Jauffrais, ThierryBrisset, MaeleLagourgue, LauraPayri, Claude E....
9页
查看更多>>摘要：To assess the photophysiological capacity of the recently described Ulva batuffolosa to form blooms in coral reefs, we monitored its biomass and photophysiological capacity with pulse amplitude modulated (PAM) fluorometry over a year period on a coastal barrier reef in New Caledonia, along with temperature and light. Effective and maximum quantum efficiencies of the photosystem II measured on this Ulva species indicated that the algae was in a "good health " all over the year with high quantum efficiencies under either light (Fq'/Fm') or dark incubated conditions and (Fv/Fm). Photo-acclimation and-regulation status used by this Ulva sp. were driven by seasons (i. e., light and temperature) in the lagoon. Although photo-inhibition was an evidence during the warm period, U. batuffolosa was overall well adapted to tolerate the range of irradiance and temperature that characterized the lagoon over the year, which suggests that photosynthesis is not an impediment to green tides by this species.
查看更多>>摘要：The decomposition process in wetlands is affected by various factors, among which hydrology and litter quality are very important. We studied the decomposition rate of Phragmites australis upper and lower leaf litter from the lake and the riparian sites at the intermittent Lake Cerknica (Slovenia), exposed to flooded and dry conditions. Xray fluorescence spectrometry revealed that leaf litter element composition was related to soil element composition. Fresh leaves also differed according to their age, especially regarding leaf silicon, which ranged from 2.8% to 6.1% dry matter, and leaf phosphorus, which ranged from 0.12% to 0.17% dry matter for the different leaf groups. According to factorial ANOVA, leaf litter decomposition rate was significantly affected by sampling site, exposure location, and leaf age (p <= 0.01). Decomposition rate was significantly lower at the dry location compared to the flooded location, and was not related to leaf silicon content. However, leaf sulphur, chlorine, and calcium contents had a significant positive impact on leaf litter decomposition rate at both the dry and the flooded locations. Leaf phosphorus significantly positively affected leaf litter decomposition rate only at the dry location.
查看更多>>摘要：Brown algae have the unique ability to produce phlorotannins, which are phenolics with potent antioxidant capacity. These valuable metabolites have numerous applications in medicine, cosmetics, and food industries. Therefore, it is extremely important to develop strategies to continuously produce these compounds without having to constantly harvest seaweeds from the environment. In this work, the possibility of growing Fucus spiralis under artificial conditions by tissue culture techniques was evaluated and optimized. After growing for four months, callus were excited from the original explants and evaluated for phlorotannin content by the FolinCiocalteu method and scavenging potential by the 2,2-diphenyl-2-picrilhidrazil (DPPH) scavenging assay. Phlorotannin content and scavenging potential were compared with wild-collected tissue. Fucus spiralis grown callus exposed to 60 mu mol photons.m(-2).s(-1) presented the highest phlorotannins' content and the highest scavenging potential with 250.02 +/- 7.24 mg phloroglucinol equivalents/g extract and an IC50 of 125.2 (101.3-139.5) mu g/mL, respectively. This research represents the first evaluation of the potential of Fucus spiralis to be cultured under artificial conditions for phlorotannins extraction, opening a new window for further optimization and development of photobioreactors for continuous phlorotannins production.
O'Connor, Mary I.Griffiths, GwendolynSanders-Smith, RheaHessing-Lewis, Margot...
12页
查看更多>>摘要：In aquatic foundation species, composition and abundance of associated epibionts can change substantially over small spatial distances. Such spatial variation can reflect top-down control by consumers, bottom-up control by abiotic factors or facilitation, or a combination of processes. We used visual and molecular surveys to describe spatial patterns in the abundance and distribution of the epiphytic red macroalga Smithora naiadum in a meadow of the seagrass Zostera marina on the Central Coast of British Columbia. We detected Smithora using 18 S ribosomal RNA molecular marker throughout the seagrass meadow at both interior and edge sites, even in the absence of macroscopic Smithora. We used a reciprocal transplant experiment to test two hypotheses: that patterns in Smithora abundance reflect local environmental conditions, or alternately, that patterns reflect spatial variation in the host plant attributes, microbiota and grazers. Zostera shoots hosted more Smithora at meadow edges relative to meadow interior sites, and shoots with Smithora were associated with distinct invertebrate grazer and bacterial communities relative to shoots 5 m in from the meadow edge without Smithora. Macroscopic Smithora grew on shoots experimentally transplanted from the interior to the meadow edge and shoots hosting Smithora that were transplanted to the interior did not lose Smithora. Our survey and experimental results suggest that presence of macroscopic Smithora blades on Zostera shoots changes the Zostera microbiota. Altogether, we conclude that environmental variation, not host plant attributes or dispersal limitation, affects Smithora colonization on Zostera, and once established, Smithora alters the microbiota on Zostera.
Kim, Jang K.Xing, QikunKim, Young WooKim, Daehyeon...
4页
查看更多>>摘要：Oxybenzone is one type of ultraviolet (UV) filters that have been widely used as active ingredients in sunscreen and personal care products. The input of oxybenzone in the ocean through wastewater and swimmers has been a serious environmental pollution issue. Although oxybenzone has been reported as a toxicant to some marine animals and microalgae, its toxicity effect on macroalgae is still unknown. This study investigates the physiological responses of an aquaculture red macroalga, Gracilaria vermiculophylla, after twenty-days exposure to three different concentrations (0.1, 0.001 and 0.00001 mM) of oxybenzone. At the concentration of 0.1 mM, oxybenzone significantly decreased the growth rate, pigment content and photosynthetic rate, suggesting a high toxicity to G. vermiculophylla. At other two lower concentrations, oxybenzone induced no significant changes on physiological responses besides a decrease of pigment content at 0.001 mM. Our results revealed the toxicity and tolerance of oxybenzone on G. vermiculophylla.
查看更多>>摘要：Although macroalgae is regarded as the emerging fourth category of "blue carbon ", few studies are available on its carbon sequestration and DOC (dissolved organic carbon) release mechanism at present. In addition, tidal action is an important environmental factor in the intertidal zone, which affects the carbon sequestration and DOC release of macroalgae. Therefore, we set 4-h desiccation and 1-h rehydration to examine the effects of drying-rewetting on the photosynthetic carbon fixation capacity and DOC release mechanism of Sargassum thunbergii. The flowing seawater can provide the nutrients for the growth of marine plants, which plays a vital role in the growth and reproduction of marine plants, so a measurement system that can adjust the flow speed was designed to study the effects of 1 h-rehydration on S. thunbergii. The results showed the desiccation decreased carbon fixation capacity, but increased the protection of PSII by down-regulating F-v/F-m and Phi(PSII) and up regulating NPQ, thereby promoting the recovery of carbon fixation capacity during 1-h rehydration period. It was found that the DOC release rate of S. thunbergii decreased with the carbon fixation rate increase and it was much greater than the carbon fixation rate in the 1-h rehydration period. The DOC release after rehydration was somehow a passive release, which was related to the increase of osmotic pressure, cell membrane damage, and carbon accumulation caused by desiccation. This measurement system can provide a practical reference for the study of carbon sink of macroalgae.
查看更多>>摘要：Coastal ecosystems are increasingly affected by recurring and frequent extreme temperature events as well as by high nutrient load. Current warming scenarios indicate that rapidly fluctuating temperatures will become the norm; however, the interactive effects of global and local stressors on the performance of coastal species (especially under environmental fluctuations) have not been investigated. This study evaluated the combined effects of elevated temperature and nitrogen enrichment on the ecophysiology of algae Pyropia haitanensis. Algae were exposed to three different temperature regimes (20 degrees C, 24 degrees C, and increasing from 20 degrees C to 24 degrees C, then decreasing to 20 degrees C at a rate of 1 degrees C per day) and two nutrient concentrations (40 mu mol center dot L-1 and 300 mu mol center dot L-1). The resulting growth rates, photosynthetic performances, and photosynthetic pigment concentrations were determined and compared between treatments. All three metrics increased with increasing temperature, but decreased when the temperature increased at the thermal threshold of P. haitanensis (24 degrees C). Moreover, under fluctuating temperatures condition, both growth and pigment contents increased significantly. These results indicate that in current warming scenarios, both the yield and quality of P. haitanensis would improve. This effect is further increased by elevated nitrogen supply, due to coastal eutrophication.
NSTL
Elsevier