MEHMET AKSU, Aslı KAYMAKÇI-BAŞARAN, Özdemir EGEMEN

Doğu Akdeniz’de Kıyı Ötesi Mavi Yüzgeçli Orkinos Besiciliğinin Su Kalitesine Etkileri

Akdeniz'de mavi yüzgeçli orkinos yetiştiriciliği 1990'ların ortalarından başlayarak gelişmiştir. Orkinos yetiştiriciliğinin yaygınlaşmasını izleyen süreçte, faaliyetin deniz ortamına etkileri ile ilgili önemli kaygılar oluşmuştur. Bu çalışmanın amacı, Gerence Körfezi'nde avcılığa bağlı kurulmuş olan bir orkinos çiftliğinin su kolonu ve sedimente olan etkilerinin araştırılmasıdır. Bu amaç doğrultusunda, su kolonunda sıcaklık, tuzluluk, pH, çözünmüş oksijen, klorofil a ve besleyici tuzlar ile sedimentte organik karbon değişkenleri 2011 ile 2012 yılları arasında mevsimsel olarak ölçülmüştür. Örneklemeler 2 referans istasyonu ve kafeslerin etrafındaki 5 istasyonda gerçekleştirilmiştir. Kafes istasyonlarında su kolonundaki nütrient konsantrayonlarının referans istasyonlarından daha fazla artış gösterdiği fakat bu artışların istatistiksel olarak önemli olmadığı saptanmıştır. Benzer şekilde, su kolonundaki fiziko-kimyasal değişkenler ve klorofil a ile sedimentte organik karbon değerleri de orkinos besiciliğinin etkilerinin önemli seviyelerde olmadığını göstermiştir. Bu durumun çalışma bölgesinde mevcut olan güçlü akıntılar, kafeslerin kıyıdan uzak yerleşimi dolayısıyla derinliklerin fazla olması ve beslemenin kontrollü yapılmasından kaynaklandığı söylenebilir. Orkinos besiciliğinin sürdürülebilirliğini sağlamak ve potansiyel etkilerini belirleyebilmek için izleme çalışmalarının devam ettirilmesinin gerekli olduğu düşünülmektedir

Effects of Off-Coast Bluefin Tuna Fattening on Water Quality in the Eastern Mediterranean Sea

Bluefin tuna farming in the Mediterranean has been expanding since the mid-1990s. Expansion of tuna farming has been accompanied by widespread concerns about its impacts on the marine environment. The aim of the present study was to investigate impacts of a capture-based tuna farm located in the Gerence Bay on the water column and sediment. With this aim, temperature, salinity, pH, dissolved oxygen, chlorophyll a and nutrients in the water column and organic carbon variables in the sediment were measured on a seasonal basis from 2011 to 2012. Samplings were made at the two reference stations and five stations around the cages. It was found that nutrient concentrations in the water column at the cage stations increased more than those of the reference stations but these differences were not statistically significant. Similarly, physico-chemical parameters and chlorophyll a in water column and organic carbon in sediment did not show detectable impact of tuna fattening. This was probably caused by strong currents present in the area, location of the cages away from the coast, hence high water depth and controllable feeding. It is believed that conducting monitoring studies is necessary to maintain sustainability of tuna fattening and determine the related potential impacts

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