Functional and Trophic Structuring of Micronektonic Fishes in the Northeast Atlantic
Abstract
In pelagic ecosystems, sharp vertical gradients in resources and environmental conditions structure species adaptations, interactions and community assembly. Yet, the ecological mechanisms underlying these patterns remain poorly resolved. To investigate the functional and trophic structure of micronektonic fishes, specimens were collected across the epipelagic (0–200 m) and mesopelagic layers (200–1300 m) using a midwater trawl. A functional analysis of 85 species, characterized by 10 categorical traits, was conducted to define functional groups, identify key ecological trade‐offs among them and characterize the functional structure across depth strata. Stable carbon and nitrogen isotope values of fish tissues provided complementary insights into trophic structure, linking functional diversity with patterns of resource partitioning along the vertical gradient. We identified four functional groups whose trade‐offs reflect metabolic adaptations primarily shaped by diet. These adaptations enable species to cope with pressure and light gradients while enhancing resource acquisition and predator avoidance, particularly in upper layers. Communities showed a clear vertical transition from migratory, surface‐linked zooplanktivores in upper layers to resident, deeper‐dwelling assemblages with more diverse feeding guilds associated with larger body sizes and increased reliance on alternative carbon pathways. Consistent with ecological competition theory, deeper layers exhibited high functional and taxonomic diversity under food limitation, whereas food‐rich upper layers showed lower functional diversity and greater ecological similarity. Overall, vertical partitioning and functional specialization jointly structure mesopelagic communities, shaping trophic pathways, resilience and contributions to carbon cycling in pelagic ecosystems.
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BibTeX
@article{thibault2026functional,
title = {{Functional and Trophic Structuring of Micronektonic Fishes in the Northeast Atlantic}},
author = {Hélène Thibault and Frédéric Ménard and Gildas Roudaut and Anne Lebourges-Dhaussy and Yves Cherel and Alejandro Ariza and Leandro Nolé Eduardo and Séverine Martini},
journal = {Ecology and Evolution},
year = {2026},
month = sep,
doi = {10.1002/ece3.74275},
url = {https://hal.science/hal-05746619v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Functional and Trophic Structuring of Micronektonic Fishes in the Northeast Atlantic
AU - Hélène Thibault
AU - Frédéric Ménard
AU - Gildas Roudaut
AU - Anne Lebourges-Dhaussy
AU - Yves Cherel
AU - Alejandro Ariza
AU - Leandro Nolé Eduardo
AU - Séverine Martini
PY - 2026
DA - 2026/09/10
JO - Ecology and Evolution
DO - 10.1002/ece3.74275
UR - https://hal.science/hal-05746619v1
AB - In pelagic ecosystems, sharp vertical gradients in resources and environmental conditions structure species adaptations, interactions and community assembly. Yet, the ecological mechanisms underlying these patterns remain poorly resolved. To investigate the functional and trophic structure of micronektonic fishes, specimens were collected across the epipelagic (0–200 m) and mesopelagic layers (200–1300 m) using a midwater trawl. A functional analysis of 85 species, characterized by 10 categorical traits, was conducted to define functional groups, identify key ecological trade‐offs among them and characterize the functional structure across depth strata. Stable carbon and nitrogen isotope values of fish tissues provided complementary insights into trophic structure, linking functional diversity with patterns of resource partitioning along the vertical gradient. We identified four functional groups whose trade‐offs reflect metabolic adaptations primarily shaped by diet. These adaptations enable species to cope with pressure and light gradients while enhancing resource acquisition and predator avoidance, particularly in upper layers. Communities showed a clear vertical transition from migratory, surface‐linked zooplanktivores in upper layers to resident, deeper‐dwelling assemblages with more diverse feeding guilds associated with larger body sizes and increased reliance on alternative carbon pathways. Consistent with ecological competition theory, deeper layers exhibited high functional and taxonomic diversity under food limitation, whereas food‐rich upper layers showed lower functional diversity and greater ecological similarity. Overall, vertical partitioning and functional specialization jointly structure mesopelagic communities, shaping trophic pathways, resilience and contributions to carbon cycling in pelagic ecosystems.
SN - 2045-7758
ER -