Marine Research Findings of the VECTORS Project

This website provides access to the research results of the VECTORS project, which can be used to support marine management decisions, policies and governance as well as future research and investment. VECTORS was a large scale project that brought together more than 200 expert researchers from 16 different countries. It examined the significant changes taking place in European seas, their causes, and the impacts they will have on society.

Phytoplankton dynamics in relation to environmental changes in a phytoplankton-dominated Mediterranean lagoon (Sardinia, Italy)

In recent decades, increased anthropogenic inputs of nitrogen and phosphorus have led to severe eutrophication problems in many coastal areas worldwide, inducing higher phytoplankton primary production. This can, in turn, lead to significant changes in the structure and function of the affected ecosystems1. Moreover, one of the effects of eutrophication is the development and persistence of harmful algal blooms (HABs), caused both by toxic and nuisance algae. In parallel, a trend of cell size reduction in phytoplankton composition has been signalled in a wide range of aquatic environments in the last decades, suggesting that it can be one of the phytoplankton’s responses to global climate change. In this study, we assessed the dynamics of phytoplankton assemblages, including potential harmful algal species (HAS), in relation to environmental changes in the phytoplankton-dominated Cabras Lagoon (Sardinia, Italy; Fig . 1).


Increased anthropogenic inputs of nitrogen and phosphorus have led to severe eutrophication problems in Mediterranean coastal waters. Eutrophication and increased turbidity of the water can severely reduce light availability in the water column, affecting benthic communities and ecosystem biodiversity and functioning.

Chlorophyll a always expressed mean concentrations higher than 10µg/L (Fig. 2a), showing a clear seasonal trend with the highest values in autumn and winter and secondary peaks in summer, and an annual mean of about 40µg/L. Phytoplankton cell density was generally greater than 108 cells/L throughout the study period (Fig. 2b). Modifications in phytoplankton composition strongly correlated with intense rainfall. This generated an abrupt salinity decrease (from >40 to <3 PSU) that, combined with high nutrient availability, favoured the dominance of Cyanophyceae of reduced cell size, such as Cyanobium and Rhabdoderma species.


Extreme weather events, such as intense rainfall, favoured the dominance of Cyanophyceae of reduced cell size. It is suggested that the prolonged and intense dominance of Cyanophyceae, added to other HAS (Harmful Algal Species), has a negative impact on the primary economic activities of the lagoon, such as fishery.

The well known capability of Cyanophyceae in producing bioactive compounds with toxicological effects in freshwater environments, has been recently reported also in brackish and marine environments23. These potential negative effects of Cyanophyceae proliferations add to those of other HAS (Harmful Algal Species), especially in lagoons where fishery and shellfish harvest constitute the main economic activities.

Long-term investigations and comparisons at the eco-region level will be crucial for understanding whether the observed dynamics are mainly locally determined or whether they could be partially driven by global changes. This paper provided input the review conducted in WP1 with special reference to land-based pollution, eutrophication and possible impacts on fisheries.

Relevance for Policy:
  • Alien Invasive Species Directive
  • Common Fisheries Policy
  • Convention on Biological Diversity
  • Directive on Maritime Spatial Planning and Integrated Coastal Management (forthcoming)
  • Environmental Impact Assessment Directive
  • EU Biodiversity Strategy
  • International Convention for the Control and Management of Ship's Ballast Water and Sediments
  • Marine Strategy Framework Directive
  • Strategic Environmental Assessment Directive
  • Water Framework Directive


Lead Author:

Paolo Magni
Institute for Coastal Marine Environment of the National Research Council (IAMC-CNR)
Date of research: July 2012

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Population dynamics of sprat in the Baltic Sea 

Processes impacting overwintering larval survival 

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This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 266445
© Vectors 2015. Coordinated by Plymouth Marine Laboratory.