ZMT - Leibniz Zentrum für Marine Tropenforschung

Introduction

The BIOCAN project contributes to the Second International Indian Ocean Expedition (IIOE-2), a large-scale international research programme dedicated to investigating the Indian Ocean and its interactions with the atmosphere, climate and marine ecosystems.

Launched in 2015, IIOE-2 marked the 50th anniversary of the conclusion of the first International Indian Ocean Expedition (1959–1965), which represented an important milestone in the Federal Republic of Germany’s return to international marine research following World War II.

Our findings from the BIOCAN project reveal that, in contrast to the global trend and the development of the oxygen minimum zone (OMZ) in the northern Indian Ocean prior to 2013, oxygen concentrations in this region have been increasing again over recent years. We attribute this reversal to a weakening of the global thermohaline circulation, accompanied by a slowdown and reorganisation of the meridional overturning circulation in the Indian Ocean (Oboh et al., 2026).