A persistent bloom of the diatom Rhizosolenia eriensis (Smith) and other changes associated with decreases in heavy metal contamination in an Oligotrophic lake, Vancouver Island

• Published in: Environmental and experimental botany 1986-07, Vol.26 (3), p.217-226
• Main Authors: Deniseger, John, Austin, Alan, Roch, Mike, Clark, Malcolm J.R.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Fresh water ecosystems; Fundamental and applied biological sciences. Psychology; Synecology
• ISSN: 0098-8472; 1873-7307
• DOI: 10.1016/0098-8472(86)90033-X

Since May, 1967 a copperleadzinc mine has been a source of heavy metal input into a previously uncontaminated long, narrow, oligotrophic lake, Buttle Lake, situated on Vancouver Island, British Columbia. After peaking in 1980/81, metal concentations in the lake have steadily decreased as a result of improved treatment systems. Nevertheless, a single species of diatom, Rhizosolenia eriensis, now dominates the phytoplankton community to the virtual absence of other species. Changes in nutrient patterns may have give R. eriensis a competitive advantage over other species. R. eriensis is present in quantities up to 11, 000 cells/ml and the cell accumulates zinc up to 56, 000 times and copper 34, 000 times water concenrations. The dominance of R. eriensis may have contributed to the continuing decline in zooplankton numbers through unpalatability.