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The Arabian Gulf experiences extreme seasonal fluctuations in temperature and salinity, imposing strong environmental filters on benthic ecosystems. This study examined the seasonal dynamics of macrobenthic communities in the hypersaline lagoon Khor‑Al‑Adaid, Qatar, to determine how physicochemical variability shapes species composition, diversity, and functional structure. Across four seasons, 108 macrobenthic taxa were recorded, with polychaetes representing the dominant group. Macrofaunal abundance peaked in winter (1774 ind. m−2) and it was lower in summer (703 ind. m−2), whereas species richness was higher in summer (47 species). Diversity indices varied seasonally (H′ = 1.23–1.52; d = 3.7–5.3; J′ = 0.40–0.46), reflecting shifts in community structure under extreme summer hyper salinity and temperature. Multivariate analyses (cluster analysis, SIMPER, k‑dominance curves, and RDA) revealed clear seasonal separation of assemblages, with winter communities associated with higher dissolved oxygen and chlorophyll‑a, and summer communities linked to thermal and salinity stress. Overall, the results demonstrate that extreme physicochemical conditions strongly regulate benthic community patterns in this lagoon system, providing an essential ecological baseline for monitoring and conservation in hypersaline environments of the Arabian Gulf.
The siliceous sediments of the Indian Ocean hosts one of the richest deposits of polymetallic nodules, and their growth is intimately associated with these sediments. They are comprised of only 10
Hypersaline environments exhibit extreme physiochemical conditions yet support diverse microbial communities. These communities are not only ecologically important but also possess substantial potential for biotechnological exploitation. In this study, we employed a comparative metagenomic approach to assess microbial diversity using two distinct methodologies: (1) direct DNA extraction from raw sediment, and (2) DNA extraction following halophilic enrichment in selective media. Sediment samples were collected from multiple sites and pooled together within the Rann of Kachchh and close-by saltpans and were analysed using 16S rRNA sequencing coupled with bioinformatics pipelines. The results revealed pronounced differences in microbial community composition between the two approaches. Raw sediment samples exhibited significantly higher alpha diversity, with dominant taxa including Halobacterota, Cyanobacteria, and Desulfobacterota, with a substantial proportion of unclassified genera. In contrast, enriched samples were dominated by fast-growing, culturable genera such as Halobacterium, Alkalibacillus, and Candidatus haloredivivus. Principal Coordinate Analysis (PCoA) of beta diversity demonstrated distinct clustering between raw and enriched communities, even within samples from the same sites, underscoring the selective bias introduced by enrichment procedures. These findings emphasise that the methodological choice strongly influences the observed microbial diversity. The aim of this study was to compare microbial community composition in raw hypersaline sediments and enrichment cultures using metagenomic sequencing, to evaluate how enrichment selectively favours specific halophilic taxa. This comparative approach allows identification of the microbial groups that rapidly proliferate under controlled hypersaline conditions, thereby complementing direct environmental sequencing. By integrating both direct and enrichment-based metagenomic approaches, a more comprehensive understanding of microbial community structure in hypersaline environments can be achieved.
The Lakshadweep Archipelago, a tropical carbonate platform in the northeastern Arabian Sea, features diverse and understudied benthic habitats. This study provides the first integrated analysis of meiofaunal and nematode community structure across its topographic features, investigating how environmental gradients shape taxonomic and functional diversity. We sampled 11 stations (depth 18–200 m) encompassing rocky, sandy, and mixed substrates. Meiofauna was dominated by nematodes (91.9
Marine tardigrades from the Indian waters offer an important but largely overlooked component of regional biodiversity, and every new record contributes significantly to understanding their distribution and taxonomy. Expanding knowledge of this group, the present study describes a new species of Actinarctus Schulz, 1935 discovered nearly half a century after the last known addition to the genus, from the coastal region of Odisha along the northeast coast of India. This highlights the hidden diversity of marine meiofauna in the Indian subcontinent. The new species, Actinarctus odissi sp. nov., can be easily distinguished from its congeners by the structure and ornamentation of the dorsal body cuticle, shape and arrangements of lateral epicuticular alae, structure and length of leg IV sensory organ and primary clava, presence of Van der Land’s organ in the cephalic and leg sensory organs, occurrence of two small, circular, cushion-like structures between the bases of the internal and external digits.
