Among others, we seek to address fundamental questions such as “How did life originate, evolve and diversify through time?”, “What drives marine food webs and how do marine ecosystems function?”, “How can we use knowledge from these diverse marine life forms for biotechnological applications, and for developing sustainable ways for the recovery of much needed resources?” A first step to study these questions is to catalogue the organismic diversity of marine life with a focus on the microbial diversity (including viruses, archaea, bacteria, and unicellular eukaryotes) as well as macro-organisms (incl. fungi, sponges, corals, seaweeds) and reconstruct their evolution in light of the geochemical history of Earth. This not only allows us to obtain a deep understanding of the fundamental principles of life and to deepen our insight into its origin and diversification, but also builds the basis for predicting how organisms will respond to future changes. This understanding is the crucial basis that is needed to mitigate and buffer the impact of human induced changes in marine systems, and for designing ways of protecting marine life in the context of global change. In addition, we aim to determine the functional role of marine life, organisms, in the various different marine waters by investigating their diverse lifestyles and roles in food webs. Among others, this will enable us to determine and identify which compounds are used by the different microbes in the ocean. For instance, a particular focus lies on pinpointing organisms that can obtain energy through the degradation of pollutants, such as complex chemicals derived from the ever-rising amounts of plastics or oil spills, and to subsequently shed light onto how these microbes achieve such important tasks. Another focus lies on identifying the interactions that microorganisms are involved in, including their impact on macro-organisms. Indeed, survival of most marine life in nutrient-limited oceanic environments, is dependent on symbiotic relationships with other organismic groups. A prominent example is represented by corals, many of which depend on photosynthetic eukaryotic microorganisms (zooxanthellae) for survival. Reef-building corals and other ecosystem engineers are particularly susceptible to increasing ocean temperatures and carbon dioxide levels, which can lead to coral bleaching through the loss of photosynthetic symbionts. We investigate these and similar symbioses to be able to get a systematic understanding of marine life, which is essential for being able to disentangle and predict the various feedback loops – life and death in the oceans – that occur in response to changing environments. Finally, we aim to define the biological, physical and chemical parameters that shape the adaptability and population dynamics of marine life and populations.

The oceans are the great climate regulators and hold more than 98% of all bio-available carbon of the planet; minute changes in circulation can have larger effects than any human carbon (CO₂) mitigation effort. But what do we really know and understand of coupled oceanic-atmospheric carbon cycling? To reach this goal we address questions such as “What is the origin of major biogeo-chemical cycles that are driven by thousands of different microbial species and physicochemical reactions?”, “What is the role of these biogeochemical nutrient cycles in global climate change?” and “How can we use this knowledge to contribute to a sustainable Earth?” Marine biogeochemical cycles are part of, and sustain ecosystems by contributing to the recycling of nutrients. Furthermore, they influence the composition of the atmosphere and thereby play an important role for the entire biosphere. The carbon and nitrogen cycle are of particular importance in light of global climate change as some of the most potent climate gasses such as CO₂, CH₄ and N₂O are intermediates in these cycles. Terrestrial ecosystems are predominantly powered by sunlight, i.e. by photosynthetic organisms, most importantly plants, which can harvest sunlight and convert it to chemical energy: this is the basis for the functioning of food webs on land. Similarly, a large fraction of marine ecosystems is sustained through autotrophic production of biomass by photosynthetic algae & seaweeds and microorganisms. Yet, most regions of the ocean are in eternal darkness, but sinking particles can deliver biomass to deeper water masses contributing a large fraction of energy that can sustain ecosystems in the deep sea. Nevertheless, another fraction of biomass seems to be derived from chemo-autotrophic organisms that are able to contribute to biomass production in the absence of sunlight by harnessing energy from chemical (inorganic) compounds. Currently, the varying contribution of these different processes to sustaining deep-sea ecosystems is debated. By studying the key players of biogeochemical cycles in marine waters as well as the dynamics (including vertical and horizontal exchange processes) that mediate the physical and chemical cycling of nutrients, we seek to further our understanding of the processes shaping marine nutrient cycles. Furthermore, the characterization of pelagic food webs and function, including biotic and abiotic connectivity and the elucidation of the relationships and interplay of biological and chemical components, provides the basis for deciphering the role and resilience of major nutrient cycles such as the carbon and nitrogen cycles in the ocean and their impact on global change.

This aspect of our work seeks to inform questions such as: “What are the controls on large scale circulation patterns and mixing regimes, how do these change in space and time, and what are the consequences for our climate?”, “What is the influence of atmosphere-ocean interactions on ocean primary productivity?” and “How can we develop and apply proxies that allow us to reconstruct Earth’s conditions from geological record?” Our ocean is an extremely complex system and is always in motion. The global ocean circulation, particularly in the Atlantic Ocean, is a major player in modulating the global climate through changes in heat transport. Yet, the interplay between physical processes at different scales, from turbulence to the gyre circulation, is poorly understood. Old paradigms, like that of the ocean conveyor, need to be replaced with new understanding of connectivity through mesoscale processes. Understanding these natural variations, as well as the interplay and feedback mechanisms between global change induced climate variations and oceanic transport and overturning mechanisms, is thus a major research focus at NIOZ. Primary productivity in the ocean, and thus its capacity to bind carbon dioxide from the atmosphere, is strongly dependent on the transport of nutrients. Riverine input and surface runoff are huge sources of nutrients and allow coastal systems and shelf seas to bloom. But in the deep ocean other important processes provide nutrients. Upwelling and internal waves can provide these from the deep ocean to nutrient limited regions. Furthermore, Aeolian deposition of dust, which has been blown off from the continents and sometimes travelled thousands of kilometers before it settled into the sea, may be a key player that controls ocean-atmosphere carbon dioxide exchange. At NIOZ we aim to understand how these mechanisms work, how important they are in modulating ocean productivity and climate, and to define ways how these could be used to mitigate undesired changes. Because the ocean is of utmost importance in modulating climate, providing food and services of societal relevance, NIOZ also aims at deciphering variations of climate and other environmental parameters in the past. Depending on conditions such as temperature or nutrient availability, different types of microorganisms thrive in the ocean. When these organisms die, their remains sink to the ocean floor and get buried in sediments. Parts of them may be preserved for millions of years – molecular fossils. Similarly, environmental conditions may also leave a physico-chemical imprint in minerals. Analyzing communities from the past in sediment cores, or analyzing mineral phases on the atomic level, thus allow to reconstruct how the environment was at the time when these organisms lived and/or minerals were deposited. Knowledge of such past variations are the key for understanding the Earth system at present and for predicting its future.