The invasion of an alien jellyfish in an Italian touristic port
Alien species are animal and plant organisms introduced accidentally or intentionally by humans outside their origin area. Maritime traffic is one of the species’ pathways of introduction, therefore, studying the alien populations that invaded port environments can help to fill the knowledge gaps on their invasion routes and impacts on local biodiversity and ecosystems.
In 2014, the Red Sea alien jellyfish Cassiopea andromeda invaded a touristic port in Palermo, named "Cala", and since then, its abundance has increased over time. This “Quaderno” reports the results of a research on the distribution and trophic behaviour of this species in Cala, carried out by ISPRA, in collaboration with the Stazione Zoologica Anton Dohrn, Department of Integrative Marine Ecology (EMI) - Sicily Marine Centre, and the University of Palermo, Department of Earth and Marine Sciences (DiSTeM).
The observed size variations among the jellyfish in Cala suggested that the found C. andromeda population was settled at depths of less than 7.5 m. The environmental parameters recorded during the sampling, consistent with the ideal conditions for the maintaining of a population, do not seem to have influenced the jellyfish aggregation inside the port. The isotopic analyses carried out on some sampled individuals, confirmed the so-called mixotrophic behaviour of this species, i.e. the ability to feed via direct predation and through photosynthesis of symbiotic microalgae.
All obtained results confirmed the ability of C. andromeda to live and reproduce in highly anthropized areas, such as ports, which renders this jellyfish a successful invader in current and future scenarios of climate change.
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