Revisiting harmful algal blooms in India through a global lens: An integrated framework for enhanced research and monitoring.

Harmful algal bloom (HAB) events substantially impact human and aquatic ecosystem health and the global blue economy; hence, a concerted effort is required to advance our understanding of HAB ecology to better inform monitoring and mitigation measures. Here, we highlight the current state of HAB research and monitoring in India, where ∼17% of the human population resides in the vicinity of its long coastline and is dependent on the sustainable blue economy. Through the lens of established programs from countries across the globe, we identify existing gaps and highlight four broad areas for focusing future efforts: (1) the development/employment of novel technologies for HAB research and monitoring; (2) the need for integrated observation networks and a coordinated effort across different central/state agencies and research institutes; (3) clinical studies on human health effects; and (4) public outreach and citizen science initiatives to increase awareness on this topic, including policy level interventions.

In situ digital holographic microscopy for rapid detection and monitoring of the harmful dinoflagellate, Karenia brevis.

Karenia brevis blooms, also known as red tide, are a recurring problem in the coastal Gulf of Mexico. These blooms have the capacity to inflict substantial damage to human and animal health as well as local economies. Thus, monitoring and detection of K.

Optical backscattering and linear polarization properties of the colony forming cyanobacterium Microcystis.

Light scattering characteristics of the cyanobacterium Microcystis are investigated with numerical models for sphere aggregates. During summer bloom seasons, Microcystis is prevalent in many inland waters across the globe. Monitoring concentrations with remote sensing techniques requires knowledge of the inherent optical properties (IOPs), especially the backscattering properties of Microcystis cells and colonies in natural settings.

Evidence for ubiquitous preferential particle orientation in representative oceanic shear flows.

In situ measurements were undertaken to characterize particle fields in undisturbed oceanic environments. Simultaneous, co-located depth profiles of particle fields and flow characteristics were recorded using a submersible holographic imaging system and an acoustic Doppler velocimeter, under different flow conditions and varying particle concentration loads, typical of those found in coastal oceans and lakes. Nearly one million particles with major axis lengths ranging from ∼14 μm to 11.