bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/593822

Catching the big picture of the Mediterranean Sea biodiversity with an end-to-end model of climate and fishing impacts

Moullec, F.·Velez, L.·Verley, P.·Barrier, N.·Ulses, C.·Carbonara, P.·Esteban, A.·Follesa, C.·Gristina, M.·Jadaud, A.·Ligas, A.·Lopez Diaz, E.·Maiorano, P.·Peristeraki, P.·Spedicato, M. T.·Thasitis, I.·Valls, M.·Guilhaumon, F.·Shin, Y.-J.
View original source ↗Export metadata ↓

Abstract

The Mediterranean Sea is among the main hotspots of marine biodiversity in the world. Under combined pressures of fishing activities and climate change it has also become a hotspot of global change, with increased concern about the worsening status of marine exploited species. More integrated modelling approaches are needed to anticipate global change impacts in the Mediterranean Sea, in order to help decision makers prioritizing management actions and strategies, mitigating impacts and adapting to changes. Our challenge was to develop a holistic model of the marine biodiversity in the Mediterranean Sea with an explicit representation of the spatial multispecies dynamics of exploited resources under the combined influence of climate variability and fishing pressure. An individual-based ecosystem model OSMOSE (Object-oriented Simulator of Marine ecOSystEms), including 100 marine species (fish, cephalopods and crustaceans) and representing about 95 % of the total declared catches, has been implemented for the first time at a high spatial resolution (400 km2) and at a large spatial scale (whole Mediterranean basin). The coupling of OSMOSE to the NEMOMED 12 physical model, and to the Eco3M-S biogeochemical and low trophic level model has been achieved to build the OSMOSE-MED end-to-end model. We fitted OSMOSE-MED to observed and estimated data of biomass and commercial catches using a likelihood approach and an evolutionary optimization algorithm. The outputs of OSMOSE-MED were then verified against observed biomass and catches, and confronted to independent datasets (MEDITS data, diet compositions and trophic levels). Although some improvements are suggested for future developments, the model results at different hierarchical levels, from individuals up to the ecosystem scale, were consistent with current knowledge and observations on the structure, the functioning and the dynamics of the ecosystems in the Mediterranean Sea. All the modelling steps, from the comprehensive representation of key ecological processes and feedbacks, the careful parameterization of the model, the confrontation to observed data, and the positive outcome from the validation process, allowed to strengthen the degree of realism of OSMOSE-MED and its relevance as an impact model to explore the futures of marine biodiversity under scenarios of global change, and as a tool to support the implementation of ecosystem-based fisheries management in the Mediterranean Sea.

Source connections

Explore related subjects

ecologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Moullec, F., Velez, L., Verley, P., Barrier, N., Ulses, C., Carbonara, P., Esteban, A., Follesa, C., Gristina, M., Jadaud, A., Ligas, A., Lopez Diaz, E., Maiorano, P., Peristeraki, P., Spedicato, M. T., Thasitis, I., Valls, M., Guilhaumon, F., Shin, Y.-J.. 2019-03-31. Catching the big picture of the Mediterranean Sea biodiversity with an end-to-end model of climate and fishing impacts. https://doi.org/10.1101/593822

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Human-caused ignitions and plant invasion drive fire-regime change in a dryland biodiversity hotspot

Dryland ecosystems cover much of Earths terrestrial surface and are increasingly affected by climate warming, land-use change, and biological invasion. The Sonoran Desert of western North America, a biodiversity hotspot that historically experienced infrequent fire, exemplifies how these global-change processes are driving ecosystem transformation through the emergence of novel disturbance regimes. Using records of more than 73,000 wildland fire events, we quantified anthropogenic and environmental controls on fire ignition, size, and spread across the Sonoran Desert. Human-caused ignitions accounted for 95.5% of all recorded fires since the early 1990s and were concentrated near roads, buildings, and other areas of human activity, particularly during late spring. In contrast, lightning-caused ignitions were rare within the Sonoran Desert and occurred primarily in adjacent montane forests during late summer months. Consistent with broader trends across the western United States, fires were typically largest when they ignited far from roads, where access is limited, and fire management often relies on indirect attack strategies. Pre-fire annual and perennial herbaceous vegetation both promoted fire spread, with detectable effects at cover values as low as 5%, while bare ground reduced fuel connectivity and constrained fire growth. Rather than exhibiting a distinct threshold response, fire spread increased linearly with herbaceous cover, suggesting that even modest increases in fine fuels can alter fire behavior in this historically fuel-limited ecosystem. Together, our results illustrate that human ignitions determine where fires occur, whereas herbaceous fuels determine whether those ignitions spread, driving fire-regime transformation across an iconic North American desert. Managing and adapting to this novel fire regime will require coordinated efforts to reduce human-caused ignitions, limit invasive herbaceous fuels, maintain bare-ground interspaces, and rapidly suppress fires. More broadly, our findings identify the mechanisms controlling fire regime change in dryland ecosystems and provide a framework for anticipating ecosystem transformation under ongoing global change.

ecology↗
bioRxiv2026

Hidden infections: Linking parasite ecology, fish health and stakeholder perceptions in Nile tilapia aquaculture in central Kenya

Parasite infections in farmed fish may remain unrecognised when fish-health assessment relies mainly on visible signs. We investigated metazoan parasite occurrence, parasite diversity and community composition, associations between gill-parasite burden and histological alterations, and stakeholder recognition of fish-health problems in Nile tilapia (Oreochromis niloticus) aquaculture in central Kenya. We examined 157 fish from 20 farms, assessed gill histology in 137 fish, measured water quality once per farm, and collected questionnaire and interview data from 48 stakeholders. Five metazoan parasite groups were recorded, with monopisthocotylans the most prevalent (36.3%). Higher monopisthocotylan burden was associated with a greater cumulative number of gill lesion types (odds ratio 1.86, 95% CI 1.43-2.42, p < 0.001), whereas copepod burden was not. Parasite diversity was higher in the larger operational pond category across all three Hill-number orders (p = 0.006-0.008), and parasite-community composition differed between categories (PERMANOVA, p = 0.034), although these comparisons were exploratory because only four farms were in the larger category and farm category overlapped with county. Single-time-point water-quality measurements showed no clear associations with parasite burden, diversity or community composition after multiple-testing correction. Farmers and fisheries or extension officers recognised signs of poor fish health but rarely identified parasites as a specific cause, and routine diagnostic confirmation was uncommon. The findings reveal a gap between laboratory detection of parasite-associated gill alterations and farm-level recognition and diagnosis.

ecology↗
bioRxiv2026

Elevational filtering reshapes mountain understory communities through diversity decline, functional shifts, and species replacement

Mountain understory communities are structured along elevational gradients, as environmental constraints filter which species and ecological strategies can persist and where. Yet, how community differentiation, local diversity, functional strategies, and species replacement are shaped by elevational gradients remains poorly resolved. Here, we examine 107 herbaceous species across 27 sites spanning 2,202-3,696 m a.s.l. and three elevational zones. We determine how elevation reorganizes multiple dimensions of community assembly. We hypothesize that increasing elevation differentiates community composition, reduces -diversity, favors persistence-oriented strategies, and drives {beta}-diversity primarily through species turnover, rather than nestedness. We test our hypotheses by integrating taxonomic, functional, and {beta}-diversity patterns across the elevational gradient. A coherent pattern of community reassembly emerges as elevation increases: communities become increasingly distinct with elevational separation and locally less diverse toward higher elevations. Functional composition changes concurrently, with perennial and chamaephytic groups increasing as annual and therophytic groups decline. We find that increasing community differentiation primarily reflects species replacement rather than progressive species loss. Species turnover accounts for 97.95% of total Sorensen {beta}-diversity and increases with elevational separation, whereas nestedness declines. Our findings therefore show that elevation reorganizes herbaceous understory communities through linked changes in diversity, functional strategies, and species identity. Indeed, environmental filtering favors persistence-oriented strategies while progressively replacing species across elevations, linking taxonomic and functional differentiation within a common process of mountain understory community assembly.

ecology↗