Studi tentang struktur komunitas makrozoobentos dan kualitas perairan telah dilakukan di Waduk Krenceng pada November 2002 dan Maret 2003 yang masing-masing mewakili bulan November 2002 dan bulan Maret 2003. Makrozoobentos diambil dengan Peterson Grab dan kualitas air ditentukan dengan Indeks Storet dan Indeks Keanekaragaman. Dari hasil Identifikasi ditemukan 6 jenis makrozoobentos yang terdiri dari: Oligochaeta (3 jenis) dan In sect a (3 jenis). Kelimpahan jenis berkisar antara 3-2254 ind/nT dan didominasi oleh Aloudrilus pigueti Kowalewski, keanekaragaman jenis berkisar antara 0,76-1,67, dan penyebaran jenis mengelompok, kecuali Chironomus sp. yang menyebar acafc. Berdasarkan Indeks Storel, kualitas perairan Waduk Krenceng termasuk katagori tercemar sedang sampai sangat baik sedangkan dengan Indeks Keanekaragaman termasuk katagori tercemar sedang sampai tercemar berat. Kesesuaian antara indeks Storet dan Indeks keanekaragaman adalah 67% sehingga Indeks Keanekaragaman dapat digunakan untuk menilai kualitas perairan Waduk Krenceng.

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Community Structure Of Macrobenthic Faunas And Water Quality Of Waduk Krenceng In Cilegon, Banten: Community structure of macrobenthic faunas and water quality assessment was studied in Waduk Krenceng on November 2002 (dry month) and Maret 2003 (wet month). Macrobenthic fauna dredged by Peterson grab, water quality assessment used Storet index and Diversity index. From the result of macrobenthic identification, six species of two classes and 3 families were found: Oligochaeta 3 species and In sect a 3 species. Species abundance ranging from 3 to 2254 ind/ha and species diversity ranging from 0,76 to 1,67. tutodrilus pigueti Kowalewski (Oligochaeta: Tubificidae) showed the highest abundance both in November 2002 (dry month) and March 2003 (wet month). The result of dispersion analysis showed that the dispersion of all macrobenthic species in Waduk Krenceng is aggregated, except Chironomus sp. that is random dispersion. The physico-chemical condition showed that water quality of Waduk Krenceng ranging from moderatly polluted to standard for clean water condition. Based on diversity index of macrobenthic fauna showed that water quality ranging from heavily polluted to moderatly polluted. There are 67% equivalency between Storet indeks and Diversity Index. Therefore Diversity index can be used to evaluate water quality at Waduk Krenceng.