Modeling sources of nutrients in rivers draining into the Bay of Bengal—a scenario analysis
Pedde, Simona ; Kroeze, Carolien ; Mayorga, Emilio ; Seitzinger, Sybil Putnam - \ 2017
Regional Environmental Change 17 (2017)8. - ISSN 1436-3798 - p. 2495 - 2506.
Bay of Bengal - Coastal eutrophication - Nitrogen - Phosphorus - River pollution - Silica
We model future trends in river export of nutrients to the Bay of Bengal, and the sources of this pollution. We focus on total nitrogen (TN), total phosphorus (TP), and dissolved silica (DSi) inputs to the Bay of Bengal Large Marine Ecosystem (BOB LME) in the years 2000, 2030, and 2050. In 2000, rivers exported 7.1 Tg N and 1.5 Tg P to the BOB LME. Three rivers (Ganges, Godavari, Irrawaddy) account for 75–80% of the total river export of N and P. For 2050, we calculate an increase in river export of N to 8.6 Tg, while P export stabilizes at the 2000 level. Future trends are the net effect of increasing river export of dissolved N (by 40%) and P (by 80%), and decreasing river export of particulate N and P. The increases in dissolved N and P loads are associated primarily with increased N and P losses from agriculture and sewage systems. The decreasing export of particulate N and P is associated with damming of rivers and increased human water consumption. There are large differences in nutrient export among rivers. Rivers draining into the western BOB LME generally export more N and P than eastern BOB LME rivers. Most N and P in western BOB LME rivers are from anthropogenic sources. Future increases in dissolved inorganic N and P (DIN and DIP) export can be large for individual rivers: up to more than a factor of five for DIP and more than a doubling for DIN. The calculated nutrient export ratios (N and P relative to DSi) indicate an increasing risk for blooms of non-siliceous algal species, which can potentially produce toxins and otherwise disrupt coastal ecosystems. Our results indicate that basin-specific management may be the most effective approach towards reducing the risk of coastal eutrophication in the BOB LME.
First Record of Porpita porpita (Cnidaria: Hydrozoa) from the coral reef ecosystem, Bangladesh
Shah Nawaz Chowdhury, M. ; Sharifuzzaman, S.M. ; Chowdhury, Sayedur Rahman ; Rashed-Un-Nabi, Md ; Hossain, M.S. - \ 2016
Ocean Science Journal 51 (2016)2. - ISSN 1738-5261 - p. 293 - 297.
Bangladesh - Bay of Bengal - Hydrozoa - Porpita - Saint Martin’s Island
The occurrence of Porpita porpita is reported, for the first time, in the coral island of St. Martin’s located in the southeastern coastal region of Bangladesh. P. porpita was found to occur in the lower littoral zone and beach rock pools, together with molluscan species, and collected during the pre-monsoon season when both water temperature (> 30°C) and salinity (> 30‰) tend to reach a maximum. This study recounts some details on the discovery and description of the species, and thus extends the global distribution and range limits of the genus Porpita.