Benthic Biofilm Controls on Fine Particle Dynamics in Streams

Este artículo contiene 15 páginas, 7 figuras, 3 tablas.Benthic (streambed) biofilms metabolize a substantial fraction of particulate organic matter and nutrient inputs to streams. These microbial communities comprise a significant proportion of overall biomass in headwater streams, and they present a primary control on the transformation and export of labile organic carbon. Biofilm growth has been linked to enhanced fine particle deposition and retention, a feedback that confers a distinct advantage for the acquisition and utilization of energy sources. We quantified the influence of biofilm structure on fine particle deposition and resuspension in experimental stream mesocosms. Biofilms were grown in identical 3 m recirculating flumes over periods of 18–47 days to obtain a range of biofilm characteristics. Fluorescent, 8 mm particles were introduced to each flume, and their concentrations in the water column were monitored over a 30 min period. We measured particle concentrations using a flow cytometer and mesoscale (10 mm to 1 cm) biofilm structure using optical coherence tomography. Particle deposition-resuspension dynamics were determined by fitting results to a stochastic mobile-immobile model, which showed that retention timescales for particles within the biofilm-covered streambeds followed a power-law residence time distribution. Particle retention times increased with biofilm areal coverage, biofilm roughness, and mean biofilm height. Our findings suggest that biofilm structural parameters are key predictors of particle retention in streams and rivers.This study was funded by a Marie Curie Intra- European Fellowship to WRH (FP7- PEOPLE-2011-IEF-302297) and an Austrian Science Fund grant to T.J.B. (START Y420-B17). K.R.R. was supported by a CUAHSI Pathfinder fellowship and U.S. NSF Graduate Research Fellowship. J.D.D. was supported by a Fulbright-Spain fellowship. The modeling effort was supported by U.S. NSF grants EAR- 1215898 and EAR-1344280 to AIP. Supporting data are provided at doi:10.6084/m9.figshare.4252193.Peer reviewe

Joint submission to the Northern Australia Taskforce. Department of the Prime Minister and Cabinet

"Infrastructure and human capital are the two most serious bottlenecks for growth in northern Australia. Business sophistication is also weaker on average compared to the rest of Australia and is likely to act as a constraint in many areas. In contrast, economic fundamentals in northern Australia have been very high, reflecting the extent to which the resources boom has occurred, and continues to occur in northern Australia." - Summary of findingsMade available by the Northern Territory Library via the Publications (Legal Deposit) Act 2004 (NT).About the Northern Australia Research Alliance -- Summary of findings of contributed papers. Contributed Papers: Understanding the characteristics of remote Northern Australia for successful policy development -- Underpinning development: Health and health workforce in northern Australia -- The relationship between workforce mobility, liveability and development in northern Australia -- Human Services sector development in northern Australia -- What type of future for northern Australia's tourism sector? -- Northern Australia Agriculture Policy: opportunities and risks -- Themes in development of the agricultural and resource sectors in Northern Australia -- Education futures in northern Australia -- Re-imagining post-secondary education as a driver of social and economic development in northern Australia -- Defence in the three tropical cities: How to sustainably seize the potential? -- What climate change and cyclones mean for northern Australia -- Economic equity and major development -- Land Tenure and development in northern Australia -- Aboriginal Local Government and Community Sector Partnerships ? sustainable employment in northern Development