Ali ALKAN, Bayram ZENGİN, Serkan SERDAR, Temel OĞUZ

Long-term (2001-2011) temperature, salinity and chlorophyll-a variations at a southeastern coastal site of the Black Sea

Bu çalışmada, Güneydoğu Karadenizin Trabzon kıyılarında 2001-2011 dönemine ait uzun dönemli sıcaklık, tuzluluk ve klorofil-a konsantrasyonlarının aylık ve yıllık değişimleri incelenmiştir. Sıcaklık verileri, 2002-2004 göreceli soğuk dönem dışında, soğuk ara tabaka suyu oluşumunun yokluğu veya çok belirgin olmamasını göstermekte ve genel bir ısınma eğilimini işaret etmektedir. Söz konusu ısınma eğilimi 1990'lı yıllarda görülen ısınmanın devamı niteliğindedir. Bulgular, çalışma bölgesinde belirgin orta-ölçekli su sirkülasyonu hareketlerinin varlığına işaret etmektedir. Bu döngüler yaratmış oldukları dikey hareketler nedeniyle yaklaşık 100 m derinliğe kadar yöresel su kütlelerinin tabakalaşma özelliklerini etkileyebilmektedir. Yaklaşık 2 metre derinlikte gerçekleştirilen klorofil ölçümleri ise genellikle 2.0 mg m-3den büyük değerlerle tanımlanan göreceli yüksek plankton üretimlerine işaret etmektedir. Yüksek klorofil tabakası yıl boyunca yüzeyin hemen altındaki 50 m derinliğe kadar olan tabakada yer almakta, ancak orta ölçekli aktivitelere bağlı olarak zaman zaman daha derinlerdeki üretimi destekleyebilmektedir.

Karadeniz'in Güneydoğu kıyısal alanında uzun dönemli (2001-2011) sıcaklık, tuzluluk ve klorofil-a değişimleri

Long-term measurements of temperature, salinity and chlorophyll-a concentration at a coastal site off Trabzon in the southeastern Black Sea document their monthly-to-interannual variabilities during 2001-2011. The data point to a general trend of warming with either negligible or absence of the Cold Intermediate Layer except for the relatively cold period of 2002-2004. The warming trend appears to be a continuation of the one started during the early 1990s. The data further documents enhanced anticyclonic type mesoscale features of the circulation system and its impacts on the local startification characteristics in terms of ventilation of the subsurface waters. The surface chlorophyll measurements show a rather sporadic relatively high plankton production events identified by the values greater than 2.0 mg m-3. More importantly, relatively high chlorophyll concentrations prevail below the surface mixed layer up to 50 m depth throughouıt the years. The mesoscale physical processes occasionally spread this productivity well below the euphotic zone and support biological production at oxygen deficient waters of the upper layer water column. The data further point to quasi-lateral, most likely isopycnal, intrusions and ventilation of subsurface waters.

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