STRUKTUR POPULASI TIRAM (Saccostrea cuccullata Born, 1778) PADA EKOSISTEM MANGROVE DAN NON-MANGROVE DI SEMARANG, JAWA TENGAH - Rismawati, Ulfah; Afiati, Norma; Suprapto, Djoko (Management of Aquatic Resources Journal (MAQUARES), 2015)
Tiram (Saccostrea cuccullata), merupakan salah satu sumberdaya perikanan yang memiliki nilai ekonomis penting. Pengambilan tiram umumnya dilakukan secara tidak teratur baik jumlah, ukuran dan waktunya sehingga diduga hal tersebut berpengaruh terhadap struktur populasi. Penelitian ini dilakukan di Pantai Mangkang yang merupakan daerah bermangrove dan Pantai Maron yang non-mangrove, Semarang Jawa Tengah selama bulan Juli – September 2014, yang bertujuan untuk mengkaji perbedaan struktur populasi tiram berdasarkan perbedaan pada ekosistem mangrove dan non-mangrove. Metode survei deskriptif digunakan dalam penelitian ini dengan teknik pengambilan sampel bersifat purposive random. Jumlah sampel tiram yang terkumpul selama tiga bulan (Juli – September, 2014) pada daerah bermangrove yaitu 209 individu, sedangkan pada daerah non-mangrove berjumlah 253 individu. Kisaran panjang cangkang tiram pada ekosistem mangrove yaitu 12,00 – 82,20 mm dan untuk berat basah total yaitu 1,01 – 55,03 g. Pada daerah non-mangrove kisaran panjang cangkang yaitu 21,30 – 82,00 mm dan berat basah totalnya 2,04 – 83,45 g. Kerapatan populasi tiram di daerah bermangrove berkisar 16 – 96 individu/m2 dan pada daerah non-mangrove yaitu 24 – 104 individu/m2. Pola distribusi pada ekosistem mangrove dan non-mangrove umumnya mengelompok. Sifat pertumbuhan yang didapat dari analisis hubungan panjang berat yaitu alometrik negatif, dimana b<3. Pada pengamatan Indeks STORET (Kepmen LH No. 115, 2003) diperoleh hasil yaitu perairan Pantai Mangkang (Mangrove) dan Pantai Maron (Non-Mangrove) masuk kategori perairan tercemar sedang. Oysters (Saccostrea cuccullata) is the one of the fisheries resource that has an important economic value. Collection of oysters usually done in irregular either total, size and time allowing allegedly this impact on the structure of population. This research is conducted in Mangkang Beach wich is a mangrove areas and Maron beach is a non-mangrove areas, Centtral Java Sea during July – September 2014 with a purpose to study the differences of structure population based on mangrove and non-mangrove areas. Methods that used in this study was descriptive survey with purposive random sampling. Variable observed  i.e  physic, chemist, biology, social and economic factors. Total of sample that collected during three months (July – September) in mangroves areas 209 individuals and in non-mangrove areas 253 individuals. The range of shell length in mangroves ecosystem is 12,00 – 82,20 mm and the total weight is 1,01 – 55,03 g. In non-mangrove ecosystem the range of shell length is 21,30 – 82,00 mm and the total weight is 2,04 – 83,45 g. Population density of oyster in mangrove and non-mangrove areas is generally clumped. Correlation of length and weight of oysters has a meaning negative allometric both of mangrove and non-mangrove, wich  b<3. Sex ratio of oysters both of mangrove and non-mangrove areas is not balanced, wich the male less than female. The results of STORET Index (Kepmen LH No. 115, 2003) categorised that both the waters in mangrove and non-mangrove ecosystem as relatively contaminated.