The pelagic food web in forest lakes affected by alkaline mining waste in NW Russia

Abstract

The wastewaters of an iron mining company in NW Russia have changed the water quality in some forest lakes to be hard with a high pH, in contrast to the soft water and low pH in natural lakes. Two impacted lakes and a reference lake were sampled once in early August in three successive years for water quality, plankton communities, and fish. The concentrations of potassium, lithium, and sulphate were high in the impacted lakes. Total phosphorus was low (~ 10 µg L -1 ) in all lakes. The primary producers' biomass and chlorophyll a content in the impacted lakes were high because of high densities of autotrophic picocyanobacteria (Synechococcus spp.). All planktonic communities showed a changed taxa composition and lower species richness. Zooplankton was predominantly Rotatoria in all the lakes. In the impacted lakes, Cladocera was represented by Bosmina, and Copepoda by small cyclopoids. The most obvious substance to be harmful to some planktonic species was potassium. The high pH and high mineral content of the water obviously lower both the toxicity and the bioavailability of heavy metals in the impacted lakes.

Biomass, growth, and diet of fish in forest lakes affected by alkaline mining water in NW Russia

“…Consequently, the results suggest a more severe state of competition for food between perch and roach and between the age groups of perch (see Persson, 1986Persson, , 1987Persson & Greenberg, 1990) in Lake Upper Kuito than in the affected lakes, due to a shortage of macroinvertebrate food. As a general rule, the diet of perch and roach in all three lakes reflected the structure of the zoobenthos and zooplankton communities and the abundance of invertebrates in the lake (Holopainen et al, 2003(Holopainen et al, , 2008Aroviita et al, 2006). The proportion of Cladocera in the diet of perch and especially in the diet of roach was lower in Poppalijärvi than in Kento and Upper Kuito (Fig.…”

“…Despite the calcium-rich alkaline water, which should favour cyprinids, the biomass of percids in the gillnet catches from Lake Poppalijärvi and Lake Kento was higher than that of cyprinids. A probable reason for the percid dominance in those lakes is the shortage of nutrients, which is in turn related to a low chlorophyll-a content (Holopainen et al, 2008) and to a low biomass of cyprinids (see Persson et al, 1991). Moreover, fish communities in the Kostomuksha lakes are not affected by commercial or domestic fishing, which usually hits piscivorous fish such as large perch harder than smaller cyprinids such as roach (see Auvinen, 1987).…”

“…No drastic differences in diversity and abundance of zoobenthos have been observed between the reference and affected lakes, although the high pH and calcium contents have probably favoured molluscs with hard shells in the latter ones (Aroviita et al, 2006). Nevertheless, planktonic communities have obviously been harmed by the altered water chemistry in the affected lakes (Holopainen et al, 2008).…”

“…High lithium concentration in water has been shown to alter the gill membrane fluidity in fish (Tkatcheva et al, 2007a, b). The consequences for the food web have been discussed by Tkatcheva et al (2002), Holopainen et al (2003Holopainen et al ( , 2008, and Aroviita et al (2006).…”

An overview of Cladoceran studies conducted in mine water impacted lakes

“…The lucky mismatch is further reflected in increased abundance of B. longirostris, which is especially sensitive to copper pollution but thrives in eutrophicated systems, such as Lake Kirkkojärvi. Holopainen et al (2008) reported potassium to be the most harmful element to the planktonic ecosystem in Russian lakes impacted by alkaline mine water released from iron mine. Species number was low (\ 7) and the impacted lakes (pH 7.7-8.0, EC 49-391 lS/cm) were dominated by B. longirostris whereas in the nonimpacted reference lake (pH 6.7-6.8, EC 24-28 lS/cm) the dominating species was Daphnia cristata.…”