Being a primary producer, Microphytobenthos （MPB） play an important role in the benthic ecosystem of mangrove swamps. The temporal and vertical distribution of MPB biomass, expressed as chlorophyll a （Chl a）, was ...Being a primary producer, Microphytobenthos （MPB） play an important role in the benthic ecosystem of mangrove swamps. The temporal and vertical distribution of MPB biomass, expressed as chlorophyll a （Chl a）, was investigated in mangrove swamps on the Qi＇ao island and the Futian Mangrove Nature Reserve, Guangdong Province, South China. Both locations are situated in the Zhujiang （Pearl River） Estuary. For each location, bi-monthly sampling was carried out at four sites during low tide period. Except one site on the Qi＇ao Island, which was in Phragrnites australis marsh, all sites were in mangrove swamps. The Chl a concentration in surface （0-1 cm） sediment ranged from 0.2/2g/cm3 to 8.3 #g/cm3 in the Qi＇ao Island and from 2.1/zg/cm3 to 15.6/2g/cm3 in the Futian Mangrove Reserve. The peak Chl a concentration occurred in winter or early spring, while the lowest Chl a concentration, with a value of about one quarter of the peak, was observed in summer or early autumn. The vertical distribution of Chl a concentration exhibited an exponential decline with depth, which indicated a muddy sediment with high organic matter, and the slope of the curve was positively related to Chl a concentration in the surface sediment. The MPB biomass of the Qi＇ao Island was significantly lower than that of the Futian Mangrove Reserve. Our results suggest that the overlaying water quality might influence the MPB biomass in surface sediments.展开更多
The feasibility of community-based bioassessment of environmental quality status was studied using microphytobenthos（MPB） in estuarine intertidal ecosystems.The sediment samples of MPB were collected monthly during ...The feasibility of community-based bioassessment of environmental quality status was studied using microphytobenthos（MPB） in estuarine intertidal ecosystems.The sediment samples of MPB were collected monthly during a 1-year cycle（September 2006-August 2007） at four sampling stations in the Nakdong River Estuary,Korea.Environmental variables,such as salinity,radiation,grain size of sediment,Si（OH）4（Si）,nitrate（NO3^-）,nitrite（NO2^-）,ammonium（NH4~＋） and phosphates（PO4^（3-））,were measured synchronously for comparison with biotic parameters.The statistical analyses were carried out for assessment the relationship between biotic and environmental parameters.The results showed that：（1） the MPB community structures were significant differences among four sampling stations;（2） spatial variation in the MPB communities were significantly correlated with environmental variables,especially the nutrient NH4＋ in combination with salinity and grain size;（3） three species（Navicula lacustris,Pleurosigma anglulatum and Fragilaria sp.1） were significantly correlated with nutrients and/or Si;and（4） the species richness and diversity were significantly correlated with the grain size.It is suggested that MPB communities may be used as a potentially robust bioindicator for assessing environmental quality status in estuarine intertidal ecosystems.展开更多
Abstract Behavioral and physiological responses to light are the two major mechanisms by which natural microphytobenthic assemblages adapt to the intertidal environment and protect themselves from light stress. The pr...Abstract Behavioral and physiological responses to light are the two major mechanisms by which natural microphytobenthic assemblages adapt to the intertidal environment and protect themselves from light stress. The present study investigated these photoresponses with different light intensities over 8 h of illumination, and used a specific inhibitor （Latrunculin A, Lat A） for migration to compare migratory and non-migratory microphytobenthos （MPB）. Photosynthetic activity was detected using rapid light curves and induction curves by chlorophyll fluorescence. It showed distinct variation in migratory responses to different light intensities; high light induced downward migration to avoid photoinhibition, and low and medium light （50-250 ~tmol/（m2. s）） promoted upward migration followed by downward migration after certain period of light exposure. No significant difference in non-photochemical quenching （NPQ） or PSII maximal quantum yidd （Fv/Fm） was detected between low and medium light irradiance, possibly indicating that only high light influences the photosynthetic capability of MPB. Decreased photosynthetic activity, indicated by three parameters, the maximum relative electron transport rate （rETRmax）, minimum saturating irradiance （E0 and light utilization coefficient （a）, was observed in MPB after exposure to prolonged illumination under low and medium light. Lat A effectively inhibited the migration of MPB in all light treatments and induced lower Fv/Fm under high light （500 and 100 μmol/（m2·s）） and prolonged illumination at 250 μmol/（m2·s）, but did not significantly influence Fv/Fm under low light （0-100 μmol/（m2·s）） or NPQ. The increase of NPQ in Lat A treatments with time implied that the MPB assemblages can recover their physiological photoprotection capacity to adapt to light stress. Non-migratory MPB exhibited lower light use efficiency （lower a） and lower maximum photosynthetic capacity （lower rETRm^x） than migratory MPB under light intensities above 250μmol/（m2. s） after 4.0 h illumination.展开更多
C. taylorii （Chrysophaeum taylorii） Lewis and Bryan （Pelagophyceae） are benthic mucilage-producing microalgae recently recorded in the Mediterranean Sea, where its summer blooms are having detrimental effects on b...C. taylorii （Chrysophaeum taylorii） Lewis and Bryan （Pelagophyceae） are benthic mucilage-producing microalgae recently recorded in the Mediterranean Sea, where its summer blooms are having detrimental effects on benthic communities, fisheries and tourism, especially along the Sardinian coasts （western Mediterranean Sea）. Although few informations on the bloom dynamics of this microalga are available in literature jet, recent studies have hypothesized that sea water temperature plays a major role in determining the distribution and abundance of C. taylorii. The goal of this pilot study was to verify the above-mentioned statement providing experimental evidence for it. To this purpose, C. taylorii presence and abundance were investigated along a temperature gradient near the powerhouse of Torre Valdaliga （Latium coasts）, where a stream of hot water is continuously pumped out from the powerhouse into the sea. The obtained data showed that C. taylorii abundance was significantly higher in the study sites nearer to the powerhouse and a positive correlation between water temperature and cell densities was found, thus confirming that water temperature is one of the environmental variables directly influencing the bloom dynamics of this microalga in the Mediterranean Sea.展开更多
Microphytobenthos and sea ice algae comprise globally significant photosynthetic biofilms.While their microalgal and bacterial constituents are well characterized,there is very little information on their viral commun...Microphytobenthos and sea ice algae comprise globally significant photosynthetic biofilms.While their microalgal and bacterial constituents are well characterized,there is very little information on their viral communities or on the virus-bacteria and virus-algae interactions within them.While high levels of interaction might be expected because of the high density of cells,infection rates,particularly of microalgae,have been found to be low.It remains unclear whether this is a result of environment characteristics,developed resistance or because of the small number of studies.展开更多
基金The National Natural Science Foundation-Joint Founds of Guangdong Province under contract No.U0633002the NationalNatural Science Foundation of China(NSFC)under contract No.31070470the Project of Science and Technology Bureau of Zhuhai City undercontract No.200901023
文摘Being a primary producer, Microphytobenthos （MPB） play an important role in the benthic ecosystem of mangrove swamps. The temporal and vertical distribution of MPB biomass, expressed as chlorophyll a （Chl a）, was investigated in mangrove swamps on the Qi＇ao island and the Futian Mangrove Nature Reserve, Guangdong Province, South China. Both locations are situated in the Zhujiang （Pearl River） Estuary. For each location, bi-monthly sampling was carried out at four sites during low tide period. Except one site on the Qi＇ao Island, which was in Phragrnites australis marsh, all sites were in mangrove swamps. The Chl a concentration in surface （0-1 cm） sediment ranged from 0.2/2g/cm3 to 8.3 #g/cm3 in the Qi＇ao Island and from 2.1/zg/cm3 to 15.6/2g/cm3 in the Futian Mangrove Reserve. The peak Chl a concentration occurred in winter or early spring, while the lowest Chl a concentration, with a value of about one quarter of the peak, was observed in summer or early autumn. The vertical distribution of Chl a concentration exhibited an exponential decline with depth, which indicated a muddy sediment with high organic matter, and the slope of the curve was positively related to Chl a concentration in the surface sediment. The MPB biomass of the Qi＇ao Island was significantly lower than that of the Futian Mangrove Reserve. Our results suggest that the overlaying water quality might influence the MPB biomass in surface sediments.
基金The National Natural Science Foundation of China under contract No.41276137the Public Science and Technology Research Funds Projects of Ocean under contract No.201305030
文摘The feasibility of community-based bioassessment of environmental quality status was studied using microphytobenthos（MPB） in estuarine intertidal ecosystems.The sediment samples of MPB were collected monthly during a 1-year cycle（September 2006-August 2007） at four sampling stations in the Nakdong River Estuary,Korea.Environmental variables,such as salinity,radiation,grain size of sediment,Si（OH）4（Si）,nitrate（NO3^-）,nitrite（NO2^-）,ammonium（NH4~＋） and phosphates（PO4^（3-））,were measured synchronously for comparison with biotic parameters.The statistical analyses were carried out for assessment the relationship between biotic and environmental parameters.The results showed that：（1） the MPB community structures were significant differences among four sampling stations;（2） spatial variation in the MPB communities were significantly correlated with environmental variables,especially the nutrient NH4＋ in combination with salinity and grain size;（3） three species（Navicula lacustris,Pleurosigma anglulatum and Fragilaria sp.1） were significantly correlated with nutrients and/or Si;and（4） the species richness and diversity were significantly correlated with the grain size.It is suggested that MPB communities may be used as a potentially robust bioindicator for assessing environmental quality status in estuarine intertidal ecosystems.
基金Supported by the National Natural Science Foundation of China(No.41276137)the Public Science and Technology Research Funds Projects of Ocean(No.201305030)
文摘Abstract Behavioral and physiological responses to light are the two major mechanisms by which natural microphytobenthic assemblages adapt to the intertidal environment and protect themselves from light stress. The present study investigated these photoresponses with different light intensities over 8 h of illumination, and used a specific inhibitor （Latrunculin A, Lat A） for migration to compare migratory and non-migratory microphytobenthos （MPB）. Photosynthetic activity was detected using rapid light curves and induction curves by chlorophyll fluorescence. It showed distinct variation in migratory responses to different light intensities; high light induced downward migration to avoid photoinhibition, and low and medium light （50-250 ~tmol/（m2. s）） promoted upward migration followed by downward migration after certain period of light exposure. No significant difference in non-photochemical quenching （NPQ） or PSII maximal quantum yidd （Fv/Fm） was detected between low and medium light irradiance, possibly indicating that only high light influences the photosynthetic capability of MPB. Decreased photosynthetic activity, indicated by three parameters, the maximum relative electron transport rate （rETRmax）, minimum saturating irradiance （E0 and light utilization coefficient （a）, was observed in MPB after exposure to prolonged illumination under low and medium light. Lat A effectively inhibited the migration of MPB in all light treatments and induced lower Fv/Fm under high light （500 and 100 μmol/（m2·s）） and prolonged illumination at 250 μmol/（m2·s）, but did not significantly influence Fv/Fm under low light （0-100 μmol/（m2·s）） or NPQ. The increase of NPQ in Lat A treatments with time implied that the MPB assemblages can recover their physiological photoprotection capacity to adapt to light stress. Non-migratory MPB exhibited lower light use efficiency （lower a） and lower maximum photosynthetic capacity （lower rETRm^x） than migratory MPB under light intensities above 250μmol/（m2. s） after 4.0 h illumination.
文摘C. taylorii （Chrysophaeum taylorii） Lewis and Bryan （Pelagophyceae） are benthic mucilage-producing microalgae recently recorded in the Mediterranean Sea, where its summer blooms are having detrimental effects on benthic communities, fisheries and tourism, especially along the Sardinian coasts （western Mediterranean Sea）. Although few informations on the bloom dynamics of this microalga are available in literature jet, recent studies have hypothesized that sea water temperature plays a major role in determining the distribution and abundance of C. taylorii. The goal of this pilot study was to verify the above-mentioned statement providing experimental evidence for it. To this purpose, C. taylorii presence and abundance were investigated along a temperature gradient near the powerhouse of Torre Valdaliga （Latium coasts）, where a stream of hot water is continuously pumped out from the powerhouse into the sea. The obtained data showed that C. taylorii abundance was significantly higher in the study sites nearer to the powerhouse and a positive correlation between water temperature and cell densities was found, thus confirming that water temperature is one of the environmental variables directly influencing the bloom dynamics of this microalga in the Mediterranean Sea.
基金This study was funded by the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.2018SDKJ0406-6)National Key Research and Development Program of China(2018 YFC1406704)+1 种基金The Fundamental Research Funds for the Central Universities(201812002)the Natural Science Foundation of China(Nos.41976117 and 41606153).
文摘Microphytobenthos and sea ice algae comprise globally significant photosynthetic biofilms.While their microalgal and bacterial constituents are well characterized,there is very little information on their viral communities or on the virus-bacteria and virus-algae interactions within them.While high levels of interaction might be expected because of the high density of cells,infection rates,particularly of microalgae,have been found to be low.It remains unclear whether this is a result of environment characteristics,developed resistance or because of the small number of studies.
