Possible links between holothurian lipid compositions and differences in organic matter (OM) supply at the western Pacific abyssal plains. (October 2019)

• Record Type: Journal Article
• Authors: Amaro, Teresa; Danovaro, Roberto; Matsui, Yohei; Rastelli, Eugenio; Wolff, George A.; Nomaki, Hidetaka
• Is Part Of: Deep sea research. Volume 152(2019)
• Publication Date: 2019-10
• Subjects: Oceanography -- Periodicals; Océanographie -- Périodiques; 551.4605
• DOI: 10.1016/j.dsr.2019.103085
• Languages: English
• ISSNs: 0967-0637

Abstract

Abstract: Deep-sea benthic communities depend on the export of organic matter (OM) from the surface ocean. However, the effects of the pelagic-benthic coupling and the specific link between changing seasonal OM inputs and physiological changes of the mega-benthic community remain unclear. In this study, we identified differences in OM quality and quantity at two abyssal seafloor sites in the western Pacific Ocean and noted possible links between overlying primary production and the lipid composition of several deep-sea holothurian species. Phytopigment concentrations of the surface sediment were up to 16-times greater at the high productivity area (39°N) than at the oligotrophic area (1°N). Total carbohydrate and protein concentrations were also significantly higher at 39°N than 1°N, although to a lesser extent than for phytopigments. Holothurian abundances were almost 40 times higher at 39°N than 1° N. Significant differences were detected in the fatty acid (FA) compositions of the holothurian tissues in terms of proportions of the main food source indices (phytoplankton, zooplankton and bacterial FA), suggesting different food sources in the two areas. Phytodetritus and bacteria were the most dominant dietary sources at 39°N and 1°N, respectively. Stable carbon and nitrogen isotopic compositions did not contradict the FA data indicating that holothurians fed on both phytodetritus and bacteria from the sediments. Overall, our results show that high densities of abyssal holothurians at 39°N is linked with the high quality of the sedimentary OM associated with the net primary production at the surface. Further, the differences in phytodetritus inputs may lead to a different lipid composition as a consequence of different feeding habits, although there may be some other mechanisms behind. This study provides fundamental knowledge on lipid compositions of abyssal holothurians in relation to oceanic settings, thus improves our understanding of the ecosystem functioning in abyssal plains. Highlights: Organic matter qualities at the two abyssal sites differed with the surface productivity. Holothurian lipid composition coincided with OM quality. Holothurians may feed on phytodetritus at high productivity areas. Holothurian may feed on bacteria at low productivity areas. Different OM quality may lead to important nutritional responses of deep-sea holothurians.