Top Story Tipping Points: The Tip of the Issue + In the Field with... Laura Leiva: Investigating Sea Urchin Decline and Reef Resilience Around Zanzibar + Collaboration Meaningful Encounters with Marine Ecosystems +BBNJ Updates Prepcomm 3 - Recognising the Process of Governing the Ocean + Editorial View from Northwest #26 + Selected Publications + Fun Fact

TOP STORY

Tipping Points: The Tip of the Issue

We began our journey in 2025 as the HIPP Cohort “Making Sense of Tipping Points for Biodiversity: Ecosystem and Societal Perspectives” as a group of researchers working from diverse perspectives including ecology, mathematics and human geography. The prominent use of the term ‘tipping’ in environmental sciences and policy considerations has been at the heart of our collective discussions and we argue that it warrants deeper consideration. Here, we share some thoughts on what this term means and promises within our various fields and for public environmental debate at large.

'Tipping points' have a concise mathematical and physical definition linked to the modelling of how systems change over time. In this setting, tipping points characterize shifts in the stability of landscape, when a system jumps into a new state after a parameter changes. For example, a lake can remain a clear, macrophyte-dominated community, despite increasing nutrient load – until a critical moment in which the macrophytes community transforms, and is replaced by a turbid, microalgae-dominated community. Even if the nutrient load is reduced, the lake may not immediately return to its macrophyte community. An important insight from such models is that reversing changes does not always result in a return to its previous state. This is known as "hysteresis", which signals why prevention is often easier than recovery. Models provide a way to think about such complex systems, making them useful tools for both science and policy making.

From an ecological perspective, prediction can be a powerful tool and models that allow us to anticipate changes to our ecosystems are essential. This is likely why looking at 'tipping points' is an attractive framework for understanding changes and informing policy. However, it is unclear whether ecological systems follow the precise rules for a system state change. Coral reefs illustrate why tipping points are hard to identify in practice. Reefs are rarely destroyed by a single event, instead they are weakened slowly by bleaching, overfishing, and pollution over years. When a sudden event occurs, like an urchin die-off, it can look like a tipping point. But the system may have already been losing resilience gradually, exhausting its capacity to buffer disturbance. This makes it difficult to pinpoint exactly when, or whether, a classical 'tipping point' was crossed. It also changes how we think about recovery: if a reef collapsed because of many accumulated pressures rather than one critical threshold, simply removing one stressor may not be enough to bring it back. This, in turn, raises the question of when and how to intervene based on what kind of mechanism is pushing the system to cross this critical point. Recognising this complexity is essential for realistic conservation planning. The complex nature of the structure and dynamics of ecological systems shields us from seemingly abrupt changes, but we are losing this buffering capacity in light of the current biodiversity crisis. Understanding what is driving degradation in target systems and how much recovery is feasible may ultimately be more useful than debating whether a tipping point was actually crossed.

Does a focus on global tipping points obscure the view of local contexts?

These environmental discussions on tipping points further extend our attention towards reflections in geography around the key concepts of scale and discourse. Scientists and policy-makers increasingly discuss ‘global tipping points’ in relation to the global agenda of climate change. They identify Earth system components in which tipping could lead to catastrophic changes (melting of specific ice sheets, overturning of oceanic circulation), as well as ‘positive tipping points’ where small but self-amplifying social changes may lead to a more ‘sustainable world.’ The ‘global’ backdrop of both perspectives is, however, not neutral, and has come to be a dominant worldview and outlook of climate change – making climate governance a global issue in itself. But, a key question we should ask is what this means for local contexts. What might be sidelined, or ignored by prioritizing 'global challenges'? As a discourse, our interest extends to how we imagine and convince the world around us, based on how it is narrated and characterized (in the media, online, through conversation). Discourses of the global produce imaginaries of ‘scaled-up’ modes of environmental governance. They shape how we feel (and therefore, act) about the world. Do conversations of tipping points make us feel anxious, indifferent, bored? Such concerns become key governance challenges: what do we prioritize, and how?

Ecosystems are complex, and fuzzy systems with boundaries that are hard to define. Policymakers are often interested in quick and convenient solutions, whereas socio-ecological systems move at different scales and pace. The 'tipping points' discourse is ultimately shifting efforts from meaningful climate action. How can the scientific community address these issues and communicate them clearly in order for urgent actions to be taken? Our multidisciplinary engagement with ‘tipping points’ has allowed us to identify the various ways of thinking with this term and pinpoint some key (but productive) tensions, as well as reflect on how scientific terminology and thinking are received (or not) by policy or wider public narrative. By having this dialogue beyond a single viewpoint, we have stepped outside our scientific comfort zone, and encourage you to do the same.

Stay tuned for further updates from the Tipping Point cohort.

Cameron Byron, Srilena Kundu, Nadège Legroux, Laura Leiva, Amelie Luhede, Fabian Moye, Lívia Oliveira

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The HIFMB Integrated Postdoc Pool (HIPP) offers postdoctoral scientists the opportunity to develop their own research ideas and to actively shape their scientific careers. Each call runs under an umbrella topic to tackle overarching research questions related to the mission of HIFMB. Interdisciplinary interactions are particularly encouraged within the cohort, built on the principle that major scientific and societal challenges can only be solved by collaborating with experts from different areas.
HIFMB.de/hipp

HIFMB INTEGRATED POSTDOC POOL

HIPP Call 2027 now open

The HUMAN PROGRESS project aims to advance research in the natural sciences by drawing on methods, insights, and knowledge from across the humanities and social sciences. In doing so it also offers fresh frameworks of thinking for the humanities and social sciences, and works towards an interdisciplinarity that is essential in contemporary marine sciences to tackle complex environmental problems. Postdoctoral researchers funded under this project will work together as a team and in collaboration with experts from the arts, humanities, social and natural sciences.

The cohort includes five postdoc positions.
Full time | 3 years | up to salary level 13 (TVöD)

All job descirptions and more info here

IN THE FIELD WITH...

Laura Leiva: Investigating Sea Urchin Decline and Reef Resilience Around Zanzibar

In the 1980s, a mass mortality event devastated diadematoid sea urchin populations across the Caribbean. Four decades later, the same pattern resurfaced, this time spreading from the Caribbean through the Mediterranean and Red Sea, reaching the East African coast by 2023–2024. As key herbivores, sea urchins regulate macroalgal growth and clear space for coral recruitment; their sudden loss may drive phase shifts toward algal dominance, with cascading consequences for reef resilience. My research aims to assess population recovery, investigate pathogen persistence, and document early ecological impacts across affected sites in Zanzibar.

I am now at the start of the second year of an annual monitoring programme, re-surveying transects across six different sites, including four islands around Zanzibar, assessing population structure and abundance. The data are already revealing unexpected patterns. Most striking is the patchiness: some sites show high urchin densities, others just a few kilometres away have almost none, pointing to local refugia, differential pathogen exposure, or environmental conditions that buffered some populations and not others. Species composition is shifting too: some species are scarce, their niches apparently vacant; others are more prevalent than before, possibly benefiting from reduced competition, but whether they can sustain the same grazing pressure and space-clearing that reef resilience depends on remains an open question.

Understanding the conditions that enable or obstruct recovery is not only a scientific priority, it is an urgent one. With coastal development, pollution, and climate change intensifying across the region, identifying what drives reef resilience is essential for any meaningful conservation strategy.

COLLABORATION

Meaningful Encounters with Marine Ecosystems

Although our oceans remain largely unexplored, our understanding of marine ecosystems is growing steadily thanks to modern technologies. At the same time, this knowledge is becoming increasingly complex and thus often limited to the scientific community. But how can we make the digitalised oceans accessible to a wider audience, moving beyond diagrams and tables?

Max Seeger is the fourth artist to stay at HIFMB and Hanse Wissenschaftskolleg within our artist-in-residence-scheme “ArtWaves”. The designer and media artist uses code to create interactive installations and multimedia experiences.

With his installation “Interfacing with the Ocean” he translates abstract findings into a tangible and emotionally engaging experience. At the core of the installation is an aquarium, emptied of living organisms, but augmented with a transparent screen and handtracking. When visitors immerse their hand in the water, they dive into the North Sea’s biodiversity. Using hand movements, they can navigate to different locations and depths and discover the organisms living there, displayed as 3D visualisations on the translucent screen.

Max worked with scientists at HIFMB from February to April and developed a prototype of “Interfacing with the Ocean” which was then exhibited at the Schlaues Haus in Oldenburg.

BBNJ UPDATES BY PROF KIMBERLEY PETERS

**Prepcomm3 – Recognising the Process of Governing the Ocean**

You might be forgiven for thinking, in view of the extensive media coverage marking the BBNJ’s entry to force earlier this year (see also our last newsletter for the incompleteness of this process), that the new High Seas Treaty for biodiversity in areas beyond national jurisdiction is now operational.

However, as is common with any regulatory regime, simply having a law, rule, piece of guidance or otherwise, doesn’t mean it suddenly works. Laws, rules, and guidance need to be enacted.

A major gap of BBNJ has been the question of how to realise its provisions. How exactly, for example, will we (the global community who have ratified the treaty) enact Marine Protected Areas in the High Seas? This is just one of many questions.
April 2026 marked the end of the third and final Preparatory Committee meeting to deal with practical questions of how the treaty will function. So called ‘Prepcomm3’, held at the UN headquarters in New York, set about to deal with the details of making the treaty ‘real’.

When I teach my Ocean Governance and Policy class at the University of Oldenburg, sharing details of the many steps towards ocean protection is crucial so that students can understand the challenge of trying to manage the 70% of the earth’s surface that is ocean. When criticism is aimed at governance, it is often without acknowledgement of the dazzling complexity through which decisions – and actions – are made.

For international governance doesn’t just happen – not even when we have a treaty. Treaties are subject to constant, ongoing, careful (sometimes stressful) negotiation. Co-working, compromise, and commitment, must continue to bring provisions to life.

As discussed at Prepcomm3, 2027 will see the first COP (Conference of Parties) meeting for the ocean (mirroring the COP meeting for climate). It is here – in 2027 – that further questions, and decisions, will lay in wait. And myself – and my students, of course – will be ready to follow them further.

VIEW FROM NORTHWEST #26

Being Part of the Problem

Knowing more and understanding better are key motivations in science, independent of discipline and career stage. Being paid for being curious is perhaps the biggest benefit of the job “being a scientist”. Questions never end, because each new insight, all methodological progress and every increment in conceptual clarity is an invitation to dig deeper. Scientific curiosity is as close to a perpetuum mobile as we can get in the real world.

Unfortunately, this infinite excitement also loosens the brake on some essential self-reflection – a self-diagnosis at least valid for me: Instead of asking “is it really wise to apply for this tempting funding opportunity given my lack of time”, the immediate rush of excitement pushes a button deep in my brain and - within a minute - I am on the application because the call fits perfectly, my favorite colleagues are on board or there is a chance to support this brilliant student or postdoc. While this incapability of saying no to chances is perhaps my personal issue, I recently started to wonder whether it is part of a broader strategic problem.

Curiosity becomes part of the problem when the perpetuum mobile feeds a political purpose, delaying unpopular or even unwanted decisions because “we do not know enough”. In fact, if a political leadership wants to avoid unpopular decisions in environmental matters, it may seem even perfidiously elegant to spend a few million Euros on yet another scientific project exploring that matter. Thereby you can show that you care for this matter without making anyone unhappy by preventing further use of natural resources or prohibiting other destructive activities. So, what if their own curiosity makes scientists well-trained dogs that jump over every stick held out to them?

And yes, we do not know enough about the ocean. The proportion of the deep ocean floor we ever investigated is ridiculously small (and still potentially more interesting than the backside of the moon) and our knowledge of changes in marine biodiversity restricted to a few decades (or just years) of observation in a few places, strongly biased towards temperate regions. We need to understand better how organisms adapt and how this depends on their microbiomes as well as how humans relate to and interact with ocean (life) as individuals or societies. Let alone fundamental questions of the origin of life in the ocean and the evolution of human imaginations of this life.

But this quest for more insight does not preclude stating that for decision-making we know enough, especially if precautionary principles would be taken seriously. Without understanding all details, we know the risks for ocean ecosystems associated with a changing climate. Without understanding every single power dynamic, we know the economic and political forces affecting climate mitigation policies – or rather their absence.

Almost every PhD thesis and scientific paper ends with a paragraph on the new questions arising and the options for future research. Perhaps it should also have a paragraph of reinforcement: “None of this research alters the need to act politically”.
sis that publishes mini-papers (just methods and results, no intro or discussion)?

Sincerely, Helmut Hillebrand
Director — Professor of Pelagic Ecology
helmut.hillebrand@hifmb.de

RESEARCH

Selected Recent Publications

Metfies K, Bienhold C, Cornils A, Havermans C, Hoving HJ, Kraberg A, Laakmann S, […] Boetius A. (2026). eDNA as a cornerstone for holistic long-term observations of Arctic marine biodiversity across trophic levels, habitats, and spatio-temporal scales. Deep-Sea Research Part II: Tropical Studies in Oceanography.
doi.org/10.1016/j.dsr2.2026.105604

Lechón-Alonso P, Kundu S, Lemos-Costa P, Capitán JA, Allesina S. (2026). Robust coexistence in competitive ecological communities. Nature Communications.
doi.org/10.1038/s41467-026-69151-3

Rusca M, Zwarteveen M, Acharya A, Alba R, Haeffner M, Krueger T. (2026). Water justice needs careful interdisciplinary research. Nature Water.
doi.org/10.1038/s44221-026-00595-z

Byron C. Temporalities of worldly receding. (2026). Dialogues in Human Geography.
doi.org/10.1177/20438206261443546

Massing JC, Gross T, Yeakel JD, Fahimipour AK. (2026). Generalized dynamics of cross-feeding bacteria. J R Soc Interface.
doi.org/10.1098/rsif.2025.0437

Shojaei R, Gross T. (2026). Counting chemical isomers with multivariate generating functions. Network Science.
doi.org/10.1017/nws.2026.10025

+ more on Google Scholar: https://scholar.google.com/citations?user=uCoLTyAAAAAJ&hl=en