Ocean Biota Mapped in First Atlas of Marine Plankton

A group of international researchers has compiled the first atlas of marine plankton, a giant step toward the creation of a comprehensive inventory of marine biota as well as enabling researchers to gain a better understanding of marine biodiversity.

The atlas, known as the Marine Ecosystem Biomass Data (MAREDAT), catalogues the location of plankton as small as bacteria to the size of jellyfish.

The open-source, publicly-available MAREDAT, has chronicled about 500,000 measurements of plankton biomass so far. Twelve subdivisions of plankton have been established, and each group has its own database.

"The data and documentation can be downloaded by any researcher so that they can explore their own scientific questions," said Scott Doney, a collaborator on the project and senior scientist at Woods Hole Oceanographic Institution. "Over time we hope to grow the database by adding other historical and newly collected data for plankton groups already in the database as well as extend into different plankton groups."

Doney said one of the most surprising finds to come out of the project is that the size of phytoplankton and zooplankton biomass is about the same in the upper regions of the world's oceans.

"Compare that to more familiar land ecosystems where the biomass of plants greatly exceeds that of animals and it's pretty illuminating," he said.

A type of nitrogen-focusing bacteria known as diazotrophs were a particular focus for Doney and his colleagues. Diazotrophs are able to create their own supply of vital nutrients by processing nitrogen gas. As such, the bacteria play a vital role in subtropical ocean systems by providing a nitrogen source in otherwise nitrogen-poor areas. Doney, working with a team of more than 45 other scientists from oceanographic institutes around the world, established the first-ever global dataset on nitrogen-fixers by collecting data from historical scientific literature and existing databases.

It took three years to compile the first edition of MAREDAT. Updates and other additions to the dataset are sure to come in the future, but the authors say they hope the first dataset will be a good starting point and valuable reference tool for future oceanographic work and will help serve undersampled regions of the ocean, including the South Pacific and parts of the Southern Ocean.

MAREDAT was published as a special edition of the journal Earth System Science Data.