Search

Studies on coral genetics have been widely used recently for varied research purposes, including to solve the taxonomical challenge or to understand the physiological-ecological aspects of corals towards climate change. While the information provided by coral genome is crucial for those works, isolation of coral genome is still a difficult preliminary step due to coral's nature. This study aimed to evaluate and to suggest the best application of among four established methods for DNA extraction from scleractinian coral, i.e., Guanidine hydrochloride (GuHCl), Chelex chelating resin, Guanidinium thiocyanate-phenol-chloroform (AGPC), and spin-column methods. Coral samples were grounded and submitted to each extraction method's protocol. Final extracts were checked for their quality and quantity. The final extracts feasibility were tested through PCR (Polymerase Chain Reaction), followed by electrophoresis for amplicon quality screening. The scoring was done for assessment aspects: time efficiency, successful extraction process, extracted DNA quantity and quality, final extract properness, and cost effort per sample. The highest DNA concentration was obtained by spin-column methods, reaching up to 724.31 ng/µl, while other methods can only provide between 264.94±36.453 to 378.19±0 ng/µl of DNA. Among all method tested, the spin-column was able to provide reproducible and feasible quality of final extracts for the amplification. Other methods were failed to provide such consistent and proper results. The results suggesthat the spin-column is the most appropriate method for DNA isolation from scleractinian specimen.

Morphological distinctions between males and females of a species are referred to by sexual dimorphism. It may result from various selection pressures affecting either sex or both and may occur in any dioecious species, including Green Swordtail fish, which are sexually reproductive. This study examined the different rheotaxis responses of Xiphophorus hellerii based on different sexes and morphological features. We analyzed ten adult males, ten gravid females, and ten non-gravid females of Xiphophorus helleri collected down the river and transferred into the column. We counted the number of the individual that performed positive rheotaxis (+), negative rheotaxis (-), and indifference response (0). The result showed different rheotaxis responses shown by male, non-gravid female, and gravid female X. hellerii. The highest percentage of positive rheotaxis response (movement against the current) was shown by non-gravid female X. hellerii, reaching up to 89%. Morphological differences between male, non-gravid female, and gravid female X. hellerii appear to affect the orientation and ability of X. hellerii in giving response against current and certainly has an impact on their survival in nature.

Ghafari MIA, Fitrianti V. 2021. Pioneer assessment on megabenthic community suggests the recent ecological condition of coral reef in Senggigi Beach, Western Lombok Island, Indonesia. Indo Pac J Ocean Life 5: 14-21. Megabenthic communities are among the excellent bioindicator used nowadays. This study was the first to conduct in Senggigi Beach and provide preliminary useful information regarding the condition of coral reef ecosystem on-site, through assessing the megabenthic community from 2019-2020 to 202-2021. Benthos Belt Transect (BBT) method was used to collect data from 6 different observation sites. There are 3 groups of targeted megabenthic fauna assessed: the bioindicator group (sea urchin and blue starfish), the corallivorous group (drupella snail and crown-of-thorns starfish), and the commercially valued group (edible sea cucumber, giant clam, spiny lobster, and commercial top shells). Sea urchin was found to dominate all stations, indicating a decreasing live coral cover after bleaching. Presence of corallivorous megabenthos was very rare, as it is not a potential threat to corals. There is a trend of increasing density of edible sea cucumber and giant clam by 30% and 50% respectively, with a mass giant clam recruit in 2021. We suspect less or no impact of anthropogenic activity to megabenthic community dynamic in Senggigi Beach to date, but their community dynamic is purely influenced by the decline condition of coral reef ecosystem due to recent 2016 mass bleaching.