Eating at a lower trophic level PDF

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Eating&at&a&Lower&Trophic&Level& Purposes& • •

Calculate(and(compare(human(food(needs(at(different(trophic(levels,(using(the(data(to(construct( a(biomass(pyramid( Analyze(the(benefits(and(drawbacks(of(eating(at(lower(trophic(levels(on(a(global(scale(

&Background& A(trophic(level,(or(feeding(level,(is(made(up(of(all(the(organisms(whose(energy(source(is(the(same( number(of(consumption(steps(from(the(sun(in(a(given(ecosystem.(The(trophic(level(of(plants(or( producers(is(1,(while(that(of(herbivores(is(2(and(that(of(animals(that(eat(herbivores(3.(Higher(trophic( levels(can(exist(for(animals(even(higher(on(the(food(chain.(In(this(exercise,(you(will(compute(numerical( values(for(human(energy(needs(based(on(diets(at(different(trophic(levels.( In(this(case(study(the(owner(of(a(farm(raises(soybeans(and(chickens.(Grasshoppers(feed(on(the(farmers( soybeans,(and(are(in(turn(eaten(by(the(chickens.(Humans(can,(though(rarely(do,(eat(grasshoppers(for( sustenance.(Humans(can(also(eat(soybeans.(For(the(purpose(of(this(exercise,(make(the(following( assumptions:( • • • • • • •

A(human(requires(1(chicken/day(( There(are(365(days/year( 1(chicken(eats(25(grasshoppers/day( 1(grasshopper(requires(about(30(g(of(soybeans/year( 1,000(grasshoppers(have(a(mass(of(1(kg( 1(human(requires(about(600(grasshoppers/day( Dry(soybeans(have(about(3.3(cal/g(

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There(are(1,000g/kg( A(typical(human(requires(3,000(cal/day(

( Show%all%of%your%math%calculations%with%proper%unit%labels!% 1. How(many(grasshoppers(does(a(chicken(need(to(survive(for(a(year?( ( ( (

25x365=9125

( ( 2. How(many(chickens(would(a(human(need(to(survive(for(one(year?(

1x365=365 ( ( ( 3. How(many(grasshoppers(are(needed(for(a(year’s(supply(of(chickens(for(one(human?( (

9125x365= 3330625

( ( 4. What(is(the(total(mass,(in(kilograms,(of(the(grasshoppers(needed(to(feed(all(of(the(chickens( required(to(feed(a(human(for(one(year?( (

1/1000 x 3330625/1 x = 3330.625

( ( 5. How(many(kilograms(of(soybeans(are(needed(to(feed(all(of(the(grasshoppers((calculated(in( question(#3)(for(one(year?( (

3330625/1 x 30/1 x 1/1000 = 99918.75

( ( 6. Now(let’s(assume(we(decide(to(eat(grasshoppers((yummy!)(instead(of(chickens.(How(many( people(could(the(grasshoppers(feed(for(a(year(compared((to(the(one(human(that(the(chickens( (calculated(in(question(#2)(fed(for(a(year?Hint:&Use&your&answer&from&as&a&starting&point( (

1 = 600 600x365 = 219000 ( (

7. Next,(let’s(eat(only(soybeans(for(a(year(instead(of(chickens(or(grasshoppers.(How(many(people( could(we(feed(using(the(soybeans(fed(to(grasshoppers((calculated(in(question(#5)?( (

99918.75/365 = 273.75 8. Draw(a(biomass(pyramid(using(the(data(you(have(calculated(to(this(point.(Label(the(trophic( levels.(Assume(that(1(chicken(has(1(kg(of(biomass(and(1(human(has(59(kg(of(biomass.(

( ( ( ( ( ( 9. Why(do(most(terrestrial((landZbased)(food(chains(tend(to(have(less(than(five(trophic(levels?( ( (

There isn’t enough energy to be passed down into the fourth or fifth tropic level. As you progress into the next trophic level, the amount of energy that is transferred is only 10%. Therefore, by the fourth and fifth trophic level, the energy amount is so little that it has little effect usually in nature. There is not enough energy to continue the pattern.

( ( 10. Generally(speaking,(would(we(be(able(to(feed(more(humans(if(we(ate(at(a(lower(trophic(level( more(often?(Why(or(why(not?( ( ( (

Yes, Earth would be able to sustain a higher population. For an example, the soybeans could supply 301 farmers while the hen could only supply a single farmer. Eating vegetables and food that are at the first trophic level provides a healthier diet and provides a more balanced diet. Eating more producers is more economically friendly in the long run since meat has to be cultivated and processed while vegetables can be grown organically at home.

( 11. Much(of(the(earth’s(land(area(is(covered(by(grasslands(that(are(too(dry(to(cultivate(crops(but( capable(of(supporting(grazing(animals((bison,(antelope,(cattle,(sheep,(etc.)(on(a(sustainable( basis.(Humans(are(incapable(of(effectively(digesting(grass.(On(the(dry(grasslands,(eating(at(what( trophic(level(would(produce(the(most(food(for(humans?( ( (

12. List(the(foods(you(have(eaten(over(the(last(3(days(and(identify(which(trophic(level(each(food( came(from:( ( FOOD( ( ( ( ( ( ( ( TROPHIC(LEVEL( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________( ( _________________________________________________( ____________(

13. Roughly(estimate(what(percent(of(your(diet(comes(from(the(first(trophic(level.( ( ( ( ( ( 14. Roughly(estimate(what(percent(of(your(diet(comes(from(the(second(trophic(level.( ( ( ( ( ( 15. Roughly(estimate(what(percent(of(your(diet(comes(from(the(thirdor(higher(trophic(levels.( ( ( ( ( ( 16. Large(predatory(marine(fish((ex:(tuna,(swordfish,(marlin,(shark,(etc.)(usually(eat(at(the(third( through(seventh(trophic(levels.(Is(it(efficient(for(humans(to(rely(heavily(on(these(species(as(food( sources?(Why(or(why(not?( (...