Loss of pelagic fish and zooplankton density associated with subglacial upwelling in high Arctic estuaries may be mitigated by benthic habitat expansion following tidewater glacier retreat
Glacier fronts are hotspots of pelagic productivity due to upwelling of nutrient-rich water. As tidewater glaciers retreat into land, this subglacial circulation will disappear and sedimentation from terrestrial runoff will increase, leading to a decrease in pelagic productivity with a decline in th...
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Canadian Science Publishing
2025-01-01
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| Series: | Arctic Science |
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| Online Access: | https://cdnsciencepub.com/doi/10.1139/as-2024-0040 |
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| author | Victor Gonzalez Triginer Arunima Sen Maxime Geoffroy Børge Damsgård |
| author_facet | Victor Gonzalez Triginer Arunima Sen Maxime Geoffroy Børge Damsgård |
| author_sort | Victor Gonzalez Triginer |
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| description | Glacier fronts are hotspots of pelagic productivity due to upwelling of nutrient-rich water. As tidewater glaciers retreat into land, this subglacial circulation will disappear and sedimentation from terrestrial runoff will increase, leading to a decrease in pelagic productivity with a decline in the abundance of fish and zooplankton. We used Billefjorden, a high Arctic fjord with a glacier recently transitioned from sea- to land-terminating as a case study to identify spatial differences and small-scale environmental drivers of density and vertical distribution of fish and zooplankton along a gradient of glacier retreat (directly in front of the land-terminating glacier front, a river bay with terrestrial input from land-terminating glaciers further inland and a location with minimal glacial input). We developed a sustainable and efficient protocol to safely sample the glacier front and shallow coastal areas using hydroacoustics and a remote autonomous vehicle combined with oceanographic measurements and baited remote cameras. Over 2 years, pelagic density was lowest at the now land-terminating glacier front and highest at the site with lowest terrestrial input. Temperature, depth, and turbidity explained less than 8% of the variation each. The site with the least glacial input had the most heterogenous bottom habitat due to the presence of kelp forests, and the richer demersal habitat likely contributed to the higher pelagic density. In shallow fjords and areas with hard bottom substrate, it is expected that sea-ice and glacial retreat will promote macroalgal settlement, and we suggest that macroalgal expansion may compensate the loss of tidewater glacier-associated density of fish and zooplankton by the increase of benthic-driven density. Arctic pelagic ecosystems could thus be more resilient to glacier retreat than initially thought, but this is highly dependent on fjord topography, sedimentation rate, and substrate type. Our developed protocol is an efficient non-invasive method to survey shallow coastal areas and glacier fronts in the Arctic. |
| format | Article |
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| institution | Kabale University |
| issn | 2368-7460 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Canadian Science Publishing |
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| series | Arctic Science |
| spelling | doaj-art-e6ac5e44a6a248619b8317c01778fa482025-02-06T20:55:15ZengCanadian Science PublishingArctic Science2368-74602025-01-011111210.1139/as-2024-0040Loss of pelagic fish and zooplankton density associated with subglacial upwelling in high Arctic estuaries may be mitigated by benthic habitat expansion following tidewater glacier retreatVictor Gonzalez Triginer0Arunima Sen1Maxime Geoffroy2Børge Damsgård3Department of Arctic Biology, The University Centre in Svalbard, Longyearbyen, NorwayDepartment of Arctic Biology, The University Centre in Svalbard, Longyearbyen, NorwayFaculty of Biosciences, Fisheries and Economics, The Arctic University of Norway, Tromsø, NorwayDepartment of Arctic Biology, The University Centre in Svalbard, Longyearbyen, NorwayGlacier fronts are hotspots of pelagic productivity due to upwelling of nutrient-rich water. As tidewater glaciers retreat into land, this subglacial circulation will disappear and sedimentation from terrestrial runoff will increase, leading to a decrease in pelagic productivity with a decline in the abundance of fish and zooplankton. We used Billefjorden, a high Arctic fjord with a glacier recently transitioned from sea- to land-terminating as a case study to identify spatial differences and small-scale environmental drivers of density and vertical distribution of fish and zooplankton along a gradient of glacier retreat (directly in front of the land-terminating glacier front, a river bay with terrestrial input from land-terminating glaciers further inland and a location with minimal glacial input). We developed a sustainable and efficient protocol to safely sample the glacier front and shallow coastal areas using hydroacoustics and a remote autonomous vehicle combined with oceanographic measurements and baited remote cameras. Over 2 years, pelagic density was lowest at the now land-terminating glacier front and highest at the site with lowest terrestrial input. Temperature, depth, and turbidity explained less than 8% of the variation each. The site with the least glacial input had the most heterogenous bottom habitat due to the presence of kelp forests, and the richer demersal habitat likely contributed to the higher pelagic density. In shallow fjords and areas with hard bottom substrate, it is expected that sea-ice and glacial retreat will promote macroalgal settlement, and we suggest that macroalgal expansion may compensate the loss of tidewater glacier-associated density of fish and zooplankton by the increase of benthic-driven density. Arctic pelagic ecosystems could thus be more resilient to glacier retreat than initially thought, but this is highly dependent on fjord topography, sedimentation rate, and substrate type. Our developed protocol is an efficient non-invasive method to survey shallow coastal areas and glacier fronts in the Arctic.https://cdnsciencepub.com/doi/10.1139/as-2024-0040kelp forestfishzooplanktonSvalbardacousticsclimate change |
| spellingShingle | Victor Gonzalez Triginer Arunima Sen Maxime Geoffroy Børge Damsgård Loss of pelagic fish and zooplankton density associated with subglacial upwelling in high Arctic estuaries may be mitigated by benthic habitat expansion following tidewater glacier retreat Arctic Science kelp forest fish zooplankton Svalbard acoustics climate change |
| title | Loss of pelagic fish and zooplankton density associated with subglacial upwelling in high Arctic estuaries may be mitigated by benthic habitat expansion following tidewater glacier retreat |
| title_full | Loss of pelagic fish and zooplankton density associated with subglacial upwelling in high Arctic estuaries may be mitigated by benthic habitat expansion following tidewater glacier retreat |
| title_fullStr | Loss of pelagic fish and zooplankton density associated with subglacial upwelling in high Arctic estuaries may be mitigated by benthic habitat expansion following tidewater glacier retreat |
| title_full_unstemmed | Loss of pelagic fish and zooplankton density associated with subglacial upwelling in high Arctic estuaries may be mitigated by benthic habitat expansion following tidewater glacier retreat |
| title_short | Loss of pelagic fish and zooplankton density associated with subglacial upwelling in high Arctic estuaries may be mitigated by benthic habitat expansion following tidewater glacier retreat |
| title_sort | loss of pelagic fish and zooplankton density associated with subglacial upwelling in high arctic estuaries may be mitigated by benthic habitat expansion following tidewater glacier retreat |
| topic | kelp forest fish zooplankton Svalbard acoustics climate change |
| url | https://cdnsciencepub.com/doi/10.1139/as-2024-0040 |
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