11. Lipids in Marine and Freshwater Organisms
269
The impact of subzero seawater on the lipids of one bivalve (Yoldia hyperborea) and two polychaetes (Nephthys ciliata and Artacama proboscidea) has
been clarified by Parrish et aI. (l996a) by using TLC-FID. By contrast, the lipid
variations recorded for Nereis virens by Pellerin-Massicotte et aI. (1994) were
obtained by a colorimetric method developed for human serum lipids. Unfortunately, this reduces the value of the observations of seasonal variations in lipids of
this species in the cold climate of the St. Lawrence River estuary of Canada. The
actual lipid contents were ~ 1 mg . g - 1 fresh weight in May and ~2 mg . g - 1 in
September. Whether this represented any deposition of triacylglycerols as energy
storage for overwintering or for reproductive tissue could not be determined.
There are alternative methods of quantitatively analyzing lipid classes in detail
(e.g., by planar TLC; Ackman, 1991) or HPLC (high-performance liquid chromatography; Christie, 1992, 1987), although they may require 10 mg of sample as
compared with TLC-FID, which can operate with 20 f.1g of lipid. Total lipid
obtained by a colorimetric method seems an inadequate technology when so many
aspects of survival and reproduction are governed by energy reserves of neutral
lipid in both freshwater and marine milieus.
A similar problem affects the results of Bruner et aI. (1994) for lipids of zebra
mussels Dreissena polymorpha when they related lipid content to bioconcentration of polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons
(PAH). By contrast, a study of lipids in the Pacific lugworm Abarenicola pacifica,
conducted by TLC-FID, reported data for total lipids, phospholipids, sterols, free
fatty acids, triacylglycerols, and wax esters (Taghon et aI., 1994). Low levels of
lipid, reserves, primarily triacylglycerols with less wax esters, were especially
abundant (8% of ash-free dry weight) if eggs were being carried. Comparisons of
lipids of the marine benthic amphipods Pontoporeia Jemorata from diverse locations, and of Monoporeia affinis, were successfully carried out with this technique
(Hill et aI., 1992), and lipid classes explained several aspects of biochemistry for
this international family. Larger animals always had more lipid, but seasonal
effects were different in the lipid storage systems. The two marine species fed and
behaved differently, so that P. Jemorata lipids were always dominated by triacylglycerols, whereas in M. affinis this lipid class became dominant only in late
summer and fall. Females had more lipid than males. The lipids of the closely
related freshwater Diporeia hoyi have already been discussed (Cavaletto et aI.,
1996; Vanderploeg et aI., 1992).
The view that triacylglycerols are useful as a condition index of fish, bivalve,
and crustacean larvae (Fraser, 1989) is based on marine organisms but applies
equally to freshwater species. This author's proposition is that triacylglycerol
should be expressed as a ratio to sterol content because sterol itself can be related
to dry weight. An important part of this proposition extending to reproductive
success follows from the observation that the eggs of many aquatic organisms are
rich in triacylglycerols. As shown for the bonefish (Albula sp.), a great deal of
reorganization of such lipids takes place subsequent to emergence from the egg
(Padron et aI., 1996). In larvae, phosphatidylethanolamine was replaced by phos-
269
The impact of subzero seawater on the lipids of one bivalve (Yoldia hyperborea) and two polychaetes (Nephthys ciliata and Artacama proboscidea) has
been clarified by Parrish et aI. (l996a) by using TLC-FID. By contrast, the lipid
variations recorded for Nereis virens by Pellerin-Massicotte et aI. (1994) were
obtained by a colorimetric method developed for human serum lipids. Unfortunately, this reduces the value of the observations of seasonal variations in lipids of
this species in the cold climate of the St. Lawrence River estuary of Canada. The
actual lipid contents were ~ 1 mg . g - 1 fresh weight in May and ~2 mg . g - 1 in
September. Whether this represented any deposition of triacylglycerols as energy
storage for overwintering or for reproductive tissue could not be determined.
There are alternative methods of quantitatively analyzing lipid classes in detail
(e.g., by planar TLC; Ackman, 1991) or HPLC (high-performance liquid chromatography; Christie, 1992, 1987), although they may require 10 mg of sample as
compared with TLC-FID, which can operate with 20 f.1g of lipid. Total lipid
obtained by a colorimetric method seems an inadequate technology when so many
aspects of survival and reproduction are governed by energy reserves of neutral
lipid in both freshwater and marine milieus.
A similar problem affects the results of Bruner et aI. (1994) for lipids of zebra
mussels Dreissena polymorpha when they related lipid content to bioconcentration of polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons
(PAH). By contrast, a study of lipids in the Pacific lugworm Abarenicola pacifica,
conducted by TLC-FID, reported data for total lipids, phospholipids, sterols, free
fatty acids, triacylglycerols, and wax esters (Taghon et aI., 1994). Low levels of
lipid, reserves, primarily triacylglycerols with less wax esters, were especially
abundant (8% of ash-free dry weight) if eggs were being carried. Comparisons of
lipids of the marine benthic amphipods Pontoporeia Jemorata from diverse locations, and of Monoporeia affinis, were successfully carried out with this technique
(Hill et aI., 1992), and lipid classes explained several aspects of biochemistry for
this international family. Larger animals always had more lipid, but seasonal
effects were different in the lipid storage systems. The two marine species fed and
behaved differently, so that P. Jemorata lipids were always dominated by triacylglycerols, whereas in M. affinis this lipid class became dominant only in late
summer and fall. Females had more lipid than males. The lipids of the closely
related freshwater Diporeia hoyi have already been discussed (Cavaletto et aI.,
1996; Vanderploeg et aI., 1992).
The view that triacylglycerols are useful as a condition index of fish, bivalve,
and crustacean larvae (Fraser, 1989) is based on marine organisms but applies
equally to freshwater species. This author's proposition is that triacylglycerol
should be expressed as a ratio to sterol content because sterol itself can be related
to dry weight. An important part of this proposition extending to reproductive
success follows from the observation that the eggs of many aquatic organisms are
rich in triacylglycerols. As shown for the bonefish (Albula sp.), a great deal of
reorganization of such lipids takes place subsequent to emergence from the egg
(Padron et aI., 1996). In larvae, phosphatidylethanolamine was replaced by phos-