Fatty acid trophic markers in the pelagic marine environment. Adv Mar Biol

University of Copenhagen, Danish Institute for Fisheries Research, Charlottenlund Castle, DK-2920 Charlottenlund, Denmark.
Advances in Marine Biology (Impact Factor: 3.48). 02/2003; 46:225-340. DOI: 10.1016/S0065-2881(03)46005-7
Source: PubMed


Fatty acids have been used as qualitative markers to trace or confirm predator-prey relationships in the marine environment for more than thirty years. More recently, they have also been used to identify key processes impacting the dynamics of some of the world's major ecosystems. The fatty acid trophic marker (FATM) concept is based on the observation that marine primary producers lay down certain fatty acid patterns that may be transferred conservatively to, and hence can be recognized in, primary consumers. To identify these fatty acid patterns the literature was surveyed and a partial least squares (PLS) regression analysis of the data was performed, validating the specificity of particular microalgal FATM. Microalgal group specific FATM have been traced in various primary consumers, particularly in herbivorous calanoid copepods, which accumulate large lipid reserves, and which dominate the zooplankton biomass in high latitude ecosystems. At higher trophic levels these markers of herbivory are obscured as the degree of carnivory increases, and as the fatty acids originate from a variety of dietary sources. Such differences are highlighted in a PLS regression analysis of fatty acid and fatty alcohol compositional data (the components of wax esters accumulated by many marine organisms) of key Arctic and Antarctic herbivorous, omnivorous and carnivorous copepod species. The analysis emphasizes how calanoid copepods separate from other copepods not only by their content of microalgal group specific FATM, but also by their large content of long-chain monounsaturated fatty acids and alcohols. These monounsaturates have been used to trace and resolve food web relationships in, for example, hyperiid amphipods, euphausiids and fish, which may consume large numbers of calanoid copepods. Results like these are extremely valuable for enabling the discrimination of specific prey species utilized by higher trophic level omnivores and carnivores without the employment of invasive techniques, and thereby for identifying the sources of energetic reserves. A conceptual model of the spatial and temporal dominance of group-specific primary producers, and hence the basic fatty acid patterns available to higher trophic levels is presented. The model is based on stratification, which acts on phytoplankton group dominance through the availability of light and nutrients. It predicts the seasonal and ecosystem specific contribution of diatom and flagellate/microbial loop FATM to food webs as a function of water column stability. Future prospects for the application of FATM in resolving dynamic ecosystem processes are assessed.

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    • "Fatty acids were quantified by integrating the peak areas using the CHROMQUEST 4.1 software and converting them into concentrations from the area vs. concentration of the internal standards. For fatty acid grouping into classes (total Saturated Fatty Acids, SAFA; Mono Unsaturated Fatty Acids, MUFA and Poly Unsaturated Fatty Acids, PUFA), only those with concentrations higher than 1% of the total fatty acids were considered (Dalsgaard et al., 2003). This methodology has already been applied in gorgonians (Gori et al., 2012b). "
    • "Both direct observation and gut content analysis only provide a snapshot examination of recent feeding activity. In order to have an extended view of trophic ecology, researchers have also been using biochemical methods, such as fatty acids and stable isotopes analysis, which provide time-integrated information on food ingestion and uptake (Dalsgaard et al., 2003; Fry, 2008). More recently, with the advent of molecular genetics, molecular detection of trophic interactions has also been an increasingly popular approach that has been able to provide new insights on marine food webs (King et al., 2008; Pompanon et al., 2012). "
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    • "Antarctic Micractinium strains well-documented (Dalsgaard et al. 2003; Osipova et al. 2009; Fogliano et al. 2010; Blanc et al. 2012; Boelen et al. 2013). Since these Antarctic Micractinium strains also showed a higher concentration of polyunsaturated fatty acids (PUFAs) and tolerance to lower temperatures, the microalgae could be a potential biological resource to produce compounds of biochemical interest such as omega-3 and omega-6 fatty acids. "
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