TINGKAT TROFIK DAN LUAS RELUNG MAKANAN BETUTU (Oxyeleotris marmorata BLEEKER, 1852) DI WADUK SERMO KABUPATEN KULON PROGO

GUNAWAN PURNOMO AJI, Dr. Eko Setyobudi, S.Pi., M.Si.

2015 | Skripsi | S1 MANAJEMEN SUMBER DAYA PERIKANAN

Penelitian ini bertujuan untuk mengetahui tingkat trofik dan luas relung makanan betutu (Oxyeleotris marmorata Bleeker, 1852) di Waduk Sermo, Kabupaten Kulon Progo. Pengambilan sampel ikan dilakukan setiap bulan mulai bulan Desember 2013 hingga Mei 2014. Sampel betutu berjumlah 120 ekor (61 ekor jantan dan 59 ekor betina) ditangkap menggunakan jaring insang dan bubu lipat dasar. Setiap sampel betutu diukur panjang total, berat tubuh dan panjang saluran pencernaan. Pengukuran volume setiap jenis makanan dilakukan menggunakan sedgwick rafter dan gelas ukur. Analisis data meliputi distribusi panjang dan berat, komposisi makanan, frekuensi kejadian, indeks bagian terbesar (IBT), tingkat trofik, luas relung makanan dan tumpang tindih relung makanan. Hasil penelitian menunjukkan bahwa ikan merupakan makanan utama bagi betutu di Waduk Sermo dengan nilai IBT sebesar 94,30%. Selain ikan, terdapat jenis makanan lain yang ditemukan yaitu detritus (4,37%), serasah (0,34%), serangga (0,62%), Chironomus sp. (0,10%), gastropoda (0,06%) dan udang (0,21%). Terdapat variasi jenis makanan berdasarkan ukuran dan jenis kelamin betutu. Betutu berada pada puncak piramida makanan di Waduk Sermo dengan nilai tingkat trofik 3,54-4. Betutu memiliki luas relung makanan yang sempit (stenophagic). Nilai tumpang tindih relung makanan betutu berkisar antara 0,967-1 yang menunjukkan adanya persaingan, baik berdasarkan ukuran maupun jenis kelamin.

The purpose of this research was to know the trophic level and niche breadth of food of sand goby (Oxyeleotris marmorata Bleeker, 1852) habitat in Sermo Reservoir, Kulon Progo. Sampling was conducted monthly from December 2013 to May 2014 using gill net and folded trap. Fish was measured their body length, weight and the length of digestive canal individually. The volume of each food item was measured using sedgwick rafter and scalling glass. Data were analyzed descriptively in term of the length and weight distribution, food composition, occurance frequency, preponderance index, trophic level, niche breadth and food overlaping. The result showed there were 120 fish consist of 61 males and 59 females, the length was distributed from 12,0 cm to 33,00 cm and the weight from 21,04 g to 1593,68 g. The preponderance index was 94,30%, which indicates the main food of sand goby in Waduk Sermo was fishes. Other foods which were consumed by sand goby namely detritus (4,37%), litter (0,34%), insect (0,62%), Chironomus sp. (0,10%), gastropod (0,06%), and shrimp (0,21%). The food variation was affected size and sex. The trophic level was 3,54-4,0 and reaches the top of food pyramid in Waduk Sermo. The niche breadth of food of sand goby was stenophagic. The niche overlap of food was approximately 0,967-1, which demonstrated competitiveness, either based on size or sex.

Kata Kunci : betutu, niche, trofik, tumpang tindih relung, Waduk Sermo