My view is that consciousness makes it literally impossible for any perspective to be nihilistic. That's because every viewpoint contains its opposite, and consciousness makes it inevitable that we are aware of both simultaneously. Artists call it the figure-ground awareness.
For example, the idea that we have a moral debt to other species that we must discharge is balanced by the idea that we are not indebted to other species in the least (and of course vice versa).
The concept of human moral responsibility to other species is a standard tenet of Deep Ecology. I'm currently reading a fascinating paper entitled
Cross-pollinating Marxism and Deep Ecology: Towards a Post-humanist Eco-humanism (PDF) by a Canadian ecological philosopher. In it he contrasts what he calls the "soft" anthropocentrism of Deep Ecology with the "hard" anthropocentrism of humanism, Marxism and capitalism. His point is that even Deep Ecology is anthropocentric, because it describes our relationship of obligation to other species as springing from our consciousness. I've called myself a Deep Ecologist for some years now, but Mikuluk's analysis has crystallized a lingering discomfort I've always had with that philosophy: even in its attempt to be egalitarian between species Deep Ecology entrenches an anthropocentric viewpoint by ascribing special moral responsibility to humans. IMO this doesn't fully acknowledge the human role in the co-creation of the biosphere, or fully acknowledge the position of non-human species in that process.
For me the biosphere is an emergent setting that is continually being created out of the interplay between all its elements. If humans can be said to have a responsibility, IMO it is our responsibility to use our consciousness - to be mindful at all times of all our actions. When that responsibility is fulfilled, all other action (or even apparent non-action) takes it appropriate place.
The validation of moral debt alone is an anchor that can drag our consciousness to a standstill. Holding both the ideas of moral debt and moral freedom at the same time is a process that can point us toward liberation. And liberation is in no way nihilistic.