Kelps and Environmental Changes in Kongsfjorden: Stress Perception and Responses

Abstract

On rocky substrata along shallow water cold-temperate and Arctic coastlines, large brown seaweeds (``kelps'') form structure- and organism-rich habitats of vast ecological significance. The distribution of these ecosystem engineers is largely controlled by the prevailing temperature, light regime and substrate availability, but can also be influenced by biotic interactions within the kelp communities. In Kongsfjorden, right in the transition of an Arctic to an Atlantic fjord system, the aforementioned factors are likely to be altered as a consequence of regional and global environmental change. The drivers of change entail increasing surface irradiances of harmful ultraviolet B radiation due to stratospheric ozone depletion, and variations related to increased atmospheric carbon dioxide concentrations, such as increase in atmospheric and sea surface temperatures with their marked influence on sea ice formation and ocean acidification. Other factors potentially driving the Kongsfjorden system into change might be alterations of current and wind patterns resulting in the increased inflow of Atlantic waters into the bay (Atlantification), and increased precipitation, and terrestrial and glacial runoff, yielding an altered salinity regime and sediment discharge into the fjord with the potential impact of reducing light availability to marine photosynthesizers. Hence, this article is aiming to provide an overview on ecologically relevant abiotic and biotic factors influencing kelp distribution, and with the potential to eventually act as environmental stressors. We assess responses on different organisational levels of kelp by following the effects cascading from the initial sensing of the environment, signal transduction to gene expression, physiological reactions, changes in cellular ultrastructure and subsequent consequences for growth, reproduction and population biology for the different species of kelps present in Kongsfjorden.