Hamisch, Stephan (2025) Deep-water biodiversity-ecosystem functioning in temperate to Arctic shelf and fjord benthos. Masters thesis, Memorial University of Newfoundland.
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Abstract
Despite many ongoing changes in the global ocean, few studies have addressed biodiversity- ecosystem functioning relationships in deep-water benthic ecosystems across Canadian temperate to Arctic shelf and fjord habitats. Although megafaunal keystone taxa clearly influence epifauna, their impact on associated macroinfaunal communities and ecosystem functioning remains poorly understood. In this study, I consider cerianthid (tube anemone, Ceriantharia) fields as a potential keystone feature of deep-water systems, using sediment push core samples and shipboard incubations. Elevated faunal density and distinct community composition and biodiversity throughout sediment layers characterized cerianthid field sediments in comparison with adjacent sites. Greater degradation of organic matter (OM) inside cerianthid fields likely enhanced silicate efflux and potentially increased anammox processes. I attribute these differences to cerianthid predation pressure and altered hydrodynamics inside cerianthid fields that might enhance deposition of OM. On a much larger scale, multiple threats related to climate change threaten deep ocean biota and its functional role within global elemental cycles. I conducted a meta-analysis on studies investigating deep-water, soft sediment macrofaunal communities and nutrient remineralization processes from the Northwest Atlantic into the Arctic, a hotspot of accelerated climate change. Taxonomic and environmental differences indicated two distinct ecological settings (Atlantic and Arctic) within the study region. I found strong continuity in ecological variables impacting ecosystem functioning, with different variables dominating biodiversity ecosystem functioning relationships in Arctic and Atlantic settings. My study highlights the large-scale importance of biogenic habitats in contributing to ecosystem functioning and resilience throughout the region, and illustrates the scale- and context-dependence of ecosystem functioning while providing insights into potential shifts of ecosystem functioning with the ongoing Atlantification of Arctic environments.
| Item Type: | Thesis (Masters) |
|---|---|
| URI: | http://research.library.mun.ca/id/eprint/16913 |
| Item ID: | 16913 |
| Additional Information: | Includes bibliographical references -- Restricted until February 19, 2026 |
| Keywords: | BEF, global change, biodiversity, benthos, nutrient remineralization |
| Department(s): | Science, Faculty of > Ocean Sciences |
| Date: | May 2025 |
| Date Type: | Submission |
| Digital Object Identifier (DOI): | https://doi.org/10.48336/htga-6437 |
| Library of Congress Subject Heading: | Benthic ecology; Deep-sea ecology; Marine biodiversity--Canada; Climatic changes--Arctic regions |
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