The extreme turnover rates and complex biotic interactions that characterise plankton as compared to terrestrial or benthic marine communities, make plankton ecosystems a natural cyclotron for life, accelerating the pace of evolution/selection of fundamental metabolisms and phenotypes, and thus of organisms that transform matter and energy on a planetary scale. Moreover, the efficient symbiosis between plankton and scleractinian corals is a pivotal interaction for the growth and maintenance of coral reefs, known to harbour the highest benthic biodiversity in the oceans.

We currently know very little about plankton ecosystems, their evolution, and the critical roles they play in Earth's chemical, ecological and climatic states. Yet, they represent an enormous but largely untapped source of unique organisms and bioactive compounds relevant for bio-industries involved in pharmaceutics, nutrition, cosmetics, bioenergy and nanotechnology. The dramatic lack of knowledge on plankton biota has hindered the development of this kind of applications as well as our understanding of this major earth ecosystem.

On 31 March 2012, the schooner Tara – equipped with technology for sampling an 11 organism size-range covering entire plankton communities from viruses to animals, and benthic diversity in coral reef ecosystems – came back to her home port, Lorient, France.

During the two-and-a-half-year expedition, high quality and standardised genetic (total DNA/RNA), morphological, and physico-chemical (contextual) samples from 210 stations across the world oceans were collected. The sampling locations were carefully selected using near-realtime remote sensing, numerical models and in-situ hydrographic criteria.

A team of international scientists is currently analysing samples from this €10 million public/private scientific expedition (Tara Oceans 2009─2013): the total of ~35,000 biological samples and ~13,000 contextual measures from three depths constitutes the largest modern-day worldwide collection of plankton sampled 'end to end' around the world. Metagenomes and meta barcodes from stations are being built as well as well as quantitative and high-resolution image databases. Genomics data are published as soon as they are validated at EMBL-EBI, correlated with environmental data stored at Pangaea. The Tara Oceans consortium has a fast release policy of data.

From the Mediterranean to the Pacific, from the Arctic to the Antarctic, the observations are clear: traces of plastic are prevalent throughout the world’s seas and oceans. While the build-up of plastic waste on beaches is eye-catching, increasing concentrations of microplastics present a less obvious danger.

These plastic particles and the potentially toxic chemicals they may carry with them, such as solvents, dyes and pesticides, are broken down by the Sun’s ultraviolet radiation and the motion of the waves, and interact with many marine organisms. Recent studies have found that most marine species, including the tiny plankton that form the basis of many ocean ecosystems, now contain microplastics. These present a real danger for the entire marine food chain and for human health, but their impact on living organisms is still poorly documented.

Mission Microplastics aims to answer the following questions:

• What does the composition of a microplastic reveal about its source?
• How do microplastics disperse once out at sea?
• Which species of flora and fauna colonise plastic particles?
• Which types of plastics are the most toxic to marine biodiversity?
• How do the concentrations of toxic substances carried by plastics build up in the food chain?
• Where can we best focus our efforts to stop the stream of plastic into the ocean?

By approaching coastlines and sailing up rivers, the scientists will help trace ocean microplastics back to their origin on land. Unlike aggregate or global statistics, the collection of regional data will help identify local sources of plastic pollution and will aid the development of local policies to reduce the quantity of microplastics that make it out to sea.

The schooner will make 18 stopovers during its journey through the Baltic and North Seas, along Europe’s Atlantic coast and around the western Mediterranean. These stops will include activities to engage the public, scientists, stakeholders, local authorities and the private sector and to raise awareness of the risks of microplastic pollution. In addition to tours, lectures and press conferences onboard the sailboat, visitors will be greeted by an exhibition on the research conducted by the Tara Ocean Foundation.