TIME-SERIES FOCUSED ASSESSMENTS OF CHANGING MARINE BIVALVE COMMUNITIES IN THE BERING AND CHUKCHI SEAS
The Pacific Arctic has been experiencing rapid environmental change, including increasing bottom water temperatures, declining sea ice extent, and ecosystem shifts. In the northern Bering Sea (NBS), bottom water temperature was ~1.5°C higher in 2018 than previously recorded. Temperature and sea ice...
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| Other Authors: | , , , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | http://hdl.handle.net/1903/28422 https://doi.org/10.13016/pojs-sixs |
| Summary: | The Pacific Arctic has been experiencing rapid environmental change, including increasing bottom water temperatures, declining sea ice extent, and ecosystem shifts. In the northern Bering Sea (NBS), bottom water temperature was ~1.5°C higher in 2018 than previously recorded. Temperature and sea ice dynamics could alter this benthic-dominated system, potentially shifting the food web to a more pelagic-dominated system. Bivalves, a key component of the benthic macrofaunal community, are important prey items for the spectacled eider in the NBS and for walrus in both the NBS and the southeast Chukchi Sea (SEC). Here, data were collected and analyzed at established time-series stations in the NBS and SEC as part of the Distributed Biological Observatory. The objective was to evaluate changes to bivalve communities, and how those relate to overall benthic community shifts and functioning. By using both time-series and experimental techniques my research: 1) evaluated past trends in detail for a single dominant clam species, Macoma calcarea, 2) tracked the abundance, biomass, and dominant size class of two dominant bivalve species, M. calcarea and Serripes spp., from 2015-2019 when drastic physical changes have been observed, and 3) scaled up connections amongst the individual biological responses to full macrofaunal community population responses to the composite environmental changes using shipboard sediment community oxygen consumption (SCOC) incubation and individual respiration experiments. Results indicate that bottom water temperature and food availability (measured using sediment chlorophyll-a inventories as a proxy) play the largest role in controlling the population dynamics of M. calcarea, and that the population is contracting northward in the NBS. In the SEC, results suggest a shift in the hotspot of M. calcarea from station UTN5 (north) to UTN2 (south). However, size class results showed a larger number of smaller clams in the south and a smaller number of larger clams further north, indicating the ... |
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