Relationship of morphometrics, total carotenoids, and total lipids with activity and sexual and spatial features in Euphausia superba

Abstract

Morphological differences associated with sex or stage, together with total lipids and carotenoids, were studied in Euphausia superba as possible indicators of physiological condition. E. superba displays sexual dimorphism during growth. A group of mature males, called Males II herein, has a greater abdominal length, suggesting that they are faster swimmers, a feature implying higher metabolic rates and a higher demand for protecting pigments like carotenoids. Mature Males II have proportionally lower lipids but higher total lipid-soluble carotenoids, a counterintuitive finding. Males II also have bigger eyes. Significant regressions with carotenoids were found for wet weight, abdominal length, and eye diameter. On a spatial analysis, population composition reflects reproductive activity. Males II would be in search of females for fecundation and, thus, are dominant in some areas. The PCA analysis of 10 allometric and biochemical variables show a distinct Males II group differing in morphology, carotenoids, and lipid contents. The carotenoid:lipid ratio was highest for Males II, supporting the hypothesis of the role of carotenoids in the activity of the species. Mature males may experience physiological stress during reproduction and probably die shortly afterwards. A relationship between activity, morphometrics, and carotenoid content seems evident, deserving further investigation.

Summer sea-ice variability on the Antarctic margin during the last glacial period reconstructed from snow petrel (<i>Pagodroma nivea</i>) stomach-oil deposits

“…For example, krill tend to have high abundances of C 14 : 0 , C 16 : 0 , and C 18 : 1 fatty acids and a variety of carotenoid pigments (e.g. Cripps et al, 1999;Färber Lorda and Ceccaldi, 2020), as well as Cu, Zn, and Fe (Rainbow, 1989;Palmer Locarnini and Presley, 1995;Liu et al, 2013), whereas squid and fish are dominated by C 16 : 0 and C 18 : 0 fatty acids, respectively (Lewis, 1966). The presence of Cu in crustaceans (including krill) is linked to hemocyanins in invertebrates (Bridges et al, 1983), which provide an alternative oxygen carrier to the hemoglobins of vertebrate blood.…”

Improving the Accuracy of Krill Target Strength Using a Shape Catalog

“…Previous work has explored the shape variation of krill both in terms of biology and spatial differences (Finley, 2006;Färber-Lorda et al, 2009;Lorda and Ceccaldi, 2020). Geometric morphometrics is a technique widely used to analyse and compare the geometric shape, i.e., the geometric features and properties remaining when size, position and FIGURE 1 | Illustrations of the orientation of krill.…”

Summer sea-ice variability on the Antarctic margin during the last glacial period reconstructed from snow petrel (Pagodroma nivea) stomach-oil deposits

“…For example, krill tend to have high abundances of C14:0, C16:0 and C18:1 fatty acids and a variety of carotenoid pigments (e.g. Cripps et al, 1999;Färber Lorda and Ceccaldi, 2020), as well as Cu, Zn and Fe (Rainbow, 1989;Palmer Locarnini and Presley, 1995;Liu et al, 2013), whereas squid and fish are dominated by C16:0 and C18:0 fatty acids, respectively (Lewis, 1966). The presence of Cu in crustaceans (including krill) is linked to hemocyanins (Bridges et al, 1983), which provide an alternative oxygen carrier to the hemoglobins in vertebrate blood.…”