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Chlorophyll-a (Chl-a) and its correlation with different parameters are one of the major indicators to understand marine ecosystems. This study was conducted to explore the seasonal and spatial variability of Chl-a at three different stations (onshore, midshore, and offshore) across the maritime boundary of Bangladesh in the northern BoB with its response to the surface current speed and recent ENSO (El Niño/La Niña-Southern Oscillation) events by using satellite data. Moderate resolution imaging spectroradiometer (MODIS) aqua satellite level-3 data of Chl-a was used in this study. Ocean currents datasets were obtained from the Asia-Pacific Data Research Center (APDRC) live access service, LAS8.6.13 of NOAA (National Oceanic and Atmospheric Administration), whereas the SST anomalies dataset was collected from NOAA Climate Prediction Center. This study revealed that the onshore region showed the highest (1.121 mgm-3) abundance of Chl-a, whereas the offshore region showed the lowest (0.136 mgm-3). The offshore and midshore regions showed a homogenous distribution of Chl-a, whereas the observed trend of seasonal fluctuation was southwest monsoon > postmonsoon > northeast monsoon > premonsoon. There is a seasonal variation in the relationship between Chl-a and surface current speed, with moderate correlations during northeast (Dec-Feb) and premonsoon (Mar-May). The effect of ENSO on Chl-a was observed as insignificant (P>0.05) in the northern BoB. However, Chl-a variability in response to ENSO events across the northern region of BoB requires more investigation.

Data equipped with this article were collected from Northern Bay of Bengal (NBoB) wrapping both the eastern and western coast for CTD and sediment samples and only the eastern coast for water sampling. In-situ data of physical parameters, heavy metals, elements, Total Organic Carbon (TOC), nutrients, chlorophyll-a and phaeopigment were sampled across the shallow continental shelf. These data were assembled from 15 CTD points, 76 water samples, and 10 surface sediment samples adjacent to Bangladesh coast. Vertical CTD profiles were collected for Temperature ( °C), Salinity (PSU), Density (kg m−3), Turbidity (NTU), Fluorescence (mg m−3), and Dissolved Oxygen (DO, mg/l). Heavy metals (mg/l) of water column enlisted as Calcium (Ca), Cadmium (Cd), Copper (Cu), Cobalt (Co), Iron (Fe), Manganese (Mn), Magnesium (Mg), Nickel (Ni), Lead (Pb), and Zinc (Zn). Total Organic Carbon (TOC) was measured as Non-Purgeable Organic Carbon (NPOC) in ppm. Measurements of Chlorophyll - a, Nitrate, Nitrite, Phosphate, Ammonia, Silica and Phaeopigment were taken from 76 water sampling points. The survey was conducted with the assistance of a fishing vessel ‘Agro food-4 ‘of ‘Sea Resource Ltd.’ lengthening a fishing period from January to February (in winter), 2016. SBE 19 plus V2 CTD machine was deployed for sampling of vertical physical features, Niskin sampler of HYDRO-BIOS consisting of a non-metallic interior was used to collect water sample. Sediment was collected by Van Veen Grab sampler with built-in messenger. Water samples were analyzed following the standard procedure in the laboratory to access in-situ data. The shallow coastal and offshore regions of Bangladesh support for vast biological resources to its adjacent inhabitants. Therefore, understanding the influence of physico-chemical properties on other biological resources in coastal ecosystem is a crucial one to investigate. However, the shelf region of the BoB has a lack of in-situ baseline or reference data to compare with in terms of ocean biogeochemistry. Thus, these datasets can be utilized for further reference and also in validating other remotely-sensed physico-chemical parameters in this region.

In-situ measurement of physical characteristics of seawater (temperature, salinity, and density) collected with a single fire module CTD (Conductivity, Temperature, Depth) in the northern Bay of Bengal (NBoB), as a part of the Indian Ocean, are given in this article. Due to the scanty of data in the NBoB, such in-situ measurements will certainly play a crucial role in understanding regional oceanic processes. The presented data were collected onboard during two cruises covering 12 stations with high resolution (0.2 m depth) up to 50-meter contour depth from 20.5778 N, 92.3578 E to 21.287 N, 89.696 E. We present raw CTD data as ASCII (.dat) and Comma Separated Value (.csv), and processed CTD data as netCDF (.nc) format in this article. Additionally, the calculated Mixed Layer Depth that was derived from the netCDF (.nc) file was included in the tabular format. This processed in-situ data would be most useful as a baseline for further studies in coastal and offshore physicochemical properties in the NBoB.

Mangroves, which are a group of salt tolerant plant community growing in the transition zones of fresh and marine water systems, play an important role as sediment trap. In mangrove ecosystems, litterfall accumulates as organic carbon and nutrients over the sediment surface, where bioturbation profoundly affects the sediment biogeochemistry. Here, we provide a brief overview of the bioturbating organisms in mangroves and discuss their roles in controlling the sediments organic biogeochemistry. The mangrove soils formed on marine alluvium is transported as sediment and deposited by the river and sea. This type of soil is typically saline, anoxic, acidic and periodically waterlogged and composed of different combinations of sand, silt, clay and mud. The decapod crustaceans, specifically, crabs are the main bioturbating organisms in mangroves ecosystem. Moreover, amphipod, callianassid, penaeid shrimp, alpheid shrimp, thalassinid lobster, sipunculid worm, bivalves and bony (teleostei) and shark‐like (elasmobranchii) fishes contribute to the biogenic dispersal of sediment particles. Bioturbation processes by these organisms are reported to control nutrients and carbon cycling across the sediments. Activities such as feeding, burrowing and ventilation also influence the decomposition rate of sediment organic matter and nutrient exchange. However, anthropogenic pollution from power plant effluent (hot‐water outflows), heavy metals, pesticides, polychlorinated biphenyls (PCBs), industrial pollutants, eutrophication (fertilizers and sewage) and oil spills are major concerns impacting the mangrove sediments and ecosystems. [ABSTRACT FROM AUTHOR]