Detection of an unusual presence of the cubozoan Carybdea marsupialis at shallow beaches located near Denia, Spain (south-western Mediterranean)

Abstract

An unusual bloom of the cubozoan Carybdea marsupialis occurred at some beaches located near Denia (south-western Mediterranean Sea, south-eastern Spain) during the summer of 2008. The bloom was first detected and recorded by the local Red Cross first aid services. Densities of C. marsupialis in the area were characterized by quantitative sampling. The number of bathers stung totalled 3330 during the three months of summer. Sampling at shallow beaches from 15 September to 21 November 2008 gave insights into cubozoan density in the area, estimated at 265.9 individuals per 100 m2 as the highest value. These densities have never been recorded previously in the Mediterranean where the species was considered to be rare. Mean density along the 17 km of coastline which was sampled reached 5.4 ± 3.8 ind/100 m2. Data on size distribution are also given. This paper analyses the reasons behind these unusually high abundances of C. marsupialis in the north-western Mediterranean Sea and provides guidelines for future studies to elucidate the causes of this bloom