Aggregation and vertical migration behavior of Euphausia superba

We describe a novel seasonal shift in the vertical migration behavior of Chaoborus punctipennis second-instar larvae in Lake Opeongo, Ontario. An upward-looking 600 kHz acoustic Doppler current profiler (ADCP) moored at a fixed 22 m station in the lake recorded acoustic backscatter continuously during the study period. Zooplankton samples collected indicated that the abundance of C. punctipennis larval instars accounted for the greatest proportion of variance in the linear backscatter from the ADCP. The large fourth-instar larvae underwent normal diel vertical migration throughout the study. Smaller second-instar larvae underwent reverse migration during late June but switched to normal migration by late July. The acoustic record indicates that the switch occurred over a few days around late June, and at this time a double vertical migration appeared with the second instars leading and following the migration of fourth instars. We speculate that these changes in the migration of second instars are driven by seasonal shifts in predation risk from larval cisco (Coregonus artedi) and by the need to minimize spatial overlap with the larger fourth instars.

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Diel vertical migration behavior of Calanus finmarchicus and its influence on right and sei whale occurrence

Marine Ecology Progress Series ◽

10.3354/meps08931 ◽

2011 ◽

Vol 423 ◽

pp. 167-184 ◽

Cited By ~ 33

Author(s):

MF Baumgartner ◽

NSJ Lysiak ◽

C Schuman ◽

J Urban-Rich ◽

FW Wenzel

Keyword(s):

Vertical Migration ◽

Diel Vertical Migration ◽

Calanus Finmarchicus ◽

Migration Behavior

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Mysis relicta Assimilation of Hexachlorobiphenyl from Sediments

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f91-039 ◽

1991 ◽

Vol 48 (2) ◽

pp. 284-289 ◽

Cited By ~ 17

Author(s):

J. Val Klump ◽

Jerry L. Kaster ◽

Michael E. Sierszen

Keyword(s):

Particle Size ◽

Vertical Migration ◽

Specific Activity ◽

Migration Behavior ◽

Fecal Material ◽

Selective Feeding ◽

Deep Lakes ◽

Mysis Relicta ◽

Pelagic Environment ◽

Important Pathway

Assimilation and retention of a PCB congener, 2,4,5,2′,4′,5′-hexachlorobiphenyl (HCBP), by the oppossum shrimp, Mysis relicta, was followed during sediment ingestion and defecation using a 14C label. Uptake was rapid and essentially linear, with mysids reaching a [14C]HCBP specific activity equivalent to that in the labeled sediment within 2 wk. Assimilation efficiencies calculated from the relative depletion of the label in the fecal material averaged 53% (±7%). Sediment ingestion rates calculated from the activity required to supply the label retained were approximately 1 mg∙mysid−1∙d−1, in agreement with published estimates. The distribution of HCBP as a function of particle size indicates that particle-size selective feeding by detritivores can have a significant effect on calculated assimilation efficiencies. Given the vertical migration behavior of M. relicta, sediment ingestion is a potentially important pathway for the reintroduction of sediment-associated contaminants into the pelagic environment of deep lakes.

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Evaluating vertical migration behavior of harmful raphidophytes in the Delaware Inland Bays utilizing quantitative real-time PCR

Aquatic Microbial Ecology ◽

10.3354/ame040121 ◽

2005 ◽

Vol 40 ◽

pp. 121-132 ◽

Cited By ~ 40

Author(s):

SM Handy ◽

KJ Coyne ◽

KJ Portune ◽

E Demir ◽

MA Doblin ◽

...

Keyword(s):

Real Time ◽

Vertical Migration ◽

Real Time Pcr ◽

Migration Behavior ◽

Quantitative Real Time Pcr ◽

Inland Bays ◽

Delaware Inland Bays

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Circadian regulation of diel vertical migration (DVM) and metabolism in Antarctic krill Euphausia superba

Scientific Reports ◽

10.1038/s41598-020-73823-5 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Fabio Piccolin ◽

Lisa Pitzschler ◽

Alberto Biscontin ◽

So Kawaguchi ◽

Bettina Meyer

Keyword(s):

Oxygen Consumption ◽

High Latitude ◽

Vertical Migration ◽

Diel Vertical Migration ◽

Clock Gene ◽

Antarctic Krill ◽

Euphausia Superba ◽

Recent Analysis ◽

Circadian Regulation ◽

Free Running

Abstract Antarctic krill (Euphausia superba) are high latitude pelagic organisms which play a key ecological role in the ecosystem of the Southern Ocean. To synchronize their daily and seasonal life-traits with their highly rhythmic environment, krill rely on the implementation of rhythmic strategies which might be regulated by a circadian clock. A recent analysis of krill circadian transcriptome revealed that their clock might be characterized by an endogenous free-running period of about 12–15 h. Using krill exposed to simulated light/dark cycles (LD) and constant darkness (DD), we investigated the circadian regulation of krill diel vertical migration (DVM) and oxygen consumption, together with daily patterns of clock gene expression in brain and eyestalk tissue. In LD, we found clear 24 h rhythms of DVM and oxygen consumption, suggesting a synchronization with photoperiod. In DD, the DVM rhythm shifted to a 12 h period, while the peak of oxygen consumption displayed a temporal advance during the subjective light phase. This suggested that in free-running conditions the periodicity of these clock-regulated output functions might reflect the shortening of the endogenous period observed at the transcriptional level. Moreover, differences in the expression patterns of clock gene in brain and eyestalk, in LD and DD, suggested the presence in krill of a multiple oscillator system. Evidence of short periodicities in krill behavior and physiology further supports the hypothesis that a short endogenous period might represent a circadian adaption to cope with extreme seasonal photoperiodic variability at high latitude.

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