Epiphytic Bacterial Communities in Seagrass Meadows of Oligotrophic Waters of Andaman Sea

Abstract

The epiphytic microbial communities of seagrass (Cymodocea rotundata and Thalassia testudinum) along with sediments and seawater of the seagrass ecosystem of Andaman Sea were assessed for heterotrophic bacterial communities. Young leaves of C. nodosa and T. testudinum sediments and water samples were collected from two different locations at Burmanala and Havelock island. Young leaves were swabbed and transferred into Alkaline peptone water along with 1 gm of sediments and 1 ml of seawater for initial microbial enrichments, followed by culture of microbes in Salt Yeast Extract Agar. Thiosulphate Citrate Bile Salt agar was used for seagrass leaves, sediments and water for culturing of Vibrio like microbes. The observed colonies were morphologically (colour) identified first and then further identification was done by Gram staining and various biochemical tests. Sediment bacterial count was 10-fold higher than seagrass and water column communities. Morphologically 29% of total bacterial colonies identified were of grey and white colour. T. testudinum bacterial epiphytes were 2-fold higher than C. rotundata communities. Gram negative bacterial isolates of Pseudomonas, Vibrios and Aeromonas dominated the bacterial colonies than gram positive bacteria of Bacillus and Micrococcus. Vibrios were only observed on seagrass leaves. Seagrass harboured more gram positive bacterial colonies than gram negative, which were dominated in the sediments of seagrass ecosystem. The bacterial communities of landward site of Burmanala and Havelock were similar whereas 2-fold higher communities were observed at the seaward site of Havelock site on T. testudinum. Seagrass ecosystem bacterial epiphytic communities are diverse in oligotrophic waters.

Ecological association between seagrass and mangrove ecosystems increases seagrass population longevity in island ecosystem

“…The number of leaves per shoot and the number of leaves produced per year (Table 1) derived from plastochrome interval for site 1 (25.49 days per leaf) was higher compared to site 2 without mangroves, which suggests the T. hemprichii meadows being associated with mangroves have the requisite nutrients and favourable conditions to produce a single leaf within 25.49 days, whereas the site without mangroves is deprived of nutrients as the waters of Andaman Sea are oligotrophic (Mishra and Mohanraju, 2018; Mishra and Kumar, 2019 accepted article) and are under immense pressure from breaking waves. The number of leaves per shoot at site 2 (3.80±0.03) in our studies are similar (3.80) and higher at site 1 (3.98±0.01) to previously observed results of ANI (Savurirajan et al, 2018).…”

The Current Status of <em>Halophila beccarii</em>: An Ecologically Significant, Yet Vulnerable Seagrass of India

“…Secondly, the nutritional value of H. beccarii leaves (29.16 K cal g -1 ) are low with high tannin and phenol content that makes it non-edible without cooking (Pradheeba et al, 2011).However, this plant has immense potential in providing various bioactive compounds, which have been identified recently, with bioactive compounds as antidiabetic (Vani et al, 2018), anti-dengue fever treatment (Ali et al, 2012), antioxidants (Neelima et al, 2015;Kar et al, 2019) and against various human pathogens (Kavitha et al, 2020). Seagrasses like T. hemprichii that are also found associated with mangroves (Mishra and Apte, 2020a) have been found to be a good source of bioactive compounds (Mishra and Mohanraju, 2018).…”

Short Communication: Diversity of culturable epiphytic bacteria isolated from seagrass (Halodule uninervis) in Thailand and their preliminary antibacterial activity

“…They are a very unique and specialized group of marine flowering plants that have fully adapted to an underwater lifestyle (Hurtado-McCormick et al 2019). Seagrass meadows are highly productive and dynamic coastal ecosystems (Mishra and Mohanraju 2018). They provide numerous important ecological services to the marine ecosystem such as carbon dioxide capture and storage, the food source of rare marine animals, habitat, and nursery of marine life, and protection of shorelines (Horinouchi et al 2012;Ugarelli et al 2017;Rotini et al 2020).…”

“…The epiphytic species provide seagrasses with nitrogen fixation and nutrient cycling. They not only contribute to the seagrass ecosystem but also support other functions to herbivory and transfer of energy to higher trophic levels (Mishra and Mohanraju 2018). Cristianawati et al (2019) studied seagrass-associated bacteria from the North Java Sea, Indonesia.…”