Benthic microalgal production in the Arctic: Status of the current database.

The current database on benthic microalgal production in Arctic waters comprises 10 peer-reviewed and three unpublished studies. Here, we compile and discuss these datasets, along with the applied measurement approaches used. The latter is essential for robust comparative analysis and to clarify the often very confusing terminology in the existing literature. Our compilation demonstrates that i) benthic microalgae contribute significantly to coastal ecosystem production in the Arctic, and ii) benthic microalgal production on average exceeds pelagic productivity by a factor of 1.5 for water depths down to 30 m. We have established relationships between irradiance, water depth and benthic microalgal productivity that can be used to extrapolate results from quantitative experimental studies to the entire Arctic region. Two different approaches estimated that current benthic microalgal production in the Arctic is between 1.1 and 1.6X10(7) tons C year(-1). Climate change is expected to increase the overall primary production and affect the balance between pelagic and benthic productivity in the Arctic. It is therefore imperative to get better quantitative understanding of the relationship between increased freshwater run-off, shrinking sea-ice cover, light availability and benthic primary production to assess future impact on the Arctic food web and trophic coupling.