Study of diatom assemblages in Sundarbans mangrove water based on light microscopy and rbcL gene sequencing

Seasonal variability of modern benthic foraminifera assemblages in a mangrove ecosystem from northeast coastal Bay of Bengal

Benthic foraminifera assemblages, nutrient dynamics of surface and porewater from 10 intertidal sites spanning over two years (2019-2020) covering two major estuaries in Sundarbans mangrove were evaluated to understand role of seasonal precipitation and primary production (driven by eddy nutrients) with a focus on standing crop. Benthic foraminifera abundance ranged between 280 individuals/10 cc in pre-monsoon (2019), 415 individuals/10 cc in post-monsoon 2019 and 630 individuals/10 cc in post-monsoon (2020). Standing crop was highest in post-monsoon coinciding with eddy nutrients driven stoichiometry and increase in abundance of large diatom cells. Calcareous and agglutinated foraminifer taxa Ammonia sp.1, Quinqueloculina seminulum, Entzia macrescens and Textularia sp. respectively were frequent. Entzia macrescens was found in dense mangrove vegetation sites; exhibited strong relationship with sediment texture and pore water total organic carbon. One of the major findings is mangroves with pneumatophores improves oxygen availability in sediment and leads to an increase in standing crop.

Genome analysis of a plastisphere-associated Oceanimonas sp. NSJ1 sequenced on Nanopore MinION platform

Oceanimonas sp. NSJ1 was isolated from macroplastic debris collected previously from Junput, an intertidal beach, facing the northeast coastal Bay of Bengal of the Northern Indian Ocean. The genome of this isolate is closely related to Oceanimonas doudoroffii with a genome size of 3.56 Mbp. The genome annotation confirmed the presence of 5919 total genes, out of which 5809 were CDSs (coding sequences) and all are protein-coding. The genome codes for 110 RNA with 25 rRNA, 84 tRNA (transfer RNA), and one tmRNA (transfer-messenger RNA). Analyses of the annotated genome of Oceanimonas sp. NSJ1 revealed the presence of enzymes involved in the degradation of polycyclic aromatic hydrocarbons. The presence of phthalate 4,5-dioxygenase oxygenase reductase subunit pht2 within the genome also highlights the novelty of this isolate and future functional potential for studying phthalate degradation in marine environment.

A new marine epipsammic diatom species, Ambodajingensis sp. nov. (Bacillariophyceae), from the coast of Southeast China

Ambodajingensis HH Liu, Z Wang, YH Gao & CP Chen, sp. nov. is described as a new species in samples collected from sand grains at Dajing Beach, Ningde City, Fujian Province, China. Morphological details of the new species with respect to valve shape, size and valve ultrastructure are presented based on light microscopy (LM) and scanning electron microscopy (SEM). The main features of Ambodajingensis under a light microscope are elongated elliptic valves with rounded apices, two internal costae on the valve and rectangular in girdle views. SEM observation showed that externally, the frustules are comprised of two valves with a relatively deep mantle and a transition between the valve faces. Small, flabelliform spines are present along the valve margin. Internally, the valves are divided into three sectors by robust costae, which penetrate the whole valve lumen and are thickest at the mantle interior and thinner toward the center. The sternum is narrow and linear, visible only in the valve apex, set off by costae. The striae are comprised of small, round areolae and they are parallel in the middle to slightly radiate at the apices. The new species is compared with other species in the genus Ambo.