As part of a habitat restoration experiment wood substrates (red gum) were introduced to two lowland streams of SE Australia in which habitat has been severely degraded by deposition of sand eroded from higher in the catchment. We monitored net primary production (NPP) and community respiration (CR), nutrient concentrations and the succession of algae and invertebrates (abundance and species richness), sampling at 2, 4, 8, 12, 16 and 20 weeks. Colonisation by algae was rapid, and there were distinct changes in the assemblages over the first 4 weeks. Thereafter, changes were much less marked. There were also differences in nutrient concentrations and some measures of algal abundance between the two creeks. As with the algae, invertebrates colonised these substrates extremely rapidly, peaking in abundance and richness in week 8. Invertebrate abundances closely tracked changes in the abundance of algae. By the end of the study both algal and invertebrate communities were in apparent decline, with sharp decreases in invertebrate and algal abundance and invertebrate species richness. Rates of GPP also declined toward the end of the experiment, and this coincided with the detachment of large mats of filamentous algae and the recession of flows over the summer months. However, in both streams the added timber quickly created habitat with high levels of primary production in an otherwise strongly heterotrophic stream system. These hotspots of autotrophic production were quickly colonised by high numbers of macroinvertebrates indicating timber addition may provide an effective means of augmenting habitat for algae and invertebrates in sanded streams.
Inquiry-and context-based learning (IBL and CBL, respectively) can lead to improved student outcomes, including increased motivation and interest, the development of critical thinking skills, and improved assessment results. This study outlines the application of IBL research projects in third-year university Environmental Chemistry and Analytical Chemistry subjects that also incorporate elements of CBL. Informal student surveys were administered to determine student perceptions of the projects. Students reported that the projects improved their critical thinking, communication, and experimental design skills. They also appreciated being able to investigate a single topic in depth and that the projects reflected the work of real scientists. Students also commented that subject administration, the clarity of marking schemes, and access to resources needed improvement. Improved guidance was also a common theme.
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