Benthic biology of two near-shore arctic locations, and potential impacts of sea level change, coastal erosion, and climate change

Brown, Tanya (2007) Benthic biology of two near-shore arctic locations, and potential impacts of sea level change, coastal erosion, and climate change. Masters thesis, Memorial University of Newfoundland.

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Abstract

Near-shore benthic communities can undergo shifts in abundance and biodiversity in response to climate change especially changes in surface temperature, productivity, and geomorphology. One of the most dramatic effects is habitat modification: coastal erosion lead to increased deposition of sediment. Factors driving coastal erosion include isostatic sea-level rise and a variety of climatic change impacts, including reduced sea ice cover, increased summer rainfall, increased thawing of permafrost, and eustatic sea-level rise. -- Benthic communities were studied in two near-shore Arctic locations (Sachs Harbour and Gjoa Haven) associated with different degrees of coastal erosion. Sachs Harbour has a submergent shoreline with locally rapid coastal erosion. By contrast Gjoa Haven has an emergent shoreline with very little to no coastal erosion. Grab and drop-video were used to conduct benthic surveys of the two locations and detailed habitat maps were produced. Species richness was significantly greater in Gjoa Haven than in Sachs Harbour. Species composition differed greatly among locations and varied significantly among substrate types for grab and depth classes for video. Shallow (<10 m) mobile sand sheets with low biodiversity were the dominant habitat sampled in Sachs Harbour. Gravelly-sand or mud substrates (10-20 m) with high cover of macroalgae had the greatest biodiversity in Gjoa Haven. Macroalgae beds were found throughout the Gjoa Haven study area providing abundant food and shelter to benthic fauna. This high diversity is due to the heterogeneity of the substrate. Lastly, Gjoa Haven's sediment starved near-shore environment makes for a stable environment compared to Sachs Harbour near-shore environment, which receives a continuous supply of sediment as a result of coastal erosion and runoff. -- This study establishes a detailed baseline for two near-shore Arctic locations. Given the rapidity with which the Arctic ecosystems are changing this study will be valuable in designing future studies of biodiversity, and will enable detection of future climate driven change in near-shore arctic environments.

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