The study, led by Lorenzo Zacchetti of the National Research Council’s Institute for Biological Resources and Marine Biotechnologies in Ancona, together with colleagues from the University of Bologna, the National Biodiversity Future Center, the CNR Institute of Research on Terrestrial Ecosystems and Liverpool John Moores University, introduces what the authors call the Gut-Isotope-DNA, or GID, approach. According to the researchers, this is the first time such an integrated framework has been applied to a crustacean. The method weaves together three techniques that each carry different strengths and blind spots: gut content analysis, which identifies prey visually but only captures recently ingested and recognisable items; stable isotope analysis, which integrates diet over weeks to months but resolves prey only at broad categories; and DNA metabarcoding, which can detect even soft, digested or unrecognisable prey from trace genetic material.

The fieldwork took place in one of the most intriguing features of the Adriatic basin: the Pomo Pits, two deep depressions in the middle of the sea that host a legally protected Fishery Restricted Area. Specimens of Norway lobster were collected both inside and outside this protected zone during two separate surveys, in 2019 and 2023, giving the team a rare opportunity to test whether diet and gut microbiome differ between a heavily fished area and a refuge, and whether these patterns shift between years separated by a four-year gap. The samples were gathered during scientific trawl surveys funded by the Italian Ministry of Agricultural, Food, and Forestry Policies in 2019 and by the European H2020 NAUTILOS project in 2023, which was designed to validate new low-cost ocean observation instruments on fishing vessels.

When the researchers opened up the lobsters’ guts and examined the contents under the microscope, one prey species towered above all others: the squat lobster Iridonida speciosa, a small relative of the Norway lobster that shares the same muddy habitat. This visual finding was not a fluke of preservation. Stable isotope mixing models, which use the ratios of carbon and nitrogen isotopes in the predator’s tissues to estimate the proportions of different food sources, independently pointed to the same conclusion. Together, the two methods painted a picture of an animal whose diet is anchored on a single abundant resource, at least in the parts of its menu that are large and durable enough to survive digestion intact.

But the DNA metabarcoding results told a richer and more nuanced story. By amplifying and sequencing genetic markers from the gut contents, the team detected a much wider array of prey than visual inspection had revealed, including soft-bodied organisms and fragments that would never survive to be identified under a dissection microscope. The molecular data exposed the Norway lobster as a genuine mixed scavenger-predator, opportunistically consuming both live prey and carrion across the seafloor. Intriguingly, the dietary diversity recorded through metabarcoding was higher in 2019 than in 2023, and finfish contributed more to the diet in the earlier year. This temporal pattern held both inside and outside the Pomo Pits, suggesting that shifts in food availability or feeding behaviour between the two survey years rippled through the population regardless of protection status.

The most striking twist came from the gut microbiome. Sequencing the bacterial communities living inside the lobsters’ digestive tracts revealed a microbial world dominated by three families: Vibrionaceae, a group of marine bacteria that includes both harmless associates and notable pathogens; Erysipelotrichaceae; and Mycoplasmataceae, cell-wall-less bacteria frequently found in the guts of crustaceans and other animals. These microbial residents were not passive bystanders. Their composition tracked the lobsters’ trophic patterns closely, with specimens caught outside the Pomo Pits carrying significantly more diverse gut microbial communities than those from inside the protected area.

What surprised the team most was the discriminating power of the microbiome itself. When the researchers asked which data stream best separated lobsters by sampling area and by year, the gut microbial communities outperformed the strictly dietary analyses. In other words, the invisible ecosystem within the gut acted as a sensitive recorder of where and when an animal lived and fed, sometimes more sharply than the food remains it carried. This finding raises the tantalising prospect that gut microbiomes could serve as biological indicators of habitat use and environmental conditions in commercially exploited species, complementing conventional tools such as stomach content analysis and population genetics.

The study also carries a methodological caution that the authors are careful to underline. While dietary composition and gut microbiome structure in the Norway lobster appeared broadly consistent with one another, each of the three techniques in the GID approach homes in on a different biological phenomenon. Gut content analysis captures a snapshot of recent, identifiable meals. Stable isotopes integrate assimilated diet over longer timescales but blur fine taxonomic detail. DNA metabarcoding maximises taxonomic resolution and detects trace prey but can be influenced by digestion rates, primer bias and the differential survival of DNA across prey types. Integrating evidence from all three therefore requires tailored interpretations, the researchers argue, and careful consideration of what each line of evidence can and cannot support, particularly when conclusions feed into fisheries management decisions.

That management dimension is far from academic. Nephrops norvegicus, known on dinner plates as scampi or langoustine, is one of the most economically important shellfish resources in European waters, and its stocks are assessed and regulated through effort controls, minimum landing sizes and area closures such as the Pomo Pits Fishery Restricted Area. Understanding what the species eats, where it forages and how its feeding ecology responds to protection and to environmental change is central to building sustainable management plans. If the lobster’s diet shifts between years, as the 2019 to 2023 comparison suggests, then trophic models underpinning stock assessments may need to account for that variability rather than assuming a static food web.

The GID framework, its developers suggest, could now be extended beyond a single species. Any crustacean, fish or benthic invertebrate whose diet is hard to observe directly could be profiled with the same triple lens, and the microbiome component adds a layer of ecological information that traditional diet studies simply do not capture. As sequencing costs continue to fall and reference databases of prey DNA grow, the approach may become a routine instrument in the marine ecologist’s toolkit. For now, the humble Norway lobster has become the first crustacean to have its meals, its chemistry and its inner microbial world read together, and the reading suggests an animal far more flexible, opportunistic and microbially distinctive than its muddy burrow home would ever let on.

Subject of Research: Dietary ecology and gut microbiome of the Norway lobster assessed through an integrated gut content, stable isotope and DNA metabarcoding approach

Article Title: Integrating Dietary Characterisation and Gut Microbiome Analysis in Norway Lobster (Nephrops norvegicus) Through Gut-Isotope-DNA (GID) Approach

Article References: Zacchetti, L., Basili, M., Domenichetti, F., Quero, G. M., Lauteri, M., Mariani, S., Manini, E., & Martinelli, M. (2026). Integrating Dietary Characterisation and Gut Microbiome Analysis in Norway Lobster (Nephrops norvegicus) Through Gut-Isotope-DNA (GID) Approach. Microbial Ecology. https://doi.org/10.1007/s00248-026-02902-3

Image Credits: AI Generated

DOI: 10.1007/s00248-026-02902-3

Keywords: Norway lobster, Nephrops norvegicus, gut microbiome, DNA metabarcoding, stable isotopes, trophic ecology, Adriatic Sea, Pomo Pits, fisheries management, Vibrionaceae, food web, marine ecology

The project taps into iNaturalist, one of the world’s largest biodiversity platforms, where members of the public upload photos, video and audio recordings of the organisms they encounter. While iNaturalist has long been used to map where species live, the new initiative extends its power to a different layer of ecological information: what those species are actually doing when they encounter one another. Users of the platform can now explicitly tag both predator and prey within a single photograph or video, capturing a feeding interaction at the moment it happens. The predator in question may be a lion taking down an antelope or a caterpillar munching on a garden leaf; the database treats both interactions as equally valuable data points in the planetary food web.

Bradley Allf, corresponding author of the paper describing the project and currently a postdoctoral researcher at Colorado State University, began the work while a graduate student at North Carolina State University. He explains that knowledge of what organisms eat remains fundamentally incomplete and fragmented across the academic literature. iNaturalist, he notes, has already proven its worth in documenting which organisms live in different locations, and this project extends that success to feeding relationships. The result is a publicly available website, who eats whom dot org, where anyone can explore recorded trophic interactions through an easily searchable interface. What began as an effort to consolidate scattered knowledge has quickly become one of the largest structured datasets of its kind.

The numbers are already striking. To date, the Who Eats Whom project has logged approximately seventeen thousand observations of trophic interactions involving roughly five thousand seven hundred species. These records have come from around two thousand observers based in more than one hundred countries, spanning ecosystems from tropical forests to suburban backyards. Each observation represents a moment when a person witnessed and documented one organism consuming another, creating a verifiable record that researchers can analyze, visualize and cross-reference with existing scientific literature. In aggregate, these individual moments begin to sketch the outline of a global food web, a planetary-scale network of feeding dependencies that has never been mapped at this level of public participation.

Aditi Mallavarapu, co-author of the paper and an assistant professor of computer science at NC State, approached the project from the perspective of human-computer interaction and tool design. Her interest, she says, lies in building usable interactive tools and learning environments, and the food web presented an irresistibly complex system to work with. The design goals were explicit: the site had to be usable, visually engaging and ethically responsible in the way it handled data contributed by citizen scientists. Mallavarapu emphasizes that the platform is intended to serve both researchers and the general public, helping each group grasp feeding relationships that are too numerous and too intricate to be understood through static tables or technical papers alone.

One of the most revealing early findings concerns what motivates participants. Mallavarapu observes that public interest extends well beyond charismatic predators such as lions and wolves. Contributors are documenting smaller, quieter trophic relationships, such as the insects that feed on persimmon leaves, and are using the site to explore interactions tied to their personal passions and local environments. This breadth of engagement matters scientifically. Ecological research has historically skewed toward large, photogenic species, leaving the vast majority of feeding interactions — particularly those involving invertebrates, plants and microbes — poorly documented. A platform driven by thousands of curious amateurs naturally fills some of those gaps, recording interactions that professional ecologists would rarely have the time or funding to chase.

From a technical standpoint, the database opens several promising research directions. Allf notes that the team can use Who Eats Whom to identify novel trophic relationships that have not yet appeared in the academic literature, then contribute those findings formally to scientific publications. The long-term ambition is for the platform to function as a parallel database that complements the peer-reviewed literature, compiling as much feeding information as possible into a single, accessible location. Because observations are time-stamped and geolocated through iNaturalist, the dataset also carries temporal and spatial dimensions that static literature reviews cannot match, potentially allowing scientists to track how feeding relationships shift across seasons, habitats and years.

Visualization is central to that ambition, and it is where Mallavarapu’s team is investing heavily. She describes a planned visual representation of this planetary-scale food web, designed to capture how trophic interactions relate to one another and how those relationships change over time. A simple version of the interface is already live, but the developers are building richer features that will let users explore feeding patterns and pose practical, personal questions — such as what to plant in a North Carolina garden to attract hummingbirds. That framing reveals the project’s dual identity: it is simultaneously a serious scientific database and an invitation for ordinary people to see themselves as participants in the ecological networks surrounding them.

Data quality remains a central challenge for any citizen science effort, and the team is developing tools specifically to validate submissions tagged on iNaturalist. Verification workflows will help ensure that predator and prey identifications are accurate and that interactions are recorded consistently, protecting the database’s scientific value as it scales. Beyond research, the project has an educational mission. The team has already created educational games built on the database, aimed at helping children understand the food web and the interdependencies it captures, with plans to expand that work if additional funding can be secured. The project was developed with substantial contributions from NC State students, including Maithili Bhoop, Adam Biscoe, Surabhi Nair and Lavanya Middha, alongside the thousands of iNaturalist users whose field observations make the entire enterprise possible.

The underlying research, titled Who Eats Whom? A global food web derived from citizen science, was published on September 22 in the open-access journal PLOS Biology. Senior author is Rob Dunn, a professor in NC State’s College of Agriculture and Life Sciences; additional authors include Nikhil Vasudeva, a former NC State undergraduate, and David Kikuchi, an assistant professor of integrative biology at Oregon State University. The researchers report no conflicts of interest. As the database grows, its creators hope it will transform not only how scientists study food webs but also how the public understands them — turning every hiker, gardener and backyard naturalist into a node in a worldwide effort to document the fundamental question of ecology: what eats what, and why it matters for the living planet.

Subject of Research: A citizen science platform that compiles global predator-prey interaction data from iNaturalist to map the planetary food web.

Article Title: How amateur naturalists are helping scientists track what everything eats

Article References: How amateur naturalists are helping scientists track what everything eats. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: citizen science, food web, iNaturalist, trophic interactions, ecology, biodiversity, Who Eats Whom, open-source database, PLOS Biology, public engagement, predator-prey relationships, data visualization