Phosphate limitation influences the sensitivity to copper in periphytic algae

Abstract

1. To assess the influence of nutrient limitation on copper toxicity, periphitic communities from an oligotrophic stream were exposed to copper for six to 12 days with and without the supply of nutrients (mainly P). 2. In contrast to the hypothesis that nutrient cycling in mature biofilms would protect them from Cu toxicity, low and high biomass biofilms did not differ in their physiological response to copper after 6 days of exposure. 3. A clear influence of P-limitation on copper toxicity was observed. Periphytic communities that were previously fertilised for 18 days were three times more tolerant than control communities indicating that P-limitation enhanced Cu toxicity and tolerance induction were probably related to the higher P-availability. In addition, a compensation of Cu toxicity after P-addition was observed in the long-term (after 12 days). 4. We conclude that periphyton from oligotrophic streams is more sensitive to copper than periphyton from fertilised streams, and that therefore a higher effect of chronic copper exposure is expected to occur in oligotrophic P-limited fluvial systems. 5. Extrapolation of our results to the area of study (Catalonia, north-east of Spain) indicates that while the levels of Cu commonly found in the zone may negatively affect the periphyton from oligotrophic streams, because of the interaction between Cu and P, they are not able to control the growth of nuisance algae which is common under high nutrient conditions.

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

“…This particular study area is therefore an interesting example where environmental pressures such as urban activities may exacerbate stresses from past and present mining activities and thus affecting system recovery. This has been previously observed where a greater number of cumulative environmental stressors resulted in more significant impacts on diatom assemblages [19], although some antagonistically acting stressors have been evidenced (e.g., metals versus nutrients [20,21]). The present study provides groundwork for assessing stream biological integrity based on diatom descriptors, and brings valuable information to be used in further monitoring of the Junction Creek system recovery and health.…”

Seasonal variability in irradiance affects herbicide toxicity to the marine flagellate Dunaliella tertiolecta

“…Additional multi-stress factors which might interfere with the toxicity of the herbicides are nutrient limitation (Hall et al, 1989;Guasch et al, 2004) and temperature (Chalifour and Juneau, 2011). A combination of timing as well as the presence of additional multi-stress factors will determine the herbicide toxicity in the field, while the ultimate effect on the ecosystem will also depend on the ability of the microalgae to recover from damage by solar radiation (Janknegt et al, 2009b) and/or contaminants (Buma et al, 2009;Magnusson et al, 2012).…”

Structural and functional recovery of microbial biofilms after a decrease in copper exposure: Influence of the presence of pristine communities

“…Guasch et al (2004) found that biofilm photosynthetic efficiency was significantly inhibited by a 6-day Cu exposure (15 µg L−1) whatever the nutrient level, whereas Tlili et al (2010) showed that the simultaneous addition of Cu and nutrients may compensate for the inhibitory effect on physiological community response. Copper may exert its toxicity by interfering with photosynthesis in the chloroplasts and ATP production (Cid et al, 1995).…”