The effect of copper and contamination history on micro-algal type and abundance

Background/Question/Methods

Copper is an essential micro-nutrient for plants, though at higher concentrations it causes chloroplast dysfunction and inhibits photosynthesis.  Due to their close contact with their environment, unicellular algae are thought to be particularly sensitive to Cu exposure. While brown algae tend to dominate heavy-metal contaminated habitats, little is known about the effect of copper on micro-algal community structure. Additionally, despite it being widely acknowledged that historical contingencies such as land-use legacies and species arrival order affect biodiversity assessment, the effect of disturbance history remains underexplored.  This project had two objectives: (1) understand how copper contamination affects micro-algae type and abundance and (2) determine how historical contaminations may interact with other factors. For the first objective, micro-algal assemblages were developed on PVC settlement plates surrounded by copper anti-fouling paint. For the second, we developed homogenous assemblages on settlement plates and then exposed the assemblages to various time series of Cu contamination.  In both cases, field spectrometry was used to measure changes to the photosynthetic pigments of the assemblages, which is a proxy for algal type and abundance. 

Results/Conclusions

Preliminary results suggest that copper alters micro-algal assemblage composition and total biomass, though this is influenced by the effect of Cu contamination history.  This project not only investigates the effect of copper poisoning on micro-algae communities, but also provides quantified evidence for the effect of exposure timing on experimental outcomes which has ramifications for accurate biodiversity assessment and effective conservation effort.