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Zhijian Jiang - One of the best experts on this subject based on the ideXlab platform.
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physiological responses of the seagrass Thalassia hemprichii ehrenb aschers as indicators of nutrient loading
Marine Pollution Bulletin, 2014Co-Authors: Jingping Zhang, Xiaoping Huang, Zhijian JiangAbstract:To select appropriate bioindicators for the evaluation of the influence of nutrients from human activities in a Thalassia hemprichii meadow, environmental variables and plant performance parameters were measured in Xincun Bay, Hainan Island, South China. Nutrient concentrations in the bay decreased along a gradient from west to southeast. Moreover, the nutrients decreased with an increase in the distance from the shore on the southern side of the bay. Among the candidate indicators, the P content of the tissues closely mirrored the two nutrient loading gradients. The epiphytic algae biomass and the N content in the tissues mirrored one of the two nutrient loading trends. The leaf length, however, exhibited a significant negative correlation with the nutrient gradients. We propose that changes in the P content of T. hemprichii, followed by epiphytic algae biomass and N content of the tissues, may be the useful indicators of nutrient loading to coastal ecosystems.
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the effects of air exposure on the desiccation rate and photosynthetic activity of Thalassia hemprichii and enhalus acoroides
Marine Biology, 2014Co-Authors: Zhijian Jiang, Jingping Zhang, Xiaoping Huang, Chenyuan Zhou, Zhonglian Lian, Zhixin NiAbstract:The effects of air exposure on the desiccation rate and photosynthetic activity of Thalassia hemprichii and Enhalus acoroides were studied using chlorophyll fluorescence. The desiccation rate of T. hemprichii was higher than that of E. acoroides, while the critical threshold of relative water content (RWCcritical) showed opposite trend. Neither the desiccation rate nor RWCcritical of T. hemprichii was significantly affected by temperature, while the desiccation rate of E. acoroides was affected significantly. For both species, the effective photochemical efficiency of PSII decreased gradually above the RWCcritical, while declined rapidly below the RWCcritical. After initial air exposure, the relative maximum electron transport rate of both seagrasses increased gradually to a maximum and then decreased to initial value near the RWCcritical. Therefore, short-term air exposure above the RWCcritical is beneficial for both seagrasses, and the RWCcritical should be considered when examining the response of seagrass photosynthesis to air exposure and selecting transplantation sites.
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dynamics of nonstructural carbohydrates in seagrass Thalassia hemprichii and its response to shading
Acta Oceanologica Sinica, 2013Co-Authors: Zhijian Jiang, Xiaoping Huang, Jingping ZhangAbstract:A field survey was performed to examine nonstructural carbohydrate (NSC) dynamics in seagrass Thalassia hemprichii at the Xincun Bay in southern China. An indoor experiment to investigate the response of NSC in T. hemprichii to shade was conducted. Belowground tissue of T. hemprichii was the dominant site of NSC reserves, and soluble sugar was the primary storage compound. The starch content of belowground tissue was lower in high intertidal areas than in low intertidal areas, indicating that the longer air exposure in high intertidal areas resulted in less NSC synthesis and less accumulation of NSC in T. hemprichii. The lowest level of soluble sugar and its proportion to NSC in belowground tissue were observed near the cage culture area, where the nutrient concentration in water and sediment was the highest; while the highest level of that was observed near the coastal shrimp farm, Where salinity was the lowest. Soluble sugar in belowground tissue showed the following trend: summer>spring>winter>autumn. This corresponded to seasonal changes in the intensity of light. Leaf sugar accumulated during the autumn-winter period, providing a carbon and energy source for flower bud formation and seed germination. Short-term shading decreased NSC accumulation. Collectively, these results suggest that nutrient enrichment, freshwater discharge and exposure to air affect NSC dynamics in T. hemprichii. Light intensity, flower bud formation, and seed germination were all found to induce seasonal variations in NSC in T. hemprichii.
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effect of nitrate enrichment and salinity reduction on the seagrass Thalassia hemprichii previously grown in low light
Journal of Experimental Marine Biology and Ecology, 2013Co-Authors: Zhijian Jiang, Xiaoping Huang, Jingping ZhangAbstract:A sub-acute experiment that tested carbon and nitrogen metabolisms and the plant's antioxidant defence system was used to investigate the effects of nitrate enrichment and salinity reduction on the tropical seagrass Thalassia hemprichii that had previously been grown in low light conditions. Shading significantly reduced leaf growth rate, nitrate reductase activity and non-structural carbohydrate (NSC) content in both aboveground and belowground tissues, but enhanced superoxide dismutase and guaiacol peroxidase (POD) activities and free amino acids in aboveground tissue. After shade removal, salinity reduction with pre-shading decreased minimum fluorescence and maximum fluorescence under all nitrate conditions. Pre-shading aggravated the negative effect of nitrate enrichment and salinity reduction on leaf growth rate. Nitrate enrichment led to a greater reduction in NSC in aboveground tissues of pre-shading plants compared to the control. Furthermore, salinity reduction with pre-shading even induced effective NSC translocation from belowground to aboveground tissues. Nitrate enrichment and salinity reduction both increased POD activity in T. hemprichii grown previously in low light. Therefore, pre-shading increases the vulnerability of T. hemprichii to eutrophication and hyposalinity, which must be considered when predicting future responses and effective management of seagrass resources. (C) 2013 Elsevier B.V. All rights reserved.
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effects of co2 enrichment on photosynthesis growth and biochemical composition of seagrass Thalassia hemprichii ehrenb aschers
Journal of Integrative Plant Biology, 2010Co-Authors: Zhijian Jiang, Xiaopin Huang, Jingping ZhangAbstract:The effects of CO2 enrichment on various ecophysiological parameters of tropical seagrass Thalassia hemprichii (Ehrenb.) Aschers were tested. T. hemprichii, collected from a seagrass bed in Xincun Bay, Hainan island of Southern China, was cultured at 4 CO2(aq) concentrations in flow-through seawater aquaria bubbled with CO2. CO2 enrichment considerably enhanced the relative maximum electron transport rate (RETRmax) and minimum saturating irradiance (E-k) of T. hemprichii. Leaf growth rate of CO2-enriched plants was significantly higher than that in unenriched treatment. Nonstructural carbohydrates (NSC) of T. hemprichii, especially in belowground tissues, increased strongly with elevated CO2(aq), suggesting a translocation of photosynthate from aboveground to belowground tissues. Carbon content in belowground tissues showed a similar response with NSC, while in aboveground tissues, carbon content was not affected by CO2 treatments. In contrast, with increasing CO2(aq), nitrogen content in aboveground tissues markedly decreased, but nitrogen content in belowground was nearly constant. Carbon: nitrogen ratio in both tissues were obviously enhanced by increasing CO2(aq). Thus, these results indicate that T. hemprichii may respond positively to CO2-induced acidification of the coastal ocean. Moreover, the CO2-stimulated improvement of photosynthesis and NSC content may partially offset negative effects of severe environmental disturbance such as underwater light reduction.
Jingping Zhang - One of the best experts on this subject based on the ideXlab platform.
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physiological responses of the seagrass Thalassia hemprichii ehrenb aschers as indicators of nutrient loading
Marine Pollution Bulletin, 2014Co-Authors: Jingping Zhang, Xiaoping Huang, Zhijian JiangAbstract:To select appropriate bioindicators for the evaluation of the influence of nutrients from human activities in a Thalassia hemprichii meadow, environmental variables and plant performance parameters were measured in Xincun Bay, Hainan Island, South China. Nutrient concentrations in the bay decreased along a gradient from west to southeast. Moreover, the nutrients decreased with an increase in the distance from the shore on the southern side of the bay. Among the candidate indicators, the P content of the tissues closely mirrored the two nutrient loading gradients. The epiphytic algae biomass and the N content in the tissues mirrored one of the two nutrient loading trends. The leaf length, however, exhibited a significant negative correlation with the nutrient gradients. We propose that changes in the P content of T. hemprichii, followed by epiphytic algae biomass and N content of the tissues, may be the useful indicators of nutrient loading to coastal ecosystems.
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the effects of air exposure on the desiccation rate and photosynthetic activity of Thalassia hemprichii and enhalus acoroides
Marine Biology, 2014Co-Authors: Zhijian Jiang, Jingping Zhang, Xiaoping Huang, Chenyuan Zhou, Zhonglian Lian, Zhixin NiAbstract:The effects of air exposure on the desiccation rate and photosynthetic activity of Thalassia hemprichii and Enhalus acoroides were studied using chlorophyll fluorescence. The desiccation rate of T. hemprichii was higher than that of E. acoroides, while the critical threshold of relative water content (RWCcritical) showed opposite trend. Neither the desiccation rate nor RWCcritical of T. hemprichii was significantly affected by temperature, while the desiccation rate of E. acoroides was affected significantly. For both species, the effective photochemical efficiency of PSII decreased gradually above the RWCcritical, while declined rapidly below the RWCcritical. After initial air exposure, the relative maximum electron transport rate of both seagrasses increased gradually to a maximum and then decreased to initial value near the RWCcritical. Therefore, short-term air exposure above the RWCcritical is beneficial for both seagrasses, and the RWCcritical should be considered when examining the response of seagrass photosynthesis to air exposure and selecting transplantation sites.
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dynamics of nonstructural carbohydrates in seagrass Thalassia hemprichii and its response to shading
Acta Oceanologica Sinica, 2013Co-Authors: Zhijian Jiang, Xiaoping Huang, Jingping ZhangAbstract:A field survey was performed to examine nonstructural carbohydrate (NSC) dynamics in seagrass Thalassia hemprichii at the Xincun Bay in southern China. An indoor experiment to investigate the response of NSC in T. hemprichii to shade was conducted. Belowground tissue of T. hemprichii was the dominant site of NSC reserves, and soluble sugar was the primary storage compound. The starch content of belowground tissue was lower in high intertidal areas than in low intertidal areas, indicating that the longer air exposure in high intertidal areas resulted in less NSC synthesis and less accumulation of NSC in T. hemprichii. The lowest level of soluble sugar and its proportion to NSC in belowground tissue were observed near the cage culture area, where the nutrient concentration in water and sediment was the highest; while the highest level of that was observed near the coastal shrimp farm, Where salinity was the lowest. Soluble sugar in belowground tissue showed the following trend: summer>spring>winter>autumn. This corresponded to seasonal changes in the intensity of light. Leaf sugar accumulated during the autumn-winter period, providing a carbon and energy source for flower bud formation and seed germination. Short-term shading decreased NSC accumulation. Collectively, these results suggest that nutrient enrichment, freshwater discharge and exposure to air affect NSC dynamics in T. hemprichii. Light intensity, flower bud formation, and seed germination were all found to induce seasonal variations in NSC in T. hemprichii.
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effect of nitrate enrichment and salinity reduction on the seagrass Thalassia hemprichii previously grown in low light
Journal of Experimental Marine Biology and Ecology, 2013Co-Authors: Zhijian Jiang, Xiaoping Huang, Jingping ZhangAbstract:A sub-acute experiment that tested carbon and nitrogen metabolisms and the plant's antioxidant defence system was used to investigate the effects of nitrate enrichment and salinity reduction on the tropical seagrass Thalassia hemprichii that had previously been grown in low light conditions. Shading significantly reduced leaf growth rate, nitrate reductase activity and non-structural carbohydrate (NSC) content in both aboveground and belowground tissues, but enhanced superoxide dismutase and guaiacol peroxidase (POD) activities and free amino acids in aboveground tissue. After shade removal, salinity reduction with pre-shading decreased minimum fluorescence and maximum fluorescence under all nitrate conditions. Pre-shading aggravated the negative effect of nitrate enrichment and salinity reduction on leaf growth rate. Nitrate enrichment led to a greater reduction in NSC in aboveground tissues of pre-shading plants compared to the control. Furthermore, salinity reduction with pre-shading even induced effective NSC translocation from belowground to aboveground tissues. Nitrate enrichment and salinity reduction both increased POD activity in T. hemprichii grown previously in low light. Therefore, pre-shading increases the vulnerability of T. hemprichii to eutrophication and hyposalinity, which must be considered when predicting future responses and effective management of seagrass resources. (C) 2013 Elsevier B.V. All rights reserved.
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effects of co2 enrichment on photosynthesis growth and biochemical composition of seagrass Thalassia hemprichii ehrenb aschers
Journal of Integrative Plant Biology, 2010Co-Authors: Zhijian Jiang, Xiaopin Huang, Jingping ZhangAbstract:The effects of CO2 enrichment on various ecophysiological parameters of tropical seagrass Thalassia hemprichii (Ehrenb.) Aschers were tested. T. hemprichii, collected from a seagrass bed in Xincun Bay, Hainan island of Southern China, was cultured at 4 CO2(aq) concentrations in flow-through seawater aquaria bubbled with CO2. CO2 enrichment considerably enhanced the relative maximum electron transport rate (RETRmax) and minimum saturating irradiance (E-k) of T. hemprichii. Leaf growth rate of CO2-enriched plants was significantly higher than that in unenriched treatment. Nonstructural carbohydrates (NSC) of T. hemprichii, especially in belowground tissues, increased strongly with elevated CO2(aq), suggesting a translocation of photosynthate from aboveground to belowground tissues. Carbon content in belowground tissues showed a similar response with NSC, while in aboveground tissues, carbon content was not affected by CO2 treatments. In contrast, with increasing CO2(aq), nitrogen content in aboveground tissues markedly decreased, but nitrogen content in belowground was nearly constant. Carbon: nitrogen ratio in both tissues were obviously enhanced by increasing CO2(aq). Thus, these results indicate that T. hemprichii may respond positively to CO2-induced acidification of the coastal ocean. Moreover, the CO2-stimulated improvement of photosynthesis and NSC content may partially offset negative effects of severe environmental disturbance such as underwater light reduction.
M A Hemminga - One of the best experts on this subject based on the ideXlab platform.
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biomass loss and nutrient redistribution in an indonesian Thalassia hemprichii seagrass bed following seasonal low tide exposure during daylight
Marine Ecology Progress Series, 1997Co-Authors: J Stapel, R Manuntun, M A HemmingaAbstract:The intertidal reef flat of Barang Lompo Island, Indonesia, is exposed to air for several hours per day on the days around spring tides. The time of exposure shows a seasonal pattern. In the period January-June, the reef flat only runs dry at night, whereas in the period July-December, exposure only occurs during daylight. During the low tide daylight exposure period of July-December 1993, the leaf and rhizome biomasses (g m(-2)) declined significantly by 61 and 37%, respectively. Total rhizome length remained unchanged. C- and P-concentrations (% of dry weight) of leaves showed no change, while the leaf N- concentration increased by 25%. C-, N- and P-contents of leaves showed a decline that was strongly correlated to leaf biomass decline. In the rhizomes, C-concentration declined by 8%, but the N- and P-concentrations increased by 111 and 25%, respectively. Rhizome C-content (g m(-2)) declined (43%), N- content increased (46%) and P-content did not change. Total C- and P-contents of the summed biomass of leaves and rhizomes declined by 46 and 34%, respectively, but N-content showed no change. Ammonium and phosphate concentrations in the water column and pore water phosphate were not significantly different during daylight exposure compared to during nocturnal exposure. Ammonium concentration in the pore water, however, was 1.6 times higher during daylight exposure. Results show that during a period of frequent daylight exposure, the nutrient status in the intertidal Thalassia hemprichii seagrass bed changed considerably. Despite biomass reduction, the total nitrogen content in leaves and rhizomes together was constant, which was achieved by an enhanced nitrogen accumulation in the rhizomes. Two theories possibly responsible for the stable sum of the total leaf and rhizome nitrogen content are discussed. The first theory describes the seagrass bed as a relatively closed system with respect to nutrient cycles: detached leaf fragments remain trapped within the meadow. The second theory postulates that the loss of part of the photosynthesising canopy due to daylight exposure has a series of consequences for microbial N-transformation processes in the sediment, which indirectly affects the plants' nitrogen status. This study shows that Thalassia hemprichii, covering the reef flat of an intertidal tropical offshore coral island, which is often considered as a nutrient-poor environment, is rather resilient to a significant canopy die-off and concomitant nutrient losses. [KEYWORDS: daylight exposure; seagrass; biomass redistribution; nutrient contents; Thalassia hemprichii; Indonesia South sulawesi indonesia; banks ex konig; cymodocea-nodosa; syringodium filiforme; terrigenous sediments; zostera capricorni; halodule-wrightii; leaf growth; testudinum; carbonate]
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nutrient uptake by leaves and roots of the seagrass Thalassia hemprichii in the spermonde archipelago indonesia
Marine Ecology Progress Series, 1996Co-Authors: J Stapel, T L Aarts, De Groot Jd, M A HemmingaAbstract:The kinetics of ammonium and phosphate uptake by leaves and roots of the tropical seagrass Thalassia hemprichii were investigated in laboratory experiments. Uptake in leaves of plants from 3 different locations, covering the range from coastal to oceanic conditions in the region of investigation (Spermonde Archipelago, South Sulawesi, Indonesia), was compared. The leaves from all plant samples showed a clear capacity for both ammonium and phosphate uptake. This uptake could be described by Michaelis-Menten kinetics. v(max) ranged between 32 and 37 mu mol g(-1) leaf dry weight h(-1) for ammonium and between 2.2 and 3.2 mu mol g(-1) leaf dry weight h(-1) for phosphate. K-m ranged between 21 and 60 mu M for ammonium and between 7.7 and 15 mu M for phosphate. There was no significant site difference in uptake characteristics (v(max) and K-m) of ammonium and phosphate. Uptake of ammonium and phosphate by roots was investigated with plants from the intermediate location, Barang Lompo, using an approach which allowed only calculation of uptake rates at natural pore water concentrations. Uptake rates were 22 and 1.0 mu mol g(-1) root dry weight h(-1) for ammonium and phosphate, respectively Calculations suggest that at all 3 locations uptake of ammonium and phosphate by roots was probably limited by the diffusion of nutrients in the sediment rather than by their uptake capacity. Evidence was found that the availability of nutrients in the root zone relative to the leaf zone affects the uptake affinity of the leaves. The role of roots versus leaves in supplying plant nutrients is discussed. We concluded that even in the tropics, where water column nutrient concentrations are often very low, leaves clearly have a significant ability for ammonium or phosphate uptake and that in some situations nutrient uptake by the leaves may even be essential in meeting plant nutrient demands. [KEYWORDS: ammonium; phosphate; nutrient uptake kinetics; leaves; roots; seagrass; Thalassia hemprichii; Indonesia Zostera-marina-l; south sulawesi indonesia; phosphorus; epiphytes; release; phosphate; kinetics; biomass; nitrate; ammonia]
Kwangtsao Shao - One of the best experts on this subject based on the ideXlab platform.
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measurement of chlorophyll fluorescence reveals mechanisms for habitat niche separation of the intertidal seagrasses Thalassia hemprichii and halodule uninervis
Marine Biology, 2005Co-Authors: Kwangtsao ShaoAbstract:In Taiwan, Thalassia hemprichii dominates the upper intertidal zone, whereas Haloduleuninervis occupies the lower intertidal zone. We tested the hypothesis that T. hemprichii is better adapted to high irradiance and more resistant to air exposure than H. uninervis. The photosynthetic efficiency, damage, and extent of recovery were determined by measuring chlorophyll fluorescence using pulse amplitude modulated fluorometry. Both species growing in tidal pools, in response to high irradiance alone, revealed a small depression in maximal quantum yield of photosystem II (Fv/Fm) at noon. The second experiment compared the effect of air exposure alone and the combined effect of air exposure with high irradiance by interposing a shading screen on both species, growing in the intertidal zone over a diurnal cycle. Values of Fv/Fm of both the shaded and irradiated T. hemprichii remained high at low tide. However, H. uninervis exhibited a marked depression following air exposure and a synergistic depression under the combined effect. The experimental manipulations of exposure time demonstrated that the tolerance of T. hemprichii to the combined effect was longer and the recovery from air exposure following re-submersion was better than those of H. uninervis. Both species were more susceptible to the combined effect in the dry season than in the wet season. Our results suggest that air exposure is more important than high irradiance in constraining the distribution of H. uninervis in the upper intertidal zone. This was confirmed by transplantation experiments in which a rapid decline of H. uninervis was observed after transplantation into the upper intertidal zone. In the lower intertidal zone, measurements of the response of the photosynthetic electron transport rate to irradiance demonstrated that the transplanted T. hemprichii exhibited a sun-type response and H. uninervis a shade-type response.
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temporal changes in the abundance and growth of intertidal Thalassia hemprichii seagrass beds in southern taiwan
Botanical Bulletin of Academia Sinica, 1998Co-Authors: Kwangtsao ShaoAbstract:A bimonthly study of temporal changes in abundance and growth of the tropical seagrass Thalassia hemprichii on intertidal reef flats was conducted in southern Taiwan from October 1995 to December 1996. Thalassia hemprichii showed a marked temporal pattern in percentage cover, shoot density, and specific growth rate. There were no significant differences in the variables of T. hemprichii between the study sites. The percentage cover showed a unimodal or bimodal pattern in which one peak occurred in June or August and the other occurred in October. The shoot density was highest in June and lowest between December and February. The specific growth rate peaked in October or December, but declined in February or April. However, the temporal patterns in root:shoot ratio of bio- mass were different. Higher root:shoot ratios were observed in December or February, and lower between April and August. The above-ground biomass was always smaller than the below-ground biomass. Canonical correlation analy- sis indicated that temperature, water-column nutrient concentration and rainfall were positively correlated, and day- light exposure time and wind speed negatively correlated, with the dynamics of T. hemprichii. Among these variables, wind speed and rainfall were most responsible for the observed temporal changes in southern Taiwan, which has a monsoonal climate and distinct wet and dry seasons.
Yenhsun Huang - One of the best experts on this subject based on the ideXlab platform.
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carbon budget of leaves of the tropical intertidal seagrass Thalassia hemprichii
Estuarine Coastal and Shelf Science, 2013Co-Authors: Shihhan Chiu, Yenhsun HuangAbstract:Abstract The question of whether seagrass beds are effective carbon sinks has recently attracted much attention. Leaf production and consumption, and detrital export and decomposition were determined to quantify the carbon budget of leaf production in a southern Taiwan seagrass bed composed of the tropical intertidal seagrass Thalassia hemprichii , which is widely distributed in intertidal zones of the western Pacific. The influence of elevation in the intertidal zone on these processes was also investigated. Leaf production and consumption, and export of leaf detritus showed seasonal variations, with higher rates in the wet season (summer and autumn) and lower rates in the dry season (winter and spring). At the high-elevation site, leaf consumption by fish was significantly higher than that by sea urchins. At the low-elevation site, however, the proportion of leaves consumed by sea urchins was equivalent to that by fish. Leaf detritus decomposed rapidly within the first 9 days, then gradually slowed down, and stabilised after 212 days, at which only 8.7% of dry weight remained in the litterbags. The carbon budget of seagrass leaves demonstrated that 20% of leaf production was grazed by fish and sea urchins and 80% flowed to detritus. This suggests that seagrass leaves are important food sources for inhabiting herbivores. Most of the detritus decomposed (44% of leaf production) or was exported (32% of leaf production), and only 4% of leaf production or 22 g C m −2 yr −1 was stored in this tropical intertidal seagrass bed. Mass balance calculations support this tropical seagrass bed acting as a carbon sink and an outwelling system which exports organic detritus to neighboring coral reefs.