There is no top of the ecosystem without the base. Humanity is as the penthouse of a skyscraper not taking measures to ensure that the lower floors are in good order. Should they crumble, we fall. It is that simple.
When the small daily interactions of an ecosystem are under strain, the quantity of those strained interactions becomes the paramount factor when looking at the integrity of the system.
An ecosystem must have balance, too much change too fast causes damage to the entire system. Toxins introduced that are taken up by plants or small animals can become concentrated in top omnivorous or carnivorous consumers. Thus the health of an ecosystem requires keeping in safe parameters, acknowledging the natural buffering systems that exist and remaining within sustainable boundaries.
Every ecosystem is a knitwear of tiny interactions that make up the whole piece, thus by giving our attention to small details we preserve the entire community.
When I see the slaughter of a dolphin or whale pod, the word that comes to my brain is "genocide." To my heart and soul they are as sentient as we humans, and this killing must stop. That we need them as part of our ecosystem, that without them the algae that makes 85% of our oxygen will begin to die, is the biological gun to the heads of all who "don't care." Sooner or later, biological science will make you care. Let's hope everyone starts to care in time.