In a groundbreaking study that underscores the intricate and far-reaching consequences of human activity on the oceans, researchers have unveiled the dual threat that climate change and global fisheries pose to the capacity of oceanic macrofauna to sequester carbon. This critical investigation, published in Nature Communications, offers an unprecedented assessment of how these intertwined factors could significantly diminish one of Earth’s most vital natural carbon sinks over the coming decades.
The study harnesses advanced modeling techniques to integrate the impacts of both climate change and intense fishing practices on marine ecosystems, focusing primarily on large ocean-dwelling animals—a group collectively known as oceanic macrofauna. These species, ranging from large fish to marine mammals, play a pivotal role in carbon cycling through their biological processes, movements, and eventual deposition of organic carbon into the deep ocean. Their ability to store carbon is a natural counterbalance to atmospheric carbon dioxide levels, a balance now threatened by escalating anthropogenic pressures.
Central to the research is the realization that fisheries, by extracting vast quantities of biomass from the ocean, inadvertently undermine the carbon sequestration potential of these animals. Overfishing reduces the abundance and size of these key species, which in turn diminishes the biological carbon pump, a process by which marine life transports carbon from surface waters, where it is inhaled by the atmosphere, to the ocean’s depths, effectively locking it away for centuries or longer. The degradation of this pump accelerates climate change by allowing more carbon to remain in the atmosphere.
Compounding this is the direct impact of climate change itself—rising ocean temperatures, deoxygenation, and acidification—all of which stress marine species and alter their distribution. As waters warm, many large-bodied species are pushed toward cooler, high-latitude habitats, disrupting existing ecological balances and the efficiency of carbon transport mechanisms. Moreover, these environmental changes affect reproductive rates and growth patterns, further destabilizing populations already pressured by heavy fishing.
Notably, the research uses robust climate scenario modeling coupled with fishery catch data to extrapolate future trends in carbon sequestration capacity. The findings paint a stark picture: current trajectories of warming and fishing effort could reduce the ocean’s macrofaunal carbon sink by a significant margin by mid-century. This potential decline threatens to exacerbate climate change impacts, creating a vicious cycle where diminished carbon sinks foster higher atmospheric CO2 concentrations, fueling further warming, which then further stresses marine life.
This study’s intricate approach accounts for spatial heterogeneity, recognizing that the impacts will not be uniform around the globe. Some regions, particularly tropical and subtropical zones, show the greatest vulnerability due to overfishing combined with rapid warming. Conversely, high-latitude areas may experience shifts in species composition, but the overall sequestration function is expected to decline nonetheless. This geographic differentiation underscores the need for tailored management strategies that consider local environmental and socio-economic contexts.
The interdisciplinary nature of the team allowed for a comprehensive assessment that goes beyond ecological impacts to incorporate economic and social dimensions of fisheries. It highlights how sustainable fishing practices can play an instrumental role in preserving not only biological diversity but also critical ecosystem services like carbon sequestration, potentially buffering global climate change acceleration. Therefore, mitigation strategies must emphasize both stringent conservation measures and adaptive management responsive to climate-induced changes.
Interestingly, the authors shed light on the underappreciated value of oceanic macrofauna within the global carbon budget. Historically, these large marine species have received less attention compared to phytoplankton and microbial processes when considering carbon cycling. This research positions macrofauna as a crucial component in carbon storage dynamics, challenging prior paradigms and suggesting that their conservation could be as vital as terrestrial reforestation efforts for climate mitigation.
Another critical insight from the paper is the role of trophic interactions. The removal or decline of apex predators and larger fish through fisheries triggers cascading effects throughout the food web. These trophic cascades may alter plankton communities and microbial activity, indirectly influencing carbon cycling processes. These complexities reveal that simple biomass counts are insufficient; understanding ecosystem structure and interdependence is also essential.
The findings also raise poignant questions about policy implications. Existing fisheries management often centers on maximizing yield without accounting for broader ecological services such as carbon sequestration. The integration of climate and ecological models in this study advocates for a paradigm shift toward ecosystem-based management policies that explicitly recognize and value carbon storage services provided by marine life.
Furthermore, the research supports the urgent call for global cooperation, particularly under frameworks like the United Nations Convention on the Law of the Sea (UNCLOS) and the ongoing negotiations for a treaty on marine biodiversity in areas beyond national jurisdiction. Protecting oceanic macrofauna transcends national borders, given their migratory nature and the interconnectedness of marine ecosystems. International collaboration will be key to enforcing fishing regulations that safeguard both biodiversity and critical climate functions.
The paper also explores potential feedback loops between climate change and fisheries. For instance, as fish stocks decline in some regions due to warming, fishing fleets may intensify efforts elsewhere, potentially expanding fishing pressure into vulnerable areas formerly less exploited. This shifting effort may further destabilize ecosystems, making management even more challenging. Comprehensive monitoring systems and adaptive governance structures are therefore essential to respond dynamically to these rapidly evolving patterns.
Technological advances in remote sensing, autonomous underwater vehicles, and environmental DNA sampling are highlighted as promising tools for improving the resolution and breadth of marine ecosystem data. Such tools can facilitate the tracking of species distributions, population dynamics, and carbon fluxes at unprecedented scales, enhancing model accuracy and informing responsive management decisions.
In concluding remarks, the authors emphasize the critical window of opportunity that exists to mitigate these risks. Implementing stringent fishery controls, expanding marine protected areas, and aggressively targeting carbon emissions remain paramount. The ocean, often touted as humanity’s greatest ally against climate change, will require concerted and immediate action to maintain its ability to function as an effective carbon sink in the face of mounting anthropogenic pressures.
This compelling body of work fundamentally enriches our understanding of the ocean’s role in climate regulation, highlighting the vulnerability of this delicate balance to human interventions. It serves as a clarion call to scientists, policymakers, and the public alike, urging a reevaluation of how the ocean’s living resources are managed and cherished in an era of accelerating global change.
Subject of Research:
The study investigates the combined effects of fisheries exploitation and climate change on the future capacity of oceanic macrofauna to sequester carbon within marine ecosystems.
Article Title:
The combined impact of fisheries and climate change on future carbon sequestration by oceanic macrofauna.
Article References:
Mariani, G., Guiet, J., Bianchi, D. et al. The combined impact of fisheries and climate change on future carbon sequestration by oceanic macrofauna. Nat Commun 16, 8845 (2025). https://doi.org/10.1038/s41467-025-64576-8
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