scholarly journals Winter abundance and distribution of Euphausia superba, E. crystallorophias, and Thysanoessa macrura in Gerlache Strait and Crystal Sound, Antarctica

1994 ◽  
Vol 109 ◽  
pp. 131-142 ◽  
Author(s):  
W Nordhausen
Keyword(s):  
Euphausia Superba ◽  
Thysanoessa Macrura ◽  
Abundance And Distribution

Distribution and abundance of euphausiid larvae in the Prydz Bay region, Antarctica

1991 ◽  
Vol 3 (2) ◽  
pp. 167-180 ◽  
Author(s):  
G.W. Hosie
Keyword(s):  
Antarctic Circumpolar Current ◽  
Developmental Stages ◽  
Euphausia Superba ◽  
Prydz Bay ◽  
Spawning Period ◽  
North East ◽  
East Wind ◽  
Thysanoessa Macrura ◽  
Circumpolar Current ◽  
The Antarctic

In January 1985 a net sampling survey was carried out on the distribution and abundance of euphausiid larvae in the Prydz Bay region. Euphausia superba occurred in low abundance, probably due to sampling preceding the main spawning period. Thysanoessa macrura occurred throughout the study area in consistently high abundance. Euphausia crystallorophias was marginally more abundant within its restricted range. Distinct north-south variations in larval age and developmental stages of T. macrura were observed indicating regional differences in spawning. Euphausia frigida was mainly confined to the upper 200 m of the Antarctic Circumpolar Current. E. superba larvae produced north of the shelf break, between 70°–83°E, moved north-east into the Antarctic Circumpolar Current. Larvae originating on the shelf moved rapidly west in the East Wind drift. E. crystallorophias had the same westward dispersion, but some larvae appeared to return eastward via the Prydz Bay Gyre and remain in the region. The data indicate that most E. superba larvae, providing they survive injuries cold temperature an food deprivation, will leave the area, suggests that Prydz Bay krill may not be a self maintaining stock.

scholarly journals Allometric relationships of ecologically important Antarctic and Arctic zooplankton and fish species

Polar Biology ◽  
2022 ◽  
Author(s):  
Fokje L. Schaafsma ◽  
Carmen L. David ◽  
Doreen Kohlbach ◽  
Julia Ehrlich ◽  
Giulia Castellani ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Current Knowledge ◽  
Euphausia Superba ◽  
Dry Mass ◽  
The Arctic ◽  
Allometric Relationships ◽  
Age Classes ◽  
Maturity Stages ◽  
Thysanoessa Macrura ◽  
Specific Variation

AbstractAllometric relationships between body properties of animals are useful for a wide variety of purposes, such as estimation of biomass, growth, population structure, bioenergetic modelling and carbon flux studies. This study summarizes allometric relationships of zooplankton and nekton species that play major roles in polar marine food webs. Measurements were performed on 639 individuals of 15 species sampled during three expeditions in the Southern Ocean (winter and summer) and 2374 individuals of 14 species sampled during three expeditions in the Arctic Ocean (spring and summer). The information provided by this study fills current knowledge gaps on relationships between length and wet/dry mass of understudied animals, such as various gelatinous zooplankton, and of animals from understudied seasons and maturity stages, for example, for the krill Thysanoessa macrura and larval Euphausia superba caught in winter. Comparisons show that there is intra-specific variation in length–mass relationships of several species depending on season, e.g. for the amphipod Themisto libellula. To investigate the potential use of generalized regression models, comparisons between sexes, maturity stages or age classes were performed and are discussed, such as for the several krill species and T. libellula. Regression model comparisons on age classes of the fish E. antarctica were inconclusive about their general use. Other allometric measurements performed on carapaces, eyes, heads, telsons, tails and otoliths provided models that proved to be useful for estimating length or mass in, e.g. diet studies. In some cases, the suitability of these models may depend on species or developmental stages.

Abundance and distribution of Antarctic krill (Euphausia superba) nearshore of Cape Shirreff, Livingston Island, Antarctica, during six austral summers between 2000 and 2007

2010 ◽  
Vol 67 (7) ◽  
pp. 1159-1170 ◽  
Author(s):  
Joseph D. Warren ◽  
David A. Demer
Keyword(s):  
Antarctic Krill ◽  
Austral Summer ◽  
Euphausia Superba ◽  
Acoustic Backscatter ◽  
Small Scale ◽  
Biomass Density ◽  
Single Beam ◽  
Livingston Island ◽  
Abundance And Distribution ◽  
Antarctic Krill Euphausia Superba

Abundance and distribution of Antarctic krill ( Euphausia superba ) in the nearshore waters north of Livingston Island, Antarctica, were characterized from six small-boat surveys conducted in late January or early February from 2000 to 2007. The first three surveys (2000, 2002, 2004) were conducted using a 120 kHz split-beam echosounder to measure water column acoustic backscatter. The last three surveys (2005–2007) were conducted using 38 kHz and 200 kHz single-beam echosounders. A portion of the acoustic backscatter was attributed to Antarctic krill based on the results of net tows, underwater video observations, and a multiple-frequency acoustic classification algorithm. The annual mean krill biomass density in the survey area ranged from 11 to 84 g·m–2. Results are compared with the western Scotia Sea area of the US Antarctic Marine Living Resources (AMLR) program’s acoustic surveys of krill biomass density for the same years. Nearshore krill biomass densities were significantly larger (t test, p < 0.05), more stable, and the coefficients of variation were smaller than the much larger AMLR surveys. Increased competition between seals, penguins, and humans for the nearshore krill resource, especially during the austral summer months, could impact the recruitment success of these land-based krill predators. Implications of nearshore krill biomass on small-scale management units are discussed.

scholarly journals Epipelagic euphausiids assemblage in the Gerlache Strait (Antarctic Peninsula) during January 2015

2021 ◽  
Vol 50 (SuplEsp) ◽  
pp. 129-148
Author(s):  
Marisol Rivera ◽  
Alan Giraldo ◽  
Diego Mojica
Keyword(s):  
Spatial Distribution ◽  
Central Area ◽  
Austral Summer ◽  
Euphausia Superba ◽  
Abundant Species ◽  
Maximum Density ◽  
Species Assemblages ◽  
Thysanoessa Macrura ◽  
Euphausia Crystallorophias ◽  
Northern Sector

The spatial distribution of the epipelagic Euphausiids was investigated during the first Colombian Scientific Expedition to Antarctica “Expedición Caldas” in the Gerlache Strait during the austral summer of 2015. Surface zooplankton was collected at 20 oceanographic stations with a simple conical net of 0.6 m in diameter mouth and 200 µm of mesh net. Four euphausiid species were collected in 70 % of the sampling stations: Euphausia crystallorophias Holt and Tattersall 1906, Euphausia superba Dana 1850, Thysanoessa sp. and Thysanoessa macrura Sars 1883. Euphausia crystallorophias was the most abundant species with maximum density of 818 ind 1000 m-3 associated with the entrance of the Wilhelmina Bay, in the central area of the Gerlache Strait. The northern and southern sectors of the strait had significant differences in surface temperature and salinity associated with significant differences in the composition of the euphausiid species assemblages between both sectors. Although E. crystallorophias was the numerically dominant euphausiid species in the Gerlache Strait, E. superba was mostly distributed in the northern sector while Thysanoessa sp. was only distributed in the southern sector.

Summer bird abundance and distribution on set-aside fields on intensive arable farms in England

Ecography ◽  
2000 ◽  
Vol 23 (1) ◽  
pp. 50-59 ◽  
Author(s):  
Ian G. Henderson ◽  
Juliet A. Vickery ◽  
Robert J. Fuller
Keyword(s):  
Bird Abundance ◽  
Abundance And Distribution
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