Abstract. Biochemical markers developed initially for food-web
studies of terrestrial and shallow-water environments have only recently
been applied to deep-sea ecosystems (i.e., in the early 2000s). For the first
time since their implementation, this review took a close look at the
existing literature in the field of deep-sea trophic ecology to synthesize
current knowledge. Furthermore, it provided an opportunity for a preliminary
analysis of global geographic (i.e., latitudinal, along a depth gradient)
trends in the isotopic (δ15N, δ13C) and fatty acid
composition of deep-sea macro- and megafauna from heterotrophic systems.
Results revealed significant relationships along the latitudinal and
bathymetric gradients. Deep-sea animals sampled at temperate and polar
latitudes displayed lower isotopic ratios and greater proportions of
essential ω3 long-chain polyunsaturated fatty acids (LC-PUFAs) than
did tropical counterparts. Furthermore, δ15N and δ13C ratios as well as proportions of arachidonic acid increased with
increasing depth. Since similar latitudinal trends in the isotopic and fatty
acid composition were found in surface water phytoplankton and particulate
organic matter, these results highlight the link across latitudes between
surface primary production and deep-water communities. Because global
climate change may affect quantity and quality (e.g., levels of essential
ω3 PUFAs) of surface primary productivity, and by extension those of
its downward flux, the dietary intake of deep-sea organisms may likely be
altered. In addition, because essential ω3 PUFAs play a major role in
the response to temperature variations, climate change may interfere with
the ability of deep-sea species to cope with potential temperature shifts.
Importantly, methodological disparities were highlighted that prevented
in-depth analyses, indicating that further studies should be conducted using
standardized methods in order to generate more reliable global predictions.
Effects of Growth Pressure and Temperature on Fatty Acid Composition of a Barotolerant Deep-Sea Bacterium