Ahead of the big UN biodiversity conference that starts on 18 October in Nagoya, Japan, the results of major biodiversity studies are seeping in. Today the findings of the biggest ever survey and inventory of marine life were presented – the Global Census of Marine Life.

It encompasses combined research of more than 2,700 scientists, 670 institutions, more than 540 expeditions and around 9,000 days at sea. Nearly 30 million observations of 120,000 species were made. More than 6,000 new species were discovered, as well as ‘blue highways’, migratory routes used by fish, such as the endangered bluefin tuna – using satellites and various electronic tools.

The main conclusion however is on the percentage of species that remain out of sight – for instance in the deep sea. The scientists estimate this number to vary dramatically over different regions – but overall use the figure of 75% undiscovered. That would bring the total marine biodiversity at over one million different species.

As this would also include species of plankton and for instance bacteria – 90% of living marine biomass is microbial – the larger life forms have a smaller diversity. So far 16,764 species of fish have been found. The research estimates another 5,000 remain undiscovered, many in small, isolated ecosystems or underwater gorges, like the Mariana Trench. More than 20 percent of the world’s oceans, for instance many coastal waters of Antarctica, have no biodiversity database at all.

Aim of the investigation was not to establish the rate of decline. Marine scientists do fear many species may go extinct before ever being discovered, for instance by ocean acidification or overfishing. The authors of the final Census report also fear species counts may be flawed, with possible double-counts of migratory fish species.

This year has been declared by the United Nations as the International Year of Biodiversity, including an attempt to create a coordinated approach to slow down the net loss.

Another recently published baseline biodiversity study estimated 20 percent of terrestrial plant life as at risk of getting extinct.

(c) Rolf Schuttenhelm | www.bitsofscience.org