First record of Ophioblennius atlanticus ( Valenciennes , 1836 ) in Italian waters , with considerations on effective NIS monitoring in Mediterranean Marine Protected Areas

On July 2017 during a scientific survey, a single individual of Ophioblennius atlanticus (Valenciennes, 1836) was caught at the entrance of Lampedusa harbour, in proximity to the Marine Protected Area of the Pelagie Islands. This record confirms the introduction of this fish into Mediterranean waters, adding a new species to the list of Italian NIS. Possible pathways of introduction and the relevance of this finding for Mediterranean MPAs are briefly discussed.


Introduction
Fishes of the family Blenniidae, commonly known as combtooth blennies, are distributed worldwide, reaching their highest diversity in tropical and subtropical waters (Nelson 1994).This family currently includes 406 valid species, distributed in two sub families (Blenninae and Salariinae) and 58 genera (Eschmeyer et al. 2018).To date, a total of 19 species have been recorded from Italian seas (Relini and Lanteri 2010), most of which inhabit very shallow waters (Tiralongo et al. 2016).
The redlip blenny Ophioblennius atlanticus (Valenciennes, 1836), is an eastern Atlantic fish, distributed in oceanic islands and along the west coast of Africa, from Senegal to Angola (Dooley et al. 1985;Almada et al. 2001;Carneiro et al. 2014;Williams and Craig 2014).A closely related species is O. macclurei (Silvester, 1915) (Eschmeyer et al. 2018), whose distribution is limited to the western Atlantic coasts, from New York and Bermuda to northern South America (McEachran and Fechhelm 2005;Williams and Craig 2014).
The redlip blenny feeds mainly on detritus and algae (Froese and Pauly 2018).During the breeding season, nesting males develop anal glands and select a small crevice among rocks or coral reefs as a nest site (Giacomello et al. 2006).In 2014, based on underwater pictures taken along the Maltese coasts, O. atlanticus was detected for the first time in the Mediterranean Sea (Falzon 2015).Here we provide a new record of this species and its first documented capture in this basin.

Methods
On 19 th July 2017, during a scientific survey in the Marine Protected Area of Pelagie Islands (Strait of Sicily), a single individual of the redlip blenny Ophioblennius atlanticus was photographed and filmed.The fish was observed at the entrance of the harbour of Lampedusa, among the pillars of the eastern dock, at a depth of about 1 meter (35.49602ºN; 12.60368ºE).The day after, the same individual was spearfished by one of the authors (EA), photographed, measured (to the nearest millimetre), weighted (to the nearest gram) and preserved in alcohol for subsequent study (Figure 1).Morphological analyses were carried out with the help of a stereomicroscope.Taxonomic identification followed Carpenter and De Angelis (2016).

Results
The Lampedusa specimen had a total length (TL) of 159 mm and a weight of 39 g and it is described as follows: body relatively elongated and laterally compressed with elongated dorsal and anal fins; head with a vertical profile in front of eyes; a typical eye-like spot behind the eye; prominent sets of comb teeth; cirri on head present: simple and relatively elongated on the eyes, branched on anterior nostrils and bifid on the nape; lateral line discontinuous.Body uniformly dark-brown; lower lip, lower part of the pectoral fins and upper and lower margin of the caudal fin bright pink.Meristic and morphometric characters are reported in Table 1.(Falzon 2015) and provides a first documented record of this species for Italian waters (Tiralongo 2015).So far, and to our best knowledge, other three species of exotic blennies have been reported from the Mediterranean Sea.These are Omobranchus punctatus (Valenciennes, 1836), recorded only once by Golani (2004) within the harbour of Ashod in Israel; Parablennius thysanius (Jordan and Seale, 1907), recorded only once in the harbour of Antalya, Turkey by Ozbek et al. (2014), and Petroscirtes ancylodon Rüppell, 1835, firstly reported from Nizzanim, Israel by Goren and Galil (1989) and later detected by other authors in the Levantine basin (Taskavak et al. 2000;Corsini et al. 2005).Finally, Ben Soussi et al. (2011), within an unpublished congress communication, reported the occurrence of Istiblennius edentulus (Forster and Schneider, 1801) in Tunisian waters, but this finding has still to be validated.None of these species has established successful populations in the Mediterranean Sea, and biotic resistance is theoretically considered to be very high for this family (Azzurro et al. 2014).Nevertheless, O. atlanticus may reach very high abundances along the subtropical shallow rocky shores of the Atlantic Ocean and in the Canary Islands (Azzurro, pers. observation).Being a species of subtropical origin, rising water temperatures are expected to increase habitat suitability for O. atlanticus, as probably happened for other native combtooth blennies, such as Parablennius pilicornis (Cuvier, 1829) and Scartella cristata (Linnaeus, 1758) (Nieder et al. 2000;Pastor and Francour 2010).As for other exotic blennies (Wonham et al. 2000), O. atlanticus might be easily transported through ballast waters or directly by ships, which are known to be one of the main vectors for marine bio-invasions (Galil 2009).Both, the Lampedusa (present finding) and the Malta (Falzon 2015) individuals, were detected in proximity of harbours, supporting the hypothesis of a shipmediated introduction.On the contrary, other means of arrival, such as natural transport through the Strait of Gibraltar, due to the aquarium trade or a secondary spread from an established population seems to be less probable.
Yet, further monitoring activities needs to be regularly conducted, especially in proximity of Marine Protected Areas (MPAs), which do not escape the consequences of global warming and biological invasions (Otero et al. 2013;Simard et al. 2016;Galil 2017).Furthermore, many Mediterranean MPAs are located in proximity to major ports and experience similar challenges, including the scarcity of information on management practices and a lack of trained local staff to effectively detect new introductions (Otero et al. 2013).It is therefore advisable to train MPA teams to identify non-indigenous organisms.This will improve our potential for early detection and rapid response, which is a desired approach for managing the issue of biological invasions in European seas and beyond (Genovesi et al. 2010;Katsanevakis et al. 2015;Giakoumi et al. 2016).A more direct action concerning marine bioinvasions is also requested globally, as stated by the Aichi Target 9 of the Convention on Biological Diversity (CBD 2015) and regionally, by the "Descriptor 2" of the European Union Marine Strategy Framework Directive (EU 2008).For these reasons, and in consideration of the rapidity and magnitude of biotic changes, NIS species should be taken into serious consideration in monitoring activities and management plans of Mediterranean MPAs.

Figure 1 .
Figure 1.The redlip blenny Ophioblennius atlanticus caught from Lampedusa Island (Italy) on 20 th July 2017 at a depth of about 1 metre.Photograph by E. Azzurro.

Table 1 .
Morphometric and meristic characters of the specimen of O. atlanticus caught from Lampedusa island.