Zone) conditions are uniform or nearly so down to bottom (Deepwater Benthic zone) ± Mesopelagic, bathypelagic and deepwater benthic habitats are the most extensive on earth ± Mean ocean depth 4000 m 98% of volume below 100 m 75% below 1000 m Deepsea environments . .. ± Probably the most numerous fishes in existence are small pelagic forms, particularly bristlemouths, genus Cyclothone Deep scattering layer = millions of swimbladders ± Diversity and abundance is indicated by midwater trawling 12 km 2 off Bermuda, 1500 trawl hauls 115,000 individuals, 46 families, 220 spp
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Deepsea environments . .. ± In eastern Pacific 61 trawl hauls, 49 families, 113 spp ± In both areas 90% of fishes in two families: Gonostomatidae (bristlemouths) and Myctophidae (lanternfishes) ± Most spp are rare, and rarity is the common condition for most spp--few are abundant Deepwater fauna ± Diversity highest in tropical and subtropical waters ± Depleted in higher latitudes, especially
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This note was uploaded on 09/13/2010 for the course OCS 4012 taught by Professor Baltz,d during the Spring '08 term at LSU.

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07 Deep Sea Habitat - The Deep Sea Vast and stable...

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