Effects of warming on Potamogeton crispus growth and tissue stoichiometry in the growing season

Song

2016

Environ Sci Pollut Res

In July 2005, the first outbreak of cyanobacterial blooms, dominated by Microcystis, occurred in Xuanwu Lake, Nanjing, upon which clay flocculation was adopted to control algal blooms. The cyanobacterial blooms were restrained, after which Potamogeton crispus appeared in November 2005 and spread rapidly in the whole lake. Since then, large populations of P. crispus have occurred in Xuanwu Lake annually in winter for the last 10 years. To determine the reasons for the occurrence of P. crispus populations in Xuanwu Lake during 2005-2006, water quality indices were monitored regularly. The data collected included dissolved oxygen, transparency, pH, total nitrogen, and total phosphorus content. Data analysis indicated that the transparency was improved by 179.5 % after clay flocculation, dissolved oxygen content increased by 24.1 %; total nitrogen and total phosphorus content decreased by 54.1 and 74.5 %, respectively, and pH fell from 9.1 to 8.7, all of which can be attributed to the emergency control measures for the cyanobacterial bloom. Data analysis also indicated that the improved water transparency after clay flocculation was the key factor in turion sprouting and seedling propagation of P. crispus. The ameliorative light intensity and favorable nutrient level all promoted the growth of seedlings of P. crispus and later quick colonization. It is suggested that ecological restoration of macrophytic and algal lakes be conducted by some physical or chemical means to improve transparency, reduce nutrient concentration, and adjust water pH, with the purpose of improving water quality for germination and growth of aquatic plants.

Section: Discussionmentioning

confidence: 97%

Causes of large Potamogeton crispus L. population increase in Xuanwu Lake

Song

2016

Environ Sci Pollut Res

“…Additionally, warming can advance the spring phenology of aquatic (Hansson et al., ; Velthuis, Domis et al., ; Winder & Schindler, ; Zhang et al., ) and terrestrial organisms (Parmesan, ). Indeed, we detected an advanced spring phenology and an additional delayed decrease of M. spicatum abundance under warmed conditions underlying the observed differences in M. spicatum abundance between our treatments.…”

Section: Discussionmentioning

confidence: 99%

“…Until September, labile organic carbon (LOC) accumulated in the sediment in both treatments, as sedimentation rates were larger than decomposition rates (see Figure 2 and (Cebrian & Lartigue, 2004;Handa et al, 2014;Zhang, Hui, Luo, & Zhou, 2008). Warming can lead to shifts in carbon:nutrient ratios of aquatic plants (Ventura et al, 2008;Zhang et al, 2016), but the direction of change is not uniform across studies (Velthuis, van Deelen et al, 2017). In our experiment, aboveground plant C:N ratios were higher in the warm treatment compared to the control (Table 2), indicating a decreased quality of these plants.…”

Section: Warming Effects On Organic Carbon Burialmentioning

confidence: 99%

Warming enhances sedimentation and decomposition of organic carbon in shallow macrophyte‐dominated systems with zero net effect on carbon burial

Velthuis

Kosten

Aben

et al. 2018

Global Change Biology

Self Cite

Temperatures have been rising throughout recent decades and are predicted to rise further in the coming century. Global warming affects carbon cycling in freshwater ecosystems, which both emit and bury substantial amounts of carbon on a global scale. Currently, most studies focus on the effect of warming on overall carbon emissions from freshwater ecosystems, while net effects on carbon budgets may strongly depend on burial in sediments. Here, we tested whether year-round warming increases the production, sedimentation, or decomposition of particulate organic carbon and eventually alters the carbon burial in a typical shallow freshwater system. We performed an indoor experiment in eight mesocosms dominated by the common submerged aquatic plant Myriophyllum spicatum testing two temperature treatments: a temperate seasonal temperature control and a warmed (+4°C) treatment (n = 4). During a full experimental year, the carbon stock in plant biomass, dissolved organic carbon in the water column, sedimented organic matter, and decomposition of plant detritus were measured. Our results showed that year-round warming nearly doubled the final carbon stock in plant biomass from 6.9 ± 1.1 g C in the control treatment to 12.8 ± 0.6 g C (mean ± SE), mainly due to a prolonged growing season in autumn. DOC concentrations did not differ between the treatments, but organic carbon sedimentation increased by 60% from 96 ± 9.6 to 152 ± 16 g C m yaer (mean ± SE) from control to warm treatments. Enhanced decomposition of plant detritus in the warm treatment, however, compensated for the increased sedimentation. As a result, net carbon burial was 40 ± 5.7 g C m year in both temperature treatments when fluxes were combined into a carbon budget model. These results indicate that warming can increase the turnover of organic carbon in shallow macrophyte-dominated systems, while not necessarily affecting net carbon burial on a system scale.

“…The number of studies in our analysis was rather low ( n = 3) and included a positive (Zhang et al, 2016), negative (Ventura et al, 2008), and neutral (Touchette et al, 2003) response. The different directions of responses indicate that effects of temperature on the carbon:nutrient stoichiometry of aquatic plants are not necessarily linked to the temperature increments they are exposed to.…”

Section: Discussionmentioning

confidence: 99%

Impact of Temperature and Nutrients on Carbon: Nutrient Tissue Stoichiometry of Submerged Aquatic Plants: An Experiment and Meta-Analysis

et al. 2017

Self Cite

Human activity is currently changing our environment rapidly, with predicted temperature increases of 1–5°C over the coming century and increased nitrogen and phosphorus inputs in aquatic ecosystems. In the shallow parts of these ecosystems, submerged aquatic plants enhance water clarity by resource competition with phytoplankton, provide habitat, and serve as a food source for other organisms. The carbon:nutrient stoichiometry of submerged aquatic plants can be affected by changes in both temperature and nutrient availability. We hypothesized that elevated temperature leads to higher carbon:nutrient ratios through enhanced nutrient-use efficiency, while nutrient addition leads to lower carbon:nutrient ratios by the luxurious uptake of nutrients. We addressed these hypotheses with an experimental and a meta-analytical approach. We performed a full-factorial microcosm experiment with the freshwater plant Elodea nuttallii grown at 10, 15, 20, and 25°C on sediment consisting of pond soil/sand mixtures with 100, 50, 25, and 12.5% pond soil. To address the effect of climatic warming and nutrient addition on the carbon:nutrient stoichiometry of submerged freshwater and marine plants we performed a meta-analysis on experimental studies that elevated temperature and/or added nutrients (nitrogen and phosphorus). In the microcosm experiment, C:N ratios of Elodea nuttallii decreased with increasing temperature, and this effect was most pronounced at intermediate nutrient availability. Furthermore, higher nutrient availability led to decreased aboveground C:P ratios. In the meta-analysis, nutrient addition led to a 25, 22, and 16% reduction in aboveground C:N and C:P ratios and belowground C:N ratios, accompanied with increased N content. No consistent effect of elevated temperature on plant stoichiometry could be observed, as very few studies were found on this topic and contrasting results were reported. We conclude that while nutrient addition consistently leads to decreased carbon:nutrient ratios, elevated temperature does not change submerged aquatic plant carbon:nutrient stoichiometry in a consistent manner. This effect is rather dependent on nutrient availability and may be species-specific. As changes in the carbon:nutrient stoichiometry of submerged aquatic plants can impact the transfer of energy to higher trophic levels, these results suggest that eutrophication may enhance plant consumption and decomposition, which could in turn have consequences for carbon sequestration.