AB 15:275-281 (2012)  -  doi:10.3354/ab00432

Exceptional lipid storage mode of the copepod Boeckella poopoensis in a pampean salt lake, Argentina

Germán A. Kopprio1,4,*, Gerhard Kattner2, Martin Graeve2, R. Hugo Freije3, Rubén J. Lara1,4

1Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto Argentino de Oceanografía, Bahía Blanca B8000FWB, Argentina
2Ecological Chemistry, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven 27570, Germany
3Environmental Chemistry, Universidad Nacional del Sur, Bahía Blanca B8000CPB, Argentina
4Wetland Dynamics, Leibniz Center for Tropical Marine Ecology, Bremen 28359, Germany

ABSTRACT: The lipid biochemistry of zooplankton was investigated in Lake Chasicó, a pampean salt lake in Argentina. The lipid biomass of the zooplankton community was dominated by the calanoid copepod Boeckella poopoensis. The major storage lipids during winter were wax esters and triacylglycerols, which reached up to 59 and 37% of the total lipids, respectively. A striking feature of the zooplankton fatty acid composition was the extraordinarily high level of 18:4(n‑3) and 20:4(n-3) fatty acids, the highest ever reported for the latter in zooplankton. During winter, 20:4(n-3) accounted on average for 20% of the total fatty acids in the wax ester fraction and 7% in the triacylglycerols. The close relationship (r = 0.83, p < 0.001) between the 2 fatty acids implies the biosynthesis of 20:4(n-3) in B. poopoensis by chain elongation of 18:4(n-3), a dietary precursor and flagellate marker. The accumulation of 20:4(n-3) may be also partially related to B. poopoensis grazing on heterotrophic protozoa or non-flagellated chlorophytes, although this fatty acid was almost absent in the seston fraction. In summer, wax esters were slightly lower (45%), compensated by higher phospholipid levels. The 16:0 fatty alcohol moiety was predominant in the wax esters of all samples, corroborating the opportunistic feeding behavior of B. poopoensis. The high amounts of wax esters in zooplankton are typical of marine species, suggesting that the wax ester biosynthesis of B. poopoensis and the extraordinary fatty acid composition are adaptations to the unstable environmental conditions of salt lakes.

KEY WORDS: Polyunsaturated fatty acids · Biosynthesis · Trophic markers · Wax esters · 20:4(n-3)

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Cite this article as: Kopprio GA, Kattner G, Graeve M, Freije RH, Lara RJ (2012) Exceptional lipid storage mode of the copepod Boeckella poopoensis in a pampean salt lake, Argentina. Aquat Biol 15:275-281

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