Poly(β-hydroxyalkanoate) accumulation in bacterioplankton from Lake Cisó (Spain)

1995 ◽  
Vol 41 (13) ◽  
pp. 80-83 ◽  
Author(s):  
J. Mas-Castellà ◽  
R. Guerrero
Keyword(s):  
Light Availability ◽  
Growth Conditions ◽  
Phototrophic Bacteria ◽  
Light Limitation ◽  
Limiting Factor ◽  
Specific Content ◽  
Unbalanced Growth ◽  
Bacterial Counts ◽  
Large Populations ◽  
Different Depths

The specific poly(β-hydroxyalkanoate) (PHA) content of the bacterioplankton from Lake Cisó (Spain) was measured at different depths. Phototrophic bacteria reach large populations in this lake and the PHA concentration changed seasonally according to their biomass. During summer stratification of the lake, phototrophic bacteria formed a metalimnetic peak. Bacterial counts were maximal at a depth of 1.5–2.0 m, whereas the PHA specific content reached a maximal value at 3.0–3.5 m. Since the limiting factor in this ecosystem is light availability, we assume that cells beneath the dense metalimnetic peak have unbalanced growth conditions and thus accumulate large amounts of PHA.Key words: bacterioplankton, PHA accumulation, Lake Cisó, light limitation.

scholarly journals Atmospheric Stilling Promotes Summer Algal Growth in Eutrophic Shallow Lakes

Biology ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1222
Author(s):  
Wei Zou ◽  
Guangwei Zhu ◽  
Hai Xu ◽  
Mengyuan Zhu ◽  
Chaoxuan Guo ◽  
...  
Keyword(s):  
Water Level ◽  
Shallow Lakes ◽  
Algal Blooms ◽  
Lake Taihu ◽  
Light Availability ◽  
Algal Growth ◽  
Light Limitation ◽  
Limiting Factor ◽  
High Background ◽  
Level Elevation

Algal blooms are environmental challenges confronting lakes worldwide and are significantly influenced by chlorophyll a yields per unit phosphorus (Chla/TP), or nitrogen (Chla/TN). Here, the influence of inter-annual hydrometeorological variations on Chla/TP and Chla/TN were evaluated in eutrophic shallow Lake Taihu, China. Our results demonstrated significant increases (p < 0.001) in both Chla/TN and Chla/TP from 2005 to 2017, and increased Chla yields during the winter months were mainly correlated with higher water temperature and longer sunshine hours, which may cause severer blooms in winter and spring. In remaining months from 2005 to 2017, typical associations between atmospheric stilling (or water level elevation) and higher Chla yields were observed. The results also indicate that atmospheric stilling and water level elevation significantly (p < 0.001) decreased background turbidity and promoted buoyant cyanobacterial biomass, alleviating phytoplankton light limitation. Given the subtropical location, eutrophic status, and high background turbidity of Lake Taihu, light may be the critical limiting factor for summer phytoplankton growth; thus, improved light availability would promote Chla yields until self-shading caused further light limitations. If the mechanism is general, promoting the effect of atmospheric stilling on annual peak Chla in shallow lakes may be greatly underestimated, and our finding will affect future bloom mitigation efforts in such systems.

scholarly journals The effects of cutting regimes on natural regeneration in submountain beech forests: species diversity and abundance

2008 ◽  
Vol 54 (No. 12) ◽  
pp. 533-544 ◽  
Author(s):  
M. Barna
Keyword(s):  
Natural Regeneration ◽  
Growth Conditions ◽  
The Other ◽  
Limiting Factor ◽  
Beech Forests ◽  
Clear Cut ◽  
One Year ◽  
Cutting Regimes ◽  
Cutting Intensity ◽  
The Given

The paper summarizes the results of 15-year natural regeneration for beech of five plots with different densities situated in the Western Carpathians Mts. Three of the plots were subjected to differently intensive shelterwood cuttings (plots L, M, H), one plot was clear-cut (CC), and one was left without intervention – as a control (C). The number of one-year-old seedlings decreased proportionally with increasing cutting intensity. The ANOVA results document a significant influence of cutting intensity on the abundance of both one-year-old and older seedlings. The abundance of beech seedlings was initially increasing with increasing cutting intensity, and, having reached the peak on plot M (medium intensity), there followed a decrease in the seedling abundance. Lower numbers of beech seedlings on plots subjected to less intensive cutting (C, L) result from less favourable growth conditions in comparison with plot M. On the other hand, cutting of higher intensity (H, CC) resulted in lower numbers of fructifying parent trees. The medium cut intervention having provided the plot M with stocking of 0.5 (50% of the stand) resulted in a lower number of seed resources (limiting factor for natural regeneration). However, for the other factor – seedling establishment (survival and recruitment) this plot (M) represents an ecological optimum in beech regeneration in the given conditions.

scholarly journals Mechanisms of northern North Atlantic biomass variability

2018 ◽  
Vol 15 (20) ◽  
pp. 6049-6066 ◽  
Author(s):  
Galen A. McKinley ◽  
Alexis L. Ritzer ◽  
Nicole S. Lovenduski
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Light Availability ◽  
Light Limitation ◽  
Climate Indices ◽  
Biogeochemical Model ◽  
Full Time ◽  
Subpolar Gyre ◽  
Phosphate Supply ◽  
Biomass Variability

Abstract. In the North Atlantic Ocean north of 40∘ N, intense biological productivity occurs to form the base of a highly productive marine food web. SeaWiFS satellite observations indicate trends of biomass in this region over 1998–2007. Significant biomass increases occur in the northwest subpolar gyre and there are simultaneous significant declines to the east of 30–35∘ W. These short-term changes, attributable to internal variability, offer an opportunity to explore the mechanisms of the coupled physical–biogeochemical system. We use a regional biogeochemical model that captures the observed changes for this exploration. Biomass increases in the northwest are due to a weakening of the subpolar gyre and associated shoaling of mixed layers that relieves light limitation. Biomass declines to the east of 30–35∘ W are due to reduced horizontal convergence of phosphate. This reduced convergence is attributable to declines in vertical phosphate supply in the regions of deepest winter mixing that lie to the west of 30–35∘ W. Over the full time frame of the model experiment, 1949–2009, variability of both horizontal and vertical phosphate supply drive variability in biomass on the northeastern flank of the subtropical gyre. In the northeast subpolar gyre horizontal fluxes drive biomass variability for both time frames. Though physically driven changes in nutrient supply or light availability are the ultimate drivers of biomass changes, clear mechanistic links between biomass and standard physical variables or climate indices remain largely elusive.

scholarly journals Is thermal stability a factor that influences environmental heterogeneity and phytoplankton distribution in tropical lakes?

2018 ◽  
Vol 30 (0) ◽  
Author(s):  
Luciana Gomes Barbosa ◽  
Francisco Antônio Rodrigues Barbosa ◽  
Carlos Eduardo de Mattos Bicudo
Keyword(s):  
Thermal Stability ◽  
Functional Groups ◽  
Environmental Heterogeneity ◽  
Driving Forces ◽  
Light Availability ◽  
Climatic Conditions ◽  
Tropical Lakes ◽  
Light Limitation ◽  
Water Column Stability ◽  
Vertical Heterogeneity

Abstract Aim To evaluate the effects of environmental heterogeneity promoted by thermal stratification on the distribution of limnologic variables and phytoplankton functional groups (FGs) in two natural lakes. Methods Monthly measurements were performed over a five-year period in the vertical profile of a warm monomitic shallow lake (Lago Carioca) and in a deep and meromictic (Lake Dom Helvécio). Results The vertical zonation generated by the high thermal stability during the stratification period promoted an increase in the spatial heterogeneity and, consequently, in the richness of functional groups of the two lakes. In the epilimnion, the dominance of small chlorophytes and desmids (NA, A and X1, ≤20μm) and larger dinophyceans (Lo, ≥20μm) were associated with high turbulence and light availability and soluble phosphorus limitation. In the metalimnion, the presence of filamentous cyanobacteria (R) and colonial chlorophyceans (F) of larger size (≥20µm) were associated with stable habitats with high concentrations of N-NH4 and P-PO4-3 and light limiting conditions. Comparatively, Lake Dom Helvécio presented a higher richness of FGs in the meta-hipolimnetic layers (SN, P) as well as a higher number of species per functional group. Seasonal changes in the climatic conditions (e.g. the decrease in air temperature with the consequent heat loss) caused the break of the water column stability, which promoted the redistribution of the dissolved nutrient forms and the increase of light limitation in the two lakes during the mixing period. Therefore, there was a drastic reduction in the richness and population biomass of FGs (≤80%). Conclusions Thermal stability and atelomixis were the main driving forces of vertical heterogeneity during the stratification, favoring the coexistence of FGs and, consequently, their increase in richness and biomass.

scholarly journals Quantification of purple non-sulphur phototrophic bacteria and their photosynthetic structures by means of total reflection X-ray fluorescence spectrometry (TXRF)

2016 ◽  
Vol 31 (10) ◽  
pp. 2078-2088 ◽  
Author(s):  
Joanna Fiedor ◽  
Beata Ostachowicz ◽  
Monika Baster ◽  
Marek Lankosz ◽  
Květoslava Burda
Keyword(s):  
Correlation Analysis ◽  
Trace Element ◽  
Rhodobacter Sphaeroides ◽  
Growth Conditions ◽  
Phototrophic Bacteria ◽  
Total Reflection ◽  
Fluorescence Spectrometry ◽  
Bacterial Cells ◽  
X Ray

TXRF spectrometry proves useful in analysing bacterial cells and their substructures as exemplified byRhodobacter sphaeroides. Trace element profiling complemented with correlation analysis under varying growth conditions.

scholarly journals Light alters the impacts of nitrogen and foliar pathogens on the performance of early successional tree seedlings

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11587
Author(s):  
Alexander Brown ◽  
Robert W. Heckman
Keyword(s):  
Fungal Pathogens ◽  
Nitrogen Availability ◽  
Light Availability ◽  
High Light ◽  
Plant Performance ◽  
Forest Understory ◽  
Light Limitation ◽  
Tree Seedlings ◽  
Low Light ◽  
Foliar Damage

Light limitation is a major driver of succession and an important determinant of the performance of shade-intolerant tree seedlings. Shade intolerance may result from a resource allocation strategy characterized by rapid growth and high metabolic costs, which may make shade-intolerant species particularly sensitive to nutrient limitation and pathogen pressure. In this study, we evaluated the degree to which nitrogen availability and fungal pathogen pressure interact to influence plant performance across different light environments. To test this, we manipulated nitrogen availability (high, low) and access by foliar fungal pathogens (sprayed with fungicide, unsprayed) to seedlings of the shade-intolerant tree, Liquidambar styraciflua, growing at low and high light availability, from forest understory to adjacent old field. Foliar fungal damage varied with light and nitrogen availability; in low light, increasing nitrogen availability tripled foliar damage, suggesting that increased nutrient availability in low light makes plants more susceptible to disease. Despite higher foliar damage under low light, spraying fungicide to exclude pathogens promoted 14% greater plant height only under high light conditions. Thus, although nitrogen availability and pathogen pressure each influenced aspects of plant performance, these effects were context dependent and overwhelmed by light limitation. This suggests that failure of shade-intolerant species to invade closed-canopy forest can be explained by light limitation alone.

scholarly journals SPATIAL VARIABILITY OF THE SATURATED HYDRAULIC CONDUCTIVITY OF SOIL IN COCOA FARMING IN RECÔNCAVO BAIANO

2019 ◽  
Vol 32 (3) ◽  
pp. 786-794
Author(s):  
GERLANGE SOARES DA SILVA ◽  
JUCICLÉIA SOARES DA SILVA ◽  
FRANCISCO ADRIANO DE CARVALHO PEREIRA ◽  
RODRIGO ALMEIDA SANTANA ◽  
RAFAEL SILVA FIRMO ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Spatial Variability ◽  
Irrigation Management ◽  
Gaussian Model ◽  
Constant Load ◽  
Saturated Hydraulic Conductivity ◽  
Limiting Factor ◽  
Site Management ◽  
Data Set ◽  
Different Depths

ABSTRACT Irrigated cocoa cultivation opened the way for production in Coastal Tablelands soils. However, in this region, the cohesive layer formed near the surface can be a limiting factor for production. The knowledge of physical soil water attributes enables the efficient irrigation management of cohesive soils. This study characterized and modeled the spatial variability of saturated hydraulic conductivity (K0) in a Distrocoeso Oxisoil of the Recôncavo Baiano Coastal Tablelands. The soil sampling was performed as undeformed structures from 50 spaced points in an 8.0 to 8.0 m area, at three different depths in the experimental area of the Federal University of Bahia Recôncavo in the Cruz das Almas-BA cultivated with cocoa (‘CCN 51’). In the laboratory, K0 was determined by permeameter method constant load, and the pore size distribution was determined using the voltage table and the soil density (Ds). Data were analyzed using descriptive statistics and geostatistics. On average, the K0 values were 40.41, 26.49, and 37.82 mm-1 h-1 at the depths from 0.0-0.15 m, 0.15-0.30, and 0.30-0.45 m. The Gaussian model was the best fit to the K0 data set. For soil class, the K0 showed a strong spatial dependence due to their relationship with the physical properties of the soil, its use, and handling. Since an important attribute for the delimitation of homogeneous areas for specific site management purposes as well be considered.

scholarly journals Structural changes of the phytoplankton and epiphyton in an urban hypereutrophic reservoir

2016 ◽  
Vol 28 (0) ◽  
Author(s):  
Lucineide Maria Santana ◽  
Carla Ferragut
Keyword(s):  
Species Richness ◽  
Water Flow ◽  
Structural Changes ◽  
Light Availability ◽  
Temporal Changes ◽  
Nutrient Concentrations ◽  
Nitrogen And Phosphorus ◽  
Nutrients Availability ◽  
High Species Richness ◽  
Different Depths

Abstract: Aim This study evaluated the temporal changes of phytoplankton and epiphyton structure and their relationships with limnological factors in an urban hypereutrophic reservoir (Rasgão Reservoir, Brazil). Methods We collected water sample and phytoplankton in different depths at two sites (dam and near tributary input) in summer and winter 2010. Epiphyton on Salvinia spp. was sampled only at site near the tributary input. We determined limnological variables and structural attributes (species composition, density, biovolume, descriptors species, diversity) for both communities. Results Phytoplankton density and epiphyton density and biovolume were higher in the winter (dry season), which occurred the higher nutrient concentrations and lower water flow. Chlorophyceae was dominant in the phytoplankton in both period and Cyanobacteria was the second most abundant class in the winter. In the epiphyton, Bacillariophyceae was dominant in the summer and Cyanobacteria in the winter. The increase in light availability and water flow can have provided high species richness and diversity in the summer. Conclusion Temporal changes in the structure of phytoplankton and epiphyton on Salvinia were more related to increased nutrients availability (nitrogen and phosphorus) and flow variations in a hypereutrophic reservoir.

Unusual occurrence of a Didymosphenia bloom in a lentic habitat: Observation of Didymosphenia laticollis blooming on the eastern shore of Lake Hövsgöl (Mongolia)

Phytotaxa ◽  
2016 ◽  
Vol 263 (2) ◽  
pp. 139 ◽  
Author(s):  
MARCO CANTONATI ◽  
DITMAR METZELTIN ◽  
NERGUI SONINKHISHIG ◽  
HORST LANGE-BERTALOT
Keyword(s):  
Light Availability ◽  
Limiting Factor ◽  
Running Waters ◽  
Eastern Shore ◽  
Bloom Formation ◽  
Lake Hovsgol ◽  
Western Shore ◽  
High Alkalinity ◽  
Unusual Occurrence ◽  
Formation Conditions

The stalked diatom Didymosphenia is being thoroughly studied because it can cause serious nuisance blooms. The species most commonly involved is D. geminata. Although Didymosphenia species occur in running waters and lakes, published reports generally refer to lotic habitats. Given the applied interest in Didymosphenia, as well as its suitability for fundamental ecological studies, here we report an observation of a Didymosphenia bloom occurring on the southern part of the eastern shore of the large oligotrophic Lake Hövsgöl (Mongolia). LM and SEM observations revealed that the bloom was formed by Didymosphenia laticollis. The bloom extended for a long stretch of the eastern shore whilst on the opposing lake margin no bloom was visible, where a different Didymosphenia species was collected (D. mongolica). We interpreted the Lake Hövsgöl D. laticollis bloom in light of the most updated knowledge on Didymosphenia blooms ecophysiology. Lake Hövsgöl meets all main environmental requirements for Didymosphenia bloom formation: conditions are oligotrophic and phosphorus is the limiting factor, waters are very transparent and benthic light availability is consequently high, alkalinity is relatively high, and stable rocky substrata in a hydrologically-turbulent environment are widespread. The light-brown color of the bloom is in good agreement with experimental results suggesting that low-SRP conditions promote bloom formation in the presence of high light and alkalinity, because energy is converted to stalk material (the primary site of alkaline phosphatase production in Didymosphenia) rather than in cells. We speculate that the occurrence of the bloom on the eastern shore and its absence on the western shore might depend upon morphology, land use, and climate change causing alkalinity and organic phosphate inputs on the eastern side.

scholarly journals Neurotrophic Activity of the CarrageenophyteKappaphycus alvareziiCultivated at Different Depths and for Different Growth Periods in Various Areas of Indonesia

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Gabriel Tirtawijaya ◽  
Maria Dyah Nur Meinita ◽  
Bintang Marhaeni ◽  
Md. Nazmul Haque ◽  
Il Soo Moon ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Hippocampal Neurons ◽  
Kappaphycus Alvarezii ◽  
Growth Conditions ◽  
Culture Conditions ◽  
Coastal Areas ◽  
Eucheuma Denticulatum ◽  
Neurotrophic Activity ◽  
Primary Hippocampal Neurons ◽  
Different Depths

The carrageenophyteKappaphycus alvarezii(Rhodophyta) has neurotrophic activity in primary hippocampal neurons. This seaweed is abundant and easily cultivated in tropical coastal areas. To determine the best growth conditions for neurotrophic activity, thalli were grown at different depths and for different periods in various areas of Indonesia. Neurotrophic activity was measured based on the number of primary neurites, the total length of the primary neurites, and the length of the longest neurite.K.alvareziihad higher neurotrophic activity than carrageenophytesK.striatumandEucheuma denticulatumcultured under the same conditions.K.alvareziigrown at the surface for 45 days had higher (1.4- to 1.8-fold) neurotrophic activity than thalli grown at depth (2 m) or harvested sooner (15 days) (P< 0.05). Relatively high activities were detected in thalli cultured at Ternate and Garut, Indonesia. Therefore, from a commercial perspective, the culture conditions at the surface for 45 days were optimal for the production of both neurotrophic compounds and carrageenan.K.alvareziiproduced neurotrophic compounds under various environmental conditions, although some conditions were optimal.

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