Art © US State Dept./Doug Thompson

We wrote on these two biodiversity conservation ideas in the last month, and will continue to develop that theme for some time. Writing for The Guardian, biologist James Dyke explains a recent scientific study he was involved in that divided organisms into three distinct types, with “canary” species being the most important to monitor as indicators for ecosystem health:

The Earth’s biodiversity is under attack. We would need to travel back over 65 million years to find rates of species loss as high as we are witnessing today.

Conservation often focuses on the big, enigmatic animals – tigers, polar bears, whales. There are many reasons to want to save these species from extinction. But what about the vast majority of life that we barely notice? The bugs and grubs that can appear or vanish from ecosystems without any apparent impact?

Biodiversity increases resilience: more species means each individual species is better able to withstand impacts. Think of decreasing biodiversity as popping out rivets from an aircraft. A few missing rivets here or there will not cause too much harm. But continuing to remove them threatens a collapse in ecosystem functioning. Forests give way to desert. Coral reefs bleach and then die.

New research that I have been involved in suggests that there biodiversity has a value that has been overlooked, but could be vitally important if we are to manage our impacts on ecosystems. Our study, published in the journal Ecology, shows that crucial information about the overall health or resilience of an ecosystem may be lurking in data about supposedly inconsequential species. In fact, the presence or absence of some of the rarest species may be giving us important clues as to how near an ecosystem is to a potential collapse.

Such rare species we call ecosystem canaries. Like canaries that coal miners used to check for poisonous gasses deep underground, ecosystem canaries are often the first species to disappear from a stressed ecosystem. Their vanishing can be linked to changes in the functioning of ecosystems, which can serve as a warning that a collapse is approaching.

Our study used data collected from lakes in China that showed changes in the abundance of species from algae (diatom) and aquatic midges (chironomid) communities as they compete for resources under environmental pressures. From this data it was possible to identify three types of organism: slowly-replicating but strongly competitive ‘keystone’ species; weakly-competitive but fast-replicating ‘weedy’ species; and slowly-replicating and weakly-competitive ‘canary’ species.

Runoff of fertiliser from surrounding fields has a major environmental impact on these lake ecosystems. As the situation worsens the canary species is the first to suffer.

With continuing degradation affecting all species, this leads to the eventual collapse of the keystone species as they are replaced by the weedy species. The loss of keystones tips the ecosystem into a critical transition – the point at which a system shifts into an alternate state which in lakes is dominated by smothering algae and absence of many plant and animal species. Moving a lake back to a clear water, high biodiversity state can be extremely difficult.Better to avoid the collapse in the first place.

Read the rest of the article here.