Chapter 8- oceans and fisheries Flashcards
coral reefs
really struggling will be the canary in the coal mine for climate change
Ocean ecosystems
- 72% of Earth’s surface
- up to 9000m (no O2 when really deep)
- costal zones & continental shelves= most productive (in top 100m) (find estuaries)
- Nutrient availability, temperatures, and light=major ecological factors
- large bodies of water have a higher specific heat capacity
- can regulate temperatures around land masses
Land
limiting factor=water
- productivity increases from poles to tropics
- biotic pyramids- reduced at each trophic level
Ocean
limiting factor= nutrients
some most productive areas in Canada
-rapid turnover at 1st trophic level
-some areas in arctic are most productive due to interplay between ocean & land
Nutrients in the Ocean
- concentrations increase with depth
- most productive area=costal zones and areas of upwellings
- can be held for long periods of time due to low oxygen and bacterial influence
- Hope to Vancouver estuary= VERY diverse
Carbon sequestration
All carbon stored in dead animals in the ocean sink to the bottom of ocean and deompose there
1/4 to 1/3 of human CO2 emissions are absorbed creating carbonic acid= change in pH
-potential way to combat climate change
Carbon in the ocean
- oceans key in absorbing CO2
- carbon moved out of surface water to deeper ocean
- stored in dead organisms, ocean sediments, coral reefs
- takes up 2 billion tonnes of carbon/year
Coral Reefs
- regulation of environmental disturbances (due to biodiversity)
- treatment of organic waste too much= death of coral reef
- food production
- recreational opportunities
- high biodiversity= higher resilience
Coral Bleaching
happens when exposed to higher acidity
Coral and Global Warming
CaCO3 + COOH= erosion/dissolve
zooxanthellae produce CHO that feed corals, helps with photosynthesis
increased temperatures=expelling zooanthellae so coral leaching occurs
Coral
individual polyps and calcium carbonate skeletons
Dead coral
white due to absence of algae
Marine food webs
HUGE biodiversity
complex=resilient
global warming=negative implications
Marine Food Webs cold water
- simple in colder waters
- cannot afford to lose a lot of species
Thermocline
line where temperature in ocean gets colder
- sharp transition in temperature between warm surface waters and cool deeper waters
- colder water below thermocline due to carbon being absorbed and sinking
Thermocline Circulation
- Cooled water sinks into deeper basin with water close to 0C (not frozen due to salt)
- High salt content critical (increases water density)
- Dense water sinks and carries carbon with it
Implications of Global warming on thermocline circulation
- Ocean temperature increases therfore changing water density
- Freshwater glaciers melting males seas water less salty which changes the salt:fresh water ratio
Management Challenges
The real problem is that we do not undersatnd our ocean ecosystems and we have yet to learn they cannot be managed
- need to learn about them before we can manage them well
- deep sea vents 50 to 100 years behind general natural history because they are really hard to explore
Costal Development
half of world’s costal wetlands destoryed to support development
-lose estuary ecosystem and interface between terrestrial and ocean world just so we can have an inner harbour
-Canada= bad
US=worse
How much of the world’s population lives in costal zones?
60%
Implications of Costal Development
lots of flooding
no way to absorb storms *hurricane Katrina
loss of biodiversity with loss of land/water interface (waves hit a wall and head back out to sea)