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HUBUNGAN PARAMETER KUALITAS AIR DENGAN STRUKTUR IKHTIOFAUNA PERAIRAN DARAT PULAU SIBERUT DEDE IRVING HARTOTO dan ENDANG MULYANA Penelitian ini beaujuan mengungkapkan parameter-parameter mutu air yang berpengaruh terhadap komposisi jenis, indeks keanekaragaman dan biomasa ikhtiofauna di perairan darat Pulau Siberut. Pengambilan contoh dilakukan dengan alat jala bemkuran mata janng 1 cm yang dioperasikan sepuluh kali untuk setjap stasiun. Pengawetan dan analisis sampel air dilakukan dengan metode-metode yang disajikan pada Standard Methods (RAND et al. 1975). Hasil pengambilan contoh pada 49 stasiun yang terdiri daft ruas-ruas sungai yang terdapat di pulau tersebut menunjukkan bahwa ikan hanya tertangkap pada 27 stasiun (55.1%) terdiri dan 19 jenis. Kesembilan belas jenis ikan yang tertangkap termasuk dalam sebelas suku. Sebaran ikhtiofauna tidak merata dan didominasi oleh Puntius binotatus dan Suku Cyprinidae. Fakta yang ada menunjukkan biomasa ikan rata-rata (1,45 0,89 g basah/m2) yang relatif rendah, seperti juga indeks keanekaragaman jenisnya (0,377 0, 178). Keanekaragaman jenis ini di ruas-ruas sungai ini dipengaruhi secara nyata oleh suhu (r* = 0,53, P = 0,01, n = 27), sedangkan biomasa ikan dipengaruhi secara sangat nyata oleh konsentrasi amonia dan konduktivitas (r** multiple = 0,69; P = 0,01). Parameter-parameter limnologis lain yang secara bersama-sama turut mempengaruhi besarnya biomasa ikan adalah pH, N-nitrat, oksigen terlarut (dissolved oxygen = DO), total ortofosfat - P04), konduktivitas (S/cm) dan kecepatan arus. Bagaimana parameter mutu air tersebut mempengaruhi biomasa dan keanekaragaman ikan dibahas secara singkat.

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Relationship of water quality parameters to ichthyofauna community structures in the inland waters of Siberut island. DEDE IRVING HARTOTO dan ENDANG MULYANA Abstract RELATIONSHIP OF WATER QUALITY PARAMETERS TO ICHTHYOFAUNA COMMUNITY STRUCTURES IN THE INLAND WATERS OF SIBERUT ISLAND. The study is aimed to determine water quality parameters that have the greatest influence upon species composition, species diversity index and ichthyofauna biomasa in the inland waters of Siberut island. Sampling was conducted using a cash-net of I cm meshsize which was operated ten times at each station. Water samples were preserved and analyzed following the methods as described in Standard Methods (Rand et al. 1975). Fish samplings have been conducted at 49 stations for two years (1993 - 1994) and the results showed that only at 27 stations (55. 1%) were fish samples obtained, which contained 19 species. These 19 species belong to eleven families. One species of Cvprinidae, Puntius binotatus, was found dominating the fish populations in the tributaries, which showed a patchy horizontal distribution pattern. The existing fact showed that a relatively low fish biomass (1.45 0.89 g/m2 or 14.2 kg/ ha) and a low index of species diversity (0.377 +/- 0.178) were found in Siberut island waters. Fish species diversity was significantly correlated to temperature only (r* = 0.53; P = 0.05; n = 27), whilst fish biomass was very significantly correlated multiply to both ammonia and conductivity (r* multiple = 0.69; P = 0.01; n = 27). Other limnological parameters, i.e., pH, N-nitrate, dissolved oxygen, total ortophosphate P (P04), conductivity (uS/cm) and current velocity were also multiply correlated to fish biomass. How the water quality parameters influence the fish biomass and the fish species diversity is discussed.

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