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Ecology 101: Trophic Levels – What Level Are You?

By Amanda Crow, Guest Contributor

Although farming was once a way of life for many people in this country, today most of our food is produced by a very small number of farms.  Ironically, we all know many non-vegans that supposedly live down the road from a local farm because that is their rebuttal to why eating animals is wrong, cruel, gross, etc.  Ethical vegans will argue that killing any animal is immoral, and I certainly agree!  However, there is another moral issue here regarding the planet’s resources and all humans.

Because I was formally trained in ecology and evolution, I also look at eating animals from an ecological perspective.  Ecology is the study of nature as a whole because lots of components (plants, animals, bacteria, soil, environmental factors, etc.) “work together” to create an ecosystem and should be studied as one.  The scale of an ecosystem is as broad and narrow as one can imagine, and scientists analyze ecosystems in numerous facets.

Trophic is defined as anything relating to eating/food/nutrition, so ecological trophic levels are divisions that animals fall into according to what they eat.  So to speak, the “food chain” is comprised of trophic levels.  The different steps or levels are quite simple. Primary producers are at the bottom making their own food – a great example being plants!  In case you fell asleep during the botany portion of biology, plants are primary producers because they directly use the sun’s energy to make “plant food” via the process photosynthesis.  The next step in the food chain is primary consumers, which cannot make their own food and must eat primary producers.  As far as we are concerned here, secondary consumers are the top level; therefore, they eat plant-munching animals.

Ecologists use trophic levels to analyze (chemical) energy transfer within an ecosystem.  We now know the general rule of thumb is that only 10% of energy intake is available from one trophic level to the next.  A plant needs lots of energy to grow and maintain, but when it is eaten by an herbaceous creature, only a small amount of total energy can be utilized by the herbivore’s body.  Then, a predator may eat that creature and still can only utilize a very small amount of energy that was required to grow and maintain the herbivore.  Overall, A lot of energy is used then lost between photosynthesis and secondary consumption.

Let’s put this framework over humans’ dietary habits.  Plants are the primary producers.  Humans can be primary consumers (vegans) or secondary consumers (non-vegans).  Without knowing any specific math, we can understand that there is a HUGE difference between the total energy required to produce food for vegans and non-vegans.  Vegans are eating at the lowest possible trophic level and are only consuming primary producers aka plants; non-vegans eat a large quantity of primary consumers aka cows, pigs, goats, chickens, etc.  This means those farm animals, the primary consumers, require a ton of energy to grow to the point where they can be eaten by the secondary consumers.  Since only a small amount of the energy that goes into raising the animal is actually available the next trophic level, animals are a very energy-intensive food compared to just eating plants directly.

The worst part?  Humans require (or are highly recommended) an extensive intake of nutrients: vitamins, minerals, phytonutrients, antioxidants, fiber, protein, fats, and carbohydrates.  However, the energy gained from eating animals is pretty much only protein and (undesirable) fats with a huge side of cholesterol.  The required nutrients are mostly only found in plant sources and cannot be “passed on” through eating a plant-munching creature.  In other words, humans still have to eat plants to live!

So back to the moral question of eating animals raised at that neighboring farm…

It does not matter if you do this in your backyard (as many have learned the hard way), raising animals still takes a huge amount of energy with an extremely low yield of return.  With our planet covered in humans, one third of whom are starving, there is absolutely no sustainable way for all humans to eat necessary energy requirements to live, let alone thrive, as secondary consumers.  Actually, I will argue that even the relatively small number of secondary consumers is still using an unsustainable amount of resources.  From a basic human rights stance, using plants to feed animals is directly taking food humans could and should be eating.  Because our food comes from a controlled, agricultural source, it isn’t just about the actual plants fed to farm animals.  Raising farm animals take a HUGE amount of water, land, food, and oil (as energy for machines, transportation, etc.).

I’ve noticed people respond to this with arguments about economics or resource availability in certain countries (you know, since we are rich and “deserve” more)…well, guess what?

  • No one is immune to resource depletion of the planet because as ecology teaches us, every ecosystem has a limit of resource production.  You can’t eat your money or guns (well…)
  • Those people are assholes that only care about themselves and not the well-being of all humans.

A few disturbing statistics:

  • 216 pounds of grain = 1 lb of meat
  • 5 gallons of water = 1 lb wheat

As a vegan, I care about all life including all animals – nonhuman and human.  Veganism is not just about “animal rights” but also about the rights of all life to live.

RELATED READING: The Environment & Veganism

Photo credit: Tom & Jen