Keanekaragaman dan Distribusi Spons pada Tiga Pulau Berbeda di Selat Makassar, Indonesia

Abstract

Kondisi ekosistem terumbu karang secara global semakin memburuk akibat aktivitas manusia dan peningkatan sedimentasi dari daratan. Hal tersebut dapat berdampak buruk pada organisme penyusunnya, termasuk spons yang dapat menyebabkan kepunahan. Oleh karena itu, perlu diketahui data keanekaragaman, distribusi, dan komposisi spons yang ada di suatu wilayah, untuk dapat menentukan tindakan konservasi yang tepat. Penelitian ini bertujuan untuk menganalisis keanekaragaman dan distribusi spons di tiga pulau di Selat Makassar, yaitu Pulau Gusung Toraja, Barrang Caddi, dan Pannikiang.

Pengambilan data spons dilakukan dengan SCUBA diving menggunakan metode Underwater Photo Transect (UPT) dengan transek seluas 0.58 m x 0.44 m. Pengamatan dilakukan pada transek garis sepanjang 20 meter pada kedalaman 5 meter. Masing-masing pulau dibagi menjadi empat stasiun sehingga total 12 stasiun pengamatan. Selain pengamatan di lapangan, fragmen spons juga diambil untuk diidentifikasi lebih lanjut di laboratorium.

Sebanyak 3978 individu dari 137 morfospesies spons tercatat dalam penelitian ini. Jumlah spesies dan individu terbanyak diperoleh di Pulau Pannikiang (92 spesies, 2129 individu), disusul Barrang Caddi (59 spesies, 1498 individu), dan di Gusung Toraja (39 spesies, 351 individu). Perbedaan morfologi dan luasan terumbu merupakan salah satu faktor utama yang berpengaruh terhadap keanekaragaman spons di masing-masing pulau. Pulau Pannikiang memiliki keanekaragaman spons terbesar (H’=3.35), disusul Barrang Caddi (H’=3.25), dan di Gusung Toraja (H’=3.19). Tingginya keanekaragaman di Pannikiang dapat disebabkan karena luas wilayah dan area terumbunya terbesar dibandingkan kedua pulau lainnya, serta dikelilingi oleh hutan bakau.

Selain itu, keanekaragaman spons juga dipengaruhi oleh kondisi substrat. Pulau Gusung Toraja yang memiliki keanekaragaman terendah akibat substratnya yang didominasi oleh sedimen pasir dan lumpur. Kondisi substrat tersebut juga berpengaruh terhadap morfologi spons. Tercatat sepuluh morfologi yang diperoleh dari penelitian ini, dengan tipe yang dominan adalah encrusting. Tipe encrusting merupakan morfologi spons yang lebih tahan terhadap tekanan yang tinggi akibat sedimentasi dan arus yang kuat dibandingkan morfologi lainnya.

Hasil analisis nMDS dan ANOSIM menunjukkan perbedaan komposisi spesies spons di Pannikiang yang terletak di antara kedua pulau lainnya, sementara pulau Barrang Caddi dan Gusung Toraja tidak berbeda signifikan (p=0.3508). Penelitian menunjukkan bahwa persebaran spons di Selat Makassar tidak bergantung pada kedekatan jarak antar pulau.

The condition of coral reef ecosystems globally is getting worse due to human activities and increased sedimentation from the mainland, which can harm the organisms that compose it, including sponges, and cause extinction. Therefore, it is necessary to know the diversity, distribution, and composition of sponges in an area to determine appropriate conservation measures. This study aimed to analyze the diversity and distribution of sponges in three islands in the Makassar Strait i.e. Gusung Toraja Island, Barrang Caddi Island, and Pannikiang Island. The collection of sponge was carried out by SCUBA diving, using Underwater Photo Transect (UPT) method with a 0.58 m x 0.44 m transect area. Observations were made on a 20 meter line transect at a depth of 5 m..Each island was divided into four stations, so a total of 12 stations were observed. In addition to field observations, sponge fragments were also taken for further identification in the laboratory. There were 3978 individuals belongs to137 morphospecies of sponges were reported in this study. The highest number of species and individuals was found in Pannikiang Island (92 species, 2129 individuals), followed by Barrang Caddi (59 species, 1498 individuals), and Gusung Toraja (39 species, 351 individuals). Differences in morphology and reef area are one of the main factors that affect the diversity of sponges in each island. Pannikiang Island had the largest diversity (H’=3.35), then Barrang Caddi (H’=3.25), and the lowest in Gusung Toraja (H’=3.19). The high number of sponges diversity in Pannikiang was caused by the largest area compared to other islands and surrounded by mangrove forests. In addition, the diversity of sponges is also influenced by substrate conditions. Gusung Toraja Island, had a lowest diversity due to its substrate, which is dominated by sand and mud sediments. The condition of the substrate also affects the morphology of the sponge. Encrusting was the dominant types of the morphologies recorded from this study, as it known that this type is more resistant to high pressure due to sedimentation and strong currents than other morphologies. The results of the nMDS and ANOSIM analysis showed differences in the species composition of sponges at Pannikiang, which was located between the other two islands. In contrast, the islands of Barrang Caddi and Gusung Toraja were not significantly different (p=0.3508). Thus, sponge distribution in the Makassar Strait does not depend on the proximity of the distances between islands.