Keanekaragaman dan Kelimpahan Nudibranch di Pantai Penimbangan Buleleng Bali
Authors: Amelia Jasmine Masyitha , Prasetia I Nyoman Dodik , Setiabudi Gede Iwan 
Published: October 2022

Pantai Penimbangan terletak Desa Baktiseraga, Kecamatan Buleleng merupakan kawasan pusat kota Kabupaten Buleleng, Bali yang memiliki hamparan pasir hitam. Kegiatan konservasi penyu di kawasan ini meningkatkan gairah masyarakat dalam menjaga kelestarian ekosistem terumbu karang. Salah satu biota yang beriteraksi di ekosistem terumbu karang adalah nudibranch. Keberadaan nudibranch di Pantai Penimbangan diharapkan mampu menjadi alternatif potensi wisata yang bisa dikembangkan, sehingga antusiasisme masyarakat untuk menjaga kelestarian ekosistem pesisir akan terus terjaga.  Penelitian bertujuan untuk memperkuat data dasar ekologi tentang keanekaragaman dan kelimpahan nudibranch. Penelitian populasi nudibranch dinilai dengan sensus visual mengikuti line intercept transect. Penelitian nudibranch di Pantai Penimbangan menunjukkan bahwa terdapat 12 famili yaitu  Chromodorididae, Phyllidiidae, Discodorididae, Aeolidiidae, Elysiidae, Aglajidae, Bornellidae, Facelinidae, Flabellinidae, Hexabranchidae, Limapontiidae, dan Pleurobranchidae, dengan 42 jenis. Kelompok Chromodorididae dan Phyllidiidae adalah kelompok yang umum dijumpai di Perairan Pantai Penimbangan.  Kedua kelompok ini memanfaatkan patahan karang yang menjadi subsrat perairan sebagai tempat berlindung. Komposisi substrat sangat menentukan kekayaan nudibranch, kategori substrat yang menentukan keberadaan nudibranch adalah dead coal with alga, sponge, dan hard coral. Tingginya persentase dead coral with alga, dan sponge berbanding lurus dengan keanekaragaman nudibranch, dan hard coral berbanding terbalik dengan keanekaragaman nudibranch.  Kriteria indeks keanekaragaman tinggi dengan nilai 2,6199, Indeks keseragaman 0,7055 dan nilai dominansi 0,0342.  Tingkat kelimpahan tertinggi pada jenis Hypselodoris tryoni. Penimbangan Beach is located in Baktiseraga Village, Buleleng District, which is the downtown area of Buleleng Regency, Bali which has a stretch of black sand. Turtle conservation activities in this area increase the enthusiasm of the community in preserving the coral reef ecosystem. One of the biota that interacts in the coral reef ecosystem is the nudibranch. The existence of nudibranchs at Penimbangan Beach is expected to be an alternative tourism potential that can be developed, so that public enthusiasm for preserving coastal ecosystems will continue to be maintained. This study aims to strengthen the basic ecological data on the diversity and abundance of nudibranchs. The study of the nudibranch population was assessed by visual census following the line intercept transect. Research on nudibranchs at Penimbangan Beach showed that there were 12 families namely Chromodorididae, Phyllidiidae, Discodorididae, Aeolidiidae, Elysiidae, Aglajidae, Bornellidae, Facelinidae, Flabellinidae, Hexabranchidae, Limapontiidae, and Pleurobranchidae, with 42 species. Chromodorididae and Phyllidiidae groups are common groups found in Penimbangan Beach. Both of these groups take advantage of coral fractures which become the substrate of the waters as a shelter. Substrate composition greatly determines the richness of nudibranchs, the substrate categories that determine the presence of nudibranchs are dead coral with algae, sponges, and hard corals. The high percentage of dead coal with algae, and sponges is directly proportional to nudibranch diversity, and hard coral is inversely proportional to nudibranch diversity. The criteria for the high diversity index are 2.6199, the uniformity index is 0.7055 and the dominance value is 0.0342. The highest abundance level was in Hypselodoris tryoni.