When an ecosystem becomes overfished, some species may be able to step in and fill the food chain gaps until others can recover, according to a new study published in Science. The bearded goby, a fish that lives off the coast of southwest Africa, has become the predominant prey species in the area because the rest have been overfished. The goby should be threatened under the weight of so many predators, but it isn’t—in fact, researchers find it’s doing better than ever, thanks to its ability to adapt while supporting the rest of the region’s food chain.
The coast of southwest Africa used to be home to one to some of the most successful fisheries in the world. Fishing boats collected huge amounts of sardines and anchovies, the base of any self-respecting predator’s food pyramid, until the species became heavily overfished. Now, the waters are dominated by jellyfish, unsuitable for eating by most predators in the area.
Yes, that is a pretty obvious statement I made but it is fascinating to me that in the ecosystem discussed above, one species is finding a way to fill the niches that we have emptied by overfishing.
Darwin envisioned an ecosystem like a plank of wood with hundreds of wedges pounded into it. A strong ecology resulted in little room between wedges and little ability of individual species to really change the niche the ecosystem provided them.
But here, changing condition has removed many of the wedges, allowing those that survive to move into other areas not normally allowed in a health environment, where others might outcompete them. Here we have a species that was already predisposed for the altering conditions, has changed its behavior to adapt and become very successful covering a whole new niche.
So, under conditions that destroy many species, one is surviving. This suggests that the entire ecosystem, while greatly harmed with reduced diversity, will be able to survive in some form.
Then, as time progresses, natural selection will provide other species to fill the unused niches found here.
Life will always find a way to replenish a devastated ecosystem. It can just happen a little faster with these sorts of bridge species.