Diurnal vertical motions over a seamount of the southern Gulf of California

Valle‐Levinson, Arnoldo; Castro, Armando Trasviña; Velasco, Guillermo Gutiérrez de; Armas, Rogelio González

doi:10.1016/j.jmarsys.2003.09.016

Cited by 24 publications

(18 citation statements)

References 25 publications

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“…Echo anomaly ( EA ) is a normalization of EI , which included finding anomalies from the time mean (over the entire time series) of the echo intensity profile (

\overset{true¯}{E I}

) as done in Valle‐Levinson et al . [] and explained in Rippeth and Simpson []. EA can be used as a proxy to determine the location of the pycnocline (in space and time) as scatterers tend to accumulate in this region [ Farmer and Armi , ; Valle‐Levinson et al ., ].…”

Section: Discussionsupporting

confidence: 78%

Baroclinic annular variability of internal motions in a Patagonian fjord

et al. 2015

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Time series of horizontal velocities, echo intensity, wind velocity, and atmospheric pressure were collected for $200 days in a Patagonian fjord to explore pycnocline motions produced by the Southern Hemisphere's baroclinic annular mode (BAM). The BAM variability occurs between 20 and 30 days and is associated with fluctuations in atmospheric kinetic energy and in turbulent fluxes of heat. Spectra of horizontal velocities and normalized echo intensity in the fjord's water showed highest energy between 25 and 30 days. This was explained by sustained westerly winds associated with extreme low-pressure systems ($900 hPa) that had periodicity related to the BAM. Wind forcing produced >40 cm s 21 along-channel and cross-channel currents in the surface layer, which in turn created a wind-induced setup toward the head of the fjord. The setup was accompanied by a deepening of the pycnocline (from 5 to 15 m depth) with $25 to 30 day periodicity, as derived from the normalized echo intensity. The dominant empirical orthogonal function mode of the normalized echo intensity profiles explained 70.8% of the variance and also exhibited a $25-30 day periodicity. Further, a wavelet and spectral analysis of 10 years of atmospheric pressure indicated peaks between 25 and 30 days each year, indicating that the BAM consistently influences weather patterns in Chilean Patagonia. This is the first documented case of baroclinic annular variability in a specific region of the Southern Hemisphere, and of its effects on fjord systems.

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“…Echo anomaly ( EA ) is a normalization of EI , which included finding anomalies from the time mean (over the entire time series) of the echo intensity profile (

\overset{true¯}{E I}

Section: Discussionsupporting

confidence: 78%

Baroclinic annular variability of internal motions in a Patagonian fjord

et al. 2015

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“…Recent in situ investigations using stable isotope and fatty acid analyses point to a close coupling of L. pertusa with pelagic resources such as zooplankton and phytodetritus (Spiro et al, 2000;Duineveld et al, 2004;Kiriakoulakis et al, 2005). While tidal pumping (Davies et al, 2009) and internal waves (Frederiksen et al, 1992;Duineveld et al, 2004) deliver a diverse range of particles to the coral, ranging from fresh to resuspended material, the vertical migration (daily or seasonal) of zooplankton can also contribute to the linkage between surface-water production and CWC nutrition (Hind et al, 2000;Valle-Levinson et al, 2004;Dodds et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Opportunistic feeding on various organic food sources by the cold-water coral <i>Lophelia pertusa</i>

et al. 2014

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Abstract. The ability of the cold-water coral Lophelia pertusa to exploit different food sources was investigated under standardized conditions in a flume. The tested food sources, dissolved organic matter (DOM, added as dissolved free amino acids), bacteria, algae, and zooplankton (Artemia) were deliberately enriched in 13 C and 15 N. The incorporation of 13 C and 15 N was traced into bulk tissue, fatty acids, hydrolysable amino acids, and the skeleton ( 13 C only) of L. pertusa. Incorporation rates of carbon (ranging from 0.8-2.4 µg C g −1 DW d −1 ) and nitrogen (0.2-0.8 µg N g −1 DW d −1 ) into coral tissue did not differ significantly among food sources indicating an opportunistic feeding strategy. Although total food assimilation was comparable among sources, subsequent food processing was dependent on the type of food source ingested and recovery of assimilated C in tissue compounds ranged from 17 % (algae) to 35 % (Artemia). De novo synthesis of individual fatty acids by L. pertusa occurred in all treatments as indicated by the 13 C enrichment of individual phospholipid-derived fatty acids (PLFAs) in the coral that were absent in the added food sources. This indicates that the coral might be less dependent on its diet as a source of specific fatty acids than expected, with direct consequences for the interpretation of in situ observations on coral nutrition based on lipid profiles.

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“…However, these organisms did not make directed horizontal movements as observed in the micronekton around the main Hawaiian Islands. In other systems, diel vertical migratory patterns have been shown to lead to retention around topographic features, despite the strength of the advective field (Valle- Levinson et al 2004, Wilson & Boehlert 2004.…”

Section: Introductionmentioning

confidence: 99%

Behavior exceeds physical forcing in the diel horizontal migration of the midwater sound-scattering layer in Hawaiian waters

McManus¹,

Benoit‐Bird²,

Woodson³

2008

Mar. Ecol. Prog. Ser.

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The mesopelagic sound-scattering layer around the Hawaiian Islands undergoes diel vertical migrations. This migration also includes a significant diel horizontal onshore-offshore component. Before this study, the mechanisms underlying the horizontal movement of the mesopelagic layer had not been investigated. We took an interdisciplinary approach to evaluate relationships between the mesopelagic layer and physical oceanographic processes in the water column. The study area extended west of the leeward coast of Oahu, Hawaii. We found that the nightly inshore movement of micronekton occurs very predictably each day; onshore migration brings animals nearshore between 20:00 and 20:13 h and offshore migration commences between 03:30 and 03:45 h during the months of April and May. Simultaneous observations of nearshore physical flow and micronekton distribution indicate that the observed nightly inshore movement of micronekton in the sound-scattering layer is not directly due to physical processes in the nearshore environment. Rather, this nightly inshore movement of micronekton can be attributed primarily to micronekton swimming behavior. This behavior may be cued by changes in sunlight, but that cue is strongly mediated by a factor tied to the lunar phase, potentially moonlight. Horizontal migration velocities exceeded the maximum across-slope physical flow by 5 to 6-fold. Thus, typical across-slope flows likely represent a relatively small additional cost or benefit to onshore-offshore swimming, depending on flow direction. We suggest that energy acquisition via increased prey availability nearshore far exceeds the high energetic cost of onshore and offshore migrations. KEY WORDS: Mesopelagic layer · Diel migration · Physical processesResale or republication not permitted without written consent of the publisher

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Diurnal vertical motions over a seamount of the southern Gulf of California

Cited by 24 publications

References 25 publications

Baroclinic annular variability of internal motions in a Patagonian fjord

Baroclinic annular variability of internal motions in a Patagonian fjord

Opportunistic feeding on various organic food sources by the cold-water coral <i>Lophelia pertusa</i>

Behavior exceeds physical forcing in the diel horizontal migration of the midwater sound-scattering layer in Hawaiian waters

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Diurnal vertical motions over a seamount of the southern Gulf of California

Cited by 24 publications

References 25 publications

Baroclinic annular variability of internal motions in a Patagonian fjord

Baroclinic annular variability of internal motions in a Patagonian fjord

Opportunistic feeding on various organic food sources by the cold-water coral &lt;i&gt;Lophelia pertusa&lt;/i&gt;

Behavior exceeds physical forcing in the diel horizontal migration of the midwater sound-scattering layer in Hawaiian waters

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Opportunistic feeding on various organic food sources by the cold-water coral <i>Lophelia pertusa</i>