Kajian Kualitas Perairan dan Stabilitas Ekosistem di Perairan Pantai Tugu, Semarang - Muh. Yusup (ILMU KELAUTAN: Indonesian Journal of Marine Sciences, 2002)
Penelitian ini dilaksanakan dengan tujuan untuk mengkaji kondisi kualitas air, struktur komunitas makrozoobenthos, dan stabilitas ekosistem perairan di muara sungai Karanganyar, Tugu, Semarang. Metode penelitian yang digunakan adalah studi kasus. Sampling air dan sedimen dilakukan sebanyak tiga kali, dengan interval 14 hari. Penelitian dilaksanakan pada bulan Maret - Oktober 2001 di muara sungai Karanganyar, Tugu, Semarang. Hasil pengukuran parameter fisika-kimia air menunjukkan bahwa beberapa parameter yakni, kekeruhan, COD, dan unsur-unsur logam berat Cu, Cd, Pb, Ni telah melampaui Baku Mutu Air Laut. Nilai IMLP antara 56,858-66,121. Berdasarkan nilal ini, dikatakan bahwa kualitas perairan di daerah penelitian termasuk ke dalam kriteria sedang. Nilai Indeks Keanekaregaman jenis (H') berkisar dari rendah sampai sedang yaitu antara 1,132-2,10. Sedangkan nilai indeks keseragaman jenisnya (E) relative tinggi, yakni antara 0,80 sampai 0,95. Kondisi ekosistem yang tampak membaik ke arah yang stabil dari waktu ke waktu adalah stasiun I, II, dan V, ditunjukkan oleh perubahan model dari Motomura ke Preston. Sedangkan kondisi lingkungan yang tampak semakin memburuk ke arah yang tidak stabil adalah stasiun III dan IV, ditunjukkan oleh perubahan model dari Preston ke Motomura.Kata kunci : kualitas perairan; ekosistem; makrozoobenthos  The research was done to investigate the condition of water quality, community structure of macrozoobenthos, and ecosystem stability of coastal waters of estuarine of river Karanganyar. The method used in the present research was case study. Sampling was done three times, with time interval between 14 days. The research was done from March until October, 2001 at estuarine of Karanganyarr river, of Tugu coastal waters, Semarang City. Based on the result of measurement of physical-chemical parameters of water showed that several parameters include: muddines, COD and heavy metal elements Cu, Cd, Pb, Ni have passed over sea water quality standard. The results of the research showed that the waters environmental quality index (IMLP) range from 56,858 until 66,121. Based on this value, the water quality in the research area include to middle criteria. The diversity index (H`) range from low to middle that is between 1,132-2,10. Whereas the equatability index (E) was high, that that is between 0,80-0,95. The condition of environmental quality in the research area which seems to stable time to time were station I, II and V which is shown by the changed of model from Motomura to Preston. Whereas the condition of environmental quality which seems to fall into unstable way, were station III and IV, which is shown by changed of model from Preston to Motomura.Keywords: water quality; ecosystem; makrozoobenthos