A new record of the invasive seaweed Caulerpa cylindracea Sonder in the South Adriatic Sea

Abstract

The green alga Caulerpa cylindracea Sonder is one of the most infamous and threatening invasive species in the Mediterranean Sea. Since 1985, it started rapidly spreading to all Mediterranean regions causing many ecological changes on natural communities. In the present study, we present an example of this proliferation with the first record in the Marine Protected Area of Tremiti Island (MPATI) in the South Adriatic Sea. Fifteen sites along the coast and 5 different depths have been investigated. Our results provide eveidence of a wide invasion of this pest in three islands, San Domino, San Nicola and Capraia. This study fills a particular data gap in the ongoing biomonitoring of invasive seaweeds in the Mediterranean Sea representing a base line of this invasive species for the MPATI.

Keywords: Aquatic ecology; Bioinvasion; Biological pollutants; Caulerpa cylindracea; Ecology; Ecosystem change; Environmental science; Flora; Invasive macrophytes; Mediterranean sea; Tropicalisation.

Fig. 1

a) Updated geographical distribution of Caulerpa cylindracea in the Mediterranean Sea. Black dots denote invaded locations cited in Verlaque et al., (2000); Ruíz et al., 2007; Sciberras and Schembri (2007); Klein and Verlaque (2008); Bouiadjra et al., (2010); Guillén et al., 2010; Rivera-Ingraham et al., (2010); Tsiamis et al., (2010); Bentaallah and Kerfouf (2013); Otero et al., (2013); Altamirano et al., (2014); star with black arrow indicates the new reported presence; b) Map of the MPA of Tremiti Islands with the 15 transects (7 labeled in yellow with presence of C. cylindracea; 8 labeled in white without); and the four alleged pollution sources; Gas station (sky blue triangle Site A); Port of San Domino (green triangle Site B); Port of San Nicola (orange triangle Site C); Water Tanker Vessel (fuchsia triangle Site D). The circle size and color refer to the cover of C. cylindracea as total sum in all quadrats and in all depths of the sites where it has been reported.

Fig. 2

a) Species accumulation curves and b) bar plots illustrating the abundance of C. cylindracea as cumulative cover and standard deviation in all quadrats where it was recorded, grouped by depth and isle; n = number of plots with C. cylindracea.

Fig. 3

Constrained correspondence analysis (CCA) on fauna and flora P/A data collected at Capraia, San Domino and San Nicola from 5, 10, 15, 20 and 25 m depth. Species vectors are indicated in grey, and species names in black. Environmental variables vectors and names are shown in red. Each point refers to a single replicate quadrat.