Marine biodiversity loss, fishing, and climate change

Climate change is but the latest in a series of ever-increasing anthropogenic pressures on natural systems. I will give a brief overview of observed impacts of recent climate change in natural systems stemming from the most recent IPCC 6th Assessment Report. Similarities and differences between marine and terrestrial systems will be highlighted in terms of observed impacts on species, ecosystems and their services. I will briefly touch on how these changes in natural systems are already having negative effects on society, particularly increasing risks of diseases and food security. In terms of solutions space, achieving climate stability within the next century requires both emissions reductions and uptake of atmospheric carbon. While technological solutions have been invaluable for emissions reductions, they are insufficient and costly when it comes to drawing down atmospheric carbon. Nature-based solutions continue to be the most efficient in the near-term, cost-effective, and comprehensive means of stabilizing global climate. The IPCC concluded that climate resilient development fundamentally relies upon safeguarding natural biodiversity and associated healthy ecosystem functioning to achieve both adaptation and mitigation targets. Based on dozens of modeling studies coupled with long-term field studies and experiments, IPCC concluded that "the resilience of biodiversity and ecosystem services at a global scale depends on effective and equitable conservation of approximately 30% to 50% of Earth’s land, freshwater and ocean areas, including currently near-natural ecosystems (high confidence)."

Professor Camille Parmesan

Centre national de la recherche scientifique, France

Professor Camille Parmesan

Centre national de la recherche scientifique, France

Camille Parmesan came to France as a "Make Our Planet Great Again" Laureate and is currently Director of the CNRS Station for Experimental and Theoretical Ecology (SETE). Her research focuses on the impacts of climate change on wild plants and animals and spans from field-based work on butterflies to synthetic analyses of global impacts on a broad range of species across terrestrial and marine biomes. Her 1996 Nature publication documented the first northward/upward shift of a wild species. Her 2003 Nature study provided the first analysis documenting that climate change had impacted wild species on a global scale, and was ranked the most highly cited paper in climate change by Carbon Brief (2015). She continues to work on the implications of climate-change induced changes in wild species, communities and ecosystem processes for conservation of biodiversity, human health, and services to society.

She is an elected Fellow of the European Academy of Sciences, Fellow of the Ecological Society of America, Honorary Fellow of the Royal Entomological Society and received an Honorary Doctorate from the University of Stockholm in 2025. She received the Conservation Achievement Award by the National Wildlife Federation and was named "Outstanding Woman Working on Climate Change" by IUCN. She has worked with the Intergovernmental Panel on Climate Change for >25 years, and shares in the IPCC's Nobel Peace Prize (2007) and Gulbenkian Prize for Humanity (2025). In 2025, she received the BBVA Foundation Frontiers of Knowledge Award in Climate Change and Environmental Sciences. Parmesan is also an Adjunct Professor at the University of Texas at Austin (USA).

The ocean’s capacity to sustainably, equitably, and safely produce food is declining due to biodiversity losses driven by overexploitation, climate change, and other human-induced stressors such as pollution. While solutions like fisheries management, aquaculture, and marine protected areas have been proposed to reverse these declines, recent global analyses reveal growing trade-offs and inequities across seafood production, biodiversity conservation, and climate action. This talk explores the application of integrated models—linking climate, biodiversity, seafood production, and economic impacts—to assess how solution portfolios can achieve sustainable and equitable food and conservation goals under climate change. These models incorporate scenarios accounting for both direct and indirect drivers, including ocean conditions, demographic shifts, seafood demand and pricing, fisheries governance, and aquaculture development. Projections indicate that achieving sustainable seafood security and biodiversity goals will require ambitious action across multiple fronts: reducing fishing effort, advancing sustainable aquaculture, expanding marine protected areas, and strengthening climate mitigation. Climate change particularly threatens the capacity to provide nutrient-rich seafood and restore biodiversity and biomass in low and middle-income tropical nations and vulnerable communities in extra-tropical regions. The findings highlight the synergies and trade-offs in pursuing food, climate, and biodiversity targets. The presentation emphasises the need for equity- and conservation-focused ocean governance and for limiting global warming to below 1.5°C, and underscores the value of participatory scenario modelling to co-develop resilient, just, and sustainable marine conservation strategies.

Professor William Cheung

The University of British Columbia, Canada

Professor William Cheung

The University of British Columbia, Canada

Dr William Cheung is a Professor and Director of the Institute for the Oceans and Fisheries, the University of British Columbia, and a Canada Research Chair in Ocean Sustainability and Global Change. He studies the nexus of food-climate-biodiversity in the ocean. His research applies transdisciplinary approaches that integrate scenarios and models with participatory methods to (1) understand the risk and impacts of climate change on marine ecosystems, biodiversity, fisheries and people who are dependent on it, and (2) explore solution options and pathways to desirable and sustainable ocean futures. He serves as director for the 6-year international Partnership “Solving Sustainability Challenges at the Food-Climate-Biodiversity Nexus (Solving-FCB)”. His work addresses policy-relevant research questions and cuts across multiple disciplines, from oceanography to ecology, economics and social sciences. His research ranges from local to global scales. William is actively involved in international and regional initiatives that bridge science and policy, including the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES).

Phytoplankton are the base of the marine foodweb and play important roles in biogeochemical cycles, such as the export of carbon from the surface oceans. These organisms are incredibly diverse, spanning many orders of magnitude in size, and have many different ecological biogeochemical roles. Though crucial parts of the earth's system we still have very limited understanding of the global patterns of diversity, what controls these patterns, and how plankton will respond to a warming ocean. In this talk I will describe some numerical modelling and theoretical approaches to addressing these issues. We utilise key phytoplankton traits (eg size) to model diverse plankton populations globally and question what physical and biological drivers set diversity. We show that regional patterns of supply of multiple nutrients, trophic interactions, and the transport by water parcels are key to maintaining different aspects of biodiversity, such as number of co-existing size classes, functional groups, and thermal norms. But each of these drivers will be altered in the future changing ocean. We will examine some of these predicted changes and how the model suggests plankton community structure may be altered in a future world.

Dr Stephanie Dutkiewicz

Massachusetts Institute of Technology, USA

Dr Stephanie Dutkiewicz

Massachusetts Institute of Technology, USA

Stephanie Dutkiewicz is a senior research scientist at Massachusetts Institute of Technology. She holds a PhD in Oceanography from the University of Rhode Island and a BS from the University of Miami (Florida). Her research focuses on how physics, light, biogeochemistry, and biotic interactions control plankton ecology. She is one of the lead developers of the MIT Darwin Model - a trait-based numerical ecosystem model that is flexible on the numbers, functional role, and trophic strategies on plankton analogs. Dutkiewicz uses this model along with ecological theory to examine the drivers of plankton biogeography and diversity, including how plankton productivity and distributions will alter in a future world. Her research is guided through links to satellite, field and laboratory studies.

The Tara Oceans expedition (2009-2013) pioneered a global pan-ecosystemic strategy to systematically study the ocean's largest ecosystem: the plankton. This expedition sampled the microscopic majority of marine life, spanning seven orders of magnitude in size from viruses to zooplankton, across 210 sites worldwide to create an unprecedented view of the microbial ocean. Driven by the need to understand life's complexity and ocean processes driving it, the project established a holistic methodology to sample and analyse it. This involved high-throughput DNA sequencing and automated quantitative imaging, which generated extensive open- access datasets. This resulting resource provides a critical "time zero point" for understanding the 21st century planktonic ecosystem and the environmental conditions driving their compositions and distributions. Key insights on biodiversity estimates across viruses, prokaryotes, phytoplankton, and protists will be discuss. We will further explore how these microbes govern community ecology, define the intricate biogeography of our oceans, and shape essential biogeochemical cycles, offering necessary context for assessing future climate change impacts.

Dr Lionel Guidi

Centre national de la recherche Scientifique, France

Dr Lionel Guidi

Centre national de la recherche Scientifique, France

Lionel Guidi is a researcher at the Laboratories d'Oceánographie de Villefranche (LOV), which is part of the French National Centre for Scientific Research (CNRS) and Sorbonne University (SU). He joined the CNRS in 2013 after a postdoctoral position at the University of Hawaii. Dr Guidi earned a PhD in Oceanography in 2008 through a joint program between SU (France) and Texas A&M University (USA). In 2018, he was awarded the CNRS Bronze Medal, which recognises early career researchers for their promising work. His research focuses on marine biology and oceanography, particularly the study of planktonic ecosystems and the biological carbon pump. He is one of the co-coordinators of the Tara Oceans expedition and now lead of the Féderation de Recherche Global Ocean Systems Ecology & Evolution "GO-SEE" which focus on research outcomes from the different expedition supported by the Tara Ocean Foundation.

Coral reefs host vast number of species, but studies of reef diversity have traditionally focused on large, well-known and conspicuous taxa. Meanwhile, a multitude of small eukaryotic and prokaryotic taxa that are found hidden within the three-dimensional structure of reefs, the cryptobiota, remain understudied. This is despite the cryptobiota representing the majority of reef diversity and being important for reef function and persistence. Understanding how biogeographical, environmental and anthropogenic drivers shapes this group of organisms is imperative for forecasting future trends in reef taxonomic and functional biodiversity as reefs continue to degrade worldwide. This talk will highlight some of our key findings from studying the drivers of reef cryptobiota diversity across the world. By combining 370 sequencing datatsets across 143 sites, spanning five oceanic regions, we show that reef connectivity (+), habitat (-), fishing (+), and cyclone activity (+) best predict global eukaryotic richness on tropical reefs. However, we find that phyla-level richness responses to predictors are region specific and highlight the groups of organisms that may dominate reefs in the future. While we show that anthropogenic stress can increase eukaryotic diversity, different patterns are observed for prokaryotes. We show that eukaryotic richness and temperature are the dominant drivers of prokaryotic richness, with thermal tipping points that can shift bacterial richness on reefs. This work underscores the importance of standardised global sequencing datasets and cross-domain studies to elucidate the ecosystem-scale impacts on complex stressors on reefs.

Dr Emma Ransome

Imperial College London, UK

Dr Emma Ransome

Imperial College London, UK

Emma is an Associate Professor at Imperial College London, UK. Her research group uses multi-omics to understand the biodiversity of microbial communities and their hosts in our natural environments. She is particularly interested in the impact that anthropogenic change is having on biodiversity and ecosystem services in coastal zones and how we can use multi-omics data to aid conservation actions. While her work mostly focuses on coral reefs, she has applied her skill set to seagrass ecosystems, SARS-CoV-2 transmission, and soil and avian microbiomes.

Ocean systems are characterised by diverse phytoplankton assemblages that themselves vary on a range of time-scales, but the question remains how phytoplankton biodiversity is reflected in the stoichiometry of particulate matter, the Redfield Ratio, in the ocean. In the open ocean it is generally concluded that the linkage between biodiversity and stoichiometry is through the variability in larger phytoplankton (eg diatoms) to smaller picophytoplankton (eg cyanobacteria). At the Bermuda Atlantic Time-series Study (BATS) site, this is generally the case with a seasonal increase in particulate organic carbon to phosphorus (POC:P) ratios that align with the seasonal accumulation of Prochlorococcus biomass. A similar pattern is observed over longer time series records, where again at BATS a multi-year increase in the POC:P ratio is aligned with the dramatic reduction in the presence of larger phytoplankton. The same observation cannot be said for spatial relationships between phytoplankton biodiversity and stoichiometry where despite similar patterns in phytoplankton assemblages, variability in the physical environment induces a complex interplay between biodiversity and phytoplankton physiological acclimation. A broader ocean look at the relationships between phytoplankton physiology, biodiversity, and plankton stoichiometry support a similarly complicated relationship mediated by ocean physics. These relationships are not just restricted to the tropical and subtropical latitudes. With ocean warming, populations of cyanobacteria, Synechococcus, are becoming more prevalant in Arctic ecosystems and already having a demonstrated impact on stoichiometry. The impacts of these interactions on marine biogeochemistry and the functioning of ocean food webs is only now beginning to be understood.

Dr Michael Lomas

Bigelow Laboratory for Ocean Sciences, USA

Dr Michael Lomas

Bigelow Laboratory for Ocean Sciences, USA

Michael Lomas is a marine biogeochemist with a broad interest in the role that phytoplankton diversity and physiology plays in mediating the key processes of the biological carbon pump, and the associated macronutrient cycles. Lomas holds a PhD in Biological Oceanography from the University of Maryland at College Park, where he studied how different marine phytoplankton assimilate nitrogen under variable light regimes. After his PhD Lomas spent 12 years in Bermuda as a principle investigator (PI) on the Bermuda Atlantic Time-series Study (BATS) program. While remaining a BATS co-PI, Lomas has since moved on to become a Senior Research Scientist at Bigelow Laboratory for Ocean Sciences where his oceanographic research interests in microalgae physiology and ecology and marine biogeochemistry have remained the same, but now also include work in the US Arctic seas. In 2014, Lomas was appointed as Director of the Provasoli-Guillard National Center for Marine Algae and Microbiota (NCMA) which is based at Bigelow Laboratory. During his tenure as Director, NCMA has expanded its capabilities as a biological resource for algae science and innovation, in particular he has spearheaded development of a regional US project focused on improving the efficiency with which amazing algal research is being translated into use-inspired innovations that may solve some of our largest societal challenges.

The Continuous Plankton Recorder (CPR) survey provides the longest and most spatially extensive plankton time-series in the North Atlantic, essential for detecting long-term biodiversity changes. Using CPR data from the Labrador Sea and North-West Atlantic, we show that since the 1980s, warming has driven increased diatom abundance at higher latitudes, where enhanced stratification and a weakened Labrador Current have reduced light limitation. Meanwhile, diatom abundance has declined in subtropical regions due to intensified nutrient limitation.

Ecological niche models suggest this trend may soon reverse, with nutrient constraints increasingly outweighing light availability, leading to an overall decline in diatoms and a shift towards more elongated taxa and dinoflagellates, signalling a potential tipping point toward reduced productivity and carbon export in the Subpolar Gyre (SPG).

These findings highlight how shifts in plankton communities could cascade through marine ecosystems, affecting food webs and carbon cycling, given varying carbon export efficiencies among species. Long-term datasets provided by the CPR alongside enhanced measurements, remain vital for tracking these dynamics, improving our ability to predict and respond to emerging biophysical shifts in the ocean.

Dr Clare Ostle

The Marine Biological Association, UK

Dr Clare Ostle

The Marine Biological Association, UK

Clare specialises in marine biogeochemistry, data integration, and analysis, particularly exploring the impact of plankton communities on the marine carbonate system. Her PhD at the University of East Anglia investigated the influence of plankton activity and abundance on carbon dioxide flux variability in the North Atlantic. Clare has worked with CPR data since her undergraduate studies at Swansea University, where she analysed copepod abundance and distribution in relation to temperature. She also has experience estimating net community production using oxygen optodes on volunteer ships and is interested in instrument development and sampling enhancements for the CPR. Clare has contributed to synthesis reports on topics including ecological indicators for European marine policy, ocean warming, acidification, and marine plastics. In 2020, she became the coordinator of the Pacific CPR survey, and in 2024, she was appointed Chair of the Global Alliance of CPR Surveys (GACS).

Marine plankton are an essential component of the earth climate system, form the base of the oceanic food web and thereby play an important role in influencing food security and contributing to the Blue Economy. Despite their importance, open ocean biological properties are significantly under-sampled in time and space compared to physical and chemical properties. This lack of information hampers our ability to understand the role of plankton in regulating in biogeochemical processes and fuelling higher trophic levels, now and in future ocean conditions. Traditionally, many of the methods used to quantify biological and ecosystem essential ocean variables (EOVs), measures that provide valuable information on the ecosystem, have been expensive and labour- and time-intensive, limiting their large-scale deployment. In the last two decades, however, new technologies have been developed and matured, making it possible to greatly expand biological ocean observing capacity. This talk will present recent advances in building international coordination to incorporate routine open ocean observations of marine biological properties and processes into the existing GO-SHIP decadal repeat hydrography program. Existing challenges in observing technology and infrastructure and the progress that can be achieved over the next decade with expanded observations of ocean biology will be discussed.

Dr Sophie Clayton

National Oceanography Centre, UK

Dr Sophie Clayton

National Oceanography Centre, UK

Dr Sophie Clayton received her PhD in Physical Oceanography from the MIT/WHOI Program in Oceanography, was an Innovation in Data Science Postdoctoral Fellow at the University of Washington in Seattle and then spent five years as an Assistant Professor in Oceanography at Old Dominion University, Virginia, USA. She recently returned to the UK to take up a Principal Investigator in Marine Biogeochemistry position at the UK's National Oceanography Centre. Her research is broadly focused on better understanding how dynamic physical features in the ocean (eddies, fronts, boundary currents) interact with chemical and biological processes to shape phytoplankton communities and modulate vertical and lateral biogeochemical fluxes. She has worked with numerical models to understand the balance of physical circulation and ecological processes in creating hotspots of phytoplankton biodiversity in boundary current regions, as well as collecting data in the field to further understand the role ocean physics in modulating plankton biodiversity. She works towards developing international coordination in expanding observations of open ocean biodiversity and developing best practices for biogeochemical sensors and phytoplankton imaging instruments, as well as collaborating with technologists and engineer to develop new sampling systems to support the expansion of routine biological sampling at sea.

Most large-scale ocean biogeochemical models rely on highly simplified and discrete representations of plankton, structured around a strict distinction between phytoplankton and zooplankton across a limited number of immutable plankton functional types. This discrete approach overlooks the empirical reality that the ocean microbiome is functionally far more diverse, with individual species occupying a continuum of ecological strategies. As an illustrative case, the widespread prevalence of mixotrophic organisms in the ocean calls into question an understanding of ocean biogeochemistry that assumes a strict dichotomy between photosynthetic phytoplankton and heterotrophic zooplankton. In this talk I shall discuss how modelling approaches that describe the marine microbiome in terms of continuously varying traits - rather than as a discrete selection of functional groups - is well suited to addressing this functional diversity. Where mixotrophy has been included in models, it can be seen that access to nutrients from prey can support larger cell sizes, longer food chains, and more efficient carbon export. I will explore how these findings impact ocean biogeochemistry and climate at the global scale, over long time periods. I will also discuss how such models are impact by crude underlying assumptions, and what empirical constraints are needed to bring down large uncertainties. This talk will therefore focus on recent efforts to include mixotrophy and greater functional diversity in trait-based and adaptive ecosystem models, and will explore what these models can teach us, what their limitations are, and what kinds of data are needed to make further progress.

Dr Ben Ward

University of Southampton, UK

Dr Ben Ward

University of Southampton, UK

Ben Ward is an associate professor and University Research Fellow working at the University of Southampton. He uses ecological theory and computer modelling to understand the global-scale structure of marine microbial communities and how these influence ecosystem functions including productivity and climate regulation. A particular challenge of this approach is the sheer abundance of organisms within these systems - there are more plankton in the ocean than stars in the observable universe. In light of this complexity, Ward's research focusses on developing models that allow large-scale patterns of biodiversity and ecosystem function to emerge given simple assumptions regarding how organisms compete and evolve within the fluid ocean environment. A current focus in Ward's research group in Southampton is to broaden the scope of marine ecology to better account for the previously under-investigated roles of rapid evolution, dispersal and genetic drift, and how these impact the dynamic ocean and Earth system.