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Hilsa shad Tenualosa ilishais of the indigenous fish species and the icon of the Labuhanbatu Regency, Indonesia. Presently, a very limited study was done in this species. Hence, the purpose of this study was to analyse the distribution and growth patterns based on the length-weight relationship of Hilsa shad T. ilishaon Bilah River, Labuhanbatu District, Sumatera Utara Province, Indonesia. Sampling was carried out for 3 months starting in February-April 2019 with the exploration method. Determination of sampling locations based on information from local fishermen. Analysis of distribution data used the Morisita index and growth patterns used the Linear Allometric Model (LAM). The analysis results of Hilsa shad distribution indicated that these fish were distributed in groups/clustered with the Morisita index value of 2.211-2.314. The growth pattern of the fish was negative allometric with a value of b3. Correlation analysis showed that DO was closely related to distribution (r2=0.661), meanwhile, light penetration was closely related to growth patterns (r2=0.914). It is concluded that the distribution of Hilsa shad fish in the Bilah River was in groups or clustered, with a negative allometric growth pattern. Keywords: Hilsa Shad, distribution, growth pattern, Tenualosa ilisha

Mangrove-associated bacteria are of industrial interest due to their diverse and versatile enzyme properties. This study investigates the culturable bacteria from a wide range of habitat in a Bruguiera cylindrica mangrove ecosystem in North Sumatra. Screening of extracellular hydrolytic enzymes showed multiple potential traits in amylase, cellulase, chitinase, phosphatase, protease, and urease production by bacterial isolates. Molecular identification based on 16S rDNA region of a potential strain, Vibrio alginolyticus Jme3−20 is then reported as a newly proteolytic agent. The strain also showed a stable growth under salinity (NaCl) stress with considerable phosphate solubilization activities. Protease activity was enhanced by optimizing the 0.5 % (w/v) sucrose and soy peptone in the fermentation medium. SDS-PAGE and zymogram analysis showed the presence of a 35-kDa MW protease. Hence, our study revealed important insights into the bacterial diversity and activity in mangrove ecosystems, evidencing the importance of microbial exploration in this ecosystem.