Response of Growth-Related Traits of Submerged Macrophytes to Light Reduction: A Meta-Analysis

Abstract

Underwater light reduction is presumably becoming more frequent and intensified due to eutrophication and algal blooms, which may significantly affect submerged macrophytes’ growth. However, a comprehensive understanding of how light reduction influences growth-related traits and responses is currently lacking. Here, we compiled data from 333 records of 62 published works that used controlled experiments to explore the responses of functional traits associated with growth to light reduction. Our results indicated that light reduction significantly decreased the relative growth rate (RGR), ramet number (RM), shoot biomass (SB), root biomass (RB), soluble carbohydrates (SC), and leaf number (LN) by 38.2%, 60.0%, 59.2%, 55.4%, 30.0%, and 56.1%, respectively, but elevated the chlorophyll content (Chl) by 25.8%. Meanwhile, the responses of RGR to light reduction increased significantly with the responses of RM, SB, RB, and root-to-shoot ratio (R/S). Considering the relationships among the growth-related traits, we further found that the responses of RGR to light reduction were mainly driven by the RM rather than leaf photosynthetic capability, indicating the importance of tiller ability under low light stress. We also identified a tipping point of the response of RGR to light reduction, which might be incorporated into hydrophyte dynamic models to improve precision. Our results highlight the importance of growth-related traits, andthese traits may need to be incorporated into models to improve the prediction of distribution and area for submerged species or to provide guidance for the restoration and sustainable development of aquatic ecosystems.

A Bibliometric Analysis of Lake Restoration with Submerged Macrophytes

“…A previous study suggested that light conditions could explain as much as 77% of the variation in macrophyte presence frequency [56]. Based on a meta-analysis, Gao et al (2023) [57] showed that the effect of light reduction on the growth rate of submerged macrophytes existed at a threshold value (c. 20%). Namely, slight light reduction promoted, but more than 20% light reduction inhibited the growth of submerged macrophytes.…”

“…Light affects the growth and distribution of submerged macrophytes mainly via photosynthesis, metabolism, and the rhizosphere microbial community [57]. First, low light decreases the photosynthesis rate, and then carbon assimilation decreases.…”

“…Submerged macrophytes can adapt to low-light stress via tolerance and avoidance strategies [65]. The tolerance strategy is characterized by high investment in leaf area and photosynthetic efficiency to increase light utilization, and greater investment in vertical growth, characterized as the avoidance strategy to acquire more light in shallow water bodies [57,65]. However, a meta-analysis revealed that the response of the relative growth rate to light reduction is mainly driven by the tiller ability rather than the photosynthesis capability of submerged macrophytes [57].…”