Research Progress in Area 1 方向 ( 一 ) 課題進展 71 Abstract Current ocean models provide a limited understanding of the link between biodiversity and productivity by only accommodating a few phytoplankton species. This contrasts with the fact there are often hundreds of species in a single drop of seawater. Prof. Chen’s teamproposes to integrate two key factors (acclimation and biodiversity) into the plankton model to fully understand the factors controlling phytoplankton diversity and primary production in the Northern South China Sea. This work will have significant applications across several academic fields and contribute towards evaluations of global warming effects in the ocean. Research Activities and Progress • Modelled how phytoplankton thermal diversity affects the temperature sensitivity of community productivity and validated the theoretical findings with experimental data; • Analyzed a global dataset of phytoplankton occurrences and examined the global latitudinal gradientofphytoplanktondiversitybyconsidering species similarity at different scales; • Developed an individual-based neutral model incorporating ecological drift, speciation, and dispersal to understand what are the key processes underlying the observed latitudinal gradient of phytoplankton diversity; • Investigated how phytoplankton acclimation contributes to the paradoxical surface summer peak of primary production in the subtropical, oligotrophic ocean gyre. Key Findings • Responses of the community productivity to temperature tend to be dampened at high diversity than at low diversity, which relates to the fact that the interspecific activation energy is lower than the intraspecific one. In addition, thermal diversity also increases community mean optimal temperature; • Phytoplankton diversity peaks in the tropics if we only consider abundances or species similarity. However, when we consider both relative abundance and species similarity, the peak of diversity moves to higher latitudes, suggesting that the dominant species are less similar at higher latitudes compared to the tropics; • The individual-basedmodel suggests that simply speeding up the birth and speciation rates in the tropics due to high temperature cannot lead to the high species richness in the tropics because death and extinction rates also increase; • The surface peak of primary production in the oligotrophic ocean gyre is mostly caused by the higher concentrations of phytoplankton carbon instead of growth rate. Research Output Publication 0 Trained personnel 4 Modelling Phytoplankton Diversity and Productivity across the South China Sea Continental Slope Prof. Bingzhang Chen University of Strathclyde Fig 1. Numerical simulations showing that high thermal diversity leads to lower but more stable temperature sensitivity (Ew) of the community than low diversity. Also, the more diverse community tends to have a greater mean optimal temperature (Topt ).
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