Striking similarities in marine food webs across the world’s oceans

From the frigid waters of the Arctic to the tropical seas of the Coral Triangle, marine vertebrate communities living under similar environmental conditions tend to organise themselves in remarkably similar ways. A new global study led by Juan David González-Trujillo and Miguel B. Araújo, published this week in Proceedings of the National Academy of Sciences, shows that even in distant oceans, unrelated species often fulfil the same ecological roles—forming comparable food webs shaped by climate, depth, and productivity, rather than by shared ancestry or geography.

“By examining the diets and ecological roles of marine vertebrates across thousands of kilometres, we found striking regularities in how food webs are assembled,” said lead author Juan David González-Trujillo, a former researcher of the Universidade de Évora now at the Universidad Nacional de Colombia. “This trophic convergence reveals that nature often finds similar solutions to similar environmental challenges—even in completely different oceans.”

The team compiled and harmonised dietary information for 5,569 marine vertebrate species, including fish, seabirds, turtles, and marine mammals. These species were classified into eleven trophic guilds—groups of species that share similar feeding strategies—based on resources such as plankton, benthic invertebrates, algae, or fish. Mapping the global distribution of these guilds revealed the emergence of six distinct trophic community types, which occur repeatedly across the globe in areas with similar temperature, productivity, salinity, and depth profiles.

Importantly, these patterns of functional similarity often appeared in ecosystems composed of completely different species, highlighting the role of ecological constraints in shaping community structure across evolutionary divides.

“We’re moving beyond simply cataloguing where species occur,” said senior author Miguel B. Araújo, Research Professor at the National Museum of Natural Sciences (CSIC) who is also Chair of Biogeography at the University of Évora. “Our work shows that the environment imposes constraints that lead to functional convergence in marine ecosystems. This shifts the paradigm toward understanding ecosystems through the lens of their ecological functions and interactions.”

To test the robustness of their classification, the authors performed sensitivity analyses by modifying the dietary profiles of species and using different algorithms for clustering communities. In all cases, the core finding remained: functionally analogous trophic communities recur globally, even when composed of species from entirely different evolutionary lineages.

While classical marine biogeography emphasises species distributions and evolutionary history, this study introduces a complementary framework that foregrounds function over identity. “Trophic community types proved to be better aligned with oceanographic conditions than with regions defined by species endemism, suggesting that the environment can override historical biogeographic patterns.”, explains González-Trujillo.

“These patterns of trophic convergence imply that ecosystems may respond more predictably to climate change than we previously thought,” added Araújo. “By focusing on functional roles, rather than just species identity, we may be better equipped to model and manage biodiversity under future environmental scenarios.”

He concluded: “This research lays the groundwork for a new generation of biodiversity models—ones that integrate ecological function and environmental tolerance to better anticipate the fate of ocean life in a rapidly changing world.”