Primary production dynamics of dominant hydrophytes in Lake Provala (Serbia)

The objective of this investigation was to analyze the primary production of the dominant hydrophytes by monitoring levels of organic matter and organic carbon and estimating photosynthetic potential via the total chlorophyll content. The survey was conducted in Lake Provala (Serbia) throughout the peak vegetation period of the year 2000. The contents of organic matter and organic carbon for Myriophyllum spicatum L. were 105.11 g m⁻² and 73.66 g m⁻², Nymphoides peltata (Gmel.) Kunt. were 95.51 g m⁻² and 45.26 g m⁻² and Ceratophyllum demersum L. were 52.17 g m⁻² and 29.75 g m⁻². Chlorophyll A (Chl a) and chlorophyll A+B (Chl a+b) pigments ranged from 1.54 mg g⁻¹(Chl a) and 2.1 mg g⁻¹(Chl a+b) in M. spicatum to 5.27 mg g⁻¹(Chl a) and 7.53 mg g⁻¹(Chl a+b) in C. demersum. At full leaf out, the latter aquatic plants exceeded 50% cover of the open water surface. All species achieved maximum growth in June, but significant differences in growth dynamics were observed. At the end of the vegetation period, these plants sink to the bottom and decompose     

Mercury in the muscle tissue of fish in the Central and South Vietnam

The content of mercury has been determined in the muscle tissue of 18 fish species in rivers, lakes, and reservoirs of Central and South Vietnam. The region is characterized by lower metal concentrations than those in water bodies in temperate and northern latitudes. In 76% of samples (n = 986), the content of Hg was ≤0.5 μg Hg/g of dry (≤0.1 μg/g of wet) tissue weight. In water bodies and watercourses of tropical latitudes, interspecific variations in fish can be one of the factors responsible for a wide range of Hg variation within the same species.     

Diurnal variations of chlorophyll and dry matter contents of Senna occidentalis in response to zinc and soil moisture

The effect of concentration of zinc ions on chlorophyll (Chl) and dry matter contents in Senna occidentalis (L.) Link plants was studied under various availability of soil water. Diurnally, the internal Zn2+ content was predominantly affected by supplied Zn2+ and by daytime (Tm). Chl content, Chl a/b ratio, and Chl stability to heat were mainly affected by soil water content, and the dry matter content depended mostly on Tm. This revised version was published online in August 2006 with corrections to the Cover Date.     

Impacts of seabird-derived nutrients on water quality and diatom assemblages from Cape Vera,Devon Island,Canadian High Arctic

Relationships between key phytoplankton attributes including Chl a-specific light absorption, pigment composition and concentration, photosynthesis, primary production and community structure were studied in two open shallow nutrient-poor coastal systems receiving similar amounts of sewage water. Both systems were significantly nitrogen limited. However, differences in wastewater treatment (primary vs secondary) and sewage dilution (50%) between the two systems caused a greater difference between systems than locally around the outflows. For both systems, water at the outlet had significantly lower water transparency caused by a 20% higher absorption by coloured dissolved organic matter. Nutrient concentrations were also elevated, gradually decreasing with distance north (governing current) of the outflows, causing higher abundance of nano-sized phytoplankton, higher content of carotenoid pigments, 20–50% higher Chl a-specific absorption coefficients and higher photosynthetic capacity. Although maximum rates of Chl a-normalised photosynthesis were strongly related to nitrate availability, no effects were found on the derived areal primary production or algal biomass suggesting that photosynthetic and optical parameters are more sensitive indicators of nutrient enrichment than biomass or productivity. Handling editor: Tasman Peter Crowe     

The rapid yellowing of spruce at a mountain site in the Central Black Forest (Germany). Combined effects of Mg deficiency and ozone on biochemical, physiological and structural properties of the chloroplasts

Biochemical, physiological and ultrastructural changes of the chloroplasts were examined in the course of the rapid yellowing process of spruce (Picea abies (L.) Karst.) at a Mg-deficient and ozone polluted mountain site (Sch?llkopf mountain, Central Black Forest, Germany, 840 m a.s.l.). While at an early stage of yellowing the chlorophyll (Chl) content of the needles decreased slowly, significant changes occurred in the chloroplasts: The lability of the light-harvesting Chl a/b protein complex LHC II increased; the thylakoid cross-sectional area of chloroplasts in the outer mesophyll of the needles decreased, and their Chl fluorescence showed typical changes like the decrease of Fv/Fm and the increase of the photoinhibitory Fv quenching. Later on, the Chl content decreased rapidly, the changes in the chloroplasts continued and the needles turned yellow. Lutein and the pigments of the xanthophyll cycle were enhanced in relation to Chl a. Light and dark reactions of the xanthophyll cycle were highly active indicating efficient proton pumping and NADPH formation. The ratio of nonappressed to appressed thylakoid membranes increased with decreasing Fv/Fm suggesting that structural and fluorescence properties of the chloroplasts were related. The response of the needles to defined shading and improved Mg supply was also examined. The combined effects of strong sun light, low levels of non-Chl-bound Mg (Mg(free)) and ozone concentrations exceeding 80 microg m(-3) are shown to be necessary to induce the rapid yellowing process. For needles with Mg(free) < 0.12 mg g(-1) needle dry matter, the lability of the LHC II was correlated with the ozone concentration suggesting that the destabilization of the LHC II plays a central role in the rapid yellowing process.     

The influence of water quality and sediment geochemistry on the horizontal and vertical distribution of phosphorus and nitrogen in sediments of a large,shallow lake

Distinct horizontal water column concentration gradients of nutrients and chlorophyll a (Chl a) occur within large, shallow, eutrophic Lake Taihu, China. Concentrations are high in the north, where some of the major polluted tributaries enter the lake, and relatively low in the south, where macrophytes generally are abundant. It is not clear, however, whether these water column concentration gradients are similarly reflected in spatial heterogeneity of nutrient concentrations within the bottom sediments. The main objective of this study was therefore to test if horizontal and vertical variations in the phosphorus and nitrogen content in bottom sediments of Lake Taihu are significantly related to (1) horizontal variations in overlying water column nutrient concentrations and (2) other sediment geochemical constituents. We measured the concentration of total phosphorus (TP) and total nitrogen (TN) in surficial sediments (0–2 cm) and TP, TN and Chl a concentrations in water column samples, collected from 32 sites in 2005. In 2006 sediment, TP, TN, carbon, iron and manganese concentrations were measured vertically at 2 cm intervals, extending to a depth of approximately 20 cm, at an additional eight sites. Linear correlation analysis revealed that surficial sediment TP concentrations across the 32 stations were related significantly, though weakly, to annual mean water column concentrations of TP, TN as well as Chl a. Correlations of surficial sediment TN with water column variables were, however, not significant (P > 0.05). Amongst the geochemical variables tested, the vertical variability of sediment TP concentrations was most strongly related to sediment manganese and carbon concentrations. A multiple stepwise linear regression revealed that the combination of sediment manganese and carbon concentrations explained 91% of the horizontal variability in sediment TP concentrations and 65% of the vertical variability. Handling editor: Luigi Naselli-Flores     

The chlorophyll content in water and bottom sediments of the Rybinsk Reservoir

The seasonal dynamics of chlorophyll content in the plankton and bottom sediments in the Rybinsk Reservoir were studied. The highest temporal (seasonal) variability of the chlorophyll concentration is characteristic of water, and the highest spatial variability is characteristic of bottom sediments (BSs). The positive dependence between the chlorophyll content in water and bottom sediments in the reservoir was revealed, which reflects the role of phytoplankton in the formation of bottom biotopes productivities. Average values of the ratio of water and BS chlorophyll contents were comparable to the rates of sedimentation as calculated by the data on BS probing.     

The Status and Characteristics of Eutrophication in the Yangtze River (Changjiang) Estuary and the Adjacent East China Sea, China

Eutrophication has become increasingly serious and noxious algal blooms have been of more frequent occurrence in the Yangtze River Estuary and in the adjacent East China Sea. In 2003 and 2004, four cruises were undertaken in three zones in the estuary and in the adjacent sea to investigate nitrate (NO₃–N), ammonium (NH₄–N), nitrite (NO₂–N), soluble reactive phosphorus (SRP), dissolved reactive silica (DRSi), dissolved oxygen (DO), phytoplankton chlorophyll a (Chl a) and suspended particulate matter (SPM). The highest concentrations of DIN (NO₃–N+NH₄–N+NO₂–N), SRP and DRSi were 131.6, 1.2 and 155.6 μM, respectively. The maximum Chl a concentration was 19.5 mg m⁻³ in spring. An analysis of historical and recent data revealed that in the last 40 years, nitrate and SRP concentrations increased from 11 to 97 μM and from 0.4 to 0.95 μM, respectively. From 1963 to 2004, N:P ratios also increased from 30–40 up to 150. In parallel with the N and P enrichment, a significant increase of Chl a was detected, Chl a maximum being 20 mg m⁻³, nearly four times higher than in the 1980s. In 2004, the mean DO concentration in bottom waters was 4.35 mg l⁻¹, much lower than in the 1980s. In comparison with other estuaries, the Yangtze River Estuary was characterized by high DIN and DRSi concentrations, with low SRP concentrations. Despite the higher nutrient concentrations, Chl a concentrations were lower in the inner estuary (Zones 1 and 2) than in the adjacent sea (Zone 3). Based on nutrient availability, SPM and hydrodynamics, we assumed that in Zones 1 and 2 phytoplankton growth was suppressed by high turbidity, large tidal amplitude and short residence time. Furthermore, in Zone 3 water stratification was also an important factor that resulted in a greater phytoplankton biomass and lower DO concentrations. Due to hydrodynamics and turbidity, the open sea was unexpectedly more sensitive to nutrient enrichment and related eutrophication processes.     

Predictive capability of a leaf optical meter for determining leaf pigment status during senescence

We conducted an experiment to assess the predictive capability of a leaf optical meter for determining leaf pigment status of Acer mono Maxim., A. ginnala Maxim., Quercus mongolica Fisch., and Cornus alba displaying a range of visually different leaf colors during senescence. Concentrations of chlorophyll (Chl) a, Chl b, and total Chl [i.e., Chl (a+b)] decreased while the concentration of carotenoids (Car) remained relatively static for all species as leaf development continued from maturity to senescence. C. alba exhibited the lowest average concentration of Chl (a+b), Chl a, and Car, but the highest relative anthocyanin concentration, while Q. mongolica exhibited the highest Chl (a+b), Chl b, and the lowest relative anthocyanin concentration. A. mono exhibited the highest Chl a and Car concentrations. The relationships between leaf pigments and the values measured by the optical meter generally followed an exponential function. The strongest relationships between leaf pigments and optical measurements were for A. mono, A. ginnala, and Q. mongolica (R ² ranged from 0.64 to 0.95), and the weakest relationships were for C. alba (R ² ranged from 0.13 to 0.67). Moreover, optical measurements were more strongly related to Chl a than to Chl b or Chl (a+b). Optical measurements were not related to Car or relative anthocyanin concentrations. We predicted that weak relationships between leaf pigments and optical measurements would occur under very low Chl concentrations or under very high anthocyanin concentrations; however, these factors could not explain the weak relationship between Chl and optical measurements observed in C. alba. Overall, our results indicated that an optical meter can accurately estimate leaf pigment concentrations during leaf senescence — a time when pigment concentrations are dynamically changing — but that the accuracy of the estimate varies across species. Future research should investigate how species-specific leaf traits may influence the accuracy of pigment estimates derived from optical meters.     

Life in the dark: far-red absorbing cyanobacteria extend photic zones deep into terrestrial caves

Chlorophyll (Chl) f and d are the most recently discovered chlorophylls, enabling cyanobacteria to harvest near-infrared radiation (NIR) at 700–780 nm for oxygenic photosynthesis. Little is known about the occurrence of these pigments in terrestrial habitats. Here, we provide first details on spectral photon irradiance within the photic zones of four terrestrial cave systems in concert with a detailed investigation of photopigmentation, light reflectance and microbial community composition. We frequently found Chl f and d along the photic zones of caves characterized by low light enriched in NIR and inhabited by cyanobacteria producing NIR-absorbing pigments. Surprisingly, deeper parts of caves still contained NIR, an effect likely attributable to the reflectance of specific wavelengths by the surface materials of cave walls. We argue that the stratification of microbial communities across the photic zones of cave entrances resembles the light-driven species distributions in forests and aquatic environments.     

The Pool of Chlorophyllous Pigments in Barley Seedlings of Different Ages under Heat Shock and Water Deficit

The effects of a high temperature (3 h, 40°C) and water deficit (45 h on 3% PEG 6000) on the pool of chlorophyllous pigments in the leaves of 4-, 7-, and 11-day-old barley (Hordeum vulgare L.) seedlings were studied. Heating resulted in a decrease in the total content of chlorophylls (Chl) (a + b) in 4-day-old plants but not in the older leaves. Water deficit induced an increase in the pigment content in young seedlings but reduced it in the leaves of 11-day-old plants. In young seedlings, hyperthermia and dehydration affected similarly Chl (a + b) degradation, leading to a marked inhibition of the chlorophyllase (Chlase) activity hydrolyzing Chl to chlorophyllides and phytol. In old leaves, an activation of this enzyme was observed. The stress factors under study affected different stages of pigment biosynthesis. High temperature inhibited the activity of dark and light stages of Chl(a + b) biosynthesis. Dehydration did not change markedly the resynthesis of protochlorophyllide, while the enzymes of the light stage of Chl biosynthesis were activated in young but inhibited in old barley leaves. The results thus obtained allowed us to conclude that heat treatment and dehydration specifically affected the Chl biosynthesis. At the same time, the Chlase response was nonspecific.     

Photosynthetic pigments of plants and lichens inhabiting arctic tundra of West Spitsbergen

The content of photosynthetic pigments and the ratios between them were studied in 71 species of vascular plants, 17 species of Bryophyta, and 10 species of lichens inhabiting West Spitsbergen. With an increase in the level of organization from lichens to vascular plants, the content of photosynthetic pigments (chlorophylls (Chl) and carotenoids (Car)) increased; the Chl a/b ratios and light-harvesting complex values varied independently of organism taxonomy; the Chl/Car ratio tended to increase. The content of pigments is related to taxon advancement at the level of both divisions and higher plant families. In plants inhabiting Arctic region, the pigment content in primitive species was lower than in more advanced ones. In angiosperms inhabiting Spitsbergen, the amount of Chl was lower than in plants inhabiting other botanicgeographical regions.     

Photosynthetic responses to solar UV-A and UV-B radiation in low-and high-altitude populations of <Emphasis Type="Italic">Hippophae rhamnoides</Emphasis>

Two contrasting sea buckthorn (Hippophae rhamnoides L.) populations from the low (LA) and high (HA) altitudinal regions were employed to evaluate the plant physiological responses to solar UV-A radiation and near-ambient UV-B radiation (UV-B+A) under the sheltered frames with different solar ultraviolet radiation transmittance. LA-population was more responsive to solar UV-A. Some modification caused by UV-A only existed in LA-population, such as significant reduction of leaf size, relative water content, and chlorophyll (Chl) b content as well as δ¹³C elevation, coupled with larger increase of contents of total carotenoids (Cars). This higher responsiveness might be an effective pre-acclimation strategy adapting for concomitant solar UV-B stress. Near-ambient UV-B+A radiation caused significant reduction of leaf size and Chl content as well as slight down-regulation of photosystem 2 activity that paralleled with higher heat dissipation, while photosynthetic rate was modestly but significantly increased. The higher photosynthesis under near-ambient UV-B+A radiation could be related to pronounced increase of leaf thickness and effective physiological modification, like the increase of leaf protective pigments (Cars and UV-absorbing compound), constant high photochemical capacity, and improved water economy.     

Combined application of remote sensing and in situ measurements in monitoring environmental processes

Combined use of remote sensing in the visible, infrared and microwave spectral regions, direct in situ measurements and model numerical experiments makes it possible to study inland water bodies as elements of water body-catchment-atmosphere-systems with good spatial and temporal resolution. In this paper examples are presented of the remote sensing methods developed for detection of hydrodynamics of large water bodies (e.g. frontal and upwelling zones, internal waves, warm and cold surface layers), monitoring of chlorophyll concentration, suspended minerals and dissolved organic matter (DOM) in lakes, mapping of shallow water zones, wetlands and landscape structures, monitoring of ecological condition and changes of drainage basins, and studying the state of the atmosphere over lakes and catchment areas.     

Toxicological and teratogenic assessment of bottom sediments from the Rybinsk Reservoir

The toxicity of bottom sediments (BSs) from different parts of the Rybinsk Reservoir has been determined by biotesting. Neither acute nor chronic toxicity are detected for ceriodaphnia Ceriodaphnia affinis Lillijeborg in tests with water extracts of sediments from all the investigated stations. The relative number of Chironomus riparius Meigen larvae with deformed mouth structures in the specimens exposed to the BSs of the reservoir is higher than in the control. Abnormalities of the mentum and mandibules (heavily chitinized structures) were the most often observed pathomorphological disturbances. The results of this study suggest that BSs from the stations located near the Cherepovets Industrial Complex (CIC) may be classified as contaminated.     

穿透雨减少下锐齿栎叶片光合色素季节动态及其反射光谱响应

通过林地穿透雨排除的方法模拟降雨减少,测定河南宝天曼自然保护区锐齿栎叶片光合色素含量与反射光谱的季节变化,对减雨处理造成的光合色素变化及其反射光谱的变化进行了定量分析,并探讨了水分控制条件下反射光谱对叶片光合色素变化的响应机制.结果表明: 锐齿栎叶片的光合色素含量和色素比率均呈现明显的季节变化.减雨样地与对照样地叶片的光合色素含量和比率在生长季的各个时期存在差异,其中,叶片叶绿素b(Chl b)含量的差异显著,说明Chl b对减雨处理的敏感性最高,叶片类胡萝卜素(Car)含量的差异较小,说明Car对减雨处理的敏感性相对较弱.550 nm处的光谱反射率对色素季节变化的响应最敏感,以其构造的简单比值指数(SR_750,550)与叶片Chl a、Chl b、总Chl和Car含量的正相关关系显著,光化学反射指数(PRI)与叶片Car/Chl的负相关关系显著.550 nm处的光谱反射率对减雨处理造成的色素变化响应最为敏感.SR_750,550对减雨处理造成的叶片Chl a、Chl b和总Chl的含量变化表现敏感(P<0.01),对Chl a/b的变化不敏感.PRI对减雨处理造成的叶片Car/Chl变化表现敏感(P<0.01).     

Biological effects of contaminated bottom sediments of water bodies in Central and South Vietnam on aquatic organisms

The levels of metal content and toxicity have been determined in bottom sediments of water bodies in Central and South Vietnam. It is found that the concentration of metals (As, Cr, Cu, Hg, Ni, Pb, and Zn) exceed the value of the abundance of elements in the Earth’s crust, which may be associated with geochemical features of the province. Acute toxicity of water-extracted sediment elutriate for Ceriodaphnia and whole (native) sediments for chironomid larvae is not recorded in any investigated water bodies. An increase in the relative abundance of Chironomus riparius larvae with deformations of mouthpart structures compared to the control was observed for most of the water bodies. This index reaches the value in the Khe River (Cân Th? city). Antenna anomalies prevailed in pathomorphological disorders.     

Effect of zinc and cadmium on physiological and production characteristics in <Emphasis Type="Italic">Matricaria recutita</Emphasis>

Effects of zinc (12–180 μM) alone and in mixtures with 12 μM Cd on metal accumulation, dry masses of roots and shoots, root respiration rate, variable to maximum fluorescence ratio (F_V/F_M), and content of photosynthetic pigments were studied in hydroponically cultivated chamomile (Matricaria recutita) plants. The content of Zn in roots and shoots increased with the increasing external Zn concentration and its accumulation in the roots was higher than that in the shoots. While at lower Zn concentrations (12 and 60 μM) the presence of 12 μM Cd decreased Zn accumulation in the roots, treatment with 120 and 180 μM Zn together with 12 μM Cd caused enhancement of Zn content in the root. Presence of Zn (12–120 μM) decreased Cd accumulation in roots. On the other hand, Cd content in the shoots of plants treated with Zn + Cd exceeded that in the plants treated only with 12 μM Cd. Only higher Zn concentrations (120 and 180 μM) and Zn + Cd mixtures negatively influenced dry mass, chlorophyll (Chl) and carotenoid content, F_V/F_M and root respiration rate. Chl b was reduced to a higher extent than Chl a.     

Pigment patterns in suspended matter from the Elbe estuary,Northern Germany

In the Elbe hardly anything is known about the actual fate of phytoplankton and the resultant pigment composition of suspended matter. As part of a longterm study on the role of suspended matter in the cycles of nitrogen and associated oxygen consumption processes in the Elbe estuary in northern Germany (‘Sonderforschungsbereich 327 Elbe’ project) and the characterization of estuarine and coastal water bodies with regard to the transport of pollutants such as heavy metals, we have started to characterize suspended matter with regard to the pigments present therein. This will allow us to study phytoplankton turnover and to determine the role of phytoplankton decay mechanisms in the mobilization, binding, and transport of pollutants associated with particulate matter. Our first data on the pigment composition of suspended matter from the Elbe and particularly over the region of Hamburg harbour, obtained using a High Performance Liquid Chromatography (HPLC) method, is presented. The pigment concentrations varied considerably over the summer months. Values up to 250 mg l⁻¹ of chlorophyll a were observed upstream of Hamburg. We found that on its course through Hamburg the concentrations (μg g⁻¹ of particulate matter) of all pigments in the Elbe drop to under half those found upstream of Hamburg. The pigment concentrations in the turbidity maximum were significantly lower than in the rest of the estuary due to the decline of algae as a result of inadequate light conditions and the salinity gradient. The highest particulate matter concentrations were found in the turbidity maximum and just downstream of Hamburg. The highest particulate organic carbon values were found just downstream of Hamburg. The presence of of fucoxanthin and the chlorophyllsc andb, and the changes in pigment patterns were indicative for the dominant algal classes and the phytoplankton succession in the suspended matter. The ratio of chlorophylla to lutein was found to be a possible indicator of phytoplankton breakdown.     

Spatial-temporal variation of Aureococcus anophagefferens blooms in relation to environmental factors in the coastal waters of Qinhuangdao,China

The brown tides occurring in the coastal scallop cultivation area of Qinhuangdao, China, in recent years are caused by Aureococcus anophagefferens and significantly impact the scallop industry and the marine ecosystem in this region. Long-term investigations of phytoplankton and hydrological variables in the Qinhuangdao sea area were conducted in this study to understand the spatial-temporal variations of A. anophagefferens in relation to environmental factors. Samples were collected during twelve cruises from July 2011 to December 2013 and were analyzed for the temperature, salinity, dissolved oxygen (DO), nutrients and phytoplankton pigments. All diagnostic pigments of A. anophagefferens, such as chlorophyll c₃ (Chl c₃), Chl c₂, 19′-butanoyloxyfucoxanthin (But-fuco), fucoxanthin (Fuco), and diadinoxanthin (Diad), were detected in the surface water by using high-performance liquid chromatography (HPLC). The highest concentrations of But-fuco (5.64 μg L⁻¹), Fuco (37.94 μg L⁻¹) and chlorophyll a (Chl a, 17.25 μg L⁻¹) occurred in different seasons and sampling sites. The A. anophagefferens bloom (as indicated by But-fuco) usually expanded from the south to the north of the Qinhuangdao sea area, close to scallop-culturing regions. The bloom unusually starts in May, reaches its peak in June and almost disappears in August, with the temperature ranging from ca. 19 °C to 23 °C. The redundancy analysis (RDA) indicated that relatively high salinity (>29) and low inorganic nutrients were suitable for the development of the A. anophagefferens bloom. The ratios of diagnostic pigments to Chl a were not constant during different cruises and generally obeyed two different linear relationships, thus indicating the co-occurrence of the blooms of A. anophagefferens and other species, such as Minutocellus polymorphus. In summary, our work reports the long-term variation of A. anophagefferens blooms based on diagnostic pigments and environmental controls, which may provide more insights into the formation mechanisms of the brown tide in this region.