Impacts of Aurelia sp. 1 outbreaks in a Mediterranean coastal lagoon (Varano, SE Adriatic coast)
Scorrano, S. (2014). Impacts of Aurelia sp. 1 outbreaks in a Mediterranean coastal lagoon (Varano, SE Adriatic coast). PhD Thesis. Università degli Studi della Tuscia, Dipartimento di Scienze Ecologiche e Biologiche: Viterbo. 157 pp.
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Document type: Dissertation
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| Keywords |
MED, Italy, Puglia, Varano Lagoon
Trophic level
Aurelia aurita (Linnaeus, 1758) [WoRMS]; Aurelia coerulea von Lendenfeld, 1884 [WoRMS]
Varano Lagoon [Marine Regions]
Marine/Coastal |
| Author keywords |
Aurelia spp., plankton dynamics, cryptic species |
| Abstract |
In recent decades, scientific efforts focused on observed increase of jellyfish outbreaks, particularly in coastal ecosystems, as both causes and consequences of significant alterations in zooplankton community and dynamics. One of the most common and ubiquitous outbreak - forming species, the scyphomedusa Aurelia sp.1 (sensu Dawson, 2003), occurs worldwide throughout many coastal areas. In Mediterranean sea, it recently established in enclosed areas, like the coastal lagoon of Varano (Apulia, SE Adriatic coast). The total absence of bibliographic data requested a broad-spectrum investigation, with the main aim of creating the basis for a general knowledge of the impacts Aurelia sp. outbreaks. In the framework of the VECTORS project, a two-year investigation was launched in 2011 in order to collect data about population dynamics and trophic ecology of Aurelia sp.1 in the coastal lagoon of Varano. The results showed that the population dynamic of the established Aurelia sp.1 is regulated by the variation in physical factors as temperature and salinity. Spatial and temporal analysis of plankton community showed also that trophic cascades on food web are the result of a sudden increase in the abundance of jellyfish population. Gut content and stable isotope analysis clarified the trophic role of Aurelia sp.1 in the lagoon according to size, and showed that jellyfish can vary the diet over the year by an opportunistic and omnivorous foraging behavior. The study also unveiled the key role of micro-zooplankton as food source for the early jellyfish life stages. Furthermore, morphological analyses provided a complete description based on life stages for the population resident in the coastal lagoon of Varano. Molecular data (COI barcoding) documented the first record of Aurelia sp.1 along the Adriatic coasts and the first undisputable evidence of its establishment in the Mediterranean. Moreover the integration of morphology/morphometrics and molecular systematics applied to Aurelia spp. populations from Mediterranean and North Sea, demonstrated to be a powerful tool for species identification and for determining geographical distributions of Aurelia spp. cryptic species. Finally, testing natural and artificial inducers of strobilation on Aurelia spp. polyps, elucidated differences in the developmental patterns regulating the initiation of jellyfish outbreaks of different Aurelia species |
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