New ‘Twilight Zone’ Forms Around Dying Coral Reefs in Response to Climate Change

It’s another fascinating but distressing example of our changing climate. A new study in “Nature“ describes a brand new ‘twilight’ ocean zone, dubbed the “rariphotic“ – the direct result of warming oceans.

As coral reefs die, shallow water species are adapting to this shift by creating a new ecological zone at a lower depth.

While the resiliency of ecological systems is remarkable, not all of these marine species will survive. We are, after all, in the Anthropocene – a geological moment in time defined by the rapid shift in climate due to human activity.

From an ecological perspective, the Anthropocene is defined by mass extinctions, both in the ocean and in terrestrial ecosystems. The disappearance of coral reefs will leave many species unable to shift to the rariphotic or survive in other new ocean zones.

These ecological, geologic and atmospheric shifts mark something else: a point of no return.

When an ecosystem has enough biodiversity to survive major climatic changes rather than entirely collapsing, we are reminded that nature does not give up easily. Life finds a way — but not a way back.

Once coral reefs have disappeared and surviving reef species have fully shifted to a new environment, we won’t be able to rebuild that complex ecosystem with its incredible diversity. The changed ocean conditions wouldn’t allow it, and we won’t have managed to catalog every critical species prior to its disappearance.

The new ecosystem — one interconnected with the rest of the ocean — will be a permanent replacement, and the rest of the planet will have to adjust.

We are likely to see similar shifts in terrestrial ecosystems: forests shifting from one type to another or to grassland, grasslands shifting to deserts and coastal regions shifting to swampland or barren rock.

Coral reef ecosystems are among the most diverse in the world — the marine equivalent of a tropical rainforest. Ecological resilience is directly tied to biodiversity, so it’s not surprising that these species are managing to adapt to changed ocean conditions — albeit not without species loss and knockdown effects throughout marine ecosystems.

But what about less diverse ecosystems in this age of extinction? Total collapse is more likely in those cases. So we should view the formation of the rariphotic ocean zone not as a sign of hope, but as a serious cry for help from the biosphere.

Without rigorous climate mitigation efforts, we soon won’t recognize the world we live in — and our species, too, will struggle to survive it.

Toby Hudson

==================================================================

source:https://www.care2.com/causes/new-twilight-zone-forms-around-dying-coral-reefs-in-response-to-climate-change.html