Morphological and Physiological Responses to Sediment Nutrients in the Submerged Macrophyte Myriophyllum spicatum

Abstract

To improve the understanding of morphological and physiological changes of submerged macrophytes in response to different nutrient availabilities, Myriophyllum spicatum (a widely used lake restoration species due to its eutrophic tolerance in China) was planted in low-nutrient (TN 0.47 mg g−1, TP 0.10 mg g−1) and high-nutrient (TN 2.20 mg g−1, TP 1.91 mg g−1) sediments. The high-nutrient treatment reflected the eutrophication conditions in most lakes in the Middle and Lower Yangzi River Basin. Our results showed that the high nutrient level significantly increased the total biomass and affected shoot morphology traits; whereas the low sediment nutrient level significantly increased the root length of M. spicatum. The sediment nutrient enrichment significantly decreased the plant carbohydrate concentrations. Soluble sugar was positively correlated with the plant growth; however, carbohydrate concentrations in the auto-fragments only differed throughout its production period. It is noteworthy that most traits of M. spicatum respond rapidly between the treatments. These data demonstrate that M. spicatum can achieve a trade-off between its growth and storage by adjusting the pattern of biomass allocation in response to different sediment nutrients. Our study also implies that such flexible strategies would help M. spicatum adapt to the eutrophic environments.