Summer monsoon promotes the energy transfer efficiency of the zooplankton community in northern South China sea

Abstract

The summer monsoon shows a fundamental influence on the pelagic ecosystem of the South China Sea. Zooplankton are a major link for energy transfer between primary producers and upper trophic levels. Therefore, evaluating the energy transfer efficiency (ETE) of zooplankton is crucial to understand the function of pelagic ecosystem under the influence of monsoon. In this study, field surveys were conducted during May (intermonsoon) and August 2021 (summer monsoon) focusing on the variation of zooplankton size and trophic structures across the shelf and slope. The result showed that the summer monsoon reinforced the gradient of abundance, biovolume, and biomass from slope to shelf, and greatly intensified the role of environmental factors in driving spatial variation in most taxa. Both the results of size and trophic structures indicated that the ETE of zooplankton decreased from slope to shelf. The size structure also indicated that the ETE of zooplankton significantly increased under the influence of summer monsoon. These results were consistent with previous studies by different methods, suggesting that these approaches of size and trophic structures had important potential value in assessing changes in the function of marine pelagic ecosystem, especially when compared with sufficient historical data or reanalyzing historical samples.