Impact of a catastrophic flood on the heavy metal pollution status and the concurrent responses of the bentho-pelagic community in a tropical monsoonal estuary

• Published in: Marine pollution bulletin 2020-06, Vol.155, p.111191-111191, Article 111191
• Main Authors: Vineetha, G., Kripa, V., Karati, Kusum Komal, Rehitha, T.V., Vishal, C.R., Vineetha, V., Manu, M.
• Format: Article
• Language: English
• Subjects: Abundance; Aquatic crustaceans; Benthos; Blooms; Carnivores; Cochin estuary; Community structure; Crustaceans; Environmental indicators; Environmental quality; Estuaries; Estuarine dynamics; Eutrophic rivers; Eutrophication; Flood; Floods; Habitats; Heavy metals; Indicators; Macrobenthos; Metal concentrations; Metals; Mollusks; Nutrients; Phytoplankton; Plankton; Pollution; Sediments; Tropical climate; Water pollution; Zoobenthos; Zooplankton
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2020.111191

Consequences of a catastrophic flood on the habitat quality and the concurrent responses of the bentho-pelagic community were studied in Cochin estuary, a eutrophic estuary along the southwest coast of India. The episodic flood in 2018 led to a marked decline in the dissolved nutrients and heavy metal concentrations in water and sediments of the estuary. The pre-flood phytoplankton abundance dominated by a bloom-forming species Cerataulina bicornis experienced a significant drop after the flood. Contrarily, zooplankton and macrobenthos responded favorably towards the flood-imposed habitat alterations. Higher susceptibility to heavy metal pollution and increased grazing pressure from gelatinous carnivores restricted the abundance of Copepoda, the dominant zooplankton taxon during pre-flood. The lower heavy metal concentration in the sediment after the flood favored higher macrobenthic abundance and diversity with a conspicuous change in the community structure from opportunistic polychaetes, indicators of pollution to molluscans and crustaceans, indicators of the healthy benthic zones. [Display omitted] •Cochin estuary (CE) is a eutrophic wetland ecosystem in the west coast of India.•We studied the effect of flood on heavy metal pollution and bentho-pelagic community in CE.•Hydrological attributes and heavy metal concentration exhibited marked variability.•Phytoplankton abundance dropped significantly subsequent to flood.•Zooplankton and benthos responded favorably to flood-imposed habitat changes.