Sinan Mavruk

Non-native fishes in the Mediterranean from the Red Sea, by way of the Suez Canal

The opening of the Suez Canal in 1869 caused a migration generally from the Red Sea to the Mediterranean, rarely the opposite direction, and 63 lessepsian fish species penetrated into the Mediterranean by way of this canal. These species usually spread northward and most of them can establish wide populations in this area, but some of them can not be successful with respect to establishment. Thus, it is clearly seen that there are a lot of factors influencing the success of species with respect to migration, spreading and establishment. So, the lessepsian migration has been formed by the effects of these factors. Lessepsian species also have the ability to adapt to the ecological conditions of their new environment. Therefore, the influential factors, their effectiveness and the observed changes in lessepsian species due to the effects of these factors have been discussed by considering fishes in this paper.

Macrobenthic assemblages of newly introduced Caulerpa taxifolia from the Eastern Mediterranean coast of Turkey.

Caulerpa taxifolia is one of the most important and best-studied alien species in the Mediterranean Sea. The present study reveals the macrobenthic assemblages associated with C. taxifolia from the region. We found 26 species from Polychaeta, 31 species from Crustacea, 22 species from Mollusca and 5 species from Echinodermata. In conclusion, C. taxifolia in İskenderun Bay can be considered an ecosystem engineer that modifies local habitats and also enhances biodiversity.

Two new Lessepsian species found in the north-eastern Levantine Basin: Broadbanded Cardinalfish (Apogon fasciatus (White, 1790)) and Indian Scad (Decapterus russelli (Rüppell, 1830)) (Osteichthyes)

Broadbanded Cardinalfish, Apogon fasciatus (White, 1790) On 21.12.2009, six specimens of Apogon fasciatus were collected in a transect along the eastern shores of Iskenderun Bay (36°17’N, 35°45’E – 36°21’N, 35°47’E) near the 50 m depth contour. The total lengths of the collected specimens varied between 48.26 and 89.12 mm. Mean Total Length (TL) was 77.99 mm (SD = 17.22 mm), mean Standard Length (SL) of TL was 81.39% (SD = 1.25%). The body of the specimens is oblong and compressed. The body colour is tan-whitish, with two dark brown stripes present on the head and body. The lower stripe extends mediolaterally along the body from the snout to the tip of the caudal fin. The upper stripe above the lateral line extends from the post-temporal bone to the region behind the posterior end of the second dorsal fin. There are reddish-orange spots on the distal edges of second dorsal, anal and pectoral fins, and a reddish colour pattern was observed on the pelvic fins. There are two and three large scales on the preopercle and opercle, respectively. The preopercle edge is serrated (Fig. 1.). The metric and meristic characters used for identification are as follows; D1: VII and D2: I+9, A: II+8, Pec: 15, Pel: I+5, lateral line pored scales: 25-26, body depth at dorsal fin origin of SL (BDD): 34.84±2.64 mm, head length of SL (HL): 39.10±2.77 mm, distance from snout to first dorsal fin of SL: 37.94±1.63 mm, distance from snout to anal fin of SL: 61.17±2.50 mm, maximum pectoral fin length of SL: 23.85±1.08 mm.

Distribution dynamics of ichthyoplankton and recruitment hypotheses

Denizel kemikli baliklarin cogunda yumurta ve larval asamalar planktonik ozellik gostermektedir. Bu formlar aktif hareket kabiliyeti kazanincaya dek balik planktonu anlamina gelen ihtiyoplankton kapsaminda degerlendirilmektedir. Kemikli baliklar genellikle cok sayida yumurta uretmekte; bu yumurtalardan onemli bir kismi, aclik, predasyon, anormal suruklenmeler ve sacilmalar gibi nedenlerle stoka katilim oncesinde olmektedir. Bu surecte, yasam oranlarindaki kucuk degisimler stoka katilimda onemli farkliliklar yaratabilmektedir. Diger taraftan, maksimum sayida yavruyu hayatta tutabilecek ideal habitatlarin varligi alan ve zamansal acidan degiskenlik sergilemekte; bu nedenle, yavrularin ideal cevresel kosullarla bulusturulmasi kritik onem arz etmektedir. Baliklar, bu eslestirmeyi saglamak amaciyla cesitli ureme stratejileri gelistirmislerdir. Bu derleme calismasinda, ihtiyoplanktonun alansal ve zamansal dagilimini etkileyen ic (yumurtlama stratejisi) ve dis (cevresel kosullar) faktorler teorik bir cercevede ele alinmis, planktonik evrelerin stoka katilim basarisindaki rollerini vurgulayan hipotezlerle birlikte tartisilmistir.

Yumurtalık Açıklarında (İskenderun Körfezi) Kış Dönemi Larval Balık Topluluklarının Bolluk ve Çeşitliliği

Bu calismada Iskenderun Korfezi’nde kis mevsimi ihtiyoplankton topluluklarinin bolluk, cesitlilik ve kompozisyonu cevresel kosullarla birlikte ele alinmistir. Bu amacla 7/12/2015 ile 1/3/2016 tarihleri arasinda 6 saha calismasi gerceklestirilmis; Iskenderun Korfezi, Yumurtalik aciklarindaki 10, 30 ve 60m derinlik konturlarina yerlestirilmis 6 istasyonda oblik Bongo-60 Net cekimleri yapilmistir. Calisma boyunca 67 ture ait yumurta ve larvalarla karsilasilmis olup, istasyon basina medyan tur sayisi 6, bolluk ise 36 adet/10m 2 olarak tespit edilmistir. Shannon-Wiener cesitlilik indeksi ile Pielou duzenlilik indeksine ait medyan degerleri sirasiyla 1.86 ve 0.98 olarak hesaplanmistir. Bregmaceros nectabanus , Sparus aurata , Etrumeus golanii , Gobius paganellus ve Sardina pilchardus baskin turlerdir. Ihtiyoplankton topluluklarinin bolluk, zenginlik ve cesitliligi 10m derinlik konturunda istatistik acidan onemli olcude dusuk bulunmustur. Ihtiyoplankton kompozisyonunun kis mevsimi icindeki zamansal degisimlerinin istatistik acidan onemli oldugu tespit edilmistir. Olculen cevresel kosullardan yalnizca sicaklik degisimlerinin tur kompozisyonu uzerinde etkili oldugu belirlenmistir.