TY - JOUR
T1 - Influence of elevated river flow on hypoxia occurrence, nutrient concentration and microbial dynamics in a tropical estuary
AU - Lee, Choon Weng
AU - Lim, Joon Hai
AU - Heng, Pei Li
AU - Marican, Nurul Fitrah
AU - Narayanan, Kumaran
AU - Sim, Edmund Ui Hang
AU - Bong, Chui Wei
N1 - Funding Information:
We are grateful to the Ministry of Higher Education Malaysia for the FRGS grant (FP061-2018A or FRGS/1/2018/WAB09/UM/02/1) and HiCoE grant (IOES-2014D). Acknowledgements
Funding Information:
We would like to thank the Malaysia Meteorological Department for providing the rainfall data and the Department of Irrigation and Drainage Malaysia for the Klang River flow rates.
Publisher Copyright:
© 2020, Springer Nature Switzerland AG.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2020/9/25
Y1 - 2020/9/25
N2 - We sampled the Klang estuary during the inter-monsoon and northeast monsoon period (July–Nov 2011, Oct–Nov 2012), which coincided with higher rainfall and elevated Klang River flow. The increased freshwater inflow into the estuary resulted in water column stratification that was observed during both sampling periods. Dissolved oxygen (DO) dropped below 63 μM, and hypoxia was observed. Elevated river flow also transported dissolved inorganic nutrients, chlorophyll a and bacteria to the estuary. However, bacterial production did not correlate with DO concentration in this study. As hypoxia was probably not due to in situ heterotrophic processes, deoxygenated waters were probably from upstream. We surmised this as DO correlated with salinity (R2 = 0.664, df = 86, p < 0.001). DO also decreased with increasing flushing time (R2 = 0.556, df = 11, p < 0.01), suggesting that when flushing time (> 6.7 h), hypoxia could occur at the Klang estuary. Here, we presented a model that related riverine flow rate to the post-heavy rainfall hypoxia that explicated the episodic hypoxia at Klang estuary. As Klang estuary supports aquaculture and cockle culture, our results could help protect the aquaculture and cockle culture industry here.
AB - We sampled the Klang estuary during the inter-monsoon and northeast monsoon period (July–Nov 2011, Oct–Nov 2012), which coincided with higher rainfall and elevated Klang River flow. The increased freshwater inflow into the estuary resulted in water column stratification that was observed during both sampling periods. Dissolved oxygen (DO) dropped below 63 μM, and hypoxia was observed. Elevated river flow also transported dissolved inorganic nutrients, chlorophyll a and bacteria to the estuary. However, bacterial production did not correlate with DO concentration in this study. As hypoxia was probably not due to in situ heterotrophic processes, deoxygenated waters were probably from upstream. We surmised this as DO correlated with salinity (R2 = 0.664, df = 86, p < 0.001). DO also decreased with increasing flushing time (R2 = 0.556, df = 11, p < 0.01), suggesting that when flushing time (> 6.7 h), hypoxia could occur at the Klang estuary. Here, we presented a model that related riverine flow rate to the post-heavy rainfall hypoxia that explicated the episodic hypoxia at Klang estuary. As Klang estuary supports aquaculture and cockle culture, our results could help protect the aquaculture and cockle culture industry here.
KW - Dissolved oxygen dynamics
KW - Hypoxia
KW - Klang estuary
KW - Klang River flow rate
KW - Peninsular Malaysia
UR - http://www.scopus.com/inward/record.url?scp=85091418550&partnerID=8YFLogxK
U2 - 10.1007/s10661-020-08625-3
DO - 10.1007/s10661-020-08625-3
M3 - Article
C2 - 32975666
AN - SCOPUS:85091418550
SN - 0167-6369
VL - 192
JO - Environmental Monitoring and Assessment
JF - Environmental Monitoring and Assessment
IS - 10
M1 - 660
ER -