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Title: Diversity and functioning of Arctic benthic ecosystems and their resilience to climate change driven alterations in food supply
Author: Mäkelä, Anni
ISNI:       0000 0004 6353 2362
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2017
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Climate change is rapidly reducing the Arctic Ocean summer sea ice cover, consequently altering the patterns of primary production, with reducing ice algal-, but increasing phytoplankton primary production. As benthic consumers rely on the sinking phytodetritus for food, changes to food availability could render the benthos vulnerable if they prefer ice algae as a food source. The aim this thesis was to investigate the benthic macroinfaunal dietary reliance on ice algae and phytoplankton in North Water Polynya (NOW) and Lancaster Sound (LS) in Canadian Arctic Archipelago, and how a shift from one food source to another impacts the benthic community resource utilisation and nutrient cycling processes. I hypothesised that ice algae would be preferentially consumed and respired by the benthos. Natural abundance stable isotope analysis showed that phytoplankton is the main food source for macroinfauna in NOW and LS. 13C-15N isotope tracer experiments showed that while in NOW the accumulative macroinfaunal uptake of ice algal C was higher than uptake of ice algae, in LS more ice algal C and N was consumed. None of the major taxonomic groups exclusively preferred ice algae. No difference in bacterial uptake of the two algal types was observed at either site, but the respiration of phytoplankton C was significantly higher than respiration of ice algal C. The processing rates of phytoplankton-derived C were 39–46% higher than processing rates of ice algal C. Therefore, the hypothesis of ice algal preference by benthos must be rejected. I conclude that benthic macroinfauna exhibit great dietary flexibility, making them resilient against climate mediated changes in food sources, and that increasing availability of phytoplankton food can benefit the benthos in the future. Additionally, the transition from ice algae to phytoplankton dominated food can significantly enhance benthic organic matter processing, and especially respiration, rates in the future.
Supervisor: Not available Sponsor: Natural Environment Research Council ; ArcticNet
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Benthos