Demersal Fish Community Dynamics in Marine Ecosystems

Demersal fish communities occupy the interface between benthic habitats and the pelagic environment, playing a central role in nutrient cycling, energy transfer and benthic–pelagic coupling. These assemblages span continental shelves, slopes and deep-sea areas, and their structure is shaped by depth gradients, substrate heterogeneity and hydrodynamic regimes. Species composition typically shifts from fast-growing, short-lived taxa in shallower waters to longer-lived, slow-growing species in deeper zones, reflecting adaptations to nutrient availability and predation pressure. Fishing activities, notably bottom trawling, have historically altered community size structure and diversity, selectively removing large individuals and reducing functional redundancy. Climate-driven changes in temperature and oxygen concentration further influence distributional limits and reproductive success, with cascading effects on trophic interactions. Advances in trait-based approaches have revealed that functional diversity metrics—such as richness, evenness, divergence and dispersion—provide sensitive indicators of community resilience and ecosystem function. Management strategies that integrate depth-stratified biomass spectra, catch-per-unit-effort indices and functional trait analyses can improve stock assessments and conservation measures. Emerging technologies, including remote sensing and autonomous underwater vehicles, now permit high-resolution surveys of demersal assemblages, facilitating adaptive spatial management and the designation of depth-specific protection zones. Understanding the interplay between environmental drivers, anthropogenic pressures and community trait composition is essential to safeguard the global food security and biodiversity services delivered by demersal fish ecosystems.

Research from Nature Portfolio

Recent studies have refined global assessments of fish community functional diversity by incorporating unreported catches—such as bycatch, discards and small-scale fisheries—into catch reconstructions. These analyses demonstrate that while global-scale patterns of functional diversity remain broadly consistent, local and regional estimates can vary by up to 46% when unreported components are included. This work underscores the need for improved catch data integration in routine assessments, and it proposes a research agenda focused on standardising functional trait databases, enhancing reporting protocols and developing management-relevant indicators of ecosystem integrity and resilience.

Demersal Fish Community Dynamics in Marine Ecosystems publication trend

The graph below shows the total number of articles in demersal fish community dynamics in marine ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Demersal fish: Species living and feeding on or near the seabed.

Functional diversity: Range and distribution of ecological traits within a community.

Bottom trawling: Fishing method dragging heavy nets along the seafloor.

Biomass spectrum: Distribution of organism biomass across body-size classes.

Catch per unit effort (CPUE): Measure of catch relative to the amount of fishing effort expended.

Large Fish Indicator (LFI): Proportion of total community biomass composed of large-bodied individuals.

References

1. Improving understanding of the functional diversity of fisheries by exploring the influence of global catch reconstruction. Scientific Reports (2017).
2. Out of Sight, But Within Reach: A Global History of Bottom-Trawled Deep-Sea Fisheries From >400 m Depth. Frontiers in Marine Science (2018).
3. How functionally diverse are fish in the deep? A comparison of fish communities in deep and shallow‐water systems. Diversity and Distributions (2021).
4. Size-based indicators show depth-dependent change over time in the deep sea. ICES Journal of Marine Science (2017).