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.

The impact of invasive mussels on the carbon flow from primary producers to benthic consumers

In the marine environment, the introduction of non-indigenous mussels may cause major modifications to native assemblages1. Yet, how invasive mussels alter the carbon transfer from the first to the second trophic levels of the benthic food webs remains unknown.

Invasive mussels can have positive effects on the microalgal uptake by deposit-feeders because of the production of biodeposits, due to mussel feeding, and alteration of depositional environment, due to the shells, increases the availability of suspended microalgae into the sediment. In addition, invasive mussels may indirectly reduce the availability of suspended food sources to deposit-feeders through the interaction with other bivalves.

We compared the impacts of the Asian mussel Arcuatula sehnousia on the amount of suspended microalgae taken up by the polychaete deposit-feeder Cirriphormia tentaculata to those of the native clam Ruditapes decussatus in the laboratory by using the suspended microalgae previously enriched with 13C1.


This study provides the first evidence that invasive mussels can benefit by an association with local clams, increasing the food intakes while reducing those of clams, and reduce food availability for deposit feeders, by impairing feeding, incorporation and biodeposition of clams.

Contrary to our expectations, the microalgae C-uptake of C. tentaculata was lower in the presence of the invasive mussels than in the presence of the native clam, indicating that the invasive mussel has a negative effect on the transfer of carbon from suspended microalgae to this deposit-feeder (1 in Fig.1).

In addition, there was an interactive effect of the invasive mussel and the native clam on the microalgae C-uptake of C. tentaculata (2). The invasive mussels benefit by the association with native clams, increasing the food intakes (3) while reducing those of clams (4). By doing this, it indirectly reduces the food availability for deposit-feeders (5). These negative (direct and indirect) effects of the invasive mussels were found to be independent of mussel’s densities, indicating the C flow from the first to the second trophic levels of the benthic food web to be at risk from this invasion.


The alteration of the C-flow imposed by the presence of the invasive mussels may drive the changes in the distribution of abundances and biodiversity of native benthic assemblages, so that it should be taken into account in future studies of management and conservation of coastal systems.

The invasive mussel A. senhousia has a short lifespan and a high ability of dispersal and recruitment that ensures the periodic formation of the mussel’s patches in a system. The alteration of the C flow imposed by the presence of the invasive mussel may drive the changes on biodiversity and abundances of native populations over long periods, so that it should be taken into account in future studies of management and conservation of coastal systems.

Relevance for Policy:
  • Alien Invasive Species Directive
  • Convention on Biological Diversity
  • Directive on Maritime Spatial Planning and Integrated Coastal Management (forthcoming)
  • Environmental Impact Assessment Directive
  • EU Biodiversity Strategy
  • Guidelines for the Control and Management of Ships’ Biofouling to Minimize the Transfer of Invasive Aquatic Species
  • Habitats and Birds Directive
  • ICZM Protocol to the Barcelona Convention
  • Marine Strategy Framework Directive
  • Water Framework Directive


Lead Author:

Serena Como
Institute for Coastal Marine Environment of the National Research Council (IAMC-CNR)
Date of research: May 2014

Related articles:

Ecosystem impacts of non-indigenous species

Invasive ecosystem engineers and biodiversity

Food web change along a nearshore-offshore gradient

Food webs along the European Atlantic coast

Impact of the non-indigenous Chinese mitten crab 

Invasive species and ballast waters mitigation 

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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.