Citizen Science Tools Reveal Changes in Estuarine Water Quality Following Demolition of Buildings

Turbidity and water colour are two easily measurable properties used to monitor pollution. Here, we highlight the utility of a low-cost device—3D printed, hand-held Mini Secchi disk (3DMSD) with Forel-Ule (FU) colour scale sticker on its outer casing—in combination with a mobile phone application (‘TurbAqua’) that was provided to laymen for assessing the water quality of a shallow lake region after demolition of four high-rise buildings on the shores of the lake. The demolition of the buildings in January 2020 on the banks of a tropical estuary—Vembanad Lake (a Ramsar site) in southern India—for violation of Indian Coastal Regulation Zone norms created public uproar, owing to the consequences of subsequent air and water pollution. Measurements of Secchi depth and water colour using the 3DMSD along with measurements of other important water quality variables such as temperature, salinity, pH, and dissolved oxygen (DO) using portable instruments were taken for a duration of five weeks after the demolition to assess the changes in water quality. Paired t-test analyses of variations in water quality variables between the second week of demolition and consecutive weeks up to the fifth week showed that there were significant increases in pH, dissolved oxygen, and Secchi depth over time, i.e., the impact of demolition waste on the Vembanad Lake water quality was found to be relatively short-lived, with water clarity, colour, and DO returning to levels typical of that period of year within 4–5 weeks. With increasing duration after demolition, there was a general decrease in the FU colour index to 17 at most stations, but it did not drop to 15 or below, i.e., towards green or blue colour indicating clearer waters, during the sampling period. There was no significant change in salinity from the second week to the fifth week after demolition, suggesting little influence of other factors (e.g., precipitation or changes in tidal currents) on the inferred impact of demolition waste. Comparison with pre-demolition conditions in the previous year (2019) showed that the relative changes in DO, Secchi depth, and pH were very high in 2020, clearly depicting the impact of demolition waste on the water quality of the lake. Match-ups of the turbidity of the water column immediately before and after the demolition using Sentinel 2 data were in good agreement with the in situ data collected. Our study highlights the power of citizen science tools in monitoring lakes and managing water resources and articulates how these activities provide support to Sustainable Development Goal (SDG) targets on Health (Goal 3), Water quality (Goal 6), and Life under the water (Goal 14

Influence of selected anthropogenic impacts on ecology of Vembanad Lake

Influence of selected anthropogenic impacts on ecology of Vembanad Lak

Extended distribution of Kandelia candel along the coast of Andhra Pradesh, India – taxonomic identification with molecular confirmation

The paper describes the first report of Kandelia candel (Rhizophoraceae), a rare mangrove from Bhavanapadu, a coastal village in Srikakulam district in Andhra Pradesh, India. This species is relatively less abundant along the east coast of India. During our study covering all the 41 mangrove patches in the state of Andhra Pradesh, 16 mangrove species were observed throughout the state and the Kandelia candel was seen only in Bhavanapadu (patch 2). The plant sighted was identified using taxonomic keys and confirmed using DNA barcoding. The identified specimen is deposited in the museum repository at ICAR-Central Marine Fisheries Research Institute (CMFRI), Kochi (accession no. MB.1.1.1.1) and its gene sequence is deposited in National Center for Biotechnological Information (NCBI) (accession no. MH243746). Patch 2 where K. candel was observed is separated away from the other clusters in the principal component one, with the patch showing an average dissimilarity of about 71.79% from the other patches. K. candel is a mangrove highly sensitive to changes in salinity. The presence of a lone member of a rare species in the state at the sampling location raises questions on its endurance in the region. The study underlines the relevance of monitoring the mangroves and advocate adequate conservation measures for proper protection, proliferation and management of this globally dwindling resource