Community structure of periphyton at floating net cages and non-floating net cages in Laut Tawar Lake, Aceh Tengah

Abstract

Many activities are carried out around the Laut Tawar lake, one of which is the cultivation of floating net cages that can contribute nutrients to the waters. One of the organisms that can take advantage of the abundance of nutrients in the waters is periphyton. This study aims to examine the community structure of periphyton as natural food in Laut Tawar Lake. This research was conducted in January-April 2022. The results showed that there are 9 classes of periphyton at the KJA station, namely Bacillariophyceae, Chlorophyceae, Cyanophyceae, Rhizopoda, Dinophyceae, Euglenophyceae, Trebouxiophyceae, Klebsormidiophyceae and Coscinodiscophyceae. While, at non-KJA stations there are 7 classes where the Klebsormidiophyceae class and the dinophyceae class are not found at non-KJA stations. The highest abundance at the KJA station was on the 7th day with a value of 108,655 cells/cm2 and non-KJA was 24,552 cells/cm2. The lowest abundance occurred on day 14 at both stations. Periphyton diversity index at KJA and non-KJA stations ranged from 1.88-2.76, which was moderate. The evenness index of periphyton species ranging from 0.61-0.75 was classified as high, while the dominance index ranging from 0.09-0.24 was classified as low. Based on the values obtained, the community structure of periphyton on artificial substrates in the KJA and non-KJA areas in Laut Tawar Lake experienced moderate ecological stress with the community in a stable condition. The t-test results obtained that the abundance values at KJA stations and non-KJA stations had the difference that the abundance of periphyton at KJA stations was greater than at non-KJA stations.