Zooplankton Dynamics in Marine Ecosystems

Zooplankton, the drifting animal component of plankton, underpin the structure and function of marine food webs, mediating energy transfer from primary producers to higher trophic levels. Their abundance, distribution and behaviour are shaped by physical processes such as currents, eddies and vertical stratification, as well as by biological interactions including predation and competition. Diel vertical migration, a daily ascent and descent through the water column, drives biogeochemical cycles by transporting carbon and nutrients between surface and deeper layers. Spatial heterogeneity, from coastal shelf seas to the mesopelagic zone, and temporal variability, from seasonal blooms to long-term climate trends, influence zooplankton community composition and productivity. Advances in acoustic sensing, in situ observation platforms and genomic tools have transformed our capacity to resolve fine-scale dynamics and to predict responses to stressors such as hypoxia, warming and ocean acidification. Understanding these dynamics is critical for managing fisheries, conserving biodiversity and modelling carbon sequestration in a changing ocean.

Research from Nature Portfolio

Recent studies have explored how mesoscale oceanic eddies influence the distribution of forage fauna, including small zooplankton, at a global scale. Acoustic surveys across a thousand eddies reveal that only a minority enhance the concentration of forage organisms, with positive aggregation linked to eddy amplitude and water-mass trapping. This nuanced picture challenges the assumption that eddies uniformly enrich food for higher predators and highlights the importance of characterising the physical properties that govern biological responses.

Large-scale acoustic observations of mesopelagic scattering layers have detailed regional patterns in vertical distribution and diel vertical migration. Surveys spanning diverse ocean basins show strong spatial gradients in the depth and migratory behaviour of scattering layers, reflecting variations in temperature, oxygen and turbidity. On average half of the mesopelagic biomass undertakes daily excursions to surface waters, but migration proportions vary from 20% to 90% between regions, implying significant consequences for regional carbon flux and predator–prey interactions.

Zooplankton Dynamics in Marine Ecosystems publication trend

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

Technical terms

Zooplankton: Heterotrophic organisms drifting in the water column, ranging from microscopic protozoans to small crustaceans and gelatinous forms.

Mesopelagic zone: Ocean layer between approximately 200 m and 1 000 m depth, characterised by low light levels and host to vast biomass.

Diel vertical migration (DVM): Daily movement of organisms from depth to surface waters, often driven by feeding and predator-avoidance strategies.

Scattering layer: Aggregations of organisms detectable by sonar, forming acoustically reflective horizons in the water column.

Oceanic eddy: A rotating body of water, often tens to hundreds of kilometres across, that can trap and transport nutrients and organisms.

References

1. A rare oasis effect for forage fauna in oceanic eddies at the global scale. Nature Communications (2024).
2. Large scale patterns in vertical distribution and behaviour of mesopelagic scattering layers. Scientific Reports (2016).
3. Life in the Midwater: The Ecology of Deep Pelagic Animals. Annual Review of Marine Science (2024).
4. Interactive Effects of Hypoxia and Temperature on Coastal Pelagic Zooplankton and Fish. Frontiers in Marine Science (2019).
5. Quantifying carbon fluxes from primary production to mesopelagic fish using a simple food web model. ICES Journal of Marine Science (2018).