The influence of a toxic cyanobacterial bloom and water hydrology on algal populations and macroinvertebrate abundance in the upper littoral zone of Lake Krugersdrift, South Africa

Abstract

The biological interactions and the physical and chemical properties of the littoral zone of Lake Krugersdrift were studied for a 4-month period when a dense, toxic cyanobacterial bloom dominated by Microcystis aeruginosa was present in the main lake basin. The presence of a toxic strain of M. aeruginosa was confirmed through the use of ELISA and molecular markers that detect the presence of the mcyB and mcyD genes of the mcy gene cluster that synthesizes microcystin. An increase in Microcystis toxicity at sites dominated by the cyanobacterial scum was accompanied by an increase in total abundance of the macroinvertebrate families Hirudinae, Chironomidae, and Tubificidae. Sites located away from the cyanobacterial scum had a lower abundance but a higher diversity of macroinvertebrates. The water quality under the Microcystis scum was characterized by low pH values, low concentrations of dissolved oxygen, and lower total alkalinity values. The periphytic alga Ulothrix zonata was absent in areas dominated by the cyanobacterial scum, possibly as a result of overshadowing by the scum or direct toxic allelopathic effects on growth and photosynthesis. The diatom Diatoma vulgare dominated the benthic algal flora beneath the cyanobacterial scum.

Influences of habitat type and environmental variables on benthic macroinvertebrate communities in a large shallow subtropical lake (Lake Taihu, China)

“…Ge´rard et al (2009) also found that bivalves were more sensitive to cyanobacterial bloom than pulmonates. Correspondingly, Oberholster et al (2009) observed that an increase in Microcystis toxicity at sites dominated by cyanobacterial scum was accompanied by an increase in the total abundance of Hirudinae, Chironomidae, and Tubificidae. From 1998 to 2007, algal blooms in Lake Taihu occurred at increasing frequency and with lengthened duration.…”

Bioindicators: the natural indicator of environmental pollution

“…Alternatively, under the vicinity of hexavalent chromium, the production of pigment is blocked. This pigment production can be attributed due to the relationship between concentration of chromium and the generation of blue pigmentation by the bacterium (Arora 1966;Grizzle 1984;Paoletti 1999;Oberholster et al 2009;Jain et al 2010;Aslam et al 2012;Malik & Bharti 2012).…”

Community structure and spatiotemporal patterns of macrozoobenthos in Lake Chaohu (China)

“…Toxic cyanobacteria are often reported to be the cause of mass mortality of aquatic organisms in the field. For example, in a 4 mo study, Oberholster et al (2009) observed that an increase in microcystins at sites dominated by cyanobacterial scum was accompanied by an in crease in the total abundance of the macroinvertebrate families Hirudinae, Chirono midae, and Tubi ficidae. Gérard et al (2009) observed that relative abundances of prosobranchs, pulmonates and bi valves were significantly different before and after a cyanobacterial bloom.…”