ENVIRON 102 Chapter Notes - Chapter 12, Mod 7: Intertidal Zone, Tangled, Overfishing
10 May 2018
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Chapter 12: Water (Module 7)
12.7 Oceans
Oceans are 98% of water on Earth
Surface currents ~400 m deep caused by Earth’s rotation, wind, and water temperature
o Equator warm surface waters of Atlantic, Pacific, and Indian oceans moves westward
propelled by easterly winds (remember easterly winds are winds from the east)
equatorial currents move towards S. America and Asia deflected to the poles water
flows back towards equator
o Pattern of circulation produces gyres
▪ Gyres: pattern of circulation that is clockwise in the Northern Hemisphere and
counterclockwise in the Southern Hemisphere
o Temperature of currents influence nearby continents
▪ Ex: water moving towards west coasts are generally much colder
o Velocity < 40-65 km/day
Vertical currents caused by differences in temperature and salinity
o Thermohaline: vertical circulation of water
▪ Very slow
▪ Moves a lot of heat
Ocean ecosystems are a result of variation in ocean depth and nutrient availability
Intertidal zone: submerged during high tides, exposed during low tides
o Inhabitants are used to cycles of wetting and drying and different levels of salinity
Pelagic zone: all of the oceans’ open waters
o Photic zone: sufficient penetration of light to support photosynthesis
▪ Depth varies by amount of plankton/sediment suspended
o Aphotic zone: no photosynthesis
o Production of phytoplankton highest near estuaries or zones with influx of nutrition
o Organic matter moves from the photic zone to the aphotic zone
▪ Detritus: constant rain of organic matter into the aphotic zone
Benthic zone: ocean bottom
o SHALLOW WATERS Attached seaweed provides food
o Coral reefs found primarily in shallow tropical waters on/near the equator
▪ Corals have a symbiotic relationship with single-celled algae (producers)
▪ Efficient recycling of scarce resources
▪ Fixes nitrogen
o DEEP OCEANS Benthic substrate: fine ooze made of skeletons of planktonic organisms
o Not enough light to support algae
o Invertebrates feed off of detritus
o Primary production by chemosynthetic bacteria
▪ Uses chemical energy in sulfur to produce carbohydrates
▪ Eaten by clams and worms, which are eaten by other organisms
Human use and impact = pollution, overexploitation, and climate change threaten ocean
ecosystems
Ocean pollution:
NUTRIENT POLLUTION: Nutrients from agricultural runoff and urban stormwater streams and
estuaries coastal waters nutrients engender large quantities of algae (aka organic matter)
deplete oxygen in ocean dead zones
o Dead zones: regions of ocean that contain low levels of oxygen where few animals can
survive
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Oceans are 98% of water on earth. Vertical currents caused by differences in temperature and salinity: thermohaline: vertical circulation of water, very slow, moves a lot of heat. Ocean ecosystems are a result of variation in ocean depth and nutrient availability. Intertidal zone: submerged during high tides, exposed during low tides: inhabitants are used to cycles of wetting and drying and different levels of salinity. Human use and impact = pollution, overexploitation, and climate change threaten ocean ecosystems. Oil pollution: oil spills (major and non-point) Trash: chemicals that leach out of plastics; marine animals get tangled in trash. 25% of fish species are being overfished (fao: ex: cod fishery off of canada"s east coast. Carbon dioxide dissolves in sea water carbonic acid is formed water acidity increases increase in solubility of calcium carbonate could potentially damage marine ecosystems. Global warming increases water temperature global rise in sea level because of thermal expansion of water.
