Kelimpahan Bivalvia di Muara Sungai Tuntang Morodemak Berdasarkan Kandungan Bahan Organik dan Fraksi Sedimen

Aktivitas manusia yang dilakukan disekitar wilayah Perairan Morodemak akan memberikan sumbangan terbesar terhadap kandungan bahan organik dan akan berpengaruh terhadap kondisi ekologis perairan. Tujuan dari penelitian untuk mengetahui fraksi sedimen dan kandungan bahan organik serta kelimpahan bivalvia di Muara Sungai Tuntang Morodemak. Metode penelitian ini bersifat deskriptif kuantitatif. Terdapat tiga stasiun dalam pengambilan sampel yang ditentukan secara purposive. Hasil fraksi sedimen didominasi oleh pasir (sand) berkisar antara 99,9%. Kandungan bahan organik sedimen diperoleh rata – rata sebesar 5,8% yang termasuk dalam kriteria rendah. Kelimpahan relatif tertinggi dimiliki spesies Perna viridis sebesar 78,3 ind/m2 dan kelimpahan relatif terendah dimiliki spesies Anadara granosa sebesar 21,7 ind/m2. Nilai indeks keanekaragaman (H’) dan nilai indeks keseragaman (E) tergolong dalam kriteria rendah. Hubungan kandungan bahan organik sedimen dengan kelimpahan bivalvia diperoleh nilai korelasi positif sebesar 0,99. Hal tersebut berarti terdapat hubungan yang sempurna/sangat tinggi, dimana keberadaan bahan organik pada sedimen mendukung keberlangsungan hidup bivalvia. Hubungan fraksi sedimen pasir dengan kelimpahan bivalvia diperoleh nilai korelasi negatif sebesar -0,55. Hal tersebut berarti terdapat hubungan yang rendah/lemah, dimana fraksi sedimen pasir mengalami penurunan maka kelimpahan bivalvia juga akan menurun. Human activities carried out around the Morodemak waters largely contributee to the organic matter content and affects the ecological conditions of the waters. The purpose of this study was to determine the sediment fraction and organic matter content as well as the abundance of bivalves in the Tuntang Morodemak estuary. This research method is descriptive quantitative. There are three stations in the sampling which were determined purposively. The results of the sediment fraction are dominated by sand ranging from 99,9%. The organic matter content of the sediment obtained an average of 5,8% which is included in the low criteria. Perna viridis species has the highest relative abundance of 78.3 ind/m2 and the lowest relative abundance is Anadara granosa species of 21,7 ind/m2. The diversity index value (H') and the uniformity index value (E) are classified as low criteria. The relationship between sediment organic matter content and the abundance of bivalves obtained a positive correlation value of 0,99. This means that there is a perfect/very high relationship, where the presence of organic matter in the sediment supports the survival of bivalves. The relationship between the sand sediment fraction and the abundance of bivalves obtained a negative correlation value of -0,55. This means that there is a low/weak relationship, where the sand sediment fraction decreases, the abundance of bivalves will also decrease.