Habitat selection in spatially heterogeneous environments: a test of foraging behaviour in the clonal submerged macrophyte <i>Vallisneria spiralis</i>

Inorganic carbon and temperature are 2 important factors that regulate the growth of submerged macrophytes. However, experimental evidence regarding the eco-physiological changes that occur in submerged macrophytes in response to elevated CO 2 and temperature is still limited. To investigate how the submerged macrophyte Vallisneria natans (Hydrocharitaceae), a common species in the waters of the middle and lower reaches of the Yangtze River, responds to these factors, we conducted a mesocosm experiment using simulated CO 2 elevation (by bubbling CO 2 into experimental water) and ambient temperature warming systems. During the 60 d experiment, CO 2 elevation significantly increased the inorganic carbon concentration in the water column. The warming systems elevated average water temperature by approximately 3°C. The elevation of CO 2 levels significantly enhanced the photosynthetic performance, growth and clonal propagation of V. natans. When combined with an increase in CO 2 , elevated temperatures also promoted photosynthesis and growth. The individual ramet biomass of V. natans decreased with increasing temperature, but only significantly under ambient CO 2 levels. CO 2 elevation increased both stolon elongation and bud number. At elevated CO 2 concentration, more biomass was allocated to the stolons, roots and buds, while less biomass was allocated to the leaves. These results indicate that the eco-physiological responses of V. natans should increase its stress tolerance in aquatic plant communities under future spatial and temporal variation in CO 2 levels, however, further research is required.

Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Responses of the submerged macrophyte Vallisneria natans to elevated CO2 and temperature

Cao¹,

Ruan²

2015

“…The effect of sediment nutrients on the growth of submerged macrophytes has received increasing attention during the past decade (Smith et al 2002, Hangelbroek et al 2003, Xiao et al 2006, Wang & Yu 2007. Variations in the response of plants to sediment nutrient levels have been reported for plant size (Xie & Yu 2011a), biomass and resource allocation , plastic adjustments (Mony et al 2007), root structure (Xie et al 2007), and reproductive strategy (Xiao et al 2006). Even small variations in nutrient availability can cuase large differences in plant growth and morphological responses (Sugiyama & Bazzaz 1998, Müller et al 2000.…”

Section: Introductionmentioning

confidence: 99%

“…Sediment is the primary source from which most submerged macrophytes take up macro-and microelements (Barko & Smart 1983, Barko & Smart 1986, although submerged macrophytes can take up nutrient ions from the water column in some eutrophic cases (Madsen & Cedergreen 2002). The effect of sediment nutrients on the growth of submerged macrophytes has received increasing attention during the past decade (Smith et al 2002, Hangelbroek et al 2003, Xiao et al 2006, Wang & Yu 2007. Variations in the response of plants to sediment nutrient levels have been reported for plant size (Xie & Yu 2011a), biomass and resource allocation , plastic adjustments (Mony et al 2007), root structure (Xie et al 2007), and reproductive strategy (Xiao et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Growth response of the submerged macrophyte Myriophyllum spicatum to sediment nutrient levels and water-level fluctuations

Cao¹,

Wang²,

ZunLing³

2012

Sediment nutrient levels and water-level fluctuations are important factors that affect the development and growth of submerged macrophytes; however, little is known about the adaptive responses of macrophytes to these factors. We conducted an experiment using the submerged macrophyte Myriophyllum spicatum L. grown under 2 sediment nutrient levels (high: 2.7 mg g −1 total nitrogen, TN; 1.5 mg g −1 total phosphorus, TP; low: 1.45 mg g −1 TN and 0.70 mg g −1 TP) and 3 amplitudes of water-level fluctuation (static, ± 50 cm, ±100 cm) in outdoor ponds. We hypothesized that increased nutrient supply would promote the growth of M. spicatum, which can acclimate to the negative effects of moderate water-level fluctuations. After 112 d of growth under high-nutrient conditions, the plants produced a greater shoot biomass (higher branch number and length), resulting in greater accumulation of total biomass. However, plant growth was inhibited by increasing the amplitude of the water-level fluctuations: at ±100 cm, the plants allocated more biomass to the roots and produced fewer and longer branches. Conversely, plant growth was promoted in the high-nutrient sediments at ± 50 cm amplitude. The production of auto-fragments was increased in the high-nutrient sediment but was significantly decreased by high water-level fluctuations. Thus, sediment nutrient levels and water-level fluctuations have strong interactive effects on the growth and reproduction of M. spicatum, and increased sediment nutrients in combination with moderate water level fluctuations facilitate nutrient acquisition, plant growth, and reproduction. Our study implies that moderate water-level fluctuations benefit the restoration of submerged macrophyte communities, particularly in high-nutrient habitats.

“…However, much of the research dedicated to understanding the relationship between sediment nutrients and reproductive output has focused on sexual reproduction. Although the influence of sediment nutrients on clonal plants has begun to receive attention, we do not have a thorough understanding of asexual propagation, particularly for plants in aquatic habitats (Slade & Hutchings 1987, Dong et al 1997, Hangelbroek et al 2003, Xiao et al 2006. Asexual reproduction is generally assumed to be more common in aquatic habitats than in terrestrial habitats because of unfavorable ecological conditions for sexual reproduction, e.g.…”

Section: Introductionmentioning

confidence: 99%

Turion production and nutrient reserves in Potamogeton crispus are influenced by sediment nutrient level

Xie¹,

Yu²

2011

The influence of sediment nutrient content on asexual propagule production in plants is poorly understood, especially in submersed macrophytes. To improve the understanding of turion (an aboveground asexual propagule) production, Potamogeton crispus L. was planted in 2 experimental conditions that differed in their levels of sediment nutrients. After 10 wk of growth, sediment nutrient level had significantly impacted the plants' vegetative and reproductive traits. Most vegetative trait measures of P. crispus (e.g. leaf mass fraction and stem mass fraction) were higher when plants were grown in nutrient-rich sediment compared with plants grown in nutrient-poor sediment. Reproductive trait measures (e.g. turion mass fraction and individual turion biomass) were higher in plants grown in nutrient-poor sediment compared with plants grown in nutrient-rich sediment. Plants grown in nutrient-rich sediment produced a larger number of small turions (< 50 mg), in which more nutrients (total nitrogen and total phosphorus) were stored; plants grown in nutrient-poor sediment produced more large turions (>100 mg) and stored more total nonstructural carbohydrate (the major proportion of which was starch) in them. Path analysis revealed that total plant biomass (strong positive effect), leaf and stem biomass (weak negative effects) had direct effects on total turion biomass, which consequently affected turion size and number. Moreover, ramet number and mean shoot height also had weak but direct effects (both negative effects) on turion size and number. These results demonstrate that sediment nutrient content mediates plant vegetative traits and can subsequently affect turion production and reserves in P. crispus. KEY WORDS: Asexual reproduction · Potamogeton crispus · Reserves · Sediment nutrients · TurionResale or republication not permitted without written consent of the publisher Aquat Biol 14: 21-28, 2011 strates (Hangelbroek et al. 2003). However, much of the research dedicated to understanding the relationship between sediment nutrients and reproductive output has focused on sexual reproduction. Although the influence of sediment nutrients on clonal plants has begun to receive attention, we do not have a thorough understanding of asexual propagation, particularly for plants in aquatic habitats (Slade & Hutchings 1987, Dong et al. 1997, Hangelbroek et al. 2003, Xiao et al. 2006. Asexual reproduction is generally assumed to be more common in aquatic habitats than in terrestrial habitats because of unfavorable ecological conditions for sexual reproduction, e.g. decreased pollination success and low reproductive success (for a review, see Santamaría 2002). Indeed, many asexual propagules of aquatic macrophytes can self-initiate abscission -examples include auto-fragments of Myriophyllum spicatum L. (Smith et al. 2002) For a given amount of resources that a plant can allocate to propagation, there is a compromise between propagule size and number (i.e. the size-number trade-off, Smith & Fretwell 1974). Previous st...