Extension of the Striped Eel Catfish Plotosus lineatus (Thunberg, 1787) from the eastern Mediterranean Coast to the Mersin Bay on the western Mediterranean Coast of Turkey

A group of schools of striped eel catfish Plotosus lineatus (Thunberg, 1787) was photographed during scuba diving at depths of 10 m and 17 m on 11 July 2022 and on 24 September 2022 from Kızkalesi and Boğsak regions in the Mersin Bay of the Mediterranean coast of Turkey. With the present study, P. lineatus is extending its distribution to the western Mediterranean coastal waters after its first occurrence in 2016 in the İskenderun Bay of Turkish Marine waters.


Introduction
There has been an increasing number of alien species in the Mediterranean Sea due to vectors and factors that facilitate and/or permit the invasion.Apart from the climate change, the opening of the Suez Canal in 1869 connected the tropical Red Sea with the Mediterranean and dramatically affected the biodiversity of the Mediterranean (Golani et al., 2007;Galil, 2008;Yaglıoglu et al., 2014;Turan et al., 2016;Dragičević et al., 2019).NESciences, 2022, 7(3): 240-247 doi: 10.28978/nesciences.1183740Currently, numerous lessepsian fish species have established dense populations in the Mediterranean and generated ecological and economic problems (Turan et al., 2017;Stamouli et al., 2017;Turan et al., 2018;Ragkousis et al., 2020).The striped eel catfish Plotosus lineatus (Thunberg, 1787) is rapidly becoming a dominant component of the benthic biota of the Levantine Sea.P. lineatus was first time recorded in the Mediterranean by Golani (2002) and has colonized population in the entire Israeli coast.The second record of P. lineatus was given from the Egypt coast of El-Arish city by Temraz & Ben Souissi (2013).The third record of P. lineatus was given from the Syrian coast of Tartous city by Ali et al. (2015).Then it was the first time recorded from the Turkish marine waters by Doğdu et al. (2016).Recently, P. lineatus was reported from northern Cyprus (Tiralongo et al., 2022).
This study reports the westward distribution of the striped eel catfish P. lineatus to the Mersin Bay along the Mediterranean coast of Turkey.

Materıal and Methods
One group of P. lineatus was photographed from Kızkalesi and the other group was photographed from the Boğsak region in the Mersin Bay at a depth of 16 and 21 m on 11 July 2022 and 24 September 2022, respectively in Mersin Bay (Figure 1).On the bases of underwater observation and pictures taken during scuba diving, all the morphological descriptions and colors agree with the descriptions of Golani (2002) and Doğdu et al. (2016).The habitat of P. lineatus seen in scuba diving was lichenous, rocky, and sandy for both Kızkalesi and the Boğsak regions in Mersin Bay.

Results and Discussion
P. lineatus belongs to the family Plotosidae which consists of valid 10 genera and 42 species (Nelson, 1994;Froese & Pauly, 2022).They dwell in reefs, along open coasts in estuaries, and in tidal pools from the Red Sea and east Africa to Japan and Samoa (Golani et al., 2002).Crustaceans, mollusks, worms, and, rarely, fish make up their diet (Fisher et al., 1990).In Iskenderun Bay, P. lineatus is sometimes observed in the nets of trawls and discarded of all sizes (Figure 2).The highly venomous single serrated spine at the beginning of the first dorsal and each of the pectoral fins of P. lineatus have potential risks that can cause severe pain and other health problems (Uysal & Turan, 2020).The first descriptive case of the harmful effect of P. lineatus from the Iskenderun Bay, the Northeastern Mediterranean Sea was also reported (Turan et al., 2020).Moreover, numerous observations of dense juveniles schooling in rocky habitats have been also witnessed by personnel observations (C.Turan), swimmers, and Scuba divers in the Iskenderun and Mersin Bays.
The pathway of P. lineatus in the Mediterranean starts with the first record of Golani (2002), the second record was given from the Egypt coast of El-Arish city by Temraz & Ben Souissi (2013), and the third record was given from the Syrian coast of Tartous city by Ali et al. (2015), the fourth record was from the Turkish marine waters by Doğdu et al. (2016) and fifth recorded was from northern Cyprus by Tiralongo et al. (2022) (Figure 3).It is shown that the westward extension pathway of the striped eel catfish in the Mediterranean coasts of Turkey.The number of alien or non-indigenous species has increased dramatically for a few decades in Turkish marine waters (Turan et al., 2015;Gürlek et al., 2016a,b;Turan, 2000).Physicochemical conditions, especially in the Eastern Mediterranean, have changed in the last ten years due to climate changes (Ergüden et al., 2014;Turan et al., 2016).Furthermore, minimum (winter) and maximum (summer) water temperatures are increasing in the Mediterranean Sea, which may facilitate the establishment of thermophilous species in the Mediterranean Sea (Rilov & Treves, 2010;Turan & Öztürk, 2015).As a result, the increase in seawater temperature has been considered the main reason for the increase in the introduction and establishment of tropical species in the temperate Mediterranean Sea (Ben Rais Lasram et al., 2010;Turan, 2010;Öztürk & Turan, 2012).
This study is very important to report the spread of P. lineatus toward western Mediterranean waters.The westward extension of P. lineatus indicates that it will extend first to the Gulf of Antalya on the Turkish coast in the near future, and then to the island of Rhodes in Greek sea waters.

Figure 2 .
Figure 2. P. lineatus and other aliens in a trawl haul in the Iskenderun Bay (Photo by C.Turan)