First record of the new alien sea jelly species Marivagia stellata Galil and Gershwin, 2010 off the Syrian coast

Abstract

Marivagia stellata Galil and Gershwin, 2010 (Scyphozoa: Rhizostomeae: Cepheidae), was recorded for the first time off the Syrian coast on the 6th of July 2015. Several specimens of the alien sea jelly species M. stellata were observed very close to the port of Lattakia, and a single specimen was caught, at a depth of 7 m by a professional scuba diver during a regular sea jelly monitoring program.

The occurrence of non-indigenous sea jelly species in the Syrian coastal waters may be related to the introduction of Indo-Pacific and Red Sea origin species into the Mediterranean Sea through the Suez Canal. The growing list of alien sea jelly indicates that considerable changes are occurring in the eastern Mediterranean marine environment.

Introduction

Over recent decades, man’s expanding influence on the oceans has caused significant changes on marine biodiversity, including sea jelly. There is a reason to think that in some regions, high abundances and massive new blooms of numerous non-indigenous sea jelly species are occurring in response to the cumulative effects of global change (Mills 2001, Purcell et al. 2007). Many reports of human problems with sea jelly have increased and captured public attention. Such problems come mainly from sea jelly stinging swimmers and interfering with fishing, aquaculture and power plant operations (Malej 2001; Pagès 2001; Benovic and Lucic 2001; Lynam 2006; Boero et al. 2008; Licandro et al. 2010; Sakınan 2011; Turan and Ozturk 2011; Mamish et al. 2012).

Negative impacts of the sea jelly outbreaks on human coastal activities have persuaded Tishreen University, High Institute of Marine Research and the Atomic Energy Commission of Syria, to initiate a sea jelly-monitoring program for surveying the Syrian coast (Northern Levantine coast). The list of the new alien sea jelly species recorded recently in the Syrian costal water (eastern Mediterranean Sea) is increasing. Phyllorhiza punctata von Lendenfeld, 1884, Aequorea globosa Eschscholtz, 1829, Cassiopea andromeda Forsskål, 1775, and Rhopilema nomadica Galil, 1990 have been recently recorded and they are mostly of Indo-Pacific and Red Sea origin introduced through the Suez Canal (Ikhtiyar et al. 2002; Durgham 2011; Mamish et al. 2012; Siokou et al. 2013; Mamish et al. 2015).

Here, we describe the first record of another alien sea jelly Marivagia setllata Galil and Gershwin 2010.

Material and methods

Approximately 60 specimens of this new sea jelly species were found during a regular sea jelly monitoring program by a professional scuba diver for the first time, on the 6th of July 2015, from a site very close to the port of Lattakia (lat. 32° 31“22.7’ N, long. 35° 44“35.3’ E) on the Syrian coast. A single specimen was caught at depth of 7 m using a hand-net. The temperature and salinity at the sampling time were 25 °C and 39‰ respectively. The specimen was taken to the laboratory and immediately examined while still alive, photographed, fixed in 4 % formaldehyde and stored in the zooplankton laboratory, High Institute of Marine Research (Fig. 1).

Fig. 1

Marivagia stellata Galil and Gershwin, 2010 off the Syrian coast. a and b: Aboral view. c: Oral view. d: Close up of exumbrellar pigmentation pattern. e: Lappets and radial canals

The umbrella diameter and the wet weight of the collected specimen were 14.5 cm and 150 g, respectively. The new species was identified as Marivagia stellata Galil and Gershwin, 2010 (Scyphozoa: Rhizostomeae: Cepheidae) by its unique combination of the remarkable morphological based on relevant characters as defined by Galil et al. 2010.

Marivagia stellata is a translucent bluish-white sea jelly, the exumbrella surface lacks central dome, warts, or knobs, ornamented with conspicuous pattern of reddish stars, dots and streaks clustered in center third of exumbrella (Fig. 1a, b, d and e). Subumbrella lacks filaments on oral disk and between mouths (Fig. 1c).

Results and discussion

The earliest record of Marivagia stellata Galil and Gershwin, 2010 species was initially described in 2010 from the southeastern Levantine coast of the Mediterranean Sea (Galil et al. 2010; Zaatari 2010. Later, in 2013, this species was reported from Kerala, India in the south-east of the Arabian Sea (Galil et al. 2013), and after that the species has been found off the mouth of the River Indus, Pakistan in 2014 for the first time (Gul et al. 2014). Even though the species has been discovered in the Mediterranean water before its discovery in the Indian Ocean, Galil et al. (2010) argued that M. stellata is a non-indigenous species. It is highly unlikely that a large native littoral species, markedly different from all known scyphozoans in the Mediterranean, would remain unknown until the 21 century. As the Southeastern Levant has been inundated by alien biota, it is likely M. stellata is an alien as well (Galil et al. 2010; Galil et al. 2013). It has been suggested that the origin of M. stellata species is from the Indian Ocean. It probably entered the Mediterranean Sea through the Suez Canal; in accordance with invasions of non-indigenous species continue documented recently in the eastern Mediterranean Sea (Zenetos et al. 2010; Galil et al. 2013; Galil et al. 2015). Therefore, the occurrence of this alien sea jelly species in the Syrian coastal waters may be due to the introduction of the Indo-Pacific origin species into the Mediterranean Sea through the Suez Canal. M. stellata is a true sea jelly and has a complex bipartite life-history. It has a typically cryptic sessile, asexually reproducing polypoid stage, which can asexually produce large numbers of planktonic young medusa (ephyra), followed by a pelagic and sexually reproducing medusa stage (Graham et al. 2007). Therefore, ephyra may have been carried with the Levantine coastal currents, as the case of the sea jelly species Aequorea globosa (Mamish et al. 2012), or as polyps in ship fouling or ballast water of ships, as the case of the sea jelly species Phyllorhiza punctata (Abed-Navandi and Kikinger 2007, Boero et al. 2009, Gueroun et al. 2014). The sudden appearance of 60 sexually mature specimens of the new alien sea jelly species together at the same time may be attributed to the fact that local population that has been already established close to the major port of Lattakia. This suggests transportation of species on ship hulls of the sessile polyp originates in the Indian Ocean, where the origin of all Cephidae genus were reported (Kramp 1961). However, such a complex bipartite life history severely limits our ability to understand origins and fates of this sea jelly species invasion (Graham et al. 2007).

This alien sea jelly species is rare so far in the Mediterranean Sea. There is little information about its effects on humans, apparently, it is not a sea jelly stings humans and it presumably has nematocysts. Further investigations on the isolation and characterization of venom from nematocysts of sea jelly M. stellata and its effects are needed.

New invasions of non-indigenous sea jelly species continue to be documented in the Syrian coastal waters in recent years, where M. stellata is the fourth scyphozoan species introduced to the Syrian coastal waters through the Suez Canal from the Indian Ocean. In addition, the growing list of alien sea jelly species indicates that considerable changes are occurring in the eastern Mediterranean marine environment. This makes the sea jelly monitoring program of critical importance both as an indicator of climate change, and for the ecological effects that such alien species may have on local species, communities and ecosystems (Mills 2001; Purcell et al. 2007; Zenetos et al. 2010; Galil et al. 2015).

Conclusion

Herein, we recorded a new alien sea jelly species, the Marivagia stellata Galil and Gershwin, 2010 (Scyphozoa: Rhizostomeae: Cepheidae) off the Syrian coast for the first time. The occurrence of this alien sea jelly species in the Syrian coastal waters may be related to the introduction of the Indo-Pacific origin species into the Mediterranean Sea through the Suez Canal. The sudden appearance of 60 sexually mature specimens of new alien sea jelly species together at the same time may be attributed to a local population has been already established close to the major port of Lattakia. This suggests transportation of species on ship hulls of the sessile polyp originates in the Indian Ocean introduced by vessels traversing the Suez Canal.