Krumme, Uwe, Herbeck, Lucia S. and Wang, Tianci (2012) Tide- and rainfall-induced variations of physical and chemical parameters in a mangrove-depleted estuary of East Hainan (South China Sea). Marine Environmental Research, 82 . pp. 28-39. DOI https://doi.org/10.1016/j.marenvres.2012.09.002.

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Abstract

The estuarine dynamics favoring the coexistence of mangroves, seagrass and corals at small river mouths are often poorly understood. We characterize the tidal, day/night and rainfall-induced short-term dynamics in salinity, pH, dissolved oxygen (DO), chlorophyll a (chl a), total suspended matter (TSM), water transparency, surface currents and dissolved nutrients (NOx−, NH4+, PO43−, Si(OH)4) of the Wenchang/Wenjiao Estuary (East Hainan, tropical China). Samples were taken at three fixed sites along the estuary during 24 h spring tide cycles in different seasons. Salinity, DO, water transparency and pH generally increased seawards while nutrients decreased. All parameters varied with the tidal cycle, partially in interaction with the diel cycle. Nutrients, chl a and TSM usually fluctuated inversely with water level. Stratification was strong. Inflowing bottom water was of higher salinity, DO and pH and lower temperature and nutrient concentrations than the surface water. Tidal mixing provided regular ventilation of the estuary and limited eutrophication effects of nutrients from aquaculture, agriculture and urban effluents. Under dry weather conditions, the brackish-water lagoon functioned as a sink of nutrients due to efficient uptake by phytoplankton. Presently, the runoff from common intense rains in the watershed affects the estuary with little time delay due to terrestrial deforestation, channelization and loss of mangrove area. The frequency, strength and duration of intermittent estuarization of the back-reef areas have likely increased in the past and deteriorate present seagrass and coral health.

Document Type: Article
Programme Area: UNSPECIFIED
Research affiliation: Biogeochemistry and Geology > Ecological Biogeochemistry
Ecology > Fisheries Biology
Refereed: Yes
Open Access Journal?: No
DOI etc.: https://doi.org/10.1016/j.marenvres.2012.09.002
ISSN: 01411136
Date Deposited: 29 Aug 2019 13:30
Last Modified: 01 Oct 2020 12:59
URI: http://cris.leibniz-zmt.de/id/eprint/2772

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