Freshwater Diatoms as Indicators of Combined Long-Term Mining and Urban Stressors in Junction Creek (Ontario, Canada)

Abstract

Sudbury (Ontario, Canada) has a long mining history that has left the region with a distinctive legacy of environmental impacts. Several actions have been undertaken since the 1970s to rehabilitate this deteriorated environment, in both terrestrial and aquatic ecosystems. Despite a marked increase in environmental health, we show that the Junction Creek system remains under multiple stressors from present and past mining operations, and from urban-related pressures such as municipal wastewater treatment plants, golf courses and stormwater runoff. Water samples have elevated metal concentrations, with values reaching up to 1 mg·L −1 Ni, 40 µg·L −1 Zn, and 0.5 µg·L −1 Cd. The responses of diatoms to stressors were observed at the assemblage level (metal tolerant species, nutrient-loving species), and at the individual level through the presence of teratologies (abnormal diatom frustules). The cumulative criterion unit (CCU) approach was used as a proxy for metal toxicity to aquatic life and suggested elevated potential for toxicity at certain sites. Diatom teratologies were significantly less frequent at sites with CCU values <1, suggesting "background" metal concentrations as compared to sites with higher CCU values. The highest percentages of teratologies were observed at sites presenting multiple types of environmental pressures.

Mining salinisation of rivers: its impact on diatom (Bacillariophyta) assemblages

“…The results of these studies are another piece of evidence for the decrease in diatom biodiversity in water bodies that have been affected by an anthropogenic impact. The calculated Eastern Canadian Diatom Index (IDEC) had a better biological integrity at the reference sites (Lavoie et al 2018) that had had weak anthropogenic influences that was similar to our results. Hustedt (1957) recorded that it is not the concentration of a particular salt in the water that influences freshwater diatoms the most but rather the osmotic pressure.…”

“…In our study, P. laevis comprised 73% of all of the identified diatom taxa in the Bolina River and 21% in the Mleczna River, although the values of their salinity (periodically exceeded 40 000 and 7000 μS.cm -1 , respectively) and noticeable concentration of sulfates (550 and almost 300 mg.dm -3 , respectively). During a microscopic observation, we did not observe any significant teratologies of the P. laevis frustule, which usually suggests a response to ecological stress or metal pollution (Lavoie et al 2018). Schröder et al (2015) analysed the benthic diatom assemblages of a Western Germany lowland river -the Lippe River.…”

“…The reference sites were dominated by diatom species that preferred clean, freshwater and the indices that were calculated indicated a good ecological status, while the sites that had been impacted by an agricultural or urban influence had a poor to moderate status (Walsh & Wepener 2009). Lavoie et al (2018) analysed the diatom assemblages from several streams and creeks of the Greater Sudbury River (Ontario, Canada). The results of these studies are another piece of evidence for the decrease in diatom biodiversity in water bodies that have been affected by an anthropogenic impact.…”

Assessment of Diatom Assemblages in Close Proximity to Mining Activities in Nunavik, Northern Quebec (Canada)

“…It is worth mentioning that the teratologies were also sometimes very difficult to assess (small taxa) and, therefore, certain subtle aberrations may have been missed [19] as we were conservative in our evaluation. A lack of relationship between % teratologies and a gradient in metal contamination was previously reported, but deformities were still observed in higher proportions in contaminated sites compared to reference (e.g., [11,20,21]). As a general trend, we tended to observe more teratologies at the Mesamax stations, which is surprising considering that the samples collected around the Expo site had higher metal concentrations.…”

Preface: Special Issue on Environmental Toxicology of Trace Metals

“…A multi-disciplinary community ecotoxicology approach was employed by Lavoie et al [5] to assess the health and ecological integrity of Junction Creek and its tributaries in the Sudbury region (Canada), which are under multiple stressors influence due to extended mining activity and increased nutrient load. The responses of diatoms to stressors were observed at the assemblage level, for example the presence and abundance of metal tolerant species and nutrient-loving species, as well as at an individual level, through the presence of abnormal diatom frustules.…”