Effects of local climate and hydrological conditions on the thermal regime of a reservoir at Tropic of Cancer, in southern China (original) (raw)
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PLOS ONE, 2015
Understanding how an invasive plant can colonize a large range of environments is still a great challenge in freshwater ecology. For the first time, we assessed the relative importance of four factors on the phosphorus uptake and growth of an invasive macrophyte Elodea nuttallii (Planch.) St. John. This study provided data on its phenotypic plasticity, which is frequently suggested as an important mechanism but remains poorly investigated. The phosphorus uptake of two Elodea nuttallii subpopulations was experimentally studied under contrasting environmental conditions. Plants were sampled in the Rhine floodplain and in the Northern Vosges mountains, and then maintained in aquaria in hard (Rhine) or soft (Vosges) water. Under these conditions, we tested the influence of two trophic states (eutrophic state, 100 μg.l −1 P-PO 4 3− and hypertrophic state, 300 μg.l −1 P-PO 4 3−) on the P metabolism of plant subpopulations collected at three seasons (winter, spring and summer). Elodea nuttallii was able to absorb high levels of phosphorus through its shoots and enhance its phosphorus uptake, continually, after an increase of the resource availability (hypertrophic > eutrophic). The lowest efficiency in nutrient use was observed in winter, whereas the highest was recorded in spring, what revealed thus a storage strategy which can be beneficial to new shoots. This experiment provided evidence that generally, the water trophic state is the main factor governing P uptake, and the mineral status (softwater > hardwater) of the stream water is the second main factor. The phenological stage appeared to be a confounding factor to P level in water. Nonetheless, phenology played a role in P turnover in the plant. Finally, phenotypic plasticity allows both subpopulations to adapt to a changing environment.
Annales de Limnologie - International Journal of Limnology, 1999
A natural phytoplankton assemblage from a pond was grown in semicontinuous cultures receiving phosphorus (P) pulses once every 2 or 6 days. The study shows that the structure of phytoplankton assemblage depends on the mode of P supply. Biomass, expressed as total biovolume, was greatest in cultures receiving P pulse once every 2 days. While the total amount of P administered to both pulsed cultures remained similar, differences in structure of the phytoplankton assemblage were observed during the 4 weeks experimental period. The small sized Navícula cryptocephala became dominant in cultures which did not receive P pulses. Therefore, this species seems to be «affinity specialist* well-adapted to a low P concentration. The replacement of the dominant cyanobacterium Gomphosphaeria aponina by the diatoms Navícula cryptocephala and Synedra ulna in the control and P-pulsed cultures might be due to another factor. The large sized Phormidium mucosum and Hormidium sp. were favoured in cultures pulsed with P at the lowest frequency, which seems to be due mainly to their larger P accumulation capacity. Synedra ulna was favoured to the same extent under the 2 and 6-day pulse periods. Réponse d'une communauté de phytoplancton soumise à des apports de phosphore en culture semi-continue Mots-clés : phytoplancton, phosphore, structure de communauté, algues, diatomées, culture semi-continue. Une communauté phytoplanctonique d'un étang a été cultivée en culture semi-continue avec des apports de phosphore tous les 2 ou 6 jours. L'étude montre que la structure de la communauté phytoplanctonique dépend de la fréquence des apports de P. La biomasse, exprimée en biovolume total, était maximale dans les cultures enrichies tous les 2 jours. Bien que la quantité totale de P ajoutée aux 2 cultures soit similaire, des différences dans la composition de phytoplancton étaient observées au cours des 4 semaines d'expérimentation. La petite espèce Navícula cryptocephala devenait dominante dans les cultures non enrichies en P. Cependant, cette espèce semble être une «affinity specialist* bien adaptée aux faibles concentrations en P. v Le remplacement de la cyanobactérie dominante Gomphospharium aponina par les diatomées Navícula cryptocephala et Synedra ulna dans les cultures témoins et enrichies en P peut être dû à un autre facteur. Les espèces de grande taille Phormidium mucosum et Hormidium sp. étaient favorisées dans les cultures avec les apports de P les moins fréquents ; ce qui semble hé à leur possibilité de stockage de cet élément. Synedra ulna répondait de la même façon quelle que soit la fréquence des apports.
Influence of Typha domingensis in the removal of high P concentrations from water
Chemosphere, 2015
Cu, Cr, Pb, Zn and Fe in water, sediment and tissue of the emergent macrophyte Schoenoplectus californicus were studied in three coastal environments differing in aquatic chemistry and tide amplitude: a deltaic floodplain marsh, a coastal vegetated strip of the river and a tidal marsh at the south margin of the Rio de la Plata Estuary. Metal content in water was not significantly different between the river and the floodplain marsh. Metal content in sediments showed higher values in the marshes than in the river, suggesting a retention in the marsh. Except for Cu, the highest metal content in sediments and water was observed in the tidal marsh. Pb in plants was undetectable. Metal content was higher in rhizomes, except Cr, which was mainly stored in stems. Rhizome metal content was higher in the river, probably related to the higher redox potential of its sediments. Inflorescence metal content was higher in the marshes: the highest Zn, Cr and Fe contents were measured in the tidal marsh; the highest Cu content was in the floodplain marsh, together with the highest organic matter content of the sediments. Zn, Cr and Fe increased in standing drying stems and in inflorescences in late fall. Inflorescences showed the highest metal content after seeds had been released.
International Journal of Health and Life Sciences, 2019
Background: Cyanobacteria are the most important group of algae. Many factors are involved in the rapid growth of algae such as phosphorus and nitrogen contents. Objectives: The current study aimed at evaluating the effect different phosphorus concentrations on the growth rate of Cylindrospermopsis raciborskii during the aquatic life. Methods: The experiment was carried out for 12 days at three phosphorus concentrations and one control group in Zehnder 8 and Blue-Green 11 media. The rates of cell division per day (G) and specific growth rate (µ) were separately estimated for each group. Cyanobacterium was tested at three phosphorus concentrations; 150, 300, and 600 µg/L. Results: The current study results showed that increasing phosphorus concentration had a significant effect on the growth of C. raciborskii in some particular days of cultivation. The maximum growth rate (0.9 per day) was observed at 7 g/L phosphorus concentration. Conclusions: Phosphorus was a limiting factor and contributed to the removal of toxins from the alga and its blooming. The maximum growth rate was observed in the group treated on the day 8 of cultivation with phosphorus concentration of 300 µg/L.
Limnology, 2015
Lake Monger (Perth, Western Australia) is a highly eutrophic lake, characterised by very low species richness of macrophytes with the dominance of Potamogeton crispus. Mesocosm experiments were performed using water and plants collected from the lake to determine the effects of vegetation decay on the phosphorus (P) concentrations in the overlying waters. After 2 weeks of experimental incubation of mesocosms with and without re-oxygenation, P concentrations in the water column were significantly higher, showing a quite similar effect of P. crispus on the phosphorus release in different mesocosms. The results of our study provide clear evidence that the P concentrations in overlying waters mainly depend upon the plant P content and developmental stage. Although many sources contribute to the nutrient load of Lake Monger, macrophyte harvesting, prior to its senescence, might constitute a significant in-lake measure for reducing the internal P load.
Wetlands Ecology and Management, 2006
Phosphorus content in sediment, water and tissues of three macrophyte species growing in Myall Lake, Australia were studied from January to November, 2004. The sites investigated were North–West (NW), North–East (NE), South–West (SW) bays and Central deep area of the lake (CL). The objective of this study was to investigate how total phosphorus (TP) in plant tissues relate to phosphorus pools and the role played by the aquatic macrophyte species under investigation in phosphorus recycling in the lake. Of the four investigated sites of the lake, TP in plant tissues were significantly higher in North–West and South–West bays compared to the rest. Najas marina had significantly higher TP content (e.g., 1.55 and 1.44 mg/g dw.; P < 0.05) for NW and SW respectively, than the other two species. N. marina is a rooted macrophyte while charophytes (C. fibrosa and Nitella hyalina) are pseudo-rooted macrophytes. Total phosphorus in the sediment and water column were significantly higher in Central deep area of the lake compared to the other three bays (P < 0.05, n 5). Soluble reactive phosphorus (SRP) and total dissolved phosphorus (TDP) in sediment pore water correlated significantly with phosphorus content in the tissue of N. marina ( r2rmSRP−N.marina=0.95r^{2}_{{\rm SRP}-N.\ marina}=0.95r2rmSRP−N.marina=0.95 ; r2rmTDP−N.marina=0.92r^{2}_{{\rm TDP}-N.\ marina}=0.92r2rmTDP−N.marina=0.92 ) as well as TP in sediment (␣ r2rmSRP−TP=0.90r^{2}_{\rm SRP-TP}=0.90r2rmSRP−TP=0.90 and r2rmTDP−TP=0.81r^{2}_{\rm TDP-TP}=0.81r2rmTDP−TP=0.81 ). Using the two-compartmental uptake model, it was observed that, sediment was the main compartment through which Ni. hyalina obtained phosphorus while for the other two species, water column was the uptake route for the phosphorus. These correlations suggest that, water column and sediments are important pathways for phosphorus uptake in plants.
Freshwater Biology, 2004
1. The application of functional ecology models to aquatic plants often relies on morphological and life-history traits which may reflect, in part, the phenotypic plasticity displayed by aquatic plants. The present study was designed to evaluate the use of physiological traits, such as nutrition patterns, to describe aquatic plant strategies along a gradient of increasing resource availablity. 2. Taking phosphorus (P) as an example, nutrition-use efficiencies were evaluated in five species, through the P-content in plant tissues, the variations in P-content according to nutrient availability and the perenniality of P-storage. Plasticity in P-storage was also investigated in Ranunculus peltatus, a morphologically highly plastic species. 3. In 2001, P-content was analysed in Callitriche hamulata, C. obtusangula, C. platycarpa, Elodea nuttallii and R. peltatus tissue samples. These five species were sampled at nine different sites in streams along an increasing resource gradient in the Northern Vosges Biosphere Reserve (NE France). Variations of P-content in the roots, stems and dissected and floating leaves of R. peltatus were also studied. 4. Only C. platycarpa and R. peltatus were found to occur in low nutrient availability conditions. Callitriche hamulata, C. obtusangula and E. nuttallii were restricted to mesotrophic and eutrophic sites. The highest nutrient-use efficiency was found for E. nuttallii which was able to adapt its P-storage to varying resource availabilities. Ranunculus peltatus was able to store high concentrations of P, but its P-integration within the vegetative structure was less efficient under eutrophic conditions. Callitriche spp. appeared to have relatively low nutrient-use efficiencies, although C. obtusangula displayed a high P-content. While P was stored preferentially in roots in R. peltatus populations occurring in nutrientrich sites, there was no particular P-storage organ for populations from nutrient-poor sites. 5. On the basis of P-usage, R. peltatus and E. nuttallii presented competitor traits, C. hamulata and C. platycarpa displayed stress-tolerant nutrient signatures and for C. obtusangula, ruderal or competitor characteristics dominated. The use of physiological traits, such as nutrition patterns, may provide valuable, complementary information about aquatic plant strategies, independent from the influence of morphological trait plasticity often displayed by these plants.
Dissolved phosphorus uptake in subtropical and temperate streams of Argentina
Limnetica, 2018
An abrupt CO 2-mediated decrease in pH affects growth rates, cellular features and the interspecific interaction of Scenedesmus (Acutodesmus) obliquus and Cryptomonas pyrenoidifera The technologies of anthropogenic CO 2 mitigation, such as carbon capture and sequestration, may pose an environmental threat to aquatic systems. In a scenario of CO 2 leakage from a carbon capture and sequestration process, very low-pH values might be reached and could remain over time. The main objective of this study was to detect how an abrupt lowering of pH would affect the microalgae Scenedesmus (Acutodesmus) obliquus and Cryptomonas pyrenoidifera at physiological, morphological and population levels, and also see how these effects could lead to ecological consequences. Monospecific and mixed culture experiments were run according to this purpose over 14 days and at a pH of 6.5, controlled by CO 2 injection. An increased CO 2 concentration significantly enhanced the growth rate of both species and especially affected the cell size of C. pyrenoidifera in the monoculture. The total biovolume of C. pyrenoidifera was higher than the total biovolume of S. obliquus in the control treatment, although neither of the two species were dominant in the culture experiments. Granularity responded in different ways for the species studied, being statistically different within subjects in monospecific and mixed culture experiments. Only chlorophyll and granularity have been significantly correlated in the low pH of C. pyrenoidifera monoculture. Due to its ecological relevance, the decreased colony formation ability of S. obliquus under a high CO 2 concentration is highlighted.