Marine biodiversity more responsive than land-life to temperature change

Higher global temperatures continue, with 2020 set to be hottest year on record

Marine communities in temperate regions respond more significantly to temperature change, while terrestrial communities lag behind, according to a new study published in Nature Ecology & Evolution journal.
The study focused on linking changes in biodiversity to temperature change across temperate regions. A research team from several European universities measured the change in the number of species and organisms over time in thousands of locations. The changes were comparedto air and ocean temperature changes over the same time periods.
Researchers found clear biodiversity responses to oceanic temperature changes, where warming coincided with increases in the number of species in most locations. Land communities, however, were not keeping pace with temperature change, in an effect called "climatic debt".
"Surprisingly, we did not detect any systematic responses on land, that is, there was no consistent signal among all the locations, despite a larger increase in temperature," said Laura Antão, from the University of Helsinki's Research Centre for Ecological Change and the paper's lead author. "This may be because species on land have wider tolerance and more strategies to avoid warming temperatures compared to ocean organisms."
Antão told Daily News Egypt that she and her colleagues have shown the net effects of changes in temperature on the numbers of species over the last few decades.
"We know that biodiversity change is a complex phenomenon, and that temperature is a major factor affecting species distributions and survival," Antão said. "Our study provides a clear picture of the change in the numbers of species and individuals against changes in temperature, but it also highlights nuance in the responses, showing that biodiversity change is not the same everywhere."
To get to the study's findings, the researchers used what is currently the largest global database of biodiversity time series (BioTIME). The database, the result of joint efforts by scientists in collecting and sharing data, includes studies of plants, invertebrates, birds, mammals and fish.
They also used open access global databases of temperatures, analysing data using statistical methods that account for the uncertainty in biodiversity change estimates. The team performed several sensitivity analyses to make ensure their results were robust.
"It was really exciting to be able to use so many data for so many groups of species, and to try to tease apart these big patterns in the ocean and on land," Antão said, adding, "I am a marine biologist by training, but I am really interested in understanding how ecosystems are changing, finding out where similarities and differences are, and how we can use that information to better understand how ecosystems are structured."
She added that the team anticipated stronger responses in the ocean, but she was surprised they did not detect a systematic signal on land. This relates to the nature of what they are trying to understand, that biodiversity change is complex, with much variation for different species and regions.
Antão added that she and her colleagues are working towards collecting more accurate data, from as many regions and on as many species as possible.
"One reason our study focused only on temperate regions was that we have very few data from tropical and polar regions, when in fact these regions are being particularly affected by climate change. So, we still need to work further to get a better picture of how and where biodiversity is changing," she said.
Current rates of biodiversity change (linked to several human drivers) are alarming, as has recently been summarised in the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) report.
According to Antão, there are still many things left to understand. This whether species are able to cope with such fast changes in the environment, which types of species come out as "winners" and "losers", and how these changes affect our ecosystems' integrity as whole.