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.

Molecular recognition of moon jellyfish across the Mediterranean Sea and first identification of the recently introduced Aurelia sp.1 population in the Varano coastal lagoon

The moon jellyfish (Aurelia spp.) is likely the most studied taxon of scyphomedusae, as well as the one with the widest distribution worldwide, since it has been found from polar to tropical latitudes. The taxonomy of this genus is currently in a state of upheaval, since recent molecular phylogenetics studies redrew it as composed of a few morphologically distinguishable species (A. aurita, A. limbata and A. labiata) and several other cryptic species (i.e. species not distinguishable using classical morphological characters). Many of the Aurelia species are geographically restricted, but some of them have a disjointed distribution likely due to multiple human mediated introductions. Nevertheless, information about the Aurelia jellyfish geographic distribution in the Mediterranean Sea is still poor and fragmented.

A DNA barcoding study was carried out with the purpose of improving the knowledge about the distribution of Aurelia spp. in the Mediterranean Sea and identifying, for the first time, the Aurelia population recently introduced in the Varano Lake, a coastal lagoon situated along the Italian Adriatic coast1.

Sequences of the mitochondrial Cytochrome Oxidase subunit I (COI) gene and the nuclear 28S rDNA gene obtained for all the study specimens were aligned with COI and 28S sequences from several previously identified Aurelia species present in GenBank and analysed using DNA barcoding techniques. The 54 sequences of Aurelia spp. collected across the Mediterranean Sea and northern European Seas comprised four genetically distinct species of Aurelia: Aurelia aurita (specimens from British Islands); Aurelia sp. 1 (Varano Lake, Italy; Empuriabrava, Spain); Aurelia sp. 8 (Bizerte, Tunisia; Porto Cesareo, Italy); Aurelia sp. 5 (Mljet Lake, Croatia) (Fig. 1). All data were supported by a robust “barcoding gap”, namely a well-defined difference between intra-specific and inter-specific pairwise genetic distances. These results first confirmed Aurelia sp. 5 as a species confined in the Mljet Lake and Aurelia aurita as a stable inhabitant of the European North Atlantic Ocean and North Sea coasts, not found throughout the Mediterranean Sea. They also confirm the southern distribution of Aurelia sp. 8, of probable lessepsian origin, which was identified as the species inhabiting the open waters of southern and central Mediterranean and Ionian coasts (Bizerte and Porto Cesareo)2

All of the three species in the Mediterranean Sea cohabit in the Adriatic Sea.

Until now, only Aurelia sp. 5 and Aurelia sp. 8 were considered to stably inhabit the coastal waters of this small basin, not considering the moon jellyfish population in the Varano Lake which was identified as Aurelia sp. 1. Another interesting finding of this study was the occurrence of Aurelia sp. 1 both in the Varano Lake and in the touristic harbour of Empuriabrava, namely two sheltered areas highly affected by human activities. Aurelia sp. 1 was probably introduced in the Empuriabrava marina by ships and it may also be one of the sources from which the species spread along the north-west Mediterranean Sea. Whereas a likely explanation of the Aurelia sp. 1 presence in the Varano Lake is the regular import of mussels and shrimps from other localities for aquaculture restocking purposes that may have served as vectors for the introduction of polyps or ephyrae. Nevertheless, the failed colonisation of these kind of environments by other species already present in the Mediterranean Sea (for example Aurelia sp. 5 or Aurelia sp. 8, which bloom in the Adriatic Sea), suggests that Aurelia sp. 1 might be ecologically advantaged in coastal basin environments in the Mediterranean Sea. The hypothesised adaptability of Aurelia sp. 1 to environments often subjected to sharp environmental changes (i.e. coastal lagoons and harbours) might represent the main reason for its ubiquitous distribution worldwide. This work was based on available samples deposited at the VECTORS repository DNA/tissue bank at the University of Salento.

Relevance for Policy:
  • Alien Invasive Species Directive
  • Convention on Biological Diversity
  • EU Biodiversity Strategy
Data availability:

Data used: DNA samples

Where it is held: Samples deposited at the VECTORS repository DNA/tissue bank

Contact: University of Salento


  • Scorrano, S. 2014. Impacts of Aurelia sp. 1 outbreaks in a Mediterranean coastal lagoon (Varano, SE Adriatic coast). PhD Thesis, University of Salento, Lecce and Università della Tuscia, Viterbo: 1-169.
  • Scorrano S, Aglieri G, Boero F, Dawson MN, Piraino S. In preparation. Unmasking the Aurelia jellyfish species complex within the Mediterranean: an integrated morphological and molecular approach.

Lead Author:

Stefano Piraino
Date of research: January 2015

Related articles:

Effects of invasive amphipod on native amphipods

Extreme ecological events and jellyfish outbreaks

Food web change along a nearshore-offshore gradient

Food webs along the European Atlantic coast

Habitat suitability of native and invasive species 

Impact of invasive mussels on carbon flow 

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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.