Microbial community composition associated with early developmental stages of the Indian white shrimp, Penaeus indicus

Gut microbiota is known to influence the physiology, health, nutrient absorption, reproduction, and other metabolic activities of aquatic organisms. Microbial composition can influence intestinal immunity and are considered as health indicators. Information on gut microbial composition provides potential application possibilities to improve shrimp health and production. In the absence of such information for Penaeus indicus, the present study reports the microbial community structure associated with its early developmental stages. Bacterial community associated with the early developmental stages (egg, nauplii, zoea, mysis, postlarvae-1, postlarvae-6 and postlarvae-12) from two hatchery cycles were analysed employing 16S rRNA high throughput sequencing. Proteobacteria and Bacteroidetes, were the two dominant phyla in P. indicus development stages. Sequential sampling revealed the constant change in the bacterial composition at genus level. Alteromonas was dominant in egg and nauplii stage, whilst Ascidiaceihabitans (formerly Roseobacter) was the dominant genera in both PL6 and PL12. The bacterial composition was highly dynamic in early stages and our study suggests that the mysis stage is the critical phase in transforming the microbial composition and it gets stabalised by early post larval stages. This is the first report on the composition of microbiota in early developmental stages of P. indicus. Based on these results the formation of microbial composition seems to be influenced by feeding at early stages. The study provides valuable information to device intervention strategies for healthy seed production.

Length-weight relationship of Penaeus indicus and Penaeus merguiensis in the Langsa mangrove area, Aceh Province

The two Penaeid shrimps Penaeus indicus and Penaeus merguiensis are the most common commercial species found in the Langsa mangrove forest. The growth pattern of these two Penaeid shrimps are strongly influenced by environmental factors such as temperature, pH, dissolved oxygen (DO), salinity, availability of food and predators, which ultimately determines the abundance and catch of commercial adult shrimps obtained. The present study aims to investigate the length-weight relationship of P. indicus and P. merguiensis in the Langsa mangrove forest, Aceh Province. The sampling was conducted in November 2018 with the stratified random sampling method. A total of 124 shrimps consisted of 92 samples P. indicus and 32 samples P. merguiensis. The results showed that growth pattern of two Penaeid shrimps was categorized as negative allometric. The highest b value is shown in P. merguiensis with b value of 2.87 while P. indicus 2.55. The value of the relative weight condition factor (Wr) of the two shrimps indicates a value of >100. It is concluded that the waters of the mangrove forest in Langsa City are still able to support the survival of P. indicus and P. merguiensis.

Effect of Mangrove Cover on Shrimp Yield in Integrated Mangrove-Shrimp Farming

In recent decades, mangroves have been seriously devastated by shrimp farming development in the Vietnamese Mekong Delta. As a result, integrated mangrove-shrimp farming has emerged as a potential solution to culture shrimps and protect mangroves. The present study aims to understand whether mangrove-to-pond cover ratios influence shrimp yields in an integrated mangrove-shrimp farming system. Five integrated mangrove-shrimp ponds in the Tam Giang Commune, Nam Can District, Ca Mau Province (Southern Vietnam) were chosen for this study. The study estimated that the mangrove-to-pond cover ratios ranged from 42.00 % to 72.50 %. The total shrimp yield per year (kg.ha-1 yr-1 ) was generally high, ranging from 76.62 to 249.09 (including 37.93 to 108.64 for the black tiger shrimp (Penaeus monodon Fabricius, 1798), and 38.69 to 140.45 for other shrimps, namely Penaeus indicus Milne Edwards, 1837, Penaeus merguiensis de Man, 1888, Metapenaeus ensis (De Haan, 1844), and Metapenaeus lysianassa (de Man, 1888)). Moreover, a strong positive correlation between the mangrove-to-pond cover ratios and the shrimp yields were observed (r > 0.71, P < 0.05). In conclusion the mangrove-to-pond cover ratios have a direct impact on the total shrimp yield. The mangrove-to-pond cover ratios should be 50 % to enhance shrimp yields in this system.

Gut microbial diversity and composition of Indian white shrimp (Penaeus indicus)

The endemic Indian white shrimp (Penaeus indicus) is an economically important shrimp species, distributed in the Indo-West Pacific region. Knowledge of gut microbial composition helps in dietary interventions to ensure improved health and production. Here we analyzed V3-V4 hypervariable regions of the 16S rRNA gene to examine intestinal microbiota in the wild and farmed P. indicus. The study revealed Proteobacteria, Fusobacteria, Tenericutes, and Bacteroidetes, were the dominant phyla in both the groups; though the differences in relative abundance were evident. The dominant genera in case of the wild group were Photobacterium (29.5%) followed by Propionigenium (13.9%), Hypnocyclicus (13.7%) and Vibrio (11.1%); while Vibrio (46.5%), Catenococcus (14%), Propionigenium (10.3%) and Photobacterium (8.7%) were dominant in the farmed group. The results of the study suggest the role of environment on the relative abundance of gut bacteria. This is the first report characterizing gut microbial diversity in P. indicus, which can be used to understand the role of gut microbiota in health, nutrition, reproduction, and growth.