Doğu Karadeniz Bölgesi’nde ova kurbağasının (Pelophylax ridibundus) üreme ekolojisi ve yumurta bırakma alanı seçimi

Öz

Türkiye'nin Doğu Karadeniz Bölgesi'ndeki Trabzon ilinde bulunan Darıca deresinde Ova kurbağasının (Pelophylax ridibundus) üreme ekolojisi ve yumurtlama yeri seçimi çalışılmıştır. Arazi çalışmaları, 2008 yılının Mart ayından Ağustos ayına kadar 3-4 günlük aralıklarla dere boyunca 420 m'lik bir bölümde gerçekleştirilmiştir. Bu çalışma; üreme faaliyetlerinin zamanlamasını, yumurta kümelerinin dağılımını, yapıştırıldığı substratı, büyüklüğünü, larvaların yumurtadan çıkma başarısını belirlemek amacıyla yürütülmüştür. Arazide ilk yumurta kümesi Mart ayında erkeklerin ses çıkarmalarının ardından Nisan ayı başında başlamış, Mayıs ayında zirveye ulaşmış ve Temmuz ayı sonunda sona ermiştir. Çalışma esnasında toplam 968 yumurta kümesi belirlenip kayıt altın alınmış; bunların %91,1'i dere kenarında, %8,9'u ise yağmur suyuyla oluşan su birikintilerine bırakılmıştır. Yumurta kümeleri çoğunlukla sığ ve durgun dere kenarına, %81,5'i 10 cm’den daha küçük derinlikte, %57,2'si ise dere kenarından 20 cm mesafede belirlendi. Yumurta kümelerinin %94,4'lük bir kısmı çimen, taş, su bitkileri, yosun veya sudaki organik kalıntılara yapıştırılırken, sadece %5,6'sı su yüzeyinde serbestçe yüzerken belirlendi. Yumurta kümelerindeki yumurta sayısı 132 ila 1135 arasında değişmektedir ve laboratuvarda larvaların yumurtadan çıkma başarısı ortalama %84,4 olarak belirlenmiştir. Çalışma alanında ne kurbağa ne de yumurta kümelerinin gözlemlenmediği denize yakın dere bölümüne kıyasla üreme alanlarında tuzluluk, iletkenlik ve toplam çözünmüş katı madde oranlarının önemli ölçüde daha düşük olduğu belirlenmiştir. Bu sonuçlar, P. ridibundus'un akarsu ekosistemlerinde yumurtlama için su akışının minimum olduğu sığ ve düşük tuzluluk değerlerine sahip yerleri seçici olarak kullandığını göstermektedir. Çalışma, Doğu Karadeniz Bölgesi'ndeki P. ridibundus'un üreme ekolojisi hakkında ilk kapsamlı verileri sağlayarak, bölgesel populasyonlara özgü özelliklerin daha geniş bir şekilde anlaşılmasına ve türün korunma çalışmalarına katkıda bulunmayı hedeflemektedir.

Anahtar Kelimeler

• Pelophylax ridibundus
• Üreme ekolojisi
• üreme ekolojisi
• Yumurtlama
• yumurta kümesi
• doğu karadeniz bölgesi

Reproductive ecology and oviposition site selection of marsh frog (Pelophylax ridibundus) in Eastern Black Sea Region, Türkiye

Öz

This study investigates the reproductive ecology and oviposition site selection of Marsh frog (Pelophylax ridibundus) in Darıca Stream, located in Trabzon Province, Eastern Black Sea Region, Türkiye. Field observations were conducted at 3-4 day intervals from March to August 2008 along a 420 m section of the stream. The present study was conducted to determine the timing of reproductive activity, the spatial distribution and substrate attachment of egg clutches, clutch size, and larval hatching success. Male calling activity began in March, while oviposition started in early April, reached a peak in May, and ended in late July. A total of 968 egg clutches were documented, with 91.1% deposited along the stream banks and 8.9% in rainwater-formed puddles. Most clutches (81.5%) were found at water depths of less than 10 cm, and 57.2% were located within 20 cm of the stream bank, mainly in shallow, stagnant microhabitats. The majority of egg clutches (94.4%) were attached to substrates such as grasses, stones, aquatic vegetation, moss, or organic debris, while only 5.6% were floating freely on the water surface. Egg clutch sizes ranged from 132 to 1135 eggs, and the mean hatching success under laboratory conditions was 84.4%. In contrast, no adult frogs or egg clutches were observed in a downstream river section close to the sea, where salinity, electrical conductivity, and total dissolved solids were significantly higher. These findings indicate that P. ridibundus preferentially selects shallow freshwater habitats with low salinity and minimal water flow for reproduction. This study provides the first comprehensive account of the reproductive ecology of P. ridibundus in the Eastern Black Sea Region and offers essential baseline data for understanding local population dynamics and supporting regional conservation efforts.

Anahtar Kelimeler

• Pelophylax ridibundus
• Eastern Black Sea Region
• reproductive ecology
• oviposition
• egg clutch
• eastern black sea region

Kaynakça

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