Lukman, dkk

STRUKTUR KOMUNITAS BIOTA BENTHIK DAN KAITANNYA DENGAN KARAKTERISTIK SEDIMEN DI DANAU LIMBOTO, SULAWESI

Oleh: LUKMAN, TRI SURYONO, TJANDRA CHRISMADHA, MUHAMAD FAKHRUDIN DAN JOJOK SUDARSO

Pusat Penelitian Limnologi – LIPI Received 21 April 2008, Accepted 11 November 2008

Sumber: http://www.limnologi.lipi.go.id/

ABSTRAK

Perairan Danau Limboto, sebagai land mark Provinsi Gorontalo, Sulawesi, saatini mendapat tekanan dengan terjadinya pendangkalan, pencemaran limbah domestik dan adanya perkembangan budidaya ikan sistem jaring apung yang pesat. Komunitas benthik Danau Limboto, sebagai komponen penting ekosistem perairan, belumbanyak terungkap informasinya. Perubahan yang terjadi terhadap lingkungan Danau Limboto akan memberikan pengaruh nyata terhadap komunitas benthik. Telah dilakukan penelitian struktur komunitas biota benthik di Danau Limboto dan karakteristik sedimennya dengan tujuan untuk evaluasi kondisi lingkungan perairannya. Penelitian ini dilakukan pada bulan September 2006 dengan pengambilan contoh di delapan stasiun. Parameter kualitas air yang diukur adalah kadar oksigen terlarut, suhu, kekeruhan, konduktivitas dan pH, serta bahan organik total (TOM; Total Organic Matter) air. Karakteristik sedimen danau ditentukan berdasarkan fraksi butiran, TOM, serta rasio C dan N organiknya. Pengambilan contoh sedimen dan biota benthik menggunakan Ekman grab. Kualitas air Danau Limboto menunjukkan tingkat pH cenderung basa, kekeruhan pada kisaran rendah hingga tinggi, dan TOM relatif tinggi. Karakteristik sedimen didominasi fraksi debu dan liat, dengan kadar TOM yang berkisar antara 11,5- 20,9%, dan rasio C: N organiknya relatif rendah (< 20). Sebanyak 1 Ijenis organisme benthik ditemukan, disusun oleh kelas Oligochaeta, Diptera, dan Moluska, dengan kelimpahan berkisar antara 284 – 3.409 ind/m2. Tubificid merupakan kelompok organisme benthik dominan dari kelas Oligochaeta, dan Chironomid adalah kelompok dominan dari kelas Diptera. Dari kelompok Tubificid, spesies Limnodrilus hoffmeisteri adalahpenyusun utamanya. Keberadaan Tubificid dan Chironomid yang mendominasi komunitas benthik sejalan dengan tingginya kadar TOM pada sedimen danau.

Katakunci: Danau Limboto, bahan organik total, rasio C:N organik, biota benthik, Tubificid, Chironomid.

ABSTRACT

STRUCTURE OF BENTHIC COMMUNITY AND THEIR RELATIONSHIP TO SEDIMENT CHARACTERISTIC IN LAKE LIMBOTO, SULAWESI. Environmental condition of Lake Limboto, as Gorontalo Province land mark, has stressed by sedimentation, organic pollution and development of cage system fish culture. Information of Lake Limboto benthic community as ecosystem important component, has not much been discover yet. Change of lake environmental condition will impact to benthic community, significantly. Objection of benthic community structure in Lake Limboto and sediment condition research were to evaluate of the waters environment condition. The research has been conducted on September 2006, at eight sampling stations. Water quality parameters which measured namely dissolved oxygen, temperature, turbidity, conductivity, pH and TOM. Sediment characteristed base on fraction, TOM and organic C : N ratio. Sediment and benthic organisme sampled by Ekman grab. Water quality condition showed pH tend to alkaline, turbidity concentration range between low to high and TOM was high. Characteristics of sediment dominated by silt and clay, TOM between 11.5 – 20.9%, and C: N organic ratio was low (< 20). There was 11 species benthic organisms was found, composed by class of Oligochaeta, Dipterans, dan Mollusc and their abundance between 284 – 3409 ind/m2. Tubificidae was dominant benthic organisms from class Oligochaetes with species Limnodrilus hoffmeisteri was main compose. Chironomid was dominant benthic organisms from class Dipterans. Domination of tubifiddae and chironomid on benthic community seemed accordance to high content of TOM on lake sediment.

Key words: Lake Limboto, TOM, organic C:N ratio, bentic organism, Tubificid, Chironomid.

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