Scientists' warning on endangered food webs

8 April 2020

Growing human pressure is pushing entire ecosystems outside of their safe zones, threatening the long-term functioning of the ecosystems that make our planet habitable and accelerating the spread of diseases and invasive species.

Twenty-five years ago, 1,700 concerned scientists issued a first warning to humanity, emphasizing the importance of protecting what they called the "interdependent web of life ... whose interactions and dynamics we only imperfectly understand". Since then, scientists have fully embraced the quest of understanding the rules that dictate the assembly, functioning, and resilience of the complex species interaction networks that ultimately support life on Earth. Recently, a second warning was issued and signed by more than 15,000 scientists from 187 countries stating that "To prevent widespread misery and catastrophic biodiversity loss, humanity must practice a more environmentally sustainable alternative to business as usual".

A new review published in Web Ecology shows how all organisms are ultimately dependent on each other, including humans. Global change is shifting the way animals, plants, and other organisms interact. Authors Rúben Heleno (University of Coimbra, Portugal), William Ripple (Oregon State University, USA), and Anna Traveset (CSIC-UIB, Spain) take a broader view of biodiversity and elaborate on the state of the world’s food webs, their capacity to withstand external threats, and the detection of early-warning signals of eventual food web collapse. They collate evidence to show that most global change stressors (e.g. increasing temperature, biological invasions, biodiversity loss, habitat fragmentation, and over-exploitation) tend to simplify food webs by concentrating energy flow along fewer pathways, threatening long-term community persistence. More worryingly, we now know that communities can abruptly change from highly diverse to simplified stable states with little or no warning. Altogether, evidence shows that apart from the challenge of tackling climate change and hampering the extinction of threatened species, we need urgent action to tackle large-scale biological change and specifically to protect food webs, under the risk of pushing entire ecosystems outside their safe zones. At the same time, we need to gain a better understanding of the global-scale synergies and trade-offs between climate change and biological change. Here, we highlight the most pressing challenges for the conservation of natural food webs and recent advances that might help us address such challenges.

The Earth's climate is changing, but the living organisms of the planet are also rapidly being altered by human actions, forming a very tangible global biological change. We revised the overwhelming evidence showing that such changes affect not only individual species, but simplify the structure of entire food webs, threatening long-term community persistence. We must take urgent action to protect the integrity of natural food webs, or we might rapidly push entire ecosystems outside their safe zones.

Further information:
Article in Web Ecology: Heleno, R. H., Ripple, W. J., and Traveset, A.: Scientists' warning on endangered food webs, Web Ecol., 20, 1–10, https://doi.org/10.5194/we-20-1-2020, 2020.
The Alliance of World Scientists (AWS): https://scientistswarning.forestry.oregonstate.edu/
Other warning articles: https://scientistswarning.forestry.oregonstate.edu/journal-articles-related-scientists-warning