For a marine biologist like me, it’s always a pleasure to take part in a multidisciplinary scientific campaign like M202 on a modern oceanographic vessel like the RV Meteor. In addition to the excitement of exploring the unknown that such a mission provides, the contact with researchers from different backgrounds and interests allows us to learn, open new scientific horizons and possibly establish fruitful future partnerships.

As in other areas of knowledge, the study of the marine environment is evolving at an unprecedented rate. The combination of environmental sensors with acoustic, optical and omic prospecting technologies is transforming the way we study the ocean, in particular its biodiversity and the dynamic biophysical and ecological coupling. This revolution is only possible because of the current capacity to store, manage and analyse the enormous amount of data (big data) generated by a scientific campaign like this one.

Much of the equipment used in this campaign is fitted with sophisticated acoustic probes operating at different frequencies that map and discriminate the echoes of organisms living in the water column and near the seafloor. Various prototypes, cabled, autonomous, drifting or moored to the seafloor, use high-resolution photographic and video cameras to capture images of planktonic particles or macro- and mega-organisms living in these marine environments. The water samples collected (by the CTD) are used to barcode the DNA from skin cells, scales or other tissues that marine organisms naturally shed into the water (called environmental DNA or eDNA), making it possible to identify the species that live in or have passed through that environment. The integrated management and analysis of these gigantic databases will later be carried out by powerful computers and artificial intelligence algorithms.

However, in order to interpret echoes, recognise particles detected by optical platforms, identify the presence of species based on eDNA sequences lost in the water, and design useful artificial intelligence algorithms, we need to build robust reference catalogues. Recording the density and behaviour of organisms, their shape, size and variability, and the genomes of known species, is necessary to teach machines (machine learning) to correctly interpret the data we feed them.For this reason, it is still necessary to use traditional biological sampling techniques, such as pelagic trawls targeting plankton and micronekton, which were used in this campaign.

During the M202 campaign, my colleagues Thomas Beloud, Zuzana Musilova and I worked hard to ensure that all mesopelagic fish sampled would contribute to enhancing the understanding of the ecosystem under study.

There is a growing sense of urgency to explore the ocean. This is driven by the need to provide robust knowledge to support the best-informed policies for the sustainable management of human activities at sea, in a changing planet. I also believe that this is the motivation for most of us who participate in this M202 campaign.

Perhaps in a few decades’ time we will have almost decoded the ocean, and the current maxim that “we know more about the surface of the Moon and Mars than we do about the interior of the ocean” will be history.

By Filipe M Porteiro