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one ocean-a changing sea.docx

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Department
Life Sciences
Course
LIFESCI 2H03
Professor
Luc Bernier
Semester
Winter

Description
February 28 , 2013 Life Sci 2H03: Environmental Life Sciences One Ocean: The Changing Sea - impact of predatory squid on local fisheries - surveying squid using acoustical instruments to identify squid at night when they come to surface to feed - saw a large layer of squid - squid have life span of 1-2 years and can grow very fast as it constantly feeds - hunts in packs and feeds on whatever is available - changes in schooling behaviour of fish as a result of the fish - hate now seems to be spawning off of waters outside California and could pose a problem - Monterey Bay California: Northway migration - Sudden invasion of squid - Sudden predation has been fished out in the squids home range - Big fishes eat the baby squid, in response the squid population grow (exploding population) - Fisherman have seen these squid before in warmer periods - No evidence of humble squid until 1998 El Nino - 2002 little El Nino and the squid came back and have been here ever since - episodic range expansions during El Nino is a natural phenomenon - thanks to a blanket of CO El2Nino is becoming more persistent and is driving up other temperature in the global sea - world’s fish docks are swimming poleward at a rate of 40-60km - invading species aren’t the only threat - calforis are the primary ecosystem and support creatures above and below the ocean - calforis found in cool coastal water around the world and are among the most productive ecosystems in the world - kelp does best in temp 10-16 C o - in 2006 in the deep ocean off Oregon, thousands of creatures suddenly disappeared - in 2002 fisherman show dead crabs in their traps - low oxygen is the cause - why are oxygen levels dropping? - Every year there has been a reappearance of drops in oxygen in the Oregon zone - No many rivers emptying into the coast therefor it is not related to toxins - Change in the natural rhythms by upwelling - Winds from the north drive the nutrient rich waters from the deep up to the surface feeding phytoplankton at the surface - Phytoplankton is one of the most valuable ecosystems - Large phytoplankton blooms begin to form of Oregon coast - Dead phytoplankton drops to the deep ocean and bacteria feed on them burning oxygen in the process causing a 3km area lacking in oxygen, loss of all fish in the area - Only a major disruption in the upwelling cycle could cause this, climate change is the main component - Global warming drives stronger winds supercharging the upwelling process - Off Canada in the subarctic pacific, the deep ocean is also loosing oxygen – 22% decline from 150-600m - Ventilation is how the ocean breathes and is being reduces - Oxygen absorbed at the surface seas making it able to sink, transporting oxygen into the deep water - As the planet warms and the melting of ice caps causes the surface waters to be too light due to the input of freshwater and inhibits the sinking of water causing a lack of oxyge
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