The Approximation of Coral Reef Ecosystem Quality in The Seribu Islands Using Benthic Foraminifera Proportion as Bioindicator

Abstract

Coral reef ecosystem is one of mega biodiversity environments with the highest ecological pressure especially caused by human activities. Local impact like nutrification will decrease water quality and the ecosystem. Benthic foraminifera as bioindicator can be used as early monitoring tool to observe the changes in reef ecosystems. Therefore the aims of this study were to investigate the distribution of benthic foraminifera in reef ecosystem and determine the relationship between coral ecosystems with FORAM Index as tool for benthic foraminifera to asses waters quality. Eleven stations from Karang Bongkok, Pramuka, and Onrust on Seribu Island were used for this study. Nutrient and physical parameters were measured in situ and in the laboratory. The foraminifera was separated from sediment and indentified by binocular microscope. The foraminifera then classified by functional group and calculated by FORAM Index formula (FI). The range of FI was from 3,4-8,2, which indicated marginal to suitable environment for reef development. The modification of FI (FIm) showed that the range from 1,2-5,2 where there were unsuitable environment for reef growth in Onrust Island. The results showed that Calcarina and Amphistegina are indicators of reef health ecosystem. Nevertheless, FORAM Index can be applied in Indonesia waters with some modification with considering the preference of the habitat.

Foraminifera bentik merupakan salah satu kelompok organisme yang memiliki asosiasi yang erat dengan terumbu karang, sehingga dapat digunakan sebagaibioindikatoruntukmendugakualitasekosistemterumbukarang.Beberapa penelitian mengenai foraminifera bentik di ekosistem terumbu karang telah dilakukan di Kepulauan Seribu, namun kajian yang secara langsung menghubungkan keberadaan foraminifera bentik dengan eksistensi terumbu karang belum pernah dilakukan di Indonesia. Oleh karena itu penelitian ini dilakukan dengan tujuan 1) mengetahui komposisi dan sebaran foraminifera bentik di ekosistem terumbu karang, 2) menentukan kelompok taksonomi foraminiferasebagaiindikatorekosistemterumbukarang,3)mengkajihubungan antaraFORAMIndex(FI)terhadapkondisiekosistemterumbukarangdisebagian Kepulauan Seribu, 4) membuktikan bahwa aplikasi FORAM Index di wilayah tropis khususnya Kepulauan Seribu dapat digunakan sebagai indikator ekologi dalammenilaikualitaslingkunganekosistemterumbukarang. Pulau Karang Bongkok, Pulau Pramuka, dan Pulau Onrust di Kepulauan Seribudipilihsebagaikajianuntukmencapaitujuanyangdimaksud.Pengukuran suhuair,kecerahan,salinitas,oksigenterlarut,pH,dankecepatanarusdilakukan secarain-situ.Pengukuranklorofil8a,klorofil8b,klorofil8c,fosfat,nitrat,amonia, dansilikat,sertaparametersedimenyaituNtotal,C8organik,danukuranbutiran dilaksanakan di laboratorium. Contoh air diambil di kolom dekat dasar perairan kecualipengukurankecepatanarusdilakukandikolompermukaanperairan.