BLG 144 Lecture Notes - Lecture 24: Benthic Zone, Insecticide, Lignin

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15 Aug 2016
Chapter 54: Ecosystem Ecology
Ecosystem—multiple communities that live in an area with biotic + abiotic components linked by nutrient and
energy flow
All ecosystems have four components linked by flow of energy: primary producers, consumers, decomposers
and abiotic environment
Tropic level—feeding level in an ecosystem
Food chain—connects tropic level and describes how energy is moving from one tropic level to another
Food web—complex tropic interactions in ecosystem (many food webs together)
Parasitoids—controlled pests used to get rid of troubling ones
Total biomass (mass of all living things) produced each year is greatest at the lowest tropic level
Tropic cascade: top-down control where consumers limit prey causing cascading effects 2-3 links away
Top down process is predator or consumer limit prey
Bio magnification
- Taxaphene in the Arctic – insecticide previously used but stopped b/c dangerous
- persists in the environment without breaking down into harmless substances
- POP—a persistant organic pollutant that undergoes biomagnification
Which Biomes are most productive?
- tropical wet forest + open ocean
What limits productivity?
- any factor (temperature, water, sunlight and nutrients) that limits the rate of photosynthesis
- desert + arctic tundra = lowest NPP b/c of limited T, H2), light, N & P
A Terrestrial-marine Contrast
- marine—productivity is higher along coast than deep water regions due to nutrients limitations
- shallow water = more nutrients
- nutrients are accumulated at the benthic zone
Fe-fertilization experiments
- Zn, Fe and Mg rare in ocean
- result of experiments show that NPP in marine ecosystems is limited by the abalability of nutrients and iron
is imp in open ocean
- fertilizing open ocean with iron could increase NPP in derts to reduce CO2 and slow climate change
How do nutrients cycle through ecosystems?
- biochemical cycle—path that an element takes from abiotic systems through organisms and back again
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