The vertical distribution and diel migration of euphausiids in the central waters of the eastern South Pacific

1975 ◽  
Vol 22 (8) ◽  
pp. 519-536 ◽  
Author(s):  
Marsh J. Youngbluth
Biologia ◽  
2011 ◽  
Vol 66 (2) ◽  
Author(s):  
Evangelia Doulka ◽  
George Kehayias

AbstractThe investigation of the vertical distribution of the zooplankton community in the temperate Lake Trichonis during four seasons in 2005, showed the existence of vertical segregation among species, ontogenetic stages and sexes within and between the major groups. In each season, the two or three more abundant rotifer species distributed at separate depth layers, while this feature was maintained during the entire 24 h period, since no diel vertical migrations (DVM) were performed. In contrast, the crustacean community, comprised mainly by the calanoid copepod Eudiaptomus drieschi and the cladoceran Diaphanosoma orghidani, showed various patterns of DVM, being more pronounced in spring and summer. Females of E. drieschi distributed deeper than males, while the copepod nauplii were found mainly in the surface layer in all four seasons. Temperature was the most important abiotic factor affecting directly and indirectly the vertical distribution and migration of various species. During stratification, the metalimnion was the most productive layer in Lake Trichonis, having maximum values of dissolved oxygen and low transparency due to high concentration of organic matter and phytoplankton. The DVM patterns of the crustaceans indicate that the metalimnion acts probably as a daylight refuge against predation by Atherina boyeri, which is the dominant planktivorous fish in the lake.


Crustaceana ◽  
2014 ◽  
Vol 87 (13) ◽  
pp. 1486-1499 ◽  
Author(s):  
Harmon Brown ◽  
Harmon Brown ◽  
Stephen M. Bollens ◽  
Harmon Brown ◽  
Stephen M. Bollens ◽  
...  

We sampled for vertical distribution and possible diel vertical migration (DVM) of Crangon septemspinosa Say, 1818 on and around Georges Bank, Northwest Atlantic, between 1995 and 1999. Both juveniles and adults were found to undergo DVM, being distributed within the lower water column (and perhaps on or in the bottom) during the day, and distributed throughout the water column at night, with higher abundances seen in all depth strata at night. Differences in vertical distribution were also found based on location and chlorophyll concentration for juveniles, but no effects were seen of season, salinity, temperature, lunar periodicity, year, or copepod prey for either juveniles or adults. Variation in vertical distribution and DVM were only moderately well explained (50% of the total variance) by the above factors, suggesting that some other factor(s) not measured by us (e.g., predation) were potentially also controlling the vertical distribution and diel migration of C. septemspinosa on Georges Bank.


Tellus B ◽  
2011 ◽  
Vol 63 (1) ◽  
Author(s):  
Abhay Devasthale ◽  
Michael Tjernström ◽  
Karl-Göran Karlsson ◽  
Manu Anna Thomas ◽  
Colin Jones ◽  
...  

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Katie E. Miles ◽  
Bryn Hubbard ◽  
Evan S. Miles ◽  
Duncan J. Quincey ◽  
Ann V. Rowan ◽  
...  

AbstractSurface melting of High Mountain Asian debris-covered glaciers shapes the seasonal water supply to millions of people. This melt is strongly influenced by the spatially variable thickness of the supraglacial debris layer, which is itself partially controlled by englacial debris concentration and melt-out. Here, we present measurements of deep englacial debris concentrations from debris-covered Khumbu Glacier, Nepal, based on four borehole optical televiewer logs, each up to 150 m long. The mean borehole englacial debris content is ≤ 0.7% by volume in the glacier’s mid-to-upper ablation area, and increases to 6.4% by volume near the terminus. These concentrations are higher than those reported for other valley glaciers, although those measurements relate to discrete samples while our approach yields a continuous depth profile. The vertical distribution of englacial debris increases with depth, but is also highly variable, which will complicate predictions of future rates of surface melt and debris exhumation at such glaciers.


2021 ◽  
Vol 42 (17) ◽  
pp. 6421-6436
Author(s):  
Sourita Saha ◽  
Som Sharma ◽  
K. Niranjan Kumar ◽  
Prashant Kumar ◽  
Vaidehi Joshi ◽  
...  

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