Use of fatty acids for the assessment of zooplankton grazing on bacteria, protozoans and microalgae

Abstract

1. The distribution of fatty acids in different groups of bacteria, ciliated protozoans and microalgae is reviewed emphasizing specific fatty acids like odd‐branched fatty acids and (n‐3) polyunsaturated fatty acids. 2. Odd‐branched fatty acids and (n‐6) fatty acids appear to be good indicators of zooplankton grazing on bacteria and ciliates when they are detected in microcrustacean triacylglycerols. We give several examples where these fatty acids may be used as markers. The value of (n‐3) fatty acids in describing zooplankton grazing on phytoplankton seems to be low.

Seasonal abundance and feeding patterns of copepods Temora longicornis, Centropages hamatus and Acartia spp. in the White Sea (66°N)

“…Thus, according to Graeve et al (1994a, b), Kattner et al (1994), Boyd and Newton (1995), Hagen et al (1995), Lavaniegos and Lopez-Cortes (1997), Napolitano et al (1997) and Cotonnec et al (2001), the studied species ingested diatoms and dinoflagellates, while the cryptophytes (18:3(n-6), 18:3(n-3), 20:1(n-9), 20:1(n-7)) were mostly avoided by Acartia. Our analyses also suggest that detritus particles, defined by odd-branched bacterial FAs (Desvilettes et al 1997;Colaço et al 2007), did form part of the diet of all investigated copepods, albeit to varying extents. We surmised that the copepods did not ingest free-living bacteria, but rather detritus, bacterivorous microzooplankton, or other particles associated with bacteria (Kiørboe et al 2002).…”

Seasonal variation in carbon sources of ­mesograzers and small predators in an eelgrass community: stable isotope and fatty acid analyses

“…Fatty acid analysis can be a reliable method to trace food sources in aquatic food webs, since laboratory experiments have proven that transfer of specific fatty acids is conservative (Lee et al 1971, Brett et al 2006. A number of 'indicator' fatty acids specific for algal groups, like diatoms or dinoflagellates, can be used as biomarkers (Viso & Marty 1993, Desvilettes et al 1997, and the quantitative pattern of all fatty acids, the fatty acid signature, can provide additional information (Dahl et al 2003).…”

Feeding spectra of Arctodiaptomus salinus (Calanoida, Copepoda) using fatty acid trophic markers in seston food in two salt lakes in South Siberia (Khakasia, Russia)

“…Statistically significant differences between the means after Student's t-test: * P \ 0.05; # P \ 0.01; ? P \ 0.001 document feeding on ciliates by the calanoid copepods, in both freshwater (e.g., Desvilettes et al 1997;Kagami et al 2002) and marine ecosystems (Ederington et al 1995). Notably, levels of bacterial FATM in the samples of L. Shira were quite high and varied greatly both spatially and temporally (Fig.…”

“…7,8), which can be considered as markers of organic matter originated from autotrophic flagellates (Desvilettes et al 1997). This group also contains high levels of 18:3x3 that can explain the relatively higher content of this acid (18:3) in the animals' bodies than in seston (Fig.…”

“…Meanwhile, the accumulation of storage lipids is sufficient in some zooplankton species, especially in copepods (Hagen and Auel 2001). It has been considered that bulk of fatty acyl chains in TAG originate from food and can reflect the composition of their food consumed during the preceding 3-4 weeks (Bourder and Amblard 1989;Desvilettes et al 1997).…”