Meeting Abstract
Trimethylamine oxide (TMAO) is a common osmolyte and counteracting solute. It is believed to combat the stress induced by hydrostatic pressure as some deep-sea animals contain higher TMAO levels than their shallow water counterparts. It has also been proposed that TMAO may accumulate passively during lipid storage, a hypothesis that has not been directly tested. Previous research showed that lipid content decreased with depth in a population of Hawaiian fishes presenting a novel test of these competing hypotheses. We found that TMAO is positively correlated with habitat depth (hydrostatic pressure). We further showed using phylogenetic independent contrasts that this relationship was not influenced by the evolutionary relatedness of these 27 species. Interestingly, we found that lipid content increased with depth, in direct contrast to previous studies. TMAO is thus also positively correlated with lipid content. While we are unable to distinguish between these hypotheses, we show that TMAO is strongly correlated with depth in midwater fishes.
