Seamounts are isolated terrain elevations with a depth of more than 1,000 meters above the seafloor. They can affect the circulation of seawater, inducing nutrients upwelling mobility and stimulating primary production, thereby producing organic matters.
The Tropical Western Pacific Ocean (TWPO) belongs to oligotrophic regions, while seamounts increased surrounding chlorophyll content and primary productivity levels. However, the distribution and degradation pattern of organic matter in seamounts morphology remain largely unknown.
Recently, Dr. LAI Xiaoshuang of Prof. SONG Jinming's team from the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) has unveiled the differences in organic matter degradation of M5 Pair-summit Seamount morphology in the Tropical Western Pacific Ocean.
The study was published in Ecological Indicators on Feb. 5.
To obtain the distribution of seamounts organic matter and the composition of related microorganisms, the researchers employed high-throughput sequencing technology to analyze the particulate matters. The dynamic distribution of nutrients, particulates and microbial communities of the summits, flanks and base in the M5 Pair-summit Seamount were investigated.
The researchers found that the distribution of organic matter in seamounts presented a gradual decrease from summit to base. At Summit1 (depth of 106 m), the total organic carbon reached the highest value, and organic matter was produced through phytoplankton photosynthesis.
At Summit2 (depth of 810 m) and flanks, the degradation of organic matter occurred, with a higher proportion of nitrifying bacteria Taumarchaeota, which corresponded to the process of nitrification.
The distinction between summits of organic matter distribution lies in the "seamount effect" generated by shallow seamounts. At the base of the seamount, the degradation reached the highest, and Firmicutes accounted for 38.86%.
"It indicated that the degradation of organic matter in seamount base was caused by denitrification. The organic matter was utilized as a carbon source by denitrifying bacteria," said Prof. SONG.
Seamount morphology and the surrounding hydrological environment result in differences in the distribution and degradation of organic matter, as well as the microbial community composition of seamounts.
This study was supported by the Major Program of the Pilot National Laboratory for Marine Science and Technology (Qingdao), National Natural Science Foundation of China, the Strategic Priority Research Program of the Chinese Academy of Sciences, and Natural Science Foundation of Shandong Province.
