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The recovery of submerged macrophytes is crucial for lake restoration. However, Myriophyllum spicatum usually shows an overgrowth and inhibits the growth of Vallisneria denseserrulata via light shading in many restored shallow lakes after the plant transplantation. So far, harvesting M. spicatum is the primary method to alleviate these shading effects in post-restoration lakes. Nevertheless, the effects of harvesting on the growth of V. denseserrulata and water quality are poorly elaborated. In this study, we conducted a mesocosm experiment, including both monoculture and polyculture groups, to investigate the response of V. denseserrulata growth, light climate, and nutrient concentrations in the water with M. spicatum harvesting. Moreover, the growth and morphology of M. spicatum were also examined. We hypothesized that M. spicatum harvesting would enhance the growth of V. denseserrulata and improve both the light climate and water quality. Our results showed that harvesting M. spicatum in the polyculture mesocosms substantially enhanced the relative growth rate (RGR) of V. denseserrulata compared to the non-harvesting controls. Moreover, harvesting M. spicatum reduced the light attenuation coefficient at 30 cm depth; however, the concentrations of chlorophyll-a, total nitrogen, and total phosphorus did not change significantly. As for M. spicatum, harvesting inhibited the growth of main stem and root but did not significantly affect the cumulative weight and RGR of M. spicatum. In contrast, the presence of V. denseserrulata decreased cumulative weight and RGR while promoting the root parameters of M. spicatum. Our findings imply that harvesting overgrowth nuisance submerged macrophyte species (e.g., M. spicatum) can improve the light climate and reduce its root growth, thereby enhancing the growth of target macrophyte species like V. denseserrulata without changes in the water quality which provides valuable insights for post-restoration lake management. [ABSTRACT FROM AUTHOR]

The submerged species Carolina fanwort (Cabomba caroliniana) has attracted considerable attention in Lake Taihu Basin (LTB), China. This species was widely used as a garden plant until 2016, when it was identified as invasive. In this study, we conducted a mesocosm experiment to compare the morphological traits, includingtotal dry mass, shoot/root (S/R) ratio, relative growth rate (RGR) and competition index log response ratio (ln RR), of C. caroliniana and two frequently co-occurring native submerged plants, water thyme (Hydrilla verticillata) and Eurasian watermilfoil (Myriophyllum spicatum). The results demonstrated that C. caroliniana did not show more advantageous traits (higher total dry mass, S/R ratio and RGR) or have a lower ln RR than H. verticillata or M. spicatum. We provide a counterexample to commonly accepted thought in which the successful invasion of invasive species may not be explained by outcompeting native plants. Other biotic or abiotic factors that determine the successful invasion of C. caroliniana must be studied further.

Transplantation of submerged macrophytes has been widely used to improve water quality in restoring shallow lakes in China. However, in some lakes, small omnivorous fish predominated the fish assemblages and fed mainly on submerged macrophytes. Despite significant research examining grazing selectivity in herbivorous fishes, macrophyte feeding preferences of small omnivorous fishes are poorly understood. We conducted a mesocosm experiment to examine the effects of a prolific small omnivorous bitterling fish Acheilognathus macropterus on the relative growth rate (RGR) and biomass of submerged macrophytes (Ceratophyllum demersum, Myriophyllum spicatum, Vallisneria denseserrulata, and Hydrilla verticillata). Our results showed that the presence of A. macropterus significantly increased nutrient concentrations (e.g. total nitrogen and total phosphorus). The RGR of C. demersum in the bitterling-present treatment was significantly lower than the controls, in the presence of other macrophyte species. Further, total biomass of the four species of macrophytes in the fish-present mesocosms was markedly lower than in the fish-absent treatment, suggesting considerable consumption of macrophytes by bitterling. Moreover, the percent biomass of V. denserrulata and H. verticillata were significantly enhanced by the presence of bitterling. Our findings suggest that A. macropterus may increase nutrient concentrations through excretion and reduce the biomass and RGR of certain submerged macrophytes which may shift macrophyte community structure via selective grazing.

The salinization of irrigated land affects agricultural productivity. HIGH‐AFFINITY POTASSIUM (K+) TRANSPORTER 1;5 (OsHKT1;5)‐dependent sodium (Na+) transport is a key salt tolerance mechanism during rice growth and development. Using a previously generated high‐throughput activation tagging‐based T‐DNA insertion mutant pool, we isolated a mutant exhibiting salt stress‐sensitive phenotype, caused by a reduction in OsHKT1;5 transcripts. The salt stress‐sensitive phenotype of this mutant results from the loss of function of OsDNAJ15, which encodes plasma membrane‐localized heat shock protein 40 (Hsp40). osdnaj15 loss‐of‐function mutants show decreased plant height, increased leaf angle, and reduced grain number caused by shorter panicle length and fewer branches. On the other h'and, OsDNAJ15‐overexpression plants showed salt stress‐tolerant phenotypes. Intriguingly, salt stress facilitates the nuclear relocation of OsDNAJ15 so that it can interact with OsBAG4, and OsDNAJ15 and OsBAG4 synergistically facilitate the DNA‐binding activity of OsMYB106 to positively regulate the expression of OsHKT1;5. Overall, our results reveal a novel function of plasma membrane‐localized Hsp40 protein in modulating, alongside chaperon regulator OsBAG4, transcriptional regulation under salinity stress tolerance. [ABSTRACT FROM AUTHOR]

A mesocosm study illuminated possible transfer pathways for dissolved organic carbon from the water column to zooplankton. Organic carbon was added as 13C enriched glucose to 15 mesocosms filled with natural lake water. Stable isotope analysis and phospholipid fatty acids-based stable isotope probing were used to trace the incorporation of 13C into the cladoceran Bosmina and its potential food items. Glucose-C was shown to be assimilated into phytoplankton (including fungi and heterotrophic protists), bacteria and Bosmina, all of which became enriched with 13C during the experiment. The study suggests that bacteria play an important role in the transfer of glucose-C to Bosmina. Furthermore, osmotic algae, fungi and heterotrophic protists might also contribute to the isotopic signature changes observed in Bosmina. These findings help to clarify the contribution of dissolved organic carbon to zooplankton and its potential pathways.

The submerged plant species Carolina fanwort (Cabomba caroliniana) has become a dominant invasive aquatic plant in the Lake Taihu Basin (LTB) in China. Introduced species may escape their original specialist enemies and encounter fewer enemies in their new environment. They were assumed to have suffered less herbivory than native species as they are relatively unpalatable (the enemy release hypothesis [ERH]). The objective of this study was to compare the responses of C. caroliniana with those of co-occurring native species to herbivory from native herbivores. We conducted a mesocosm experiment to record the responses of C. caroliniana and two commonly co-occurring native submerged plant counterparts, water thyme (Hydrilla verticillata) and Eurasian watermilfoil (Myriophyllum spicatum), to herbivory by two native generalist gastropod snails, Radix swinhoei and Sinotaia quadrata. Plant morphological traits (total biomass, shoot/root [S/R] biomass ratio and relative growth rate [RGR]) and physiological traits (leaf total nonstructural carbohydrate [TNC], lignin, and cellulose) were recorded. The snail S. quadrata rarely influenced the plant traits of the three submerged plants. With the increasing numbers of R. swinhoei treatments, most of the plant traits of H. verticillata and M. spicatum changed, while those of C. caroliniana showed a relatively stable fluctuation. This result indicates that C. caroliniana is more resistant to herbivory by the snail R. swinhoei , which is consistent with the ERH hypothesis. This finding indicates that herbivorous snail species contributes to the invasion of C. caroliniana , which potentially alters the species composition of submerged plants in the plant community. [ABSTRACT FROM AUTHOR]

Re-establishment of macrophyte communities is a key to restore eutrophic shallow lakes. The species composition of the plant communities may change rapidly during the recovery period. A basin in subtropical Lake Qinhu (China) was restored by biomanipulation including fish removal followed by planting of submerged macrophytes in 2011. In September-December 2011, dominance of Vallisneria spinulosa and Ceratophyllum demersum shifted to dominance of Myriophyllum spicatum. Meanwhile, the CPUE (catch per unit effort) showed that the number and biomass of grass carp (Ctenopharyngodon idella) demonstrated a marked increase. Stable isotope analyses revealed that grass carp preferred V. spinulosa and C. demersum to M. spicatum. We propose that grazing by grass carp was responsible for the observed shift in dominance towards M. spicatum but as alternative explanations are possible, further tests by controlled experiments are needed to draw firm conclusions.