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Lipids and buoyancy in Southern ocean pteropods
C F Phleger1, P D Nichols, P Virtue
1Department of Biology, San Diego State University, California 92182, USA. phleger@sunstroke.sdsu.edu
Lipids
|November 14, 1997
Summary
Southern Ocean pteropods like Clione limacina contain diacylglyceryl ether (DAGE) lipids, unlike Limacina helicina. This lipid likely provides buoyancy for Clione, compensating for its lack of flotation bubbles.
Area of Science:
- Marine Biology
- Biochemistry
- Lipid Chemistry
Background:
- Pteropods are ecologically significant zooplankton in the Southern Ocean.
- Lipid composition varies significantly among marine organisms, influencing physiological functions.
- Diacylglyceryl ethers (DAGE) are unique lipids found in some marine animals, with poorly understood functions.
Purpose of the Study:
- To characterize the lipid composition of Southern Ocean pteropods, specifically Clione limacina and Limacina helicina.
- To investigate the presence and type of diacylglyceryl ethers (DAGE) in these species.
- To explore the potential function of DAGE in Clione limacina, particularly regarding buoyancy.
Main Methods:
- Lipid extraction and analysis from pteropod tissues.
- Gas chromatography-mass spectrometry (GC-MS) for fatty acid and alkyl glyceryl ether (GE) profiling.
- Comparison of lipid profiles between Clione limacina, Limacina helicina, and Spongiobranchaea australis.
Main Results:
- Clione limacina contains 28% DAGE, while Limacina helicina lacks DAGE.
- The alkyl glyceryl ethers (GE) in Clione DAGE are primarily 16:0 and 15:0.
- Fatty acid and sterol profiles are similar between Clione and Limacina, suggesting a predator-prey relationship.
- Spongiobranchaea australis contains lower levels of DAGE (0.9-1.7%) and overall lipid content compared to Clione.
Conclusions:
- DAGE is a significant lipid component in the Southern Ocean gymnosome pteropod Clione limacina.
- The unique presence of DAGE in Clione, which lacks flotation bubbles, suggests a role in buoyancy.
- DAGE offers greater uplift than triacylglycerol, supporting its proposed function in Clione's pelagic lifestyle.
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