Implications for the mesopelagic microbial gardening hypothesis as determined by experimental fragmentation of Antarctic krill fecal pellets
Detritivores need to upgrade their food to increase its nutritional value. One method is to fragment detritus promoting the colonization of nutrient‐rich microbes, which consumers then ingest along with the detritus; so‐called microbial gardening. Observations and numerical models of the detritus‐do...
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Format: | Article in Journal/Newspaper |
Language: | English |
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John Wiley & Sons Ltd
2021
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Online Access: | https://eprints.utas.edu.au/40717/ https://eprints.utas.edu.au/40717/1/142964%20-%20Implications%20for%20the%20mesopelagic%20microbial%20gardening%20hypothesis%20as%20determined.pdf |
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ftunivtasmania:oai:eprints.utas.edu.au:40717 2023-05-15T13:42:40+02:00 Implications for the mesopelagic microbial gardening hypothesis as determined by experimental fragmentation of Antarctic krill fecal pellets Cavan, EL Kawaguchi, S Boyd, PW 2021 application/pdf https://eprints.utas.edu.au/40717/ https://eprints.utas.edu.au/40717/1/142964%20-%20Implications%20for%20the%20mesopelagic%20microbial%20gardening%20hypothesis%20as%20determined.pdf en eng John Wiley & Sons Ltd https://eprints.utas.edu.au/40717/1/142964%20-%20Implications%20for%20the%20mesopelagic%20microbial%20gardening%20hypothesis%20as%20determined.pdf Cavan, EL orcid:0000-0003-1099-6705 , Kawaguchi, S and Boyd, PW orcid:0000-0001-7850-1911 2021 , 'Implications for the mesopelagic microbial gardening hypothesis as determined by experimental fragmentation of Antarctic krill fecal pellets' , Ecology and Evolution, vol. 11, no. 2 , pp. 1023-1036 , doi:10.1002/ece3.7119 <http://dx.doi.org/10.1002/ece3.7119>. carbon sink fecal pellets krill mesopelagic zone microbial gardening zooplankton Article PeerReviewed 2021 ftunivtasmania https://doi.org/10.1002/ece3.7119 2022-01-24T23:18:28Z Detritivores need to upgrade their food to increase its nutritional value. One method is to fragment detritus promoting the colonization of nutrient‐rich microbes, which consumers then ingest along with the detritus; so‐called microbial gardening. Observations and numerical models of the detritus‐dominated ocean mesopelagic zone have suggested microbial gardening by zooplankton is a fundamental process in the ocean carbon cycle leading to increased respiration of carbon‐rich detritus. However, no experimental evidence exists to demonstrate that microbial respiration rates are higher on recently fragmented sinking detrital particles. Using aquaria‐reared Antarctic krill fecal pellets, we showed fragmentation increased microbial particulate organic carbon (POC) turnover by 1.9×, but only on brown fecal pellets, formed from the consumption of other pellets. Microbial POC turnover on un‐ and fragmented green fecal pellets, formed from consuming fresh phytoplankton, was equal. Thus, POC content, fragmentation, and potentially nutritional value together drive POC turnover rates. Mesopelagic microbial gardening could be a risky strategy, as the dominant detrital food source is settling particles; even though fragmentation decreases particle size and sinking rate, it is unlikely that an organism would remain with the particle long enough to nutritionally benefit from attached microbes. We propose “communal gardening” occurs whereby additional mesopelagic organisms nearby or below the site of fragmentation consume the particle and the colonized microbes. To determine how fragmentation impacts the remineralization of sinking carbon‐rich detritus and to parameterize microbial gardening in mesopelagic carbon models, three key metrics from further controlled experiments and observations are needed; how particle composition (here, pellet color/krill diet) impacts the response of microbes to the fragmentation of particles; the nutritional benefit to zooplankton from ingesting microbes after fragmentation along with identification of which essential nutrients are being targeted; how both these factors vary between physical (shear) and biological particle fragmentation. Article in Journal/Newspaper Antarc* Antarctic Antarctic Krill University of Tasmania: UTas ePrints Antarctic Ecology and Evolution 11 2 1023 1036 |
institution |
Open Polar |
collection |
University of Tasmania: UTas ePrints |
op_collection_id |
ftunivtasmania |
language |
English |
topic |
carbon sink fecal pellets krill mesopelagic zone microbial gardening zooplankton |
spellingShingle |
carbon sink fecal pellets krill mesopelagic zone microbial gardening zooplankton Cavan, EL Kawaguchi, S Boyd, PW Implications for the mesopelagic microbial gardening hypothesis as determined by experimental fragmentation of Antarctic krill fecal pellets |
topic_facet |
carbon sink fecal pellets krill mesopelagic zone microbial gardening zooplankton |
description |
Detritivores need to upgrade their food to increase its nutritional value. One method is to fragment detritus promoting the colonization of nutrient‐rich microbes, which consumers then ingest along with the detritus; so‐called microbial gardening. Observations and numerical models of the detritus‐dominated ocean mesopelagic zone have suggested microbial gardening by zooplankton is a fundamental process in the ocean carbon cycle leading to increased respiration of carbon‐rich detritus. However, no experimental evidence exists to demonstrate that microbial respiration rates are higher on recently fragmented sinking detrital particles. Using aquaria‐reared Antarctic krill fecal pellets, we showed fragmentation increased microbial particulate organic carbon (POC) turnover by 1.9×, but only on brown fecal pellets, formed from the consumption of other pellets. Microbial POC turnover on un‐ and fragmented green fecal pellets, formed from consuming fresh phytoplankton, was equal. Thus, POC content, fragmentation, and potentially nutritional value together drive POC turnover rates. Mesopelagic microbial gardening could be a risky strategy, as the dominant detrital food source is settling particles; even though fragmentation decreases particle size and sinking rate, it is unlikely that an organism would remain with the particle long enough to nutritionally benefit from attached microbes. We propose “communal gardening” occurs whereby additional mesopelagic organisms nearby or below the site of fragmentation consume the particle and the colonized microbes. To determine how fragmentation impacts the remineralization of sinking carbon‐rich detritus and to parameterize microbial gardening in mesopelagic carbon models, three key metrics from further controlled experiments and observations are needed; how particle composition (here, pellet color/krill diet) impacts the response of microbes to the fragmentation of particles; the nutritional benefit to zooplankton from ingesting microbes after fragmentation along with identification of which essential nutrients are being targeted; how both these factors vary between physical (shear) and biological particle fragmentation. |
format |
Article in Journal/Newspaper |
author |
Cavan, EL Kawaguchi, S Boyd, PW |
author_facet |
Cavan, EL Kawaguchi, S Boyd, PW |
author_sort |
Cavan, EL |
title |
Implications for the mesopelagic microbial gardening hypothesis as determined by experimental fragmentation of Antarctic krill fecal pellets |
title_short |
Implications for the mesopelagic microbial gardening hypothesis as determined by experimental fragmentation of Antarctic krill fecal pellets |
title_full |
Implications for the mesopelagic microbial gardening hypothesis as determined by experimental fragmentation of Antarctic krill fecal pellets |
title_fullStr |
Implications for the mesopelagic microbial gardening hypothesis as determined by experimental fragmentation of Antarctic krill fecal pellets |
title_full_unstemmed |
Implications for the mesopelagic microbial gardening hypothesis as determined by experimental fragmentation of Antarctic krill fecal pellets |
title_sort |
implications for the mesopelagic microbial gardening hypothesis as determined by experimental fragmentation of antarctic krill fecal pellets |
publisher |
John Wiley & Sons Ltd |
publishDate |
2021 |
url |
https://eprints.utas.edu.au/40717/ https://eprints.utas.edu.au/40717/1/142964%20-%20Implications%20for%20the%20mesopelagic%20microbial%20gardening%20hypothesis%20as%20determined.pdf |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Antarctic Krill |
genre_facet |
Antarc* Antarctic Antarctic Krill |
op_relation |
https://eprints.utas.edu.au/40717/1/142964%20-%20Implications%20for%20the%20mesopelagic%20microbial%20gardening%20hypothesis%20as%20determined.pdf Cavan, EL orcid:0000-0003-1099-6705 , Kawaguchi, S and Boyd, PW orcid:0000-0001-7850-1911 2021 , 'Implications for the mesopelagic microbial gardening hypothesis as determined by experimental fragmentation of Antarctic krill fecal pellets' , Ecology and Evolution, vol. 11, no. 2 , pp. 1023-1036 , doi:10.1002/ece3.7119 <http://dx.doi.org/10.1002/ece3.7119>. |
op_doi |
https://doi.org/10.1002/ece3.7119 |
container_title |
Ecology and Evolution |
container_volume |
11 |
container_issue |
2 |
container_start_page |
1023 |
op_container_end_page |
1036 |
_version_ |
1766170951909638144 |