Effects of oil sands effluent on cattail and clover: photosynthesis and the level of stress proteins

The oil sands industry located in northeastern Alberta, Canada, generates l arge volumes of effluent characterized by a high level of dissolved ions an d naphthenic acids. The dikes used to store the effluent seep, creating wet lands which are subsequently invaded by obligate wetland flora such as catt ail (Typha latifolia L.). The appearance of these wetlands prompted the oil sands industry to consider wetlands as part of their reclamation strategy. However, to ensure long-term viability of such wetlands, the response of t he flora to the industrial effluent needed to be determined. To this end, a pparent photosynthesis (APS), the level of ribulose-1,5-bisphosphate carbox ylase (RuBisCo) large subunit, dehydrin-related polypeptides, and protein d isulphide isomerase (PDI) were evaluated in cattail and alsike clover plant s (Trifolium hybridum L.) exposed to the oil sands effluent. APS measured i n plants impacted by oil sands effluent was significantly higher than that of plants in the non-impacted off-site location. Among the on-site location s, plants growing in the natural wetlands site had higher APS compared to a ll other sites. The level of RuBisCo was not increased in cattail or clover growing in effluent-contaminated sites indicating that enhanced photosynth esis was not due to greater levels of this enzyme. Dehydrin-related polypep tides were detected only in the roots of cattail and were absent in clover. The polypeptide profile was altered in cattail exposed to oil sands efflue nt indicating that they were responding to an osmotic stress. The level of PDI was unaffected in the leaves of cattail regardless of the nature of the effluent to which they were exposed. Overall, the data indicate that catta il and clover are adapted to the oil sands effluent, although further studi es are needed to assess their longterm ability to survive in the presence o f this anthropogenic stress. (C) 2001 Elsevier Science Ltd. All rights rese rved.