scholarly journals Vertical distribution and aggregation patterns of krill (Crustacea: Euphausiacea) in the Bay of Biscay: interannual and seasonal variability

2019 ◽  
Vol 97 (7) ◽  
pp. 619-630 ◽  
Author(s):  
M. Peña ◽  
R. González-Quirós ◽  
I. Munuera-Fernández ◽  
F. González ◽  
S. Romero-Romero ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Vertical Migration ◽  
Seasonal Variations ◽  
Seasonal Variability ◽  
Shelf Area ◽  
Bay Of Biscay ◽  
Acoustic Data ◽  
Epipelagic Zone ◽  
Acoustic Recording ◽  
The Vertical Distribution

Studies of krill (Crustacea: Euphausiacea) in oceanic waters of the Bay of Biscay are scarce and restricted to the epipelagic zone, overlooking vertical dynamics such as diurnal vertical migration (DVM). There is a growing interest in acoustically evaluating the biomass of krill in this area, but this requires a good knowledge of its vertical dynamics and aggregation patterns. In this work we employed acoustic data and net samples from two consecutive annual surveys covering a wide off-shelf area of the Bay of Biscay (JUVENA surveys of 2013 and 2014) and four seasonal surveys covering slope and oceanic waters in the Cantabrian Sea (SCAPA surveys of 2015). Vertical dynamics of krill were analyzed in the frame of the environmental seascape. High interannual and seasonal variations in the vertical distribution and aggregation patterns (small swarms, dense aggregations, or loose layers) of krill were observed. The vertical distribution covaried with dissolved oxygen and salinity. According to our findings, the best season to acoustically evaluate krill in the Bay of Biscay is spring, with the bulk of the biomass located above 600 m depth. Moreover, extending the acoustic recording beyond the epipelagic zone is mandatory for any season.

Diel vertical migration: A possible host-finding mechanism in salmon louse (Lepeophtheirus salmonis) copepodids?

1995 ◽  
Vol 52 (4) ◽  
pp. 681-689 ◽  
Author(s):  
Peter Andreas Heuch ◽  
Aengus Parsons ◽  
Karin Boxaspen
Keyword(s):  
Light Intensity ◽  
Vertical Distribution ◽  
Vertical Migration ◽  
Diel Vertical Migration ◽  
Host Finding ◽  
Migration Pattern ◽  
Lepeophtheirus Salmonis ◽  
Salmon Louse ◽  
Night And Day ◽  
The Vertical Distribution

The vertical distribution of pelagic nauplii and copepodids of the salmon louse Lepeophtheirus salmonis Krøyer was studied in large enclosures in the sea. Copepodids, which infect salmonid hosts, displayed a distinct diel vertical migration pattern. They gathered near the surface during the day, and spread out into deeper layers at night. Nauplii showed only small differences in depth between night and day. Copepodid distribution seems to be controlled by light intensity; no effect of either salinity or temperature was found. This migration pattern, which is the reverse of that of wild salmonids, may increase the number of parasite–host encounters as hosts will swim through populations of sinking (nighttime) and rising (dawn) parasites every 24 h. Because caged salmon feed at the surface during the day, they are likely to be more exposed to infective copepodids than wild fish.

scholarly journals Diel changes in the vertical distribution of larval cutlassfish Trichiurus japonicus

2018 ◽  
Vol 99 (2) ◽  
pp. 517-523
Author(s):  
Daichi Uehara ◽  
Jun Shoji ◽  
Yuichiro Ochi ◽  
Shuhei Yamaguchi ◽  
Kazumitsu Nakaguchi ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Vertical Migration ◽  
Similar Pattern ◽  
Diel Vertical Migration ◽  
Seto Inland Sea ◽  
Upward Movement ◽  
Swim Bladder ◽  
Diel Changes ◽  
Trichiurus Japonicus ◽  
The Vertical Distribution

Diel vertical migration of the cutlassfish Trichiurus japonicus larvae were investigated by consecutive 24-h collections at 3-h intervals at a station in the central Seto Inland Sea, Japan in June and September. Only one larva was collected in June 2017, while 224 and 40 larvae were collected in September 2016 and 2017, respectively. Larvae were present only at depths of ≥ 11 m during the day, whereas they were present at depths of 1, 6, 11 and 16 m during the night. Migration was observed in larvae in which swim bladder formation was completed. A similar pattern, namely nocturnal occurrence at shallow depths only of the developed larvae, was observed in another 24-h survey, suggesting that the swim bladder regulates the upward movement of larvae at night.

scholarly journals Community structure and vertical distribution of oncaeid copepods in Tosa Bay, southern Japan

2009 ◽  
Vol 89 (3) ◽  
pp. 491-498 ◽  
Author(s):  
Yuichiro Nishibe ◽  
Yuuichi Hirota ◽  
Hiroshi Ueda
Keyword(s):  
Community Structure ◽  
Vertical Distribution ◽  
Water Column ◽  
Distribution Patterns ◽  
Depth Range ◽  
Tosa Bay ◽  
Southern Japan ◽  
Hydrographic Conditions ◽  
Epipelagic Zone ◽  
The Vertical Distribution

Community structure and vertical distribution of oncaeid copepods were investigated at an offshore site in Tosa Bay, southern Japan. Samples were collected with a 0.063 mm closing type net from eight discrete layers between the surface and 500 m depth in August and November 2005. A total of 45 species and three form variants belonging to the genera Triconia, Oncaea, Spinoncaea, Conaea and Epicalymma were identified. The greatest number of species was consistently found in the lower epipelagic zone, at 50–100 m. The vertical distribution patterns of oncaeid copepods were similar between August and November, with the highest abundances in the upper epipelagic zone above the thermocline. The oncaeid maxima corresponded with the depth where appendicularians occurred in high numbers. Dominant species in the water column (0–500 m) were O. venusta small form, O. media, O. scottodicarloi, O. waldemari, O. zernovi, O. tregoubovi, S. ivlevi, S. tenuis and T. conifera. The vertical succession of species composition was almost the same between August and November, although several species showed a downward shift of their depth-range to some extent in November. The oncaeid copepod community could be differentiated into three distinct groups according to the depth layers, each corresponding to different hydrographic conditions in the water column.

Diverse taxa of zooplankton inhabit hypoxic waters during both day and night in a temperate eutrophic lake

2019 ◽  
Vol 41 (4) ◽  
pp. 431-447 ◽  
Author(s):  
Sean Nolan ◽  
Stephen M Bollens ◽  
Gretchen Rollwagen-Bollens
Keyword(s):  
Dissolved Oxygen ◽  
Vertical Distribution ◽  
Food Web ◽  
Vertical Migration ◽  
Diel Vertical Migration ◽  
Eutrophic Lake ◽  
Water Bodies ◽  
Marine Waters ◽  
The Common ◽  
The Vertical Distribution

Abstract As the frequency and intensity of hypoxic events increase in both fresh and marine waters, understanding the ecological effects of hypoxia becomes more important. The extant literature reports varying effects of hypolimnetic hypoxia on the vertical distribution and diel vertical migration (DVM) of zooplankton, with some but not all taxa reported to avoid hypoxic waters. We studied the vertical distribution and DVM of diverse zooplankton taxa throughout three seasons over 2 years (2014 and 2015) in Lacamas Lake, WA, USA. We observed hypoxia (<2 mg L−1 dissolved oxygen) in the hypolimnion of Lacamas Lake during five of six sampling periods, with zooplankton populations often exhibiting ‘h-metric’ values (defined as the proportion of a zooplankton population residing within hypoxic waters) ranged from 0.14 to 1.00, with an overall mean of h = 0.66. Moreover, we observed a lack of DVM in most zooplankton taxa on most occasions. Our findings indicate both community-level and taxon-specific zooplankton tolerances to hypoxia, although the exact mechanisms at play remain to be fully elucidated. Nevertheless, the common residency in hypoxic waters and the lack of DVM by diverse zooplankton taxa that we observed likely have implications for food web dynamics in Lacamas Lake and other water bodies.

scholarly journals THE REDOX POTENTIALS IN SMALL OLIGO AND MEROMICTIC LAKES

1970 ◽  
Vol 1 (1) ◽  
pp. 56-65 ◽  
Author(s):  
JOHANNES KJENSMO
Keyword(s):  
Vertical Distribution ◽  
Redox Potential ◽  
Deep Water ◽  
Lake Water ◽  
Seasonal Variations ◽  
Redox Potentials ◽  
Ecological Significance ◽  
Meromictic Lakes ◽  
The Subject ◽  
The Vertical Distribution

The redox potentials of lake water have been the subject of several investigations (Kusnetzow 1935, Pearsall & Mortimer 1939, Hutchinson, Deevey & Wollack 1939, Deevey 1941, Allgeier, Hafford & Juday 1941, Mortimer 1941-42). The ecological significance of the redox potentials is stressed in several of these works. The work of Mortimer (1941-42) also shows the importance of the seasonal variations in redox potentials for the liberation from the sediments of different important nutrients. At present very little is known about the redox potential of the deep water in meromictic lakes. Allgeier, Hafford & Juday (1941) recorded vertical distribution of redox potential in one meromictic lake, Lake Mary, Wisconsin. The redox potential of the monimolimnion of Lake Mary varied from Eh = 0.140 volts at 8 m to Eh = 0.075 volts at 20.5 m. Hutchinson (1957) assumes it probable that other, but by no means all, meromictic lakes will be found to show a similar phenomenon. In the present paper the vertical distribution of redox potential of the water of three meromictic and one oligomictic lake is described.

Sign in / Sign up

Export Citation Format

Share Document