PERKEMBANGAN STRUKTUR KOMUNITAS IKAN KARANG DI PERAIRAN KARANG TAMAN NASIONAL KEPULAUAN WAKTOBI

Wilayah Taman Nasional Kepulauan Wakatobi (TNKW) telah dikenal sebagai perairan yang terkelola dengan baik sejak 2010an. Namun dalam perjalanan waktu, aktivitas wisata dan perikanan diasumsikan akan mempengaruhi ekosistem terumbu karang dan mengubah sturktur komunitas ikan karang di kawasan tersebut. Pemantauan perkembangan sumberdaya ikan terumbu karang menjadi suatu pendekatan penting untuk mengetahui adanya perubahan tersebut dari 2015 sampai 2019. Tujuan dari penelitian ini adalah untuk mengidentifikasi perubahan struktur ikan karang di TNKW. Metode yang digunakan adalah sensus visual bawah air pada transek sabuk seluas 350 m2. Unit analisis dalam pemantauan perubahan adalah 7 suku ikan karang karnivora dan herbivora, seperti Serranidae, Lutjanidae, Lethrinidae, Haemulidae, Acanthuridae, Scaridae, Siganidae dan 1 suku obligat karang (Chaetodontidae). Data terkini menunjukkan bahwa terdapat sedikitnya 95 jenis untuk 7 suku ikan karang, dimana pada tahun basis 2015 dijumpai 111 jenis. Kelompok ikan indikator suku Chaetodontidae dijumpai 32 jenis dari semula yang dijumpai 15 jenis. Rata-rata kepadatan ikan target 392 ekor/350 m2. Biomasanya rata-rata 2.224 kg/ha. Kepadatan ikan indikator 294 ekor/350 m2. Jenis-jenis yang mendominasi komunitasnya sejak tahun basis adalah dari suku, Acanthuridae (butana), Scaridae (kakatua) dan Serranidae (kerapu). Jenis koralivora dari suku Chaetodontidae yang mendominasi sejak tahun basis adalah Hemitaurichthys polylepis dan Chaetodon kleinii. Secara umum komunitas ikan karang di perairan Wakatobi berkembang baik dari aspek keragaman, kepadatan dan biomassa ikan karang. The Wakatobi-Archipelago National Park (WANP) has been recognized as good governance management since 2010s. There was asumption that tourism and fishery activities have been going to effluence on reef ecosystems and then altering the reef fish structure communities throughout the times in the area given. Hence, trend assessment for coral reef resources monitoring is an urgent approach to identify the changes of ranging from 2015 to 2019. This study aimed to identify the reef fish structure changes in the area of WANP. An underwater census visual method was used for 350 m2 in area of belt transect. Analysis units used to monitor changes were belong to groups of carnivorous and herbivorous fishes, such as Serranidae, Lutjanidae, Lethrinidae, Haemulidae, Acanthuridae, Scaridae, Siganidae, and belong to coral obligate such as Chaetodontidae.The updating data showed that there were at least 95 species for 7 families of target reef fishes in which before they were pound out 111 species in the basis year of 2015. Meanwhile, indicator fishes of Chaetodontidae were found out 32 species that they before only found out 15 species. The mean of target fish density is 392 individal/350 m2. The mean of their biomassa is 2,224 kg/ha. The indicator fish density was 294 ekor/350 m2. The species dominated their community since the basis year included the families of Acanthuridae (surgionfish), Scaridae (parrotfish) and Serranidae (groupers). Coralivorous species of Chaetodontidae dominated since the basis year, such as: Hemitaurichthys polylepis and Chaetodon kleinii. Generally, the reef fish communities in Wakatobi reef waters get the good trends in regarding to diversity, density and their biomass.

HUBUNGAN ANTARA KOMPOSISI IKAN TARGET DAN PRESENTASE TUTUPAN KARANG HIDUP DI KEPULAUAN KEI KECIL, MALUKU

Ikan terumbu karang memiliki peranan penting baik secara ekonomi maupun ekologi, namun kondisi terumbu karang termasuk di perairan Indonesia yang menjadi habitat utama ikan karang mengalami degradasi. Penelitian ikan karang sudah banyak dilakukan, namun di Indonesia kondisi habitat ikan karang memiliki karakter yang berbeda-beda. Tujuan penelitian ini adalah untuk mengetahui hubungan antara komposisi ikan karang target dan tutupan karang hidup. Penelitian ini dilakukan pada bulan Oktober 2019 di Kepulauan Kei Kecil, Maluku. Metode yang digunakan adalah UVC (Underwater Visual Census) untuk data ikan karang dan UPT (Underwater Photo Transect) untuk mengkaji tutupan karang hidup. Hasil pengamatan menunjukkan bahwa terdapat 130 spesies ikan karang target yang mewakili 19 famili, dengan variasi jenis ikan target antar lokasi pengamatan berkisar antara 25-66 spesies. Kepadatan rata-rata ikan karang target sebesar 8.811 ± 4.107 Ind/ha, dan biomassa rata-rata 1.335 ± 899 Kg/ha. Komposisi ikan karang target yang memiliki kedekatan dengan tutupan karang hidup yaitu famili Siganidae, Serranidae, Lutjanidae, Holocentridae, dan Pomacentridae. Akan tetapi hubungan tersebut rendah, dan kemungkinan besar ada faktor lain yang mempengaruhi. Reef fishes have an important economic and ecological values. However, the coral reef of the globe including in the most of the Indonesian waters which is the vital habitat for reef fishes is degraded. Study on the reef fishes is an abundance, while the habitat characteristic of reef fishes in Indonesian waters has a differences. The aim of this study is to determine the relationship between the target reef fishes compositions and the percentage live coral covers. This study was carried out in October 2019 at the Kei Kecil islands, Maluku. The method used in this study is UVC (Underwater Visual Census) for collecting the reef fishes data, and the UPT (Underwater Photo Transect) for assessing the live coral coverage. The result shows that there are about 130 fishes, which representing 19 families, with species variation ranges from 25 to 66 species among the observation sites. The average density of target fishes was about 8.811 ± 4.107 Ind/ha, whereas the average biomass of target fishes was 1,335 ± 899 Kg/ha. The target reef fishes compositions that has relation with live coral covers is family Siganidae, Serranidae, Lutjanidae, Holocentridae, and Pomacentridae. However, this relationship is weak, and may influenced by other factors

Estimating the extended and hidden species diversity from environmental DNA in hyper-diverse regions

Species inventories are the building blocks of our assessment of biodiversity patterns and human impact. Yet, historical inventories based on visual observations are often incomplete, impairing subsequent analyses of ecological mechanisms, extinction risk and management success. Environmental DNA (eDNA) metabarcoding is an emerging tool that can provide wider biodiversity assessments than classical visual-based surveys. However, eDNA-based inventories remain limited by sampling effort and reference database incompleteness. In this study, we propose a new framework coupling eDNA surveys and sampling-theory methods to estimate species richness in under-sampled and hyper-diverse regions where some species remain absent from the checklist or undetected by visual surveys. We applied this framework to the coastal fish diversity in the heart of the coral triangle, the richest marine biodiversity hotspot worldwide. Combining data from 279 underwater visual censuses, 92 eDNA samples and an extensive custom genetic reference database, we show that eDNA metabarcoding recorded 196 putative species not detected by underwater visual census including 37 species absent from the regional checklist. We provide an updated checklist of marine fishes in the ‘Raja Ampat Bird's Head Peninsula' ecoregion with 2534 species including 1761 confirmed and 773 highly probable presences. The Chao lower-bound diversity estimator, based on the incidence of rare species, shows that the region potentially hosts an additional 123 fish species, including pelagic, cryptobenthic and vulnerable species. The extended and hidden biodiversity along with their asymptotic estimates highlight the ability of eDNA to expand regional inventories and species distributions to better guide conservation strategies

Species richness and the dynamics of coral cover in Bangka Belitung Islands, Indonesia

Pressures on the world’s tropical coral reefs that threaten their existence have been reported worldwide due to many stressors. Loss of coral cover and declines in coral richness are two of the most common changes often reported in coral reefs. However, a precise estimate of species richness and the coral cover dynamics for most Indonesian regions, particularly in the Bangka Belitung Islands, have been poorly documented. Annual monitoring data from 2015 to 2018 at 11 fixed sites in the Bangka Belitung Islands using the photo quadrat transect method identified 342 coral species from 63 genera. Of these, 231 species (>65%) were rare or uncommon, occurring in  0.05). There was a slightly increasing trend in hard coral cover in ten out of 11 sites in 2018, indicating the reefs are in a recovery process. The results support the need to identify recovering or stable areas despite apparent anthropogenic and natural variations recently. This vital information is essential for early detection and preparation for management strategies in the current context of climate change and for ensuring future coral reef survival

The reef health index for coral reefs management in Indonesia

The Indonesian coral reef faced significant challenges due to the lack of precise instruments for assessing the health status of corals, which is crucial for ensuring their long-term viability. The reef health index was established by utilizing extensive monitoring data from Indonesia, incorporating metrics such as live coral cover, resilience level, and biomass of the focal reef fish species. In the year 2021, a comprehensive collection of coral reef data was conducted at 22 distinct places within the waters of Indonesia. It is anticipated that the reef health index data will assist stakeholders in effectively and sustainably managing coral reefs. The findings indicate that the reef health index in Indonesia exhibits a range of values from 2 to 7, with 7 being the highest attainable score. Since observations began in 2014, the Indonesian reef health index has maintained a stable value of 5. The available evidence suggests that there is an ongoing occurrence of coral reef degradation in Indonesian waters, as seen by the diminished biomass of the targeted reef fish species. Nevertheless, the potential for recovery of damaged coral reefs exists if the forces that initiate the damage can be mitigated or eradicated

Accumulation curves of environmental DNA sequences predict coastal fish diversity in the coral triangle

International audienceEnvironmental DNA (eDNA) has the potential to provide more comprehensive biodiversity assessments, particularly for vertebrates in species-rich regions. However, this method requires the completeness of a reference database (i.e. a list of DNA sequences attached to each species), which is not currently achieved for many taxa and ecosystems. As an alternative, a range of operational taxonomic units (OTUs) can be extracted from eDNA metabarcoding. However, the extent to which the diversity of OTUs provided by a limited eDNA sampling effort can predict regional species diversity is unknown. Here, by modelling OTU accumulation curves of eDNA seawater samples across the Coral Triangle, we obtained an asymptote reaching 1531 fish OTUs, while 1611 fish species are recorded in the region. We also accurately predict (R² = 0.92) the distribution of species richness among fish families from OTU-based asymptotes. Thus, the multi-model framework of OTU accumulation curves extends the use of eDNA metabarcoding in ecology, biogeography and conservation

Estimating the extended and hidden species diversity from environmental DNA in hyper‐diverse regions

International audienc