Distribusi, Kelimpahan dan Variasi Morfologis serta Makanan Bintang Laut (Protoreaster nodosus) di Perairan Waleo dan Bunaken Sulawesi Utara

Abstract

Penelitian ini dilakukan untuk mengetahui hubungan antara karakteristik habitat dan biologi bintang laut P. nodosus, pola distribusi, kelimpahan, variasi morfologis, makanan dan kebiasaan makan. Pengukuran kondisi fisika-kimia perairan dilakukan bersamaan dengan waktu pengambilan sampel bintang laut. Tekstur substrat dianalisis di laboratorium Morfologi Pantai dan Hidro-Oseanografi Fakultas Perikanan dan Ilmu Kelautan Unsrat Manado, dengan menggunakan metode pengayakan. Untuk mengetahui pola distribusi dan kelimpahan bintang laut dilakukan metode transek, dengan ukuran kuadran adalah 1 x 1 meter sebanyak 10 buah pada tiap sub-stasiun dengan penempatan secara beraturan. Di lokasi penelitian dilakukan penimbanmgan bobot tubuh dan pengukuran terhadap panjang lengan, tebal cakram dari tiap individu sampel, serta pengamatan variasi warna. Untuk analisis makanan digunakan 30 individu pada tiap lokasi, sedangkan untuk mengetahui aktifitas makan dilakukan pengambilan 2 individu pada tiap interval waktu 2 jam selama 24 jam. Isi lambung tersebut diamati di Laboratorium Bioteknologi Kelautan dan Biologi Kelautan Fakultas Perikanan dan Ilmu Kelautan serta Laboratorium Dasar Unsrat Manado.

This research has been conducted in the Waleo and Bunaken waters of North Sulawesi from May to August 2000. The purpose of this study is to investigate the correlation between habitat and biological characteristics i.e. distribution path, abundance, morphological characteristics, feeding preference and habits. The method used to know the distribution and abundance was the transect method, 1x1m in size. Each location was represented by 3 stations. thirty starfishes where used to analyze stomach content. Feeding activity was observed from each 2 individuals at 2 hours interval for 24 hours. The correlations between habitat and biological characteristics of P. nodosus were analyzed by the Primary Component Analyses. The distribution path by the Index of Morisita analyses, folowed by the khi-kudrat test and by t-test for abundance. Stomach content was analyzed by the Index of Preponderance and Index of Electivity. The distribution of both small and medium size of P. nodosus was characterized by coarse sand and high temperature, low salinity and slow current speed. While those of the large size of P. nodosus was characterized by fine sand, high salinity, disolved oxygen, low coarse sand and strong current speed. The large size of P. nodosus have higher weigh of seagrass in their stomach than those of the small and medium sizes of P. nodosus. The distribution path of starfishes in two locations of research was a typical cluster. The highest abundance has been found in the waters of South Waleo (20 starfishes), and South Bunaken (17 starfishes). The length of starfish's arms is about 7.8-12 cm, 174.4-379.1 grams in weight, and 1.8-4 cm in height. The result of stomach content analyses showed that the seagrass has the highest percentage in the stomach. Food items wich were positively choosen were T. Hemprichii, C. serrulata and E. acoroides. The feeding time of starfish is at day time (06:00 18:00 hours)