Arsenic (As) contamination is a major global environmental concern with widespread effects on health of living organisms including humans. In this review, the occurrence (sources and forms) of As representing diverse aquatic habitats ranging from groundwater to marine environment has been detailed. We have provided a mechanistic synopsis on direct or indirect effects of As on different organismal groups spanning from bacteria, algae, phytoplankton, zooplankton and higher trophic levels based on a review of large number of available literature. In particular, special emphasis has been laid on finfishes and shellfishes which are routinely consumed by humans. As part of this review, we have also provided an overview of the broadly used methods that have been employed to detect As across ecosystems and organismal groups. We also report that the use of As metabolites as an index for tracking Astot exposure in humans require more global attention. Besides, in this review we have also highlighted the need to integrate ‘omics’ based approaches, integration of third and fourth generation sequencing technologies for effective pan-geographical monitoring of human gut microbiome so as to understand effects and resulting consequences of As bioaccumulation.@en