Deciphering the key stressors shaping the relative success of core mixoplankton across spatiotemporal scales

TL;DR

The study identifies key environmental factors influencing mixoplankton success across seasons and locations.

Contribution

The novel integration of core taxa identification and simulation modeling reveals stressor effects on mixoplankton.

Findings

Core mixoplankton thrive in high nitrate, low temperature, and low oxygen conditions.

Seasonal and spatial patterns show mixoplankton dominance in spring and winter.

Combined stressor analysis reveals niche shifts not evident in single-factor studies.

Abstract

Deciphering the spatiotemporal dynamics and relative competitive advantages of trophic functional traits under multiple stressors has been a long-standing challenge. Here, we integrated the core taxa identification with robust simulation modeling to reveal key environmental factors influencing the three core trophic groups (autotroph, heterotroph, and mixotroph), with a particular focus on mixoplankton. Temporally, core mixoplankton exhibited a higher relative proportion in spring and winter in contrast to core heterotrophs and a more uniform spatial distribution pattern. While seasonal patterns were observed in the environmental responses of the trophic groups, temperature, dissolved oxygen (DO), and nitrate (NO3-N) were identified as the key drivers affecting the core mixoplankton by random forest. Furthermore, through univariate regression and generalized additive mixed model (GAMM), we captured the niche preferences of core mixoplankton across three stressors gradients and characterized the coupled additive or antagonistic effects. Notably, the potential optimal threshold for core mixoplankton was a high level of NO3-N (0.64 mg/L), lower temperature (18.6°C), and DO (3.5 mg/L), which contrasted with the results obtained from single-factor regression analyses. Specifically, GAMM indicated that the preferred niche shifted upward for NO3-N and downward for DO when three drivers were included simultaneously, while temperature remained constant. Our study linked the ecological niche preference of core mixoplankton with key stressors, facilitating a more precise monitoring and comprehension of spatiotemporal dynamics of trophic functional groups under scenarios of escalating global climate change and anthropogenic disturbances.

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