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Sungai Wulan adalah sungai yang melewati tiga kabupaten yaitu Grobogan, Kudus dan Demak. Sungai Wulan yang terletak di Kabupaten Demak, mempunyai dua percabangan yaitu Wulan Lama dan Wulan Baru. Sungai ini digunakan oleh masyarakat untuk berbagai keperluan seperti kegiatan perikanan, domestik dan transportasi. Di hilir sungai juga terdapat daerah mangrove. Dampak dari kegiatan manusia tersebut kemungkinan akan berpengaruh terhadap kualitas perairan, hal tersebut diduga berdampak terhadap keberadaan fitoplankton serta kandungan klorofil-a. Penelitian dilakukan pada bulan Maret – April 2016 bertujuan untuk mengetahui kandungan klorofil-a, fitoplankton dan status perairan berdasarkan kandungan klorofil-a dan kelimpahan fitoplankton. Metode yang digunakan adalah metode survei lapangan dengan teknik purposive sampling . Pengambilan sampel dilakukan di tiga lokasi yang berbeda yaitu dekat pemukiman (Stasun 1), Wulan Baru (Stasiun 2), dan Wulan Lama (Stasiun 3). Analisis Kruskal-Wallis untuk mengetahui perbedaan kandungan klorofil-a antar stasiun dan analisis Cluster untuk mengetahui kemiripan berdasarkan komunitas fitoplankton dan variabel lingkungan antar stasiun. Hasil penelitian menunjukkan kandungan klorofil-a berkisar antara 0,4955 - 1,3527 mg/l. Tidak ada perbedaan yang nyata kandungan klorofil-a per stasiun pada taraf kepercayaan 95% (0,05). Kelimpahan fitoplankton berkisar antara 9.458 – 12.422 ind/l. Fitoplankton yang didapatkan terdiri dari 35 genera yang terdiri dari 5 kelas yaitu Bacillariophyceae, Cyanophyceae, Dynophyceae, Chlorophyceae dan Euglenophyceae. Stasiun 2 dan Stasiun 3 mempunyai kemiripan komunitas fitoplankton dan variabel lingkungan dibandingkan dengan Stasiun 1. Status perairan Sungai Wulan berdasarkan kandungan klorofil-a tergolong oligotrofik dan berdasarkan kelimpahan fitoplankton tergolong mesotrofik. Kata Kunci: Klorofil-a; Fitoplankton; Sungai Wulan ABSTRACT Wulan River is a river that passes through three regencies there are Grobogan, Kudus and Demak. Wulan River located in Demak Regency, has two branches there are Wulan Lama and Wulan Baru. This river has been used a lot by the residents for many activities such as fishery activities, domestic and transportation. There is also mangrove area in the downstream of Wulan River. The impact of those human activities presumably will affect the quality of the waters, it is also presumed to impact the existence of phytoplankton and the contents of chorophyl-a. This research was conducted on March - April 2016 aimed to know the contents of chlorophyl-a, the type and abundance of phytoplankton and the status of waters based on the content of chlorophyll-a and the abundance of phytoplankton. This research used survey method and purposive a sampling teqnique. The sampling was conducted in three different locations, that is in the nearby people residence (Station 1), Wulan Baru (Station 2) and Wulan Lama (Station 3). The Kruskal-Wallis analysis was used to determine differences of chlorophyll-a between the stations and Cluster analysis was used to determine similarity groups based on the phytoplankton community and environment variables between stations. The results showed chlorophyll-a range between 0,4955 - 1,3527 mg/l. There is no significant difference between the content of chlorophyll-a per station at the level of 95% (P < 0,05). The abundance of phytoplankton ranged between 9.458 – 12.422 ind/l. The phytoplankton was obtained consisting of 35 genus consisted of 5 classes, namely Bacillariophyceae, Cyanophyceae, Dynophyceae, Chlorophyceae and Euglenophyceae. Both Station 2 and Station 3 had a more similarity in the community of phytoplankton and the environment variable compared to the Station 1. The status waters of the Wulan Rivers based on the contents chlorophyll-a was classified into oligotrophic and based on the abundance of phytoplankton was classified into mesotrophic. Keywords: Chlorophyl-a; Phytoplankton; Wulan River |
