Crucial in example sentence
Well, it now turns out that the whales are crucial to sustaining that entire ecosystem, and one of the reasons for this is that they often feed at depth and then they come up to the surface and produce what biologists politely call large fecal plumes, huge explosions of poop right across the surface waters, up in the photic zone, where there's enough light to allow photosynthesis to take place, and those great plumes of fertilizer stimulate the growth of phytoplankton, the plant plankton at the bottom of the food chain, which stimulate the growth of zooplankton, which feed the fish and the krill and all the rest of it.