DISTRIBUSI DAN KEMELIMPAHAN KOMUNITAS ZOOPLANKTON DI PERAIRAN SELAT MALAKA, LHOKSEUMAWE, ACEH

DAWAM SUPRAYOGI, Prof. Dr. Tjut Sugandawaty Djohan, M.Sc.

2017 | Tesis | S2 Biologi

Penelitian ini mempelajari distribusi dan kemelimpahan komunitas zooplankton secara spasial dan temporal di daerah tangkapan ikan nelayan perairan Selat Malaka, Lhokseumawe, Aceh. Lokasi pengambilan sampel yaitu Stasiun 1, 2, dan 3 dengan jarak dari pantai berturut-turut 3,54; 4,27; dan 4,67 mil laut. Penelitian ini dilakukan pada dua musim: Intermonsoon (IM), 13-17 April 2016 dan Monsoon Barat Daya (MBD), 1-4 Juni 2016. Komunitas zooplankton merupakan penghubung antara fitoplankton dengan ikan dalam jejaring makanan di perairan. Kehadiran zooplankton sangat menentukan kehadiran ikan-ikan pada tingkat trofik diatasnya. Di setiap stasiun, 20 l sampel air dicuplik menggunakan modifikasi Van Dorn water sampler 5 liter di 5 jeluk titik sampling dalam kolum air, masing-masing dengan ulangan 5 kali dan disaring dengan Wisconsin plankton net 125�µm. Dua jeluk berada di atas secchi depth, satu pada secchi depth, dan dua lainnya di bawah secchi depth. Sampel dihitung cacah individunya dengan metode total strip counting menggunakan Sedgewick Rafter Counting Chamber. Parameter fisiko-kimia perairan yang diukur berupa salinitas, pH, suhu, DO, NO3 dan PO4. Fungsional grup yang ditemukan: copepoda, rotifera, protozoa, gastropoda, cnidaria, chaetognatha, tunicata, polychaeta, dan foraminifera yang terdistribusi tidak merata dalam kolum air. Pada musim IM tidak ditemukan foraminiferea, sedangkan pada musim MBD ditemukan semua fungsional grup. Copepoda mendominasi di semua jeluk di seluruh stasiun pada kedua musim dengan kecenderungan yang sama, dengan persentase 61-97%. Pada musim IM densitas copepoda terbesar yaitu 537 individu/100 l, sedangkan pada musim MBD yaitu 418 individu/100 l. Hal ini mengindikasikan bahwa perairan Selat Malaka, Lhokseumawe, merupakan perairan yang subur dan terjadi well mixing terus menerus pada kedua musim.

The purpose of this research is to study spatial-temporal distribution and abundance of zooplankton community in fishing area of Malacca Strait, Lhoksumawe, Aceh. This study was devided into Station 1, 2, and 3 with the distance from the coast are 3,54; 4,57; and 4,67 nautical miles, respectively. Zooplankton samples was collected in two seasons: Intermonson, April 13-17th 2016 and Southwest Monsoon, June 1st-4th 2016. The presence of zooplankton determines the presence of fishes at the top of trophic levels. In every station, plankton samples composite from 20 litre, were taken from 5 depths in water column using modified 5 litre of Van Dorn Water Sampler with 5 replicates and filtered using 125�µm mesh Wisconsin plankton net. Two depths at the top of secchi depth, one on secchi depth, and two others at the bottom of secchi depth. Plankton were counted with total strip counting method using Sedgewick Rafter Counting Chamber. The water quality parameter measured were salinity, pH, temperature, DO, NO3 and PO4. Nine functional groups were found in this research: copepod, rotifer, protozoa, gastropod, cnidaria, chaetognatha, tunicate, polychaeta, and foraminifera which is unevenly distributed in water column. In Intermonsoon the foraminifera were not found, whereas in Southwest Monsoon all functional groups were found. Copepod was dominated in all depth in all station of two seasons with the same trend, with 61-97% precentage. In Intermonsoon the copepod density was 537 individuals/100 l, while in Southwest Monsoon copepoda density was 418 invididuals/100 l. This indicates that Malacca Strait, Lhoksumawe, is the fertile waters and the well mixing occurs continuously in two seasons. It is mean that the marine waters of Malacca Strait is a healthy ecosystem.

Kata Kunci : laut dangkal tropika, jeluk, monsoon, area upwelling, copepoda