COMU Journal of Marine Sciences and Fisheries

11-18

Authors: Sevdan YILMAZ Ekrem Şanver ÇELİK Dilek KAHRAMAN YILMAZ Mehmet Ali KÜÇÜKER

In this study, cyanobacterial communities in mucilage samples collected from three stations in the Dardanelles Strait were analyzed with a metagenomic approach. Mucilage samples were collected at the beginning of June 2021 from three points of the Dardanelles (Station 1: 40°6'42.78"N, 26°23'57.00"E; Station 2: 40°9'8.09"N, 26°24'16.19"E; Station 3: 40°6 '21.62"N, 26°22'41.25"E). The dominant cyanobacteria were Prochlorococcus marinus (39.17%), Synechococcus sp. (20.85%), Lyngbya sp. (12.00%), Trichodesmium erythraeum (7.33%), Aphanocapsa sp. (4.33%) and Leptolyngbya sp. (3.33%), which constituted 87.00 % of the total number of sequences. In this study, cyanobacteria species that can cause harmful algal blooms and have toxic effects on the mucilage structure have been determined. The Marmara Sea and the Dardanelles Strait, which have been affected by serious disturbances, including industrial activities, anthropogenic impacts, tourism and artificial lighting, will never be fully restored to their former ecological state. In addition, cyanobacteria species in the mucilage may cause harmful algal blooms and have toxic effects that threaten the future well-being of coastal populations and ecosystem stability. Thus, the government and local authorities should pay more attention to combating the mucilage.

26-38

Authors: Deniz Anıl ODABAŞI Serpil ODABAŞI Ozan DENİZ Fikret ÇAKIR Belgin ÇAMUR ELİPEK Naime ARSLAN Onur ÖZBEK H. Barış ÖZALP

Caves are laboratories for many disciplines that work in natural sciences including mineralogy, biology, hydrogeology, and archaeology. In this study, bi-monthly samplings were carried out from three sampling locations within and around the Güvercinkaya Cave, a high-altitude cave located in northwestern Turkey, to evaluate the hydrochemical and microbiological properties and the aquatic macroinvertebrates of the cave stream. Some parameters of the water including pH, electrical conductivity, temperature, oxidation-reduction potential, and dissolved oxygen were measured in-situ, while elemental (70 in total) and ionic composition of water were analyzed in the laboratory. Microbiological analyses of the cave stream were examined through analyses of total bacteria, total coliforms, fecal coliforms, fecal Streptococcus, and Escherichia coli. According to the Piper diagram of hydrochemical data, the cave stream had mainly Ca-Mg-HCO3 character, on the other hand, the Schoeller diagram indicated a common water source in Güvercinkaya cave due to the similar components of the main ionic components of the water. As a result of microbiological analysis, fecal contamination was determined, indicating active wildlife in the cave. Additionally, several aquatic macroinvertebrates taxa, Rhynchelmis limosella, Dugesia sp., Gammarus uludagi which have non-troglobiont character were found in the cave stream. Rhynchelmis limosella detected in this study is the first record for the Turkish fauna.

48-55

Authors: Erhan MUTLU Yaşar ÖZVAROL

The present study reports the occurrence of Oceania armata in the Turkish Levantine Sea, and presents evidence to support a hypothesis established to link an increased recent and near-past records of many gelatinous zooplankton species in the Turkish seas, and particularly in the Turkish Levantine Sea to specific Mediterranean basin-scale currents (Atlantic-Ionian Stream and the Mid-Ionian Jet). One worldwide-distributed oceanic cnidarian specimen was collected from the surface water of a location of 36.59002 N and 29.02471 E by a SCUBA diver on January 18, 2019 in the eastern Mediterranean Sea. The hydrozoan specimen was then identified as O. armata and recorded for the first time in the Turkish Mediterranean coast and only second time in the Levant coast after about 30 years. This is the second report of the species from the Turkish waters, and the first report was from the Turkish Aegean coast. Recently, new records of the gelatinous species have increased from the Turkish marine coasts; Sea of Marmara, Aegean Sea, and Levantine Sea. Most of them are distributed in the West Mediterranean Sea, but are also present in the Adriatic Sea (East Mediterranean Sea). In the Mediterranean Sea, one branch of the Atlantic current (Atlantic-Ionian Stream) enters the eastern basin via the Mid-Ionian Jet, linked with the southern Adriatic current. Therefore, it is possible that zooplankton could have entered East Mediterranean by the Atlantic current through West Mediterranean.

67-76

Authors: Tekin DEMİRKIRAN Uğur ÖZEKİNCİ

This study was aimed to determine the effects of different bait types on the efficiency of fyke-nets and traps in catching narrow-clawed crayfish (Pontastacus leptodactylus (Eschscholtz, 1823)). The study was carried out in Atikhisar reservoir, Çanakkale, between July 2020 and March 2021. In the study, 12 traditional fyke-nets (“D” inlet, 5 rigid rings and a leader net) and 12 traps (double inlet) were used. Fyke-nets and traps were rigged with 34 mm stretched mesh that are commonly used in crayfish fishing in Türkiye. Three different bait types including fish, chicken and bread and a control treatment with no bait were allocated to each gear type. Baits were distributed randomly to each gear before fishing trials. The baits were placed in small bags corresponding to 1% of total trap volume. The results of 24 trials showed 68.8% (1940 crayfish) of the total catch was caught with fyke nets and 31.20% (880 crayfish) with traps. The highest average CPUEN values for both trap types were observed in those baited with the chicken meat which were 7.89±1.02 n/fyke net/day and 5.07±0.88 n/trap/day.. The mean length of the crayfish caught by the fyke nets was significantly smaller than those caught by the traps (p<0.05). When the mean CPUE values based on the number of fishing operations were compared, differences were significant for baits other than the chicken meat (p<0.05). These results showed that catching efficiencies of baited fyke-nets and traps were higher (especially chicken meat) than those of unbaited traps than those without bait.

87-93

Authors: Okan AKYOL Tevfik CEYHAN Faik Ozan DÜZBASTILAR Okan ERTOSLUK

This study presents some exotic fish diversity and catch per unit effort values of exotic fish from gillnet fishery along the southern Aegean Sea. Lessepsian puffer fish (Lagocephalus sceleratus), lionfish (Pterois miles), squirrelfish (Sargocentron rubrum), rabbitfish (Siganus sp.) and a blue crab (Portunus segnis) were caught in the Aegean Sea. Rabbitfish and blue crab sell in the fish markets. Seasonally, the average CPUE of exotic fish was calculated to be 0.7 ± 0.3 kg.1000 m-1 in autumn in catch. This value indicated that it was 72 times lesser than the total seasonal CPUE.

98-102

Authors: Seçil ACAR Yusuf ŞEN

Some morphometric and biological characteristics of a European spider crab, Maja squinado (Herbst, 1788) caught off Aksaz region, (Biga, Çanakkale, Türkiye) were investigated. In addition, an epizoic species infesting this M. squinado specimen has been identified. The crab specimen was caught by a commercial fisherman using trammel nets. Carapace length, carapace width and weight of the crab were 15.9 cm, 14.5 cm, and 1109 g respectively. The specimen was an ovigerous female with a calculated fecundity of 3.48x104 eggs. Eggs were in stage 4th of development and covered the whole carapace region. Additionaly, it was observed that the specimen was infested with the epixoic barnacle Octolasmis angulata (Aurivillius, 1894). A total of 46 O. angulata individuals were observed; 32 from the gill lamellae, and 14 from the carapace. This study reports the existence of the epizoic O. angulata on Maja squinado for the first time in Türkiye.