Fluktuasi dan Kelimpahan Fitoplankton di Danau Laguna Ternate Maluku Utara

Abstract

The objective of this research was to know the fluctuation and abundance of phytoplankton at Laguna Lake, North Moluccas. This research was conducted for 3 periods, from June to July 2005. Sampling of plankton were taken biweekly in 4 stations and 3 depths (0, 5, and 10 m) by filtration method.The results showed that there were 9 genera from 3 classes: Bacillariophyceae (6 genera), Cyanophyceae (2 genera), and Dinophyceae (1 genera).
Plankton abundance on period I ranged 1.14 x 10₄-3.49 x 10₄ ind/l, period II ranged 7.64 x 10₃ -4.73 x 10₄ ind/l, and period III ranged 9.29 x 10₃-3.78 x 10₄ ind/l, the highest on period II (3.19 x 10₅ ind/l) and the lowest on period I (2.49 x 10₅ ind/l). The phytoplankton abundance in each station were station 1 = 9.29 x 10₃-4.73 x 10₄ ind/l, station 2 = 1.51 x 10₄-4.52 x 10₄ ind/l, station 3 = 7.64 x 10₃-3.45 x 10₄ ind/l, and station 4 = 1.14 x 10₄-3.49 x 10₄ ind/l. The highest phytoplankton abundance was in station 2 (2.45 x 10₅ ind/l) and the lowest in station 4 (1.68 x 10₅ ind/l). Whereas, phytoplankton abundance based on depth were 0 m = 9,29 x 10₃-3,92 x 10₄ ind/l, 5 m = 7,64 x 10₃-4,73 x 10₄ ind/l, and 10 m = 1,18x 10₅-3,7 x 10₅ ind/l, the highest on 10 m (2.91 x 10₅ ind/l) and the lowest on 0 m (2.49 x10₅ ind/l). The range value of biological index such as diversity index (H’) on period I was 0,5276-1,1853, period II was 0,6138-1,1635, and persiod III was 0.6276-1.2264; equitability index (E) on period I was 0.4422-0.8550, period II was 0.4725-0.8393, and period III was 0.5674-0.8575; and dominant index (D) on period I was 0.3403-0.7032, period II was 0.3584-0.6597, and period III was 0.3195-0.6647.