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Typhoons greatly affect ocean hydrodynamics, thereby altering ocean productivity and biogeochemistry. This study used stable isotopes and geochemical indicators of particulate organic matter (POM) to investigate the impact of Typhoon Talim (2023) on marine productivity and POM dynamics in Zhanjiang Bay. During the typhoon, an ocean front formed in the upper bay, resulting in a nearly twofold increased POM and enhanced decomposition of resuspended POM, due to the strengthened vertical mixing. Despite of strong decomposition, the supplementation of terrestrial nutrient inputs maintained minimal changes in chlorophyll in the upper bay. By contrast, in the lower bay, chlorophyll and POM decreased significantly, primarily attributed to decomposition of fresh POM and nitrogen limitation resulting from high-salinity seawater intrusion induced by the typhoon. This study suggests that after typhoons, in the area where the ocean front forms, the decomposition degrades a large amount of resuspended POM, which is not conducive to the burial of organic carbon. • POM increased in the upper bay due to enhanced vertical mixing after the typhoon. • Typhoon induced formation of ocean front intensified decomposition of resuspended POM. • POM and Chl- a decreased in the lower bay due to decomposition induced by the typhoon. • Both regions experienced severe oxygen consumption due to POM decomposition. [ABSTRACT FROM AUTHOR]

The influence of floating marine debris (FMD) on coastal and marine communities and ecosystems is undeniable, and attention is increasingly focused on ecologically and biologically important coastal areas. To protect marine life and valuable resources from FMD pollution, identifying FMD accumulation zones is recognized as a priority. One of the coastal ocean processes found governing the distribution of FMD is water convergence (frontal zones). These fronts are driven by various oceanographical factors. To date, the transport and accumulation of FMD in relation to fronts in coastal areas is poorly understood. To address this knowledge gap, we reviewed various types of ocean fronts as well as FMD accumulation along frontal zones in coastal areas defined as the region between the coastline and the shelf break. Frontogenesis (physical processes related to frontal formation) were reviewed alongside studies on FMD accumulation in frontal zones to identify physical factors that drive the pathways and accumulation in these areas. This review will contribute to our understanding of accumulation hotspots of FMD within ocean fronts and identify gaps for further research on developing a proxy for FMD hotspot identification in ecologically important coastal areas. • Different frontal types are generated by various oceanographic processes, and coastal fronts are mainly driven by winds, tides, currents, upwelling and downwelling, bottom topography, plumes, and internal waves. • In coastal zones, floating marine debris accumulates along water convergences including gyres, eddies, slicks, salinity fronts, density fronts, thermohaline fronts and tidal fronts. • Frontal accumulated debris has an impact on marine species in coastal waters including important marine taxa such as seabirds, dolphins, and turtles. • Study on FMD accumulation in frontal zones has received more attention, with 72% of reviewed papers were published between 2017 and 2023, and the highest number of published papers (10 papers) in 2021. • This study suggests that future research exploring the impacts of frontogenesis on the transport and accumulation of FMD over the continental shelf zone would be valuable. [ABSTRACT FROM AUTHOR]

In the present study, using in-situ and satellite observations, we investigate the influence of physical processes on the enhancement of phytoplankton biomass in the eastern Arabian Sea (EAS). Water column measurements were carried out from 9⁰N to 21⁰N (stations II-2 to II-14) along 68⁰E transect in the EAS during the beginning of fall intermonsoon (FIM) of 2014. Both in-situ and satellite-derived chlorophyll a (Chl a) showed higher biomass at 15⁰N (station II-8) compared to northern and southern stations. We explored the possible physical processes which can lead to high biological productivity at this station. Our study shows that nearly two times enhancement in Chl a at station II-8 was contributed by an open-ocean front, which occurred two days before the measurement. Based on phytoplankton marker pigments, it was evident that haptophytes were abundant at II-8 with a minor contribution from diatoms and dinoflagellates. This condition also led to a high concentration (4.9 nM) of dimethylsulphide (DMS), an anti-green house gas with a net flux of 3.76 μmol m−2d−1 at this site. Among the picophytoplankton, Synechococcus were abundant at this station , however Prochlorococcus were absent as confirmed by both marker pigment and flow cytometric counts. The case study presented here demonstrates the dynamic nature of open ocean fronts and their overall contribution to the productivity of the eastern Arabian Sea during the oligotrophic inter-monsoon period. • Our studies showed that open-ocean fronts can enhance the biological productivity in the EAS even during oligotrophic periods. • Abundance of haptophytes at the frontal region might have contributed to high DMS concentration and flux. • Among the picophytoplankton, Synechococcus were abundant at the frontal region, however Prochlorococcus were absent. • A significant increase in TBC supported the dominance of the microbial loop in the region influenced by the frontal system. [ABSTRACT FROM AUTHOR]