APES Midterm Review Lets try to clear up

APES Midterm Review Lets try to clear up any confusion…. .

Vocabulary: • Littoral Zone – Shallow area, near shore to a depth where plants can no longer root (euphotic) Rich in biodiversity (many primary producers, consumers, decomposers, fringing wetland vegetation and SAV) • Limnetic Zone – Open, sunlit area AWAY from the shoreline (euphotic). Less biodiversity than littoral zone (phytoplankton, zooplankton and small fish) • Benthic Zone – Bottom, mostly decomposers (bacteria), detritus-feeding clams and scavengers, insect larvae and catfish. • Profundal Zone – Deep, open water, (aphotic) too dark for photosynthesis, cold water

Lentic Life Zones

Lentic Classification Lakes are classified based on nutrient content; Oligotrophic (nutirient – poor) and eutrophic (nutrient-rich)

Oligotrophic Lakes Characteristics: “new lake” Nutrient-poor Deep with steep banks Net primary productivity is low Clear water Small populations of smallmouth bass and trout

Eutrophic Lakes Characteristics: “old lake” Well-nourished Shallow Turbid water (low visibility =poor water clarity) High net primary productivity due to high nitrogen and phosphorous content. Large phytoplankton blooms = high biomass High biodiversity

CULTURAL EUTROPHICATION Animation

Seasonal Changes in a Lake Because water is most dense in the liquid phase at 4 degrees Celsius, THERMAL STRATIFICATION occurs seasonally in lakes.

SUMMER Thermocline acts as a barrier, where water temperature changes rapidly with depth

“FALL TURNOVER” • Temperature decreases and cool water (4 degrees Celsius) sinks to bottom. • Results: a. Nutrients from bottom go to surface b. DO from surface goes to bottom

“FALL TURNOVER”

Lake Stratification Cycle

Major Zones in a Marine Ecosystem

Nutrient Cycles • • • Nitrogen Phosphorous Sulfur Water Carbon Rock…

A handy chart…

(Hydrologic) Water Cycle

Marine Carbon Cycle

TERRESTRIAL CARBON CYCLE

NITROGEN CYCLE

NITROGEN CYCLE MAJOR STEPS IN NITROGEN CYCLE • 1. Nitrogen fixation by cyanobacteria or Rhizobium bacter. • 2. Ammonification by decomposers and/or nitrogen fixing bacteria. • 3. Nitrification by bacteria (NO 2 [toxic to plants]to NO 3 [useable by plants]). 4. Assimilation (used by plants) OR Denitrification by anaerobic bacteria in waterlogged soils or bottom of lakes convert NH 3 and NH 4 back to NO 2 and NO 3 ions and then into N 2 and NO 2 gas to atmosphere.

HUMAN IMPACTS ON NITROGEN CYCLE CONT. • Cultural Eutrophication – adding of excess nutrients of NO 2, NO 3, and PO 4, from agricultural runoff (fertilizer and animal waste), discharge of municpal sewage, and deposition of nitrogen compounds from the atmosphere.

IMPORTANCE OF NITROGEN CYCLE Organisms use nitrogen to make vital organic compounds such as amino acids, proteins, DNA, and RNA. In both terrestrial and aquatic ecosystems, nitrogen is typically in short supply and limits the rate of primary production = LIMITING FACTOR!

PHOSPHOROUS CYCLE

SULFUR CYCLE

ROCK CYCLE

Biomass = Potential Energy Heat Tertiary consumers (human) Heat Decomposers Heat 10 Secondary consumers (perch) 100 1, 000 10, 000 Usable energy Available at Each tropic level (in kilocalories) Heat Primary consumers (zooplankton) Producers (phytoplankton) Heat

Ecological Pyramids of Energy

Ecological Pyramids of Biomass

Food Webs and the Laws of matter and energy • Food chains/webs show matter and energy move from one organism to another through an ecosystem • Each trophic level contains a certain amount of biomass (dry weight of all organic matter) – Chemical energy stored in biomass is transferred from one trophic level to the next – With each trophic transfer, some usable energy is degraded and lost to the environment as low quality heat • Thus, only a small portion of what is eaten and digested is actually converted into an organisms’ bodily material or biomass (WHAT LAW ACCOUNTS FOR THIS? ) • Ecological Efficiency: – The % of usable nrg transferred as biomass from one trophic level to the next (ranges from 5 -20% in most ecosystems, use 10% as a rule of thumb) – Thus, the more trophic levels or steps in a food chain, the greater the cumulative loss of useable energy…

Generalized Food Web of the Antarctic Humans Blue whale Sperm whale Killer whale Note: Arrows Go in direction Of energy flow… Elephant seal Crabeater seal Leopard seal Adélie penguins Emperor penguin Petrel Squid Fish Carnivorous plankton Herbivorous zooplankton Krill Phytoplankton Fig. 4. 18, p. 77