Research on dugong-seagrass interactions in Indonesia was done during the period 1990 until 2005 in respectively East Aru, Maluku Province and East Kalimantan, Indonesia. This research investigated intensive rotational grazing by dugongs in intertidal inshore Halodule univervis seagrass meadows, dugong movements in relation to these grazing swards, and analyses of parameters explaining the temporal and spatial patterns of grazing in these meadows. In this paper, we report the findings of this long-term study. The patterns of movement and the results of snorkelling surveys confirmed a practice of regular recropping of restricted grazing swards by small feeding assemblages of dugongs. Dugong grazing showed a significant correlation with carbohydrate content of the below-ground biomass and no significant relation with total N. The timing of dugong grazing in these intertidal meadows coincides with high below-ground biomass and high carbohydrate content in the rhizomes of H. uninervis in the upper 0-4 cm sediment layer. Our findings support the hypothesis that temporal dugong grazing is ruled by carbohydrate content in below-ground biomass. The mechanisms of rotational grazing in restricted grazing swards are not yet well understood, and the maximisation of carbohydrates does not fully explain this phenomenon. Our research confirms that intertidal H. univervis seagrass meadows form a crucial resource for dugong survival. These relatively unknown biotopes need therefore more attention in research and conservation programmes.

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Sari YP, Kusumawati E, Saleh C, Kustiawan W, Sukartingsih. 2018. Effect of sucrose on callogenesis and preliminary secondary metabolic of different explant (Myrmecodia tuberosa). Nusantara Bioscience 10: 183-192. Myrmecodia tuberosa Jack is a medicinal plant that contains bioactive compounds, such as flavonoids, tannins, tocopherols, phenols, and an abundance of minerals, that are useful as antioxidants. With the constant increases in popularity of the medicinal plant, the M. tuberosa is threatened by extinction if over-exploitation continues. Thus, the effort to conserve this plant is vital. Tissue culture is an alternative method to conserve and produce active compounds that are similar to those of the native ant nest plant with callus. The addition of certain compounds such as sucrose can affect the secondary metabolite content through in vitro plant or callus. The aim of this research was to find the explant sources (cotyledon, stem, tuber, and root), determine the best growth regulator to produce the callus, and evaluate the optimum sucrose concentration to enhance secondary metabolite production of the callus. The results showed that callus was obtained from all explant sources and all growth regulators. The best callus that was marked by a friable green and yellowish green callus was provided by cotyledon with the growth regulator of 2 mg⋅L-1 of 2.4-dichlorophenoxyacetic acid (2.4-D) and 2 mg⋅L-1 of kinetin. Calli treated with 30 g of sucrose resulted in the best secondary metabolites, containing alkaloids, phenols, flavonoids, saponins, and steroids.

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