Antropojenik Etkilerin Detritus Ayrışım Süreci ve Bir Akarsu Organizması Olan Melanopsis buccinoidea Örneğinde İmzası

Öz

Antropojenik etki olarak tarım faaliyetlerinden akarsu kenarlarında yetiştirilen kültür bitkileri, gübre ve pestisit uygulamalarının detritus ayrışma sürecindeki etkilerini ve akarsuda yaşayan ve bu detritus ortamında beslenen Melanopsis buccinoidea (Olivier, 1801) örneğinde akarsu organizmaları üzerindeki etkilerini kararlı izotop yöntemi ile göstermek amaçlanmıştır. Detritus kaynağı olarak kültür bitkilerinden elma (Malus pumila Mill) ve mısır (Zea maysL.) yaprakları (1) hiçbir uygulama yapılmamış, (2) gübre ve (3) pestisit ile muamele edilmiş olmak üzere ikişer tekrarlı altı grup olarak yaklaşık 2.5 aylık bir ayrışma sürecine tutulmuştur. Deney sürecinde her on günde bir detritus örneği alınarak δ13C ve δ15N analizi yapılmıştır. Daha sonra M. buccionidea bireyleri bu altı farlı ortamdan alınan detritus içeren ortamlarda 25 gün boyunca tutulmuş ve belirli aralıklarla M. buccinoidea bireylerinin kas dokularındaki kararlı karbon ve izotop değerleri ölçülmüştür. İki buçuk ay boyunca elma ve mısır yapraklarında ölçülen δ13C değerlerinin her üç uygulamada da zamana bağlı bir dalgalanma ile birlikte artış gösterdiği mısır bitki yapraklarında ise sadece gübre uygulamasında artma saptanmıştır. İkibuçuk ay boyunca, her iki bitkide de detritusların δ15N değerinde doğal ve pestisit koşullarında bir zenginleşme, gübre koşullarında bir düşme görülmüştür. Her iki bitki için gübre ortamındaki iletkenliğin yüksek, pH değerinin ise düşük olduğu belirlenmiştir. Bu ortamda ölçülen ortalama δ15N oranlarının da düşük olması dikkat çekicidir. Mısır detritus ortamında tutulan M. buccinoidea bireylerinin δ13C değerinin elma detritus ortamında tutulan bireylere göre daha düşük olduğu bulunmuştur. Yirmibeş günlük deneme süresince mısır detritus ortamında tutulan M. buccinoidea bireylerinin δ13C değerlerinde bir azalma eğilimi olması ilginçtir. 

Anahtar Kelimeler

• Makroomurgasız,Kararlı İzotoplar,Antropojenik Etki,Akuatik ekoloji

Signature of Anthropogenic Impacts in Detritus Decomposition and the Freshwater Snail Melanopsis buccinoidea

Öz

The present study aims to investigate the anthropogenic impacts of crop farming, fertilizing practices, and pesticide use in riparian zones on detritus decomposition and on feeding of Melanopsis buccinoidea (Olivier, 1801) on detritus by employing the stable isotope method. For this purpose, (1) Non-treated, (2) fertilizer-treated and (3) pesticide-treated apple Malus pumila (Mill) and corn (Zea mays L.) leaves were used in duplicate as detritus material and left to decompose for about two and a half months. During the experiment, samples were collected from the detritus every ten days to conduct stable carbon and nitrogen analyses., M. buccinoidea individuals were then placed in the media containing different detritus types treatments for 25 days and the stable carbon and isotope values in the muscle tissues of M. buccinoidea were measured periodically. The δ13C values measured in the apple and corn leaves over a period of two and a half months were found to fluctuate and increased in each of the three treatments depending on the time of exposure and only in the fertilizer-treated corn leaves. The δ15N values of detrita in both plants were observed to have increased in the natural/non-treated and pesticide-treated conditions but decreased in the fertilizer-administered media during two and a half months. Conductivity and pH values in both plants were found to be high and low, respectively. In this medium, δ15N ratios were lower. The δ13C values of the M. buccinoidea kept in the corn detritus were found to be lower than those of the individuals kept in the apple detritus. It was remarkable to observe during the 25-day experiment that the δ13C values of the M. buccinoidea kept in the corn detritus tended to decrease.

Anahtar Kelimeler

• Macroinvertebrate,stable isotopes,anthropogenic impact,Aquatic ecology

Kaynakça

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