Phytoplankton Dynamics in Black Sea Ecosystems

Phytoplankton dynamics in the Black Sea are shaped by the interplay of physical stratification, nutrient inputs, light availability and biotic interactions. Distinct seasonal blooms occur in spring and summer, driven primarily by riverine discharge, atmospheric deposition and episodic upwelling. The formation of a deep chlorophyll maximum (DCM) at 30–40 m depth concentrates a substantial proportion of primary production, its depth set by winter mixing and modulated by mesoscale circulation. Since the late twentieth century, anthropogenic eutrophication has intensified blooms and shifted community composition towards opportunistic species such as Noctiluca scintillans and coccolithophores. Interannual variability reflects climatic teleconnections, dam operations and extreme weather, while shelf–offshore heterogeneity arises from gradients in nutrient supply and hydrodynamic features like the Rim Current. Phytoplankton processes underpin carbon cycling, oxygen dynamics and food-web structure, with implications for fisheries management and ecosystem health. Advances in satellite observation, autonomous sensors and numerical modelling have enhanced our capacity to monitor bloom dynamics and biogeochemical fluxes, informing mitigation strategies for eutrophication and hypoxia.

Research from Nature Portfolio

Recent studies have examined the ecological impact of an environmental shock caused by dam collapse, revealing rapid nutrient enrichment and phytoplankton response. Satellite observations coupled with hydrodynamic and biogeochemical modelling demonstrated a twenty-day persistence of intense algal blooms following massive influxes of nitrate, phosphate and suspended sediments into the north-western basin. These findings underscore the sensitivity of Black Sea productivity to abrupt anthropogenic disturbances and the value of integrated remote sensing and in situ strategies for assessing short-term ecosystem resilience.

Phytoplankton Dynamics in Black Sea Ecosystems publication trend

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

Technical terms

Deep chlorophyll maximum (DCM): A subsurface layer at which chlorophyll concentration peaks, resulting from the balance between light penetration and nutrient availability.

Eutrophication: The enrichment of water by nutrients, especially nitrogen and phosphorus, leading to excessive algal growth and potential oxygen depletion.

Coccolithophore: A group of single-celled, calcifying phytoplankton characterised by external plates (coccoliths), often forming extensive blooms detectable by satellite.

Rim Current: The dominant cyclonic circulation pattern encircling the Black Sea, influencing the transport and distribution of nutrients and planktonic organisms.

References

1. The biogeochemical response of the north-western Black Sea to the Kakhovka Dam breach. Communications Earth & Environment (2025).
2. Regional Algorithm for Estimating High Coccolithophore Concentration in the Northeastern Part of the Black Sea. Remote Sensing (2023).
3. Black Sea Eutrophication Comparative Analysis of Intensity between Coastal and Offshore Waters. Sustainability (2024).
4. Dynamics of the deep chlorophyll maximum in the Black Sea as depicted by BGC-Argo floats. Biogeosciences (2021).
5. Black Sea Ecosystem Response to Climatic Teleconnections. Oceanography (2005).