Energy in Ecosystems

Transcription

1 Energy in Ecosystems

2 Four Criteria for Sustainability Sustainable Ecosystems Need: Reliance on Solar Energy High Biodiversity Population Control Nutrient Cycling This note set aligns with this concept.

3 The Ultimate Source of Energy Almost all energy on Earth is derived from the sun! Either organisms use the sun directly to create energy (food) or organisms get the energy indirectly (eating others that made the energy) To show how energy moves around the environment, scientists use food chains and food webs

4 Food Chains Food Chain -- Linked series showing a oneway set of feeding relationships. Rule 1: Arrows always point to the predator. Rule 2: Producers ALWAYS start a chain. Terrestrial food chains are typically shorter than aquatic food chains.

5 What s wrong with this one? (screw you, Encyclopedia Brittanica!)

6 Hey Swedish Natural History Museum! Really?

7 Food Webs Show ALL the connections and potential food chains of a set of organisms.

8 Make a Food Web Create a food web from the following wetland creatures: Eagle Algae Snail Fish

9 Make a Food Web Create a food web from the following wetland creatures: Eagle Algae Snail Fish

10 Trophic Levels In Food Chains/Webs Trophic Level An expression of an organism s feeding status in a food chain/web Expressed as a number or with correct terminology Example: Trophic Level 2 OR Primary Consumer

11 Other Trophic Level Vocabulary Organisms can also be identified by the type of food they consume: Herbivores (Plants) Carnivores (Meat) Omnivores (Plants/Meat) Scavengers (Carcasses) Detritivores (Debris) Decomposers (All Dead Material)

12 Rules of Energy Transfer The 1 st Law of Thermodynamics (Law of Conservation of Energy) When energy is converted from one form to another, no energy is created or destroyed it is simply converted! However, energy in the conversion may NOT be usable for the task at hand (in the case of a food chain, the energy may not be used in the body that consumed it)

13 Rules of Energy Transfer The 2 nd Law of Thermodynamics Explains that energy transfer between trophic levels reduces the amount of usable energy available to the higher trophic level Metabolism of food releases some energy as heat (not usable), so predator efficiency is NOT 100% Energy is NOT lost though! 1000 J of energy enters plant 990 J + 10 J of energy exits plant = 1000 J

14 Rules of Energy Transfer The 2 nd Law of Thermodynamics What is the average efficiency of eating? OR How much of the energy that you ate actually stays in the next trophic level? 10% Rule -- generally, 10% of the energy in a lower trophic level is usable in the next level The 10% rule applies to consumers. The efficiency of plants taking sunlight and converting it to food is only 1%, on average!

15 What do you notice about this actual food pyramid?

16 9% energy transfer 5% energy transfer 16% energy transfer What do you notice about this actual food pyramid? The average of all 3 levels is 10%!!!

17 Vegetarianism It is said that vegetarianism is one of the top three things that someone could personally do to be more green in their life that has the most impact. WHY???? --- Think about this in terms of the ecological efficiency rule just mentioned! CREEPY!!!

18 Meat-Eating Food Chain Human Walleye Minnow Duckweed 100 kcal kcal kcal kcal Vegetarian Food Chain Human Duckweed 100 kcal kcal Each time you go up a trophic level in a food chain, most of the starting energy is lost in the form of heat. The more levels up, the more cycles of energy loss.

19 Meat-Eating Food Chain Human Walleye Minnow Duckweed 100 kcal 1,000 kcal 10,000 kcal 100,000 kcal Vegetarian Food Chain Human Duckweed 100 kcal 1,000 kcal Each time you go up a trophic level in a food chain, most of the starting energy is lost in the form of heat. The more levels up, the more cycles of energy loss.

20 What Can You Do? Try and not eat meat every dang minute of the dang day! Try Meatless Mondays! When eating meat, eat lower on the food chain! Example: Eat mussels instead of tuna in this chain! (or even sardines!) Algae Mussels Sardine Tuna

21 How Does Energy Even Get Into the Food Chain? Generally, plants and algae are KEY to life on Earth, as they start most food chains. (except for deep ocean ecosystems) How do plants do it? PHOTOSYNTHESIS!! 6 CO H 2 O + light C 6 H 12 O 6 + O 2

22 What Happens With The Food? All life, even plants, take their food (glucose) and can make energy out of it. This is called cellular respiration. Aerobic respiration looks like this: C 6 H 12 O O 2 6 CO H 2 O + energy Hmmmm is there a pattern to these processes?...hmmm

23 Some Ecosystems Make More Plant Matter (Biomass) Than Others Two Ways to Measure Ecosystem Productivity GPP (Gross Primary Productivity) measures how fast producers turn solar/chemical energy into biomass (organisms). NPP (Net Primary Productivity) measures how much leftover energy is made, after you subtract out the energy needed for cellular respiration Think of these in business terms: GPP is your gross salary in a year ($60,000/year) NPP measures the leftover money you have after you pay expenses ($60,000 $40,000 in expenses = $20,000 net).

24 Which have the highest GPP (simply make a lot of biomass)?

25 Oceans make the most biomass thus allowing these things to exist!!

26 What ecosystems have the highest NPP (highly productive and efficient systems have energy left over to grow extensive food webs)?

27 Who cares about NPP? NPP is the limiting factor determining how many consumers can be on Earth. Humans use 20-30% of Earth s NPP. Humans only represent 1% of biomass of Earth s consumers. This is main reason the environment is out of balance.