The Structure of Phytoplankton Communities in Lake Toba, North Sumatera

Abstract

ABSTRAKDanau Toba merupakan danau terbesar di Indonesia yang terletak di Provinsi Sumatera Utara. Danau Toba banyak dimanfaatkan oleh masyarakat untuk kegiatan budi daya ikan di keramba jaring apung (KJA), pertanian, pariwisata, dan pemukiman penduduk. Aktivitas-aktivitas tersebut akan memberikan masukan berupa bahan organik dan anorganik yang akan memengaruhi kualitas air dan dapat menyebabkan terjadinya eutrofikasi. Beberapa indikator eutrofikasi adalah terjadi peningkatan biomassa fitoplankton dan perubahan struktur komunitas fitoplankton. Tujuan dari penelitian ini adalah untuk mengkaji struktur komunitas fitoplankton di Danau Toba. Penelitian ini dilakukan pada tanggal 2024 Oktober 2014 di 23 stasiun di perairan sekitar Pulau Samosir, Danau Toba. Hasil penelitian menunjukkan bahwa kelimpahan fitoplankton berkisar antara 216-68.319.716 sel/m 3 . Komposisi fitoplankton terdiri dari 35 genus dari empat kelas, yaitu Cyanophyceae, Chlorophyceae, Bacillariophyceae, dan Dinophyceae. Cyanophyceae merupakan kelas fitoplankton yang dominan berdasarkan komposisi kelimpahannya (>40%). Struktur komunitas fitoplankton di Danau Toba didominasi oleh Anabaena.Kata kunci: danau toba, fitoplankton, struktur komunitas ABSTRACT Lake Toba is the largest lake in Indonesia, located in the Province of North Sumatra. Lake Toba is used to aquaculture, agricultural, tourism, and residential areas. These activities will produce organic and anorganic matter that can affect water quality and can cause eutrophication. Some indicators of eutrophication are an increase in phytoplankton biomass and changes in phytoplankton community structure. The aim of this study was to describe the phytoplankton community structure in Lake Toba. This study was conducted on 2024 October 2014 at 23 stations around the Samosir Island, Lake Toba. The results showed that the phytoplankton abundance ranged 216-68.319.716 cells/m 3 . The phytoplankton composition consists of 35 genera from four classes: Cyanophyceae, Chlorophyceae, Bacillariophyceae, and Dinophyceae. Cyanophyceae is a dominant phytoplankton groups based on the composition of abundance (>40%). Structure of phytoplankton communities in Lake Toba dominated by Anabaena.

The best incubation time for primary productivity of phytoplankton in Laguna Lake, North Maluku, Indonesia

“…At a depth of 0 m, Cyanophyceae was the dominant (54.1%), and Chlorophyceae was least dominant (4.1%). Rahman et al (2016) also observed that Cyanophyceae was mostly found (>40%) in Toba Lake. Meanwhile, Bacillariophyceae was dominant (56.6%) in a 5 m depth, while Chlorophyceae was the least observed (6.3%).…”

“…The composition of phytoplankton species The results of our study found 12 genera of phytoplankton, i.e., Bacillariophyceae (6 genera), Chlorophyceae (4 genera), and Cyanophyceae (2 genera) in Laguna Lake. The number of genera found in Laguna Lake was less than those of Zhao et al (2016) in Bange Lake who recorded 41 genera, Ganai and Parveen (2014) in Wular Lake who found 64 genera, Rudiyanti et al (2017) in Jatibarang Reservoir who found 21 genera, and Rahman et al (2016) in Toba Lake who recorded 35 genera. Among our finding, Bacillariophyceae was the dominant class in all periods of time and depths, followed by Chlorophyceae.…”

“…However, other studies (Umar 2003;El-Karim 2008); Merina et al 2014) reported that Chlorophyceae was predominant in Juanda Jatiluhur Dam, Lake Manzala, and Maninjau Lake. On the other hand, Cyanophyceae was dominant in Cirata (Baksir 1999), Toba Lake (Rahman et al 2016), and Lake Kortowskie (Jaworska et al 2014). Meanwhile, phytoplankton was dominated by nonheterocystous cyanoprokaryotes in Lake Bukoni (Nyakoojo 2010).…”

“…Other genera of phytoplankton that were also abundance in Laguna Lake were Nitzschia and Diatoma (Bacillariophyceae), while Anabaena (Cyanophyceae) was dominant in Toba Lake (Rahman et al 2016) and Cylindrospermopsis raciborskii was dominant in Lagoa Santa (Figueredo and Giani 2009). The different nature of dominance between those lakes may occur due to the differences in water quality, especially the concentration of nutrients contents.…”

The dynamics of the plankton community on Lake Siombak, a tropical tidal lake in North Sumatra, Indonesia

“…Various plankton studies have been carried out in lake waters, both natural and artificial lakes, such as Lake Pondok Lapan (Muhtadi et al 2015), Lake Toba (Rahman et al 2016), Lake Ebony (Pratiwi et al 2018a), Lake Matano (Sulawesty 2019), Lake Maninjau (Sulastri et al 2019). Some research on estuarine and mangrove waters has been widely carried out and reported, such as the Mahakam Delta, East Kalimantan (Effendi et al 2016), Belawan Estuary (Dimenta et al 2018), Segara Anakan, Central Java (Dewi et al 2019;Wiyarsih et al 2019); including bay and coastal waters, such as in Gorontalo Bay (Kadim et al 2018), Sunda Strait (Takarina et al 2019), Banten Bay, Lampung and Jakarta (Sidabutar et al 2016;Damar et al 2020).…”