Seasonal patterns in deep acoustic backscatter layers near vent plumes in the northeastern Pacific Ocean
We used moored 75 kHz acoustic Doppler current profilers (ADCPs) to examine seasonal cycles in zooplankton deep scattering layers (DSLs) observed below 1300 m depth at Endeavour Ridge hydrothermal vents. DSLs are present year-round in the lower water column near vent plumes. Temporal variations sugg...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Canadian Science Publishing
2019-06-01
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| Series: | FACETS |
| Subjects: | |
| Online Access: | https://facetsjournal.com/doi/10.1139/facets-2018-0027 |
| _version_ | 1811203134861606912 |
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| author | Brenda Burd Richard E. Thomson |
| author_facet | Brenda Burd Richard E. Thomson |
| author_sort | Brenda Burd |
| collection | DOAJ |
| description | We used moored 75 kHz acoustic Doppler current profilers (ADCPs) to examine seasonal cycles in zooplankton deep scattering layers (DSLs) observed below 1300 m depth at Endeavour Ridge hydrothermal vents. DSLs are present year-round in the lower water column near vent plumes. Temporal variations suggest passive, flow-induced displacements superimposed on migratory movements. Although the strongest DSLs are shallower than the neutrally buoyant plumes (1900–2100 m), anomalies also occur at and below plume depth. Upward movement from plume depth in the main DSL is evident in late summer/fall, resulting in shallower DSLs in winter, consistent with the timing of adult diapause/reproduction in upper-ocean migratory copepods. Movement from the upper ocean to plume depth coincides with pre-adult migration to greater depths in spring. Synchronous 20–40 d cycles in DSLs may account for patchiness in space and time of above-plume zooplankton layers observed in summer during previous net-sampling surveys, and suggests lateral and vertical migratory movements to counter current drift away from plume-derived food sources. Persistent near-bottom DSLs move vertically between the spreading plume and seafloor. Historical net data suggests that these are deep, resident fauna. Unlike upper ocean fauna, they seem to be advected considerable distances from the ridge axis, where they are evident as remnant scattering layers. |
| first_indexed | 2024-04-12T02:49:30Z |
| format | Article |
| id | doaj.art-5673c87e49de4bb3b2dbf4011ecb32ad |
| institution | Directory Open Access Journal |
| issn | 2371-1671 2371-1671 |
| language | English |
| last_indexed | 2024-04-12T02:49:30Z |
| publishDate | 2019-06-01 |
| publisher | Canadian Science Publishing |
| record_format | Article |
| series | FACETS |
| spelling | doaj.art-5673c87e49de4bb3b2dbf4011ecb32ad2022-12-22T03:51:01ZengCanadian Science PublishingFACETS2371-16712371-16712019-06-014118320910.1139/facets-2018-0027Seasonal patterns in deep acoustic backscatter layers near vent plumes in the northeastern Pacific OceanBrenda Burd0Richard E. Thomson1Institute of Ocean Sciences, P.O. Box 6000, Sidney, BC V8L 5T5, CanadaInstitute of Ocean Sciences, P.O. Box 6000, Sidney, BC V8L 5T5, CanadaWe used moored 75 kHz acoustic Doppler current profilers (ADCPs) to examine seasonal cycles in zooplankton deep scattering layers (DSLs) observed below 1300 m depth at Endeavour Ridge hydrothermal vents. DSLs are present year-round in the lower water column near vent plumes. Temporal variations suggest passive, flow-induced displacements superimposed on migratory movements. Although the strongest DSLs are shallower than the neutrally buoyant plumes (1900–2100 m), anomalies also occur at and below plume depth. Upward movement from plume depth in the main DSL is evident in late summer/fall, resulting in shallower DSLs in winter, consistent with the timing of adult diapause/reproduction in upper-ocean migratory copepods. Movement from the upper ocean to plume depth coincides with pre-adult migration to greater depths in spring. Synchronous 20–40 d cycles in DSLs may account for patchiness in space and time of above-plume zooplankton layers observed in summer during previous net-sampling surveys, and suggests lateral and vertical migratory movements to counter current drift away from plume-derived food sources. Persistent near-bottom DSLs move vertically between the spreading plume and seafloor. Historical net data suggests that these are deep, resident fauna. Unlike upper ocean fauna, they seem to be advected considerable distances from the ridge axis, where they are evident as remnant scattering layers.https://facetsjournal.com/doi/10.1139/facets-2018-0027acoustic backscatterdeep scattering layerszooplanktonhydrothermal plumesseasonal patterns |
| spellingShingle | Brenda Burd Richard E. Thomson Seasonal patterns in deep acoustic backscatter layers near vent plumes in the northeastern Pacific Ocean FACETS acoustic backscatter deep scattering layers zooplankton hydrothermal plumes seasonal patterns |
| title | Seasonal patterns in deep acoustic backscatter layers near vent plumes in the northeastern Pacific Ocean |
| title_full | Seasonal patterns in deep acoustic backscatter layers near vent plumes in the northeastern Pacific Ocean |
| title_fullStr | Seasonal patterns in deep acoustic backscatter layers near vent plumes in the northeastern Pacific Ocean |
| title_full_unstemmed | Seasonal patterns in deep acoustic backscatter layers near vent plumes in the northeastern Pacific Ocean |
| title_short | Seasonal patterns in deep acoustic backscatter layers near vent plumes in the northeastern Pacific Ocean |
| title_sort | seasonal patterns in deep acoustic backscatter layers near vent plumes in the northeastern pacific ocean |
| topic | acoustic backscatter deep scattering layers zooplankton hydrothermal plumes seasonal patterns |
| url | https://facetsjournal.com/doi/10.1139/facets-2018-0027 |
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