Global mapping of ocean species provides insights for climate change and conservation

06 November 2017
Maps from Associate Professor Mark Costello's marine biogeographic realms and species endemicity research
Maps from Associate Professor Mark Costello's marine biogeographic realms and species endemicity research

Analysis of a global database by a University of Auckland research group demonstrates for the first time that the ocean can be classified into distinct realms based on the uniqueness of their animals and plants.

The findings have been published in Nature Communications.

Early explorers discovered new and unique terrestrial species as they travelled, and classified the world into “biogeographic” realms based on those discoveries.

On land the distinctions were obvious – kiwi in New Zealand and kangaroos in Australia, for example – but the ocean was perceived as a mysterious and terrifying domain commonly illustrated on medieval and Renaissance maps with sea monsters.

The ocean has become less mysterious over the centuries, but scientists still doubted whether the same distinct biogeographic boundaries existed in the marine environment, partly because for species like whales, birds and large fish, the whole ocean is their habitat.

Until recently it has been too expensive to collate the tens of thousands of species distribution records from many thousands of publications, specimen collections’, and unpublished sources.

The Census of Marine Life programme changed that by creating an online database in 2010 called the Ocean Biogeographic Information System (OBIS).

Now, University of Auckland researchers led by Associate Professor Mark Costello have explored OBIS and published maps that show there are 30 distinct marine realms.

“New Zealand is one realm [28], with its closest relatives southern Australia [26] and South Africa [27],” Associate Professor Costello says.

“Two-thirds of all realms are coastal, because the coastal environment is less stable and more variable. The offshore and deep-sea areas offer similar environmental conditions over much larger areas, so species there have larger geographic ranges.”

“Remarkably, the most widespread species in the ocean are the smallest and largest; the microscopic plankton that drift until they find suitable conditions for growth, and the whales, birds, turtles, and large fish “megafauna” that travel across the oceans.”

Associate Professor Costello says the team’s research concluded that while the oceans are well connected for some organisms, there are still biologically distinct realms.

“It means that the widespread species will easily be able to adjust their distribution in a changing climate, but the more endemic species may not,” Associate Professor Costello says.

“This is a particular concern for New Zealand where half of all its marine species are endemic – where will they find refuge from climate change?”

In addition to improved understanding of ocean biogeography, these new maps will have practical use for conservation planning (each realm should have a network of Marine Reserves), and reporting on ocean trends (by definition each realm is unique and so needs separate surveillance).

OBIS now contains 45 million species distribution records from over 100,000 species. Five hundred scientific organisations from 56 countries continue to expand the database, and hundreds of papers each year use OBIS for analyses on topics ranging from invasive and threatened species to modelling the effects of climate change.

OBIS has a permanent home at the Intergovernmental Oceanographic Commission of UNESCO.

Read Marine biogeographic realms and species endemicity.