Research on the ocean’s most productive areas

Although they occupy less than two percent of the oceans, the coastal upwelling areas in the eastern parts of the Pacific and Atlantic Ocean are among the biologically most productive marine areas worldwide. They not only support a large biodiversity, but also provide 20 percent of the world's fish harvest. These regions therefore have an enormous societal and economic importance for the adjacent countries as well as for the global food supply. But can they still serve this function if the oceans continue to warm, acidify, and lose oxygen, and if the wind systems driving the upwelling will change?

Starting in January 2019, the Federal Ministry of Education and Research supports three joint projects under the overarching theme “Importance of climate change in coastal upwelling areas”, which will investigate the coastal upwelling areas in the north- and south-eastern Atlantic as well as in the south-eastern Pacific. Two of these projects as well as the overarching activities will be coordinated at the GEOMAR Helmholtz Centre for Ocean Research Kiel. “The aim is to better understand the sensitivities of these areas to climate change in order to identify possible consequences at an early stage”, explains Prof. Dr. Ulf Riebesell, who will coordinate the activities linking the three projects. They will receive a total funding of 8.7 million euros over a period of three years.

The coastal upwelling areas are all characterized by major ocean currents flowing parallel to the coast. In the south-eastern Atlantic this is the Benguela Current, in the north-eastern Atlantic the Canary Current and in the south-eastern Pacific the Humboldt Current. Driven by the trade winds, the currents move water masses towards the equator. Due to the Earth's rotation the surface waters are pushed off-shore. This leads to upwelling of cold, nutrient-rich deep water to the surface, which drives the high biological production.

One of the two joint projects coordinated by GEOMAR is called REEBUS (Role of Eddies for the Carbon Pump in Coastal upwelling Areas). “Based on observations we know that oceanic eddies play a central role in the physical, biogeochemical and biological properties of coastal upwelling areas”, explains REEBUS coordinator Prof. Dr. Arne Körtzinger from GEOMAR. As part of the project, the scientists want to better understand eddies by applying a novel, multi-layered observational approach combined with process models.

The REEBUS team builds on prior work by the Kiel Collaborative Research Centre 754. "Fortunately, with the Ocean Science Centre Mindelo on the Cape Verde Islands, we have a modern base for the planned field work in the area of the coastal upwelling area off West Africa”, emphasizes Professor Körtzinger. Three research expeditions in 2019 and 2020 led by GEOMAR will be the cornerstones of this project.

The second joint project CUSCO (Coastal Upwelling System in a Changing Ocean) coordinated by GEOMAR focuses on the upwelling area in the Humboldt Current off Peru. “Although it is the most productive of all coastal upwelling areas, it is completely unclear how biological productivity is related to the upwelling intensity. We want to better understand how this highly productive ecosystem reacts when the upwelling changes due to climate change”, says Professor Riebesell, who also coordinates CUSCO.

CUSCO relies mainly on an expedition with the German research vessel MARIA S. MERIAN, which is presently on-going off the coast of Peru. Another important research activity is a field experiment with the Kiel offshore mesocosm system (KOSMOS) from February to April 2020 in the coastal waters of Peru. In addition, computer simulations on different scales from specially adapted ecosystem models to regional simulations of physical and biogeochemical processes will be performed.

Jointly with REEBUS and CUSCO, the EVAR project coordinated by Prof. Dr. Heide Schulz-Vogt from the Leibniz Institute for Baltic Sea Research in Warnemünde (IOW) will focus primarily on the upwelling system of the Benguela Current. GEOMAR scientists are also involved in this project.

High-res images:

The upwelling system in the Humboldt Current off the coast of Peru is one of the most productive in the world. With the Kiel offshore mesocosm system KOSMOS, the CUSCO project aims to gain new insights into its functioning. Photo: Ulf Riebesell/GEOMAR.

The mesocosms were already in use off the coast of Peru in 2017. Photo: Ulf Riebesell/GEOMAR.

The REEBUS project deals with the upwelling system in the eastern tropical North Atlantic. The Ocean Science Centre Mindelo on the Cape Verde island of São Vicente plays an important role for the logistics of the investigations planned there. Photo: Björn Fiedler/GEOMAR

Coastal upwelling systems are located in areas of large ocean currents running parallel to the coast. In the southeast Atlantic this is the Benguela Current, in the northwest Atlantic the Canary Current and in the southeast Pacific the Humboldt Current. Trade winds drive the water masses towards the equator. The Earth's rotation ensures that near-surface water moves away from the coast. This draws cold, nutrient-rich water from the depths to the surface, thus driving biological production.

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