Differential Affinities of a Pocillopora damicornis Galectin to Five Genera of Symbiodiniaceae at Different Temperatures

The symbiosis of coral-Symbiodiniaceae is the quintessential basis of the coral reef ecosystem, and its breakdown results in coral bleaching, one of the most severe ecological catastrophes in the ocean. Critical to the establishment of the symbiosis is the host’s specific recognition of the symbionts through the binding of the coral host’s pattern recognition receptors (PRRs) to the symbiont cell surface’s glycoconjugates. However, the molecular basis for this recognition process is poorly understood. The present study investigated the binding affinities of the coral galectin PdGLT-1 to different symbiodiniacean species under different temperatures. At 25°C, the PdGLT-1 recombinant protein (rPdGLT-1) exhibited different binding affinities to different symbiodiniacean species from five genera, with a significantly higher binding affinity (p < 0.05) to Fugacium kawagutii (2.6-fold) and Cladocopium goreaui (1.9-fold) than Symbiodinium microadriaticum. The binding topology of rPdGLT-1 differed among the five symbiodiniacean species; for S. microadriaticum, Breviolum minutum, and Durusdinium trenchii, the binding was on some specific sites on the cell surface, whereas for C. goreaui and F. kawagutii, the binding signals were detected over the whole cell surface. Interestingly, PdGLT-1 binding induced agglutination of F. kawagutii cells but not of C. goreaui, explaining why C. goreaui was the most dominant symbiodiniacean symbionts in corals. Moreover, the affinity of rPdGLT-1 to Symbiodiniaceae was affected by temperature, and the highest binding affinities were observed at 30, 20, 30, 35, and 30°C for S. microadriaticum, B. minutum, C. goreaui, D. trenchii, and F. kawagutii, respectively. The optimal binding temperatures were consistent with the current understanding that D. trenchii was the most thermal resistant among these species. These results suggest that the binding affinity of the PRR PdGLT-1 may determine the specificity of host-symbiont pairing and explain why Cladocopium is the dominant symbionts of coral P. damicornis at normal temperature, and corals with Durusdinium symbionts may survive better at high temperature.

Reef fish community on Sabira Island, Kepulauan Seribu Regency, DKI Jakarta

Sabira Island is an island close to Jakarta Province but still has good water conditions and a coral reef ecosystem with a high level of diversity. The condition of the coral reef ecosystem affects the community structure of the reef fish there. This study aims to determine the community structure of the reef fish on Sabira Island. The research was conducted in August 2019 on Sabira Island, Kepulauan Seribu Regency, DKI Jakarta Province. Observations of reef fish were carried out using the Underwater Visual Census method at four observation stations. There were 47 species of reef fish found on Sabira Island from 12 families. The total reef fish found were 1315 individuals, consisting of 79 indicator fish, 417 individual target fish, and 819 major fish. The highest diversity index value on Sabira Island was found at the South Station, with a diversity index value of 2.39. Based on the community structure index at the four observation stations, the reef fish community’s condition on Sabira Island is still good ranging from unstable to stable condition with moderate diversity and low dominance index values.

Feeding preference of herbivorous fish: Family Scaridae

Parrotfish is one of dominant species in Indo-Pacific areas which have 9 genera and 83 species. In ecological perspective, the feeding behaviours of these fish very important, due to control population of algae in coral reef ecosystem. They used their jaw to excavate and scrape alga which living on coral substrata, so sometime resulted on erosion in substrates and coral. The aim of this research to record the diet preference of Scariids fish in NCF Putri Menjangan conservation area, Bali on January to february 2020. Group of Scariids fish was recorded by underwater camera for one minute then the bites scared were calculated manually and photographed. The result of study showed that 10 species from two genera (Chlorurus and Scarus) was dominantly herbivorous fish in this area. The highest number of fish bites at station 1 was obtained from S. qouyi species with a total of 41.27 bpm, while stations 2 and 3 were obtained from S. rivulatus species with a number of 40.96 bpm and 41.59 bpm, respectively. The majority of parrotfish species found chose to forage on dead coral with algae substrates because the water conditions were not optimal for the growth of coral, so many corals died and their skeletons were overgrown by algae.

Analysis of hard coral condition on coral reef ecosystem in Ternate Island

Hard coral is a type of coral building structure in coral reef ecosystems. Hard coral is a coral reef entity that plays an important function in a coral reef ecosystem, especially related to physical and ecological functions in shallow marine waters environment. This study aimed to study percentages of coral cover, species life form, diversity index, dominance index, and distribution clusters of hard corals based on environmental parameters around Ternate Island. Hard coral cover sampling was carried out systematically using the underwater photo transect (UPT) method. The number of sampling stations were 30 location points with 750 photos. The method used for analyzing ecological conditions of hard corals was coral point count with excel extensions (CPCe). Environmental parameters measured included salinity, temperature, pH, brightness level, and dissolved oxygen. The distribution of hard coral clusters was analyzed statistically using the classify-hierarchical cluster. Study results showed that coral cover percentages ranged from 19% to 93% with an average cover of 67%, species diversity range was 7 to 40 species with an average of 19 species, diversity index (H ') with a value of 1.14 to 6.02 with an average of 2.07, dominance index (D) with a value of 0.13 to 0.53 with an average of 0.23. The results of the analysis of the distribution of hard corals consisted of four clusters. The study also found that distribution of hard coral clusters in Ternate Island was related to substrate topography.

Morfometri, Pemijahan, dan Indeks Kematangan Gonad Teripang Komersial di Perairan Pulau Nyamuk, Karimunjawa

Sea cucumbers are marine organisms that live in coral reef ecosystem habitats and their associations. Sea cucumbers have been used by communities as food, cosmetics and traditional medicine in various countries. The benefits and high economic value of sea cucumbers make fisheries activities occured massively and continuously. Sea cucumbers were large commodity from Indonesian waters. However, until now it has not received proportional attention. The lack of information on morphometry, spawning in various regions has made the commodity of sea cucumbers decreased. This research was conducted to determine the character of commercial sea cucumber commodities in Pulau Nyamuk, to the occurrence of spawning based on the moon phase. This research was conducted in September - November 2020. This research method uses an analysis approach of gonadal maturity index in determining the spawning of sea cucumbers. The results showed that commercial sea cucumbers in Pulau Nyamuk were Pisang (Holothuria sp.) and Gamat (Stichopus sp.) Sea cucumber. This sea cucumber weighs 300-690 grams wet. Sea Cucumbers, Pisang and Gamat tend to have high IKG values in the new moon phase with IKG index values >10%. Teripang merupakan organisme laut yang hidup pada habitat ekosistem terumbu karang dan asosiasinya. Teripang telah dimanfaatkan oleh masyarakat di sekitar pantai sebagai bahan makanan, kosmetik serta obat tradisional di berbagai negara. Manfaat serta nilai ekonomi teripang yang tinggi membuat aktivitas pemburuan terjadi secara masif dan terus menerus. Teripang juga merupakan komoditas besar yang berasal dari Perairan Indonesia. Namun hingga saat ini belum memperoleh perhatian yang proporsional. Minimnya informasi mengenai morfometri, pemijahan di berbagai daerah membuat komoditas teripang turun secara drastis. Penelitian ini dilakukan untuk mengetahui karakter komoditas teripang komersial di Pulau Nyamuk, hingga terjadinya pemijahan berdasarkan fase bulan. Penelitian ini bulan September - November 2020 di Perairan Pulau Nyamuk Kecamatan Karimunjawa, Kabupaten Jepara. Metode penelitian ini menggunakan pendekatan analisis indeks kematangan gonad dalam menentukan pemijahan teripang. Hasil penelitian menunjukkan bahwa teripang komersial di Pulau Nyamuk adalah jenis teripang Pisang (Holothuria sp.) dan Gamat (Stichopus sp.). Teripang ini mempunyai berat 300-690 gram basah. Teripang Pisang dan Gamat cenderung mempunyai nilai IKG yang tinggi pada bulan baru dengan nilai indeks IKG >10%.

Variasi Temporal Kelompok Ikan Terumbu Karang di Pulau Tidung Kecil Menggunakan eDNA Metabarkoding dan Sensus Visual

Coral reef fish are play key role in coral reef ecosystem. The presence of reef fish affected by antrophogenic and natural factors, such seasonal changes. This study aimed to asess the temporal variation of coral reef fish group in Tidung Kecil Island using eDNA metabarcoding and Undewater Visual Census. This research was conducted at December 2019 (West season) and August 2020 (East season). Target group are dominated in west season (64.1%) and east season (59.25%) using eDNA metabarcoding. While, major group fish are the highest relative abundance in both season by using Underwater Visual Census. Family Carangidae are the highest species richness (15 species) in wet season and Serranidae (3 species) in east season, respectively. Futhermore, famili Pomacentridae are the most richness species in west and east seasons 10 and 11 species respectively. Thus, it can be concluded these two methods are effective for monitoring structure or abundance of coral reef fish based on seasonal variation. Ikan karang menjadi indikator dalam menilai keanekaragaman hayati di ekosistem tersebut. Keberadaan ikan di ekosistem terumbu karang dapat dipengaruhi oleh faktor antropogenik dan faktor alam salah satunya perubahan musim. Penelitian ini bertujuan untuk menganalisis kelimpahan kelompok ikan terumbu karang di Pulau Tidung Kecil menggunakan eDNA metabarkoding dan Sensus Visual. Pengambilan data dilakukan pada bulan Desember 2019 (musim barat) dan Agustus 2020 (musim timur). Ikan target mendominasi pada musim barat dan timur dengan persentase sebesar 64.11% dan 59.25%. Sensus visual berhasil mendeteksi ikan mayor dengan persentase tertinggi 62.5% di musim barat dan 82.8% di musim timur. Famili Carangidae merupakan famili dengan jumlah spesies tertinggi di musim barat (15 species) dan Siganidae di musim timur menggunakan eDNA metabarkoding (3 species). Hasil UVC menunjukkan famili Pomcentridae memilki jumlah spesies tertinggi di kedua musim (11 dan 10 spesies) menggundakan sensus visual. Dapat disimpulkan bahwa kedua metode tersebut dapat menjadi pendekatan dalam monitoring struktur atau kelimpahan ikan terumbu karang berdasarkan musim.

POPULATION CONDITIONS OF ECHINOIDEA AND CORAL REEF COVERS IN PONCAN GODANG ISLAND, SIBOLGA, NORTH SUMATERA

Poncan Godang Island is included in the appropriate category based on the suitability of land for the Sibolga tourist area, with the presence of tourism activities that can also affect the amount of biodiversity in it. Considering the importance of coral reefs for biodiversity and sea urchins which also have a role in coral reef ecosystems, it is necessary to conduct research on the condition of sea urchins population and the percentage of coral reefs on Poncan Godang Island. Sea urchin and coral reef data were collected using the Line Intercept Transect (LIT) method by monitoring directly on the transect line along 50 meters. The results obtained indicate that the population of sea urchins in the waters of Poncan Godang Island, North Sumatra can be described, that sea urchins do not affect the coral reef ecosystem because at stations 1 and 5 there is no sea urchin and the percentage of coral cover is classified as bad, but at station 3 there are 32 individuals with coral reef cover conditions, while at stations with The percentage of good coral cover is that at station 4 there are only 25 individuals, as well as at station 2 where the percentage of coral cover is higher than station 3 and there are no sea urchins