High-throughput screening of sediment bacterial communities from Oxygen Minimum Zones of the northern Indian Ocean
"The Northern Indian Ocean host two recognized Oxygen Minimum Zones (OMZ): one in the Arabian Sea and the other in the Bay of Bengal region. The next-generation sequencing technique was used to understand the total bacterial diversity from the surface sediment of off Goa within the OMZ of Arabian Sea, and from off Paradip within the OMZ of Bay of Bengal. [...]"
Source: Biogeosciences (preprint)
Authors: Jovitha Lincy and Cathrine Manohar
Sri Lanka's marine protection agency calls for tougher laws against ocean pollution
General Manager of the Marine Environment Protection Authority, Dr. P.B. Teney told Xinhua that authorities had discovered the formation of a dead zone in the Bay of Bengal which had spread across a 6000 square kilometer area and was 100 meters to 400 meters in depth. [...]"
Oxygen variability controls denitrification in the Bay of Bengal oxygen minimum zone
"Nitrate limits productivity in much of the ocean. Nitrate residence time is a few thousand years and changes in nitrate loss could influence ocean productivity. A major sinks for nitrate is denitrification and anaerobic ammonia oxidation in the oxygen minimum zones (OMZs). The Bay of Bengal OMZ is anomalous because large amounts of nitrate loss do not occur there, while nitrate is removed in the nearby OMZ of the Arabian Sea. Observations of nitrate and oxygen made over 5 years by 20 profiling floats equipped with chemical sensors in the Bay of Bengal and the Arabian Sea are used to understand why nitrate is removed rapidly in the Arabian Sea, but not in the Bay of Bengal. [...]"
Source: Geophysical Research Letters
Authors: Kenneth S. Johnson, Stephen C. Riser and M. Ravichandran
Study of dissolved oxygen responses to tropical cyclones in the Bay of Bengal based on Argo and satellite observations
"Effects of tropical cyclones (TCs) on dissolved oxygen (DO) in subsurface waters (20–200 m) over the Oxygen Minimum Zones (OMZs) in the Bay of Bengal (BoB) are examined based on Argo and satellite data. Five TCs (Hudhud, Five, Vardah, Maarutha and Mora) during 2013–2018 are considered. Analyses reveal three types of DO temporal variability caused by the storm-induced mixing and upwelling. The first type features temporal DO increases in subsurface waters (37–70 m) caused mainly by intense vertical mixing and downwelling. [...]"
Source: Science of the Total Environment
Authors: Huabing Xu et al.
Ventilation of oxygen to oxygen minimum zone due to anticyclonic eddies in the Bay of Bengal
"Intense oxygen minimum zone (OMZ) occurs in the mid‐depth of the Eastern Tropical Pacific (ETP), Arabian Sea (AS), and Bay of Bengal (BoB). However, the occurrence of anammox/denitrification was reported only in the ETP and AS and its absence in the BoB is attributed to presence of traces of dissolved oxygen (DO). Anticyclonic Eddies (ACE) supply high nutrient, organic‐rich and oxygen poor waters from the coastal upwelling regions leading to strengthening of OMZ in the offshore of AS and ETP. [...]"
Authors: V. V. S. S. Sarma, T. V. S. Udaya Bhaskar
Investigating the impacts of treated effluent discharge on coastal water health (Visakhapatnam, SW coast of Bay of Bengal, India)
"The present study investigated the impacts of treated effluent discharge on physicochemical and biological properties of coastal waters from three pharmaceuticals situated along the coast of Visakhapatnam (SW Bay of Bengal). Seawater samples were collected (during the months of December 2013, March 2014 and April 2014) from different sampling locations (Chippada (CHP), Tikkavanipalem (TKP) and Nakkapalli (NKP)) at 0- and 30-m depths within 2-km radius (0.5 km = inner, 1 km = middle and 2 km = outer sampling circles) from the marine outfall points. [...]"
Source: Environmental Monitoring and Assessment
Authors: Aziz Ur Rahman Shaik et al.
Oxygen Minimum Zone Contrasts between the Arabian Sea and the Bay of Bengal Implied by Differences in Remineralization Depth
"The combination of high primary productivity and weak ventilation in the Arabian Sea (AS) and Bay of Bengal (BoB) generates vast areas of depleted oxygen, known as Oxygen Minimum Zones (OMZs). The AS OMZ is the world's thickest and hosts up to 40% of global denitrification. In contrast, the OMZ in the BoB is weaker and denitrification free. Using a series of model simulations, we show that the deeper remineralization depth (RD) in the BoB, potentially associated with organic matter aggregation with riverine mineral particles, contributes to weaken its OMZ. [...]"
Source: Geophysical Research Letters
Authors: Muchamad Al Azhar, Zouhair Lachkar, Marina Lévy, Shafer Smith
Read the full article here.