Development of the phytoplankton community in a pit-lake in relation to water quality changes

An open pit-lake was formed at a Northern Saskatchewan mine site after floo ding with lake water in early 1992. Since then, water and phytoplankton sam ples have been collected regularly from the artificial lake over seven year s. The resulting data set provides a unique opportunity to examine the phys ical and chemical changes in water quality and phytoplankton community over time. Seventeen major variables were examined in a principal component ana lysis. Axes 1, 2 and 4 are significantly correlated to other three variable s, the number of days (since the first sampling after flooding of the pit), water temperature and depth, respectively. Total suspended solid (TSS), di ssolved oxygen, total phosphorus (Total-P), arsenic, and iron decreased ove r time while Mg, Ca, K, Na, total organic carbon and HCO3 increased. Canoni cal correspondence analysis was used to infer the relationship between wate r quality variables and phytoplankton community structure, which changed su bstantially over the survey period. TSS, Total-P and arsenic were considere d to be the key factors driving the change in phytoplankton community compo sition. (C) 2001 Elsevier Science Ltd. All rights reserved.