What is an ecosystem engineer?
An ecosystem engineer is a species that creates, modifies, maintains or destroys an ecosystem.
It’s worth noting that while all species leave a mark, they are not all ecosystem engineers. This title is reserved for the species that play a significant role in shaping an ecosystem.
There are two varieties of ecosystem engineers: allogenic and autogenic.
Allogenic engineers change the landscape around them — beavers build dams, which create habitat for fish, ducks, reptiles and other wildlife. But autogenic engineers change themselves — as coral grows, for example, it houses fish of all kinds, lobsters, seahorses and sponges.
Wait, what’s an ecosystem?
An ecosystem is a group of living organisms that live in and interact with each other in a specific environment.
Ecosystems come in all shapes and sizes. Examples of larger ecosystems include tropical forest ecosystems, savannah ecosystems and coral reef ecosystems. On the smaller end of the spectrum, ‘micro-ecosystems’ can be as tiny as a patch of soil, the surface area of a leaf or a single drop of water!
Adding a second concept: Keystone species
Not all ecosystem engineers are created equal — some alter an ecosystem to such a degree that other species depend on them for survival. These critical ecosystem engineers are keystone species. Remove a keystone species, and the whole ecosystem can collapse.
The Gopher Tortoise is both an ecosystem engineer and a keystone species. These tortoises dig large burrows (that can reach 7m long and 3m deep) in order to protect themselves from predators, extreme temperatures and wildfires. But these burrows are a communal resource. In fact, more than 300 other species have been documented using Gopher Tortoise burrows. Remove the Gopher Tortoise, and the burrows disappear, hundreds of species lose their shelter, habitat, hunting ground and food source, and the ecosystem will change dramatically.
For the sake of being thorough, it’s worth noting that ecosystem engineers are just one type of keystone species. Predators and mutualists are two other types of keystone species.
Predators (such as sharks and Wedge-tailed eagles) are keystone species because they control populations of prey species, which in turn, benefits less dominant plants and animals.
Mutualists (hello, pollinators) are species that interact with one another for mutual benefit. Pollinators feed on nectar and pollen, while also spreading the pollen to facilitate fertilisation and flower growth. Pollinators need flowers and flowers need pollinators.
To reiterate, ecosystem engineers can be but aren’t always keystone species, and keystone species can be but aren’t always ecosystem engineers.
Beavers, lobsters, elephants, woodpeckers, whales, termites, earthworms, oysters, kelp, trees, coral and mangroves are all ecosystem engineers.
Elephants are allogenic engineers, changing the landscape around them. As they travel through savannas and forests, tearing down trees and brush, they allow sunlight to reach the forest floor, which encourages new growth, and knock fruit and leaves down for smaller animals who can’t reach the treetops. They also use their feet, trunks and tusks to make water holes that many species utilise.
Oysters are autogenic engineers, growing off of one another to create a hardy reef habitat. As they eat phytoplankton or small bits of algae, they filter water and remove pollutants including nitrogen. This is critical to a marine ecosystem because excessive nitrogen triggers algal blooms that deplete the water of oxygen and create dead zones. In some places, oyster reefs serve as natural storms and tide barriers, preventing erosion and protecting productive estuary waters.
Use it in a sentence
By simply doing what comes naturally to them, ecosystem engineers create, alter and maintain critical habitats for other species.
Food for thought
If an ecosystem engineer is a species that creates, significantly modifies, maintains or destroys a habitat — then humans undoubtedly fit the criteria. And yet, it’s hard to compare ourselves and our behaviour to that of elephants encouraging new forest growth or whales circulating nutrients throughout the ocean. So what is our role as engineers? And what is our legacy?