Earth Science Frontiers ›› 2020, Vol. 27 ›› Issue (4): 322-331.DOI: 10.13745/j.esf.sf.2019.8.16

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Effects of Y3 seamount on nutrients influencing the ecological environment in the Western Pacific Ocean

MA Jun(), SONG Jinming*(), LI Xuegang, YUAN Huamao, LI Ning, DUAN Liqin, WANG Qidong   

  1. 1. CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
    2. Marine Ecology and Environmental Science Laboratory, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
    3. University of Chinese Academy of Sciences, Beijing 100049, China
    4. Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China
  • Received:2019-01-09 Revised:2019-04-08 Online:2020-07-25 Published:2020-07-25
  • Contact: SONG Jinming

Abstract:

Seamount is a typical landform in the ocean, yet its surrounding habitat is poorly understood. Here, we report our study on the coupling relationships between nutrients and ecological environment through a comprehensive investigation on the Y3 seamount area of the Tropical Western Pacific Ocean in the winter of 2014. The results showed that the Y3 seamount area is a typical tropical oligotrophic region. At 50-125 m depth, the combined effects of thermocline and high-salt area hinder the upward transport of high-concentration nutrients from the sea bottom, causing nutrient depletion in the upper part of the euphotic zone. Meanwhile, consumption of phytoplankton and heterotrophic bacteria also reduces nutrients in this region. However, the abrupt topography of seamount plays an important role in nutrient distribution. The Y3 seamount obstructs the current to form an upwelling, which promotes the upward transport of high-concentration nutrients from the sea bottom to break through the barriers of thermocline and high-salt area; as a result, the average nutrient concentrations are higher around the seamount than further away. The correlation analysis showed that in the euphotic zone, the signs of correlation between nutrient concentration and temperature, salinity, chlorophyll a concentration or heterotrophic bacteria abundance were (-), (+), (-) (except NO2-N) and (-), respectively. Its distinct nutrient distribution, coupled with the ecological environment, makes seamount an important factor for the unique ocean ecosystem.

Key words: seamount in the Western Pacific Ocean, nutrients, ecological environment, coupling relationships

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