Water quality fluctuations in small intermittently closed and open lakes and lagoons (ICOLLs) after natural and artificial openings

Water quality fluctuations are influenced by natural and artificial openings of ICOLLs. In this study artificial opening resulted in a greater degradation of water quality than natural openings. Artificial openings are commonly undertaken in response to flood risk to human assets but often cause fish kills. We assessed water quality (parameters: temperature, dissolved oxygen, pH, salinity) within two ICOLLs before and after natural openings and two ICOLLS before and after artificial openings. Natural openings caused only a slight decline in water quality and no fish kills, whereas the artificial openings triggered poor water quality and fish kills. Decline of dissolved oxygen concentrations were observed following two artificial opening events associated with fish kills. We conclude that there are multiple drivers and sources contributing to low dissolved oxygen concentra-tions that are unique to individual ICOLLs and the type of opening.