In this week’s blog post, we’re getting served an interesting dish all about seagrass! Author Dr. Bruno Bellisario explains the fascinating world of seagrass meadows from the article: “The fingerprint of functional strategies in Mediterranean seagrass fish assemblages”. Bruno discusses the importance of seagrass ecosystems on fish communities, and the complexity behind how they’re used, highlighting why we shouldn’t say seagrasses have a singular ecological role, Bruno is also a strong advocate for open science and talks about his passion for the ecological “big picture”, often sharing data and tools to support collaborative understanding of the natural world. With a combination of prog and hard rock, a passion for vinyl collections and a love for the journey (not the destination!), Bruno teaches us a valuable lesson on perseverance.
Seagrass meadows are more than just pretty patches on the seafloor. They are biodiversity hotspots, offering food, shelter, and nursery grounds for a wide variety of species. These meadows function like underwater neighbourhoods, where fish find a safe refuge from predators and access to rich food resources, from algae to small invertebrates. Like playgrounds for kids, seagrasses also serve as nurseries, where young fish can grow under protection before venturing into more exposed areas.
Despite their ecological importance, the roles that seagrasses play in supporting fish communities remain debated. Are they primarily nurseries, foraging grounds, or something else entirely? These functions are not mutually exclusive – seagrasses can serve multiple ecological roles simultaneously. Rather than choosing between two opposing theories, it may be more accurate to say that both are true, reflecting the structural and functional complexity of seagrass habitats. The physical characteristics of seagrass plants—such as shoot density, leaf dimensions, canopy height, and the presence of rhizomes—create a highly structured habitat. This complexity shapes both who can hide and who can hunt, influencing the ecological roles that fish can play within. Moreover, this structure is embedded in a broader landscape context: patch size, edge effects, and even epiphytic organisms contribute to the habitat’s functionality.
Our study explored how fish interact with these habitats—not just by being there, but by asking why, how, and when different species use them. We moved beyond simple species counts and focused on functional traits—measurable characteristics like body size, growth rate, and feeding mode that influence how organisms interact with their environment. These traits help reveal not just who is present, but what role each species plays in the ecosystem. Using data from fish species observed in three key Mediterranean seagrasses (Posidonia oceanica, Cymodocea nodosa, and Zostera marina), we uncovered a ‘functional fingerprint’—a consistent pattern of traits shared among species using these structurally different but functionally similar habitats.
Most fish were small to medium in size, grew quickly, and occupied lower trophic levels, often feeding directly off the substrate. These fish appeared to use seagrass meadows throughout their life cycle, functioning as both residents and grazers. In contrast, larger, slower-growing predators—especially those relying on ambush or active pursuit—appeared only occasionally and typically only as adults, using seagrasses more like feeding stations, stopping briefly to hunt before moving on. These transient predators had distinct traits and low functional redundancy, meaning few other species shared their ecological roles, making them particularly vulnerable to disturbances.
Understanding how these functional strategies distribute across species and life stages provides crucial insights for conservation. With climate change, habitat degradation, and invasive species altering the dynamics of coastal ecosystems, identifying this ‘functional baseline’ can help us predict how fish communities might respond to future changes in seagrass composition or structure. Many of these fish play key roles in local fisheries and food webs, so conserving the meadows they depend on is critical for ecological and socio-economic resilience.
2. About the Research
Collecting the data was the hardest part of the process. Information on fish presence in seagrass habitats is often fragmented, spatially biased (meaning that areas that are easier to sample, are sampled the most), or lacks temporal consistency—especially for species other than P. oceanica, the only seagrass species endemic to the Mediterranean. This paper is part of Azzurra Lattanzi’s PhD research, conducted within a broader project led by Prof. Roberta Cimmaruta at the University of Tuscia in Viterbo, which I co-supervised. During Azzurra’s first year, we developed a semi-automated pipeline to extract all available literature-based records of fish associated with Mediterranean seagrasses. This massive effort took nearly a year!
But gathering the data was just the beginning. As is often the case, ecological data come with their fair share of issues—typos, outdated taxonomy, and missing trait information. In functional ecology, missing data can be addressed in several ways.
When trait information is lacking, we often reconstruct values using phylogenetic imputation, if closely species tend to share similar functional traits. Although this method is widely used and has proven successful in many taxonomic groups (including fish) it is not free from approximation, especially when missing data does not follow a random pattern. This was the case of information on life stage, critical to understanding habitat use and, unfortunately, rarely reported—especially for species found in seagrasses other than P. oceanica. This became our biggest limitation: we had to exclude all species lacking life stage information and limit certain analyses to P. oceanica meadows.
Still, the results were compelling. Regardless of the seagrass species, the core of functional strategies of resident fish remained remarkably consistent—small-bodied, fast-growing species that exploit the substrate and seagrass structure for food and shelter across multiple life stages. Larger, predatory fish were less common and primarily use these habitats temporarily. Ultimately, what distinguishes seagrass species is not only how many fish they support, but how well they support a functionally diverse community, especially of (top)predators. This insight could have far-reaching consequences for ecosystem functioning and the services these habitats provide.
Now that we’ve established a ‘functional baseline’, we’re expanding our work to assess how invasive seagrass species may reshape fish communities. We are currently analysing fish assemblages associated with a small tropical seagrass species Halophila stipulacea, a fast-spreading species native to the Red Sea that is now invading the Mediterranean. Given its markedly different morphology (e.g., creeping rhizomes, solitary roots, and small leaves), we expect that it may favour different functional strategies in associated fish—a hypothesis we’re testing through a new master’s thesis project.
3. About the Author
Since my PhD in Ecology at the University of Tuscia, I’ve always been drawn to the big picture. That’s why I never focused on just one species or ecosystem. Instead, I explore biodiversity across contexts, integrating analytical tools to understand how various layers of ecological information shape the patterns we see in nature.
Currently, I work as a data analyst/scientist, supporting the ecological research group in my department with computational and statistical methods. I consider myself a community ecologist with a passion for open, collaborative science. I’m a strong advocate for the free sharing of data and tools, which has led me to starting to develop web apps in R (using Shiny) to help communicate and visualize ecological research. You can find some examples on my personal website: https://brunobellisario.github.io/.
Of course, it’s not all spreadsheets and R scripts. I’m also a lover of progressive and hard rock, and I collect vinyl (a habit that’s more emotionally than financially rewarding!). Music, good food, and my unconventional family—one bride, two dogs, and one cat—are my safe haven. Looking back, I’d say I’m satisfied with my journey, even if it’s included years of precarious positions. Passion and perseverance have been my guiding principles. If what you’re doing makes you feel good, you’re already winning.
