Coexistence and the comparative light relations of the submersed macrophytes Myriophyllum spicatum L. and Vallisneria americana Michx.

Abstract

The Eurasian watermilfoil (Myriophyllum spicatum L.) has partially replaced wild celery (Vallisneria americana Michx.) as a community dominant in the littoral zones of lakes of Madison, Wisconsin. The two species have very different growth forms, with that of M. spicatum corresponding more closely to the optimal growth form simulated by the macrophyte production model WEED. The objective of this research was to investigate the mechanisms by which Vallisneria could compensate for its nonoptimal growth form and coexist with Myriophyllum.A quantification of midsummer growth form for the two species at a rooting depth of 80-90 cm showed that M. spicatum had 68% of its shoot biomass within 30 cm of the surface, whereas V. americana had 62% of its leaf biomass within 30 cm of the bottom. Vallisneria had a light extinction coefficient ranging from 0.013 to 0.019 m·g, much higher than the value (ca. 0.006 m·g) for M. spicatum. This indicates less effective penetration of light to lower leaves of V. americana. Half-saturation constants describing the light-dependence of carbon uptake in "shade" and "sun" tissues ranged from 60-197 microeinsteins·m·s for V. americana, and 164-365 μeinsteins·m·s for M. spicatum. The optimum temperature for photosynthesis was 33.6°C for M. spicatum and 32.6°C for V. americana, but Myriophyllum was nearly twice as effective at carbon uptake at 10°C. Integration of all of the above features with WEED showed that, for midsummer conditions, V. americana more than compensated for apparently disadvantageous morphological features by its greater physiological adaptability to low light regimes. Coupled with the temperature-dependence of photosynthesis, it appears that V. americana is favored by midsummer conditions, whereas M. spicatum is at an advantage at other times.

The effect of water temperature and flow on respiration in barnacles: patterns of mass transfer versus kinetic limitation

“…A second example of kinetic limitation comes from measurements of nutrient uptake and photosynthesis in the freshwater plant Vallisneria americana (Nishihara and Ackerman, 2009). The thermal maximum for photosynthesis in V. americana from the Great Lakes region is 32.6°C (Titus and Adams, 1979), which is higher than the temperature (24°C) tested by Nishihara and Ackerman (Nishihara and Ackerman, 2009). This is consistent with our conclusion that kinetic limitation is likely to be limited to the lower temperature range of a species.…”

Effects of taxonomy, sediment, and water column on C:N:P stoichiometry of submerged macrophytes in Yangtze floodplain shallow lakes, China

“…The species-specific variation of nutrient composition can be an important trait for identifying the ecological strategies and for predicting the result of competition in plant communities (Tilman 1982). V. natans, for instance, had lowest C concentrations which benefited its tolerance in low light stress and was consistent with its low light compensation point Significance is indicated by * < 0.05, ** < 0.01 S-N sediment nitrogen, S-C sediment carbon, S-WC sediment water content, S-P sediment phosphorus, S-CN sediment C:N ratio, S-CP sediment C:P ratio, S-NP sediment N:P ratio, WD water depth, SD Secchi depth, TN total nitrogen in water column, TP total phosphorus in water column, Chl a chlorophyll a, K light attenuation coefficient, SD:WD Secchi depth to water depth ratio, W-NP N:P ratio in water column of photosynthesis (Su et al 2004;Titus and Adams 1979). In addition, V. natans had lower C/N metabolic level and higher carbohydrate storage than other submerged macrophytes (Yuan et al 2016).…”

“…On the contrary, P. malaianus and M. spicatum, belonging to canopy formers, had higher C:N and C:P than other submerged macrophyte species. This might be another adaptive strategy which is the result of allocating more C on stem to elongate their shoots toward water surface (Ni 2001;Titus and Adams 1979). C. demersum is a submerged, rootless, freefloating aquatic plant.…”

“…Distribution of the collected submerged macrophytes at the 14 lakes was shown in Table 2. To reduce environmental stress, these macrophyte species take different growth forms and have various adaptive strategies, including morphological feature and metabolism (Ni 2001;Su et al 2004;Titus and Adams 1979).…”

Gas Exchange Characteristics of the Submerged Aquatic Crassulacean Acid Metabolism Plant, Isoetes howellii

“…Light saturation at a low quantum flux density as for Isoetes, is likewise common in aquatics (3,6,19,26). This is particularly striking in Isoetes where, at high CO2 levels, light saturation occurs at only 1%o of full sunlight.…”