Effect of nutrient alteration on pCO2(water) and chlorophyll-a dynamics in a tropical aquaculture pond situated within a Ramsar site: a microcosm approach

• Published in: Environmental science and pollution research international 2020-02, Vol.27 (4), p.4353-4364
• Main Authors: Bhattacharyya, Sourav, Chanda, Abhra, Hazra, Sugata, Das, Sourav, Choudhury, Saroj Bandhu
• Format: Article
• Language: English
• Subjects: Anthropogenic factors; Aquaculture; Aquatic environment; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Carbon dioxide; Chlorophyll; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Fish feeds; Microcosms; Monsoons; Nitrogen; Nutrient concentrations; Nutrient dynamics; Nutrient loading; Organic matter; Partial pressure; Phosphorus; Ponds; Research Article; Seasons; Sewage; Supersaturation; Surface water; Waste Water Technology; Water Management; Water Pollution Control; Wind
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-019-07106-6

Tropical sewage-fed aquaculture ponds of East Kolkata Wetlands (EKW), a Ramsar site, act as deposition center of organic matter and nutrient-rich sewage from the Kolkata metropolis, which in turn is utilized as fish feed in aquaculture ponds. Increasing nutrient load due to multifarious anthropogenic activities usually alters the chlorophyll- a (chl- a ) and the partial pressure of carbon dioxide in water [pCO 2 (water)] dynamics in such aquatic systems. In this regard, the effect of nutrient level alteration [8 times and 24 times, dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) in addition, respectively] on chl- a and pCO 2 (water) was tested upon waters of EKW aquaculture ponds in three different seasons by means of microcosm for 8 consecutive days. In both DIN 8× and DIP 8× treatments, an overall increase in chl- a concentrations was observed by the end of experiment; however, in DIN 24× and DIP 24× treatments, chl- a in most of the seasons was found to diminish after a steep rise in its concentration during 4th or 5th day. In all the seasons, the surface waters were supersaturated with CO 2 under in situ conditions. The extent of supersaturation enhanced with nutrient addition during monsoon; however, in post-monsoon and pre-monsoon, nutrient addition led to undersaturation of CO 2 . Though chl- a concentration exhibited substantial variability during the microcosm experiments, the variation in trophic state index was not that much remarkable. In DIN-treated microcosms, uptake rate of DIP was significantly high compared to the reverse scenario, which implied that DIP has a more limiting character than DIN. In P-enriched treatments, the lack of N supplies probably limit production of autotrophic biomass. Thus it can be concluded that the nature of sewage and its DIN/DIP content can significantly alter the primary productivity the CO 2 dynamics of such aquaculture ponds in future.