Western Pacific Zooplankton Community along Latitudinal and Equatorial Transects in Autumn 2017 (Northern Hemisphere)

Yi Long,Shihao Wang,Hao Yu,Md Abu Noman,Min Wang,Dawei Chen,Hongtao Chen,Jun Sun

doi:10.3390/d13020058

Abstract

During the autumn of 2017, a study was conducted to assess the zooplankton community composition in three sections (two latitudinal, going from Japan to the equator, and one longitudinal on the equator) of the Western Pacific Ocean. A total of 384 species of zooplankton adults and 21 groups of zooplankton larvae were identified, with copepods being the predominant taxon. The common dominant species across the three sections were Acrocalanus gibber, Canthocalanus pauper, Oithona similis, Paracalanus aculeatus, and Oncaea venusta. Zooplankton abundance was the highest in the equator section, with a mean abundance of 258.94 ± 52.57 ind./m3. Comparatively, a low abundance was recovered from the Subtropical Countercurrent (STCC) region, while the highest abundance holding stations were located in the eastern equatorial and North Equatorial Countercurrent (NECC) regions. Pearson’s correlation, canonical correspondence analysis, and other methods were used to analyze the relationship between environmental factors and zooplankton. We found that the Shannon–Wiener diversity index and Pielou’s uniformity index were significantly correlated (p < 0.05) with concentrations of nitrite and chlorophyll a. The distribution of zooplankton was also limited by nutrients, chlorophyll a, and dissolved oxygen. In addition, we reveal differences in the abundance of species in the equatorial and latitudinal seas. We found that not only temperature and nutrient salinity, but also ocean currents and the movement of water masses, influence the distribution of zooplankton communities in the Western Pacific.

Highlights

IntroductionThe presence of many atolls, island groups, and seamounts in the Western Pacific
Introduction iationsThe presence of many atolls, island groups, and seamounts in the Western PacificOcean [1,2] has altered the trajectory of ocean circulation, resulting in a variety of complex vertical hydrographic features and current patterns [3], including in the major oceanic circulations such as the Kuroshio Current System and the Equatorial Current System
The abundance foundConin this reresearch is within waters the range values the tropical andzooplankton subtropical oceans search is within the range of values in the tropical and subtropical oceans sistent with previous observations in tropical and subtropical regions, copepods, especially Consistent with previous in tropical subtropical regions, copepods, small copepods, make up theobservations largest proportion of theand zooplankton community

Summary

Introduction

The presence of many atolls, island groups, and seamounts in the Western Pacific. Ocean [1,2] has altered the trajectory of ocean circulation, resulting in a variety of complex vertical hydrographic features and current patterns [3], including in the major oceanic circulations such as the Kuroshio Current System and the Equatorial Current System. The equatorial Western Pacific Ocean possesses the largest warm water mass in the global ocean, the Western Pacific Warm Pool (WPWP). The WPWP, with an annual mean surface seawater temperature of not less than 28 ◦ C, has a profound impact on global climate change, especially in China and Southeast Asia, by heating seawater, transferring radiant heat to the atmosphere, and using latent heat to transport evaporative heat [4]. The Western Pacific is of great interest due to its unique geography, ocean circulation, and special climatic characteristics [5].

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