Gotowa bibliografia na temat „Acropora tenuis”

Many corals establish symbiosis with Symbiodiniaceae cells from surrounding environments, but very few Symbiodiniaceae cells exist in the water column. Given that the N-acetyl-d-glucosamine-binding lectin ActL attracts Symbiodiniaceae cells, we hypothesized that corals must attract Symbiodiniaceae cells using ActL to acquire them. Anti-ActL antibody inhibited acquisition of Symbiodiniaceae cells, and rearing seawater for juvenile Acropora tenuis contained ActL, suggesting that juvenile A. tenuis discharge ActL to attract these cells. Among eight Symbiodiniaceae cultured strains, ActL attracted NBRC102920 (Symbiodinium tridacnidorum) most strongly followed by CS-161 (Symbiodinium tridacnidorum), CCMP2556 (Durusdinium trenchii), and CCMP1633 (Breviolum sp.); however, it did not attract GTP-A6-Sy (Symbiodinium natans), CCMP421 (Effrenium voratum), FKM0207 (Fugacium sp.), and CS-156 (Fugacium sp.). Juvenile polyps of A. tenuis acquired limited Symbiodiniaceae cell strains, and the number of acquired Symbiodiniaceae cells in a polyp also differed from each other. The number of Symbiodiniaceae cells acquired by juvenile polyps of A. tenuis was correlated with the ActL chemotactic activity. Thus, ActL could be used to attract select Symbiodiniaceae cells and help Symbiodiniaceae cell acquisition in juvenile polyps of A. tenuis, facilitating establishment of symbiosis between A. tenuis and Symbiodiniaceae cells.

Ocean warming is a major threat to coral reefs, leading to an increasing frequency and amplitude of coral bleaching events, where the coral and its algal symbiont associations breakdown. Long-term change and resilience of a symbiont community in coral juveniles is thought to be one of the most important aspects for determining thermal tolerance of the coral holobionts; however, despite its importance, they are not well documented in both under elevated temperature and even under natural condition. Here we investigated changes in symbiont communities in juveniles of the coral Acropora tenuis under controlled heat stress conditions (30 °C, 31/32 °C) and natural variations in seawater temperatures (19–30 °C) for up to four months. Compared with the ambient temperature conditions, coral survival rates were higher when exposed to 30 °C, but survival rates decreased when exposed to 31/32 °C. Symbiodinium types A3, C1, and D1-4 were detected in the juveniles under all thermal conditions; however, in higher water temperatures (31/32 °C), both the prevalence of D1-4 Symbiodinium and the number of juveniles harboring only this type of symbiont increased after two to four months later. In contrast, colonies at lower temperatures (30 °C and ambient) harbored multiple clades of symbionts over the same experimental period. These results highlight the flexibility of the coral–Symbiodinium symbiosis for juvenile A. tenuis under variable thermal conditions. In particular, the benefit of the preferential association with type D1-4 can be considered as a response when under heat-stress conditions, and that could help corals to cope with ocean warming.

Kegiatan budi daya karang hias di Indonesia perlu dilakukan untuk menjamin perdagangannya agar berjalan tanpa merusak keanekaragaman dan kondisi terumbu karang. Budi daya karang hias menggunakan rak berupa meja yang terbuat dari paralon PVC yang dinilai sangat ekonomis dan mudah diaplikasikan masyarakat lokal. Pengamatan pertumbuhan hanya dilakukan pada 1 rak masing-masing jenis karang yang dibudidayakan yaitu Acropora sp., Acropora formosa, Acropora humilis, Acropora millepora, Acropora nobilis, dan Seriatopora hystrix. Kegiatan dilakukan pada dua lokasi yaitu Pulau Simakakang-Mentawai, Sumatera Barat dan Gondol, Bali. Pengamatan dilakukan setiap dua bulan dan penelitian dilaksanakan selama 6 bulan. Hasil pengamatan diperoleh tingkat mortalitas pada lokasi Pulau Simakakang diperoleh 5,56% dari 36 sampel yang diukur dari 6 jenis karang dan 6 ulangan, pertambahan panjang jenis A. formosa 0,64 cm/bulan, lebih cepat dibandingkan dengan jenis A. millepora 0,58 cm/bulan dan jenis lain. Karang A. humilis memiliki laju perambatan pada substrat semen dan batang pengikat yang lebih cepat dari jenis lain. Pada lokasi Gondol, Bali memiliki laju pertambahan panjang karang A. millepora lebih cepat (0,50 cm/bulan) dibandingkan dengan jenis A. tenuis (0,43 cm/bulan) dan jenis lain berkisar antara 0,21—0,39 cm/bulan.Tingkat kematian 3 koloni (7,1%) dari total 42 koloni yang disampling.The culture of ornamental coral is important to be conducted to guarantee the coral trade can be run well without giving impact to coral reef biodiversities and coral reef condition in Indonesia. This cultured using table using nets as a place which is made from PVC pipe. This method can minimize cost comparing with others materials as well as applicable for coastal community. One table can be placed 12 (3x4) substrate with a distance among others of 25 cm, then fragmented coral were tied to that substrates. This activity was carried out in two locations that were Simakakang Island, Mentawai, West Sumatera, and Gondol, Bali. The observation of mortality found that the one in Simakakang Island had 5.56% of 36 fragments of 6 species and of 6 replications, length growth of A. formosa was 0.64 cm/month, more rapid than the one of A. millepora (0,58 cm/month) and others species. A. humilis had encrusted to cement substrate, it was more rapid than the one in others species. Length growth rate of A. millepora in Gondol, Bali was more rapid (0.50 cm/month) than A. tenuis (0.43 cm/month), and others (0.21—0.39 cm/month). The mortality rate was 7.1% (3 colonies) from 42 colonies.

Genotype-specific contributions to the environmental tolerance and disease susceptibility of corals are widely accepted. Yet our understanding of how host genotype influences the composition and stability of the coral microbiome subjected to environmental fluctuations is limited. To gain insight into the community dynamics and environmental stability of microbiomes associated with distinct coral genotypes, we assessed the microbial community associated with Acropora tenuis under single and cumulative pressure experiments. Experimental treatments comprised either a single pulse of reduced salinity (minimum of 28 psu) or exposure to the cumulative pressures of reduced salinity (minimum of 28 psu), elevated seawater temperature (+2 °C), elevated pCO2 (900 ppm), and the presence of macroalgae. Analysis of 16S rRNA gene amplicon sequence data revealed that A. tenuis microbiomes were highly host-genotype specific and maintained high compositional stability irrespective of experimental treatment. On average, 48% of the A. tenuis microbiome was dominated by Endozoicomonas. Amplicon sequence variants (ASVs) belonging to this genus were significantly different between host individuals. Although no signs of stress were evident in the coral holobiont and the vast majority of ASVs remained stable across treatments, a microbial indicator approach identified 26 ASVs belonging to Vibrionaceae, Rhodobacteraceae, Hahellaceae, Planctomycetes, Phylobacteriaceae, Flavobacteriaceae, and Cryomorphaceae that were significantly enriched in corals exposed to single and cumulative stressors. While several recent studies have highlighted the efficacy of microbial indicators as sensitive markers for environmental disturbance, the high host-genotype specificity of coral microbiomes may limit their utility and we therefore recommend meticulous control of host-genotype effects in coral microbiome research.

Temperature and light intensity is the most important environmental parameters that influence circadian cycle of scleractinian corals. In this context, modulation of the biomarkers Hsp60 and Hsp70 in situ was investigated by three different healthy coral species (Acropora tenuis, Echinopora lamellosa and Porites lobata) not stress induced during time course of 24h. Significance species-specific modulation under natural conditions is displayed by all corals under study. A strong fluctuation in Hsps expression is shown by the most susceptible, branched coral A. tenuis, instead of fine and low modulation is shown by the massive coral P. lobata. From the results match between morphology difference and physiological difference response its suggest and similarity pattern between Hsps with different cellular compartments location is suggested too. Starting from this study health of coral reefs could be able to be investigated in the future with a set of biomarkers composed also by Hsps which will be set up.

[Truncated abstract] The extent to which marine populations are connected by larval dispersal is crucial to their distribution, maintenance and diversity. Thus, for the effective conservation of threatened systems such as coral reefs, understanding patterns of connectivity is essential. However, the biophysical mechanisms that retain or disperse larvae within and among populations are poorly understood. Though the open ocean environment provides the opportunity for long-distance dispersal, if this potential is only rarely realised, recruits produced from afar are unlikely to contribute to the local-scale demography of populations over ecological time frames, but will limit broad-scale genetic diversification over evolutionary time. This thesis explores the extent of genetic and demographic connectivity of two species of reef-building corals over a range of spatial scales among the discontinuous reef systems of northwest Australia. ... Putative source and sink dynamics were not random, but were associated with levels of disturbance and recovery from a recent and catastrophic coral bleaching. When S. hystrix samples from another two offshore systems were included in the analysis, large differences among systems showed that gene flow over hundreds of kilometres is rare over microevolutionary time scales that account for connections over multiple generations. Levels of subdivision over the same spatial scales were markedly lower in the acroporid coral, Acropora tenuis, than in S. hystrix. These results are congruent with expectations based on reproductive mode; in contrast to S. hystrix, which releases brooded larvae that are competent to settle immediately, A. tenuis broadcasts its gametes, and after external fertilisation, the larvae need to develop for several days before they are competent to settle. Despite the differences in levels of broad-scale subdivision, in both species significant differentiation was detected between reefs within systems (>10 km), and between sites within some reefs (< 10 km). These results indicate not only that dispersal between reefs and even some reef patches is restricted, but also that hydrodynamics influence retention of brooded and spawned larvae in similar ways. Further analysis of A. tenuis populations from two coastal systems detected significant differences in genetic diversity among the four major systems of northwest Australia. Additionally, genetic divergence between the coastal and offshore zones was greater than expected by the geographic separation of systems, indicating that connectivity between these zones via transport of A. tenuis larvae on oceanic currents occurs rarely even over microevolutionary time scales. This study has two primary implications for conservation. First, since coastal and offshore reefs of northwest Australia appear to be discrete genetic entities, they have independent evolutionary potential to adapt to local conditions and environmental change. Second, systems, reefs and some reef patches of northwest Australia are demographically independent units. Therefore, designs of coral reserve networks should consider routine dispersal distances of kilometres to a few tens of kilometres.