Hydrodynamic trapping in the formation of the chlorophyll a peak in turbid, very low salinity waters of estuaries

Abstract Aim The Central Pampa of Argentina has three recognized phytogeographic regions that arise due to the decrease in rainfall towards the west. The area has numerous lakes that are mainly temporary, with hydroperiods that relate to climatic cycles, although some of them have changed due to anthropogenic influence. Some of these lakes have been studied with special reference to zooplankton, but information on their physical and chemical aspects is scarce. Consequently, managing and evaluating the anthropogenic effects on these ecosystems is challenging. The objective of this study was to explore the limnological characteristics of lakes in different regions in the Central Pampa that experience different anthropic influences. Methods Ten lakes were sampled seasonally (January, April, July, and October) during 2007. In situ measurements included transparency, pH, temperature, and dissolved oxygen concentration, and 2-L water samples were collected to determine salinity, ion composition, suspended solids, nutrient concentration, and phytoplankton chlorophyll- a concentration. Results Salinity ranged from 0.32-136.72 g L-1, with Na+ being the dominant ion in nine lakes and Cl- and HCO3- predominating in the higher- and lower-salinity lakes respectively. Nutrient concentrations were high (total Kjeldahl nitrogen: 7.97-34.69 mg L-1; total phosphorous: 4.07-14.82 mg L-1), and all lakes were hypertrophic. We determined three lake classes: i) lakes transformed from low-salinity lakes into hypersaline ones through human inactivation of the fluvial system that fed it; ii) mesosaline temporary lakes lacking fish, with low concentrations of chlorophyll-a and influenced by agricultural activities, and iii) subsaline and hyposaline lakes, highly modified by urban sewage, converted in permanent lakes (which allowed fish fauna development) and with reduced water transparency (due to high concentrations of phytoplankton chlorophyll-a). Conclusions The chemical diversity of the studied lakes is low, and their predominance of Na+ and Cl- indicated that evaporation and crystallization control the water chemistry. Additionally, this study showed the consequences of the anthropic impact, which alter water chemical composition, trophic structure and, thus, the ecological characteristics of lakes.

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Effect of Salinity on Growth and Some Photosynthetic Pigments of Improved Population in Puccinellia ciliata (Poaceae)

Current Journal of Applied Science and Technology ◽

10.9734/cjast/2020/v39i130481 ◽

2020 ◽

pp. 64-70 ◽

Cited By ~ 2

Author(s):

Ilkay Yavas ◽

Yelda Emek ◽

Aydin Unay

Keyword(s):

Chlorophyll A ◽

Seedling Growth ◽

Photosynthetic Pigments ◽

Recurrent Selection ◽

Growth Parameters ◽

Maximum Length ◽

Low Salinity ◽

Randomized Design ◽

Salinity Levels ◽

Β Carotene

Puccinellia (Puccinellia ciliata Bor.) fairly resistant to salinity and used as forage for livestock in China, Australia, and Turkey. In this study, our objective was to determine the effects of salinity on growth and various photosynthetic pigments of an improved population of Puccinellia via recurrent selection. To accomplish this, effects of salinity on seedlings growth of homogenous Puccinellia was examined, one week after emerging of radicle from seeds. Seeds were germinated on Murashige and Skoog (MS) medium with 6% agar. Seedling growth was studied under different levels of NaCl salinity (0, 10, 20, 30, 40 μS/cm). Salinity applications were carried out for 6 weeks. Cultures were maintained in growth chambers at 24±2ºC and 16/8 light/dark conditions. Germination was scored during 2 weeks after culture initiation. The experiment was performed in a completely randomized design with three replicates. Plant growth parameters such as the number of radicle and tillers, maximum radicle and shoot length, plants fresh and dry weights were investigated. Photosynthetic pigments such as total chlorophyll, chlorophyll a, b, chlorophyll a/b ratio, total carotenoid, β- carotene, lutein and neoxanthin were examined. The maximum values for tiller number per plant, the maximum length of shoot and chlorophyll b were found in the 20 µs/cm, while the maximum length of the radicle was recorded at 10 µs/cm NaCl treatment. It was concluded that low salinity levels (10-20 μS/cm) increased seedling growth, while high salinity levels (30 and 40 μS/cm) inhibited the growth significantly. These results indicate that P. ciliata is a promising salt-tolerant and can be grown productively under low to moderate saline conditions between 10-20 µs/cm.

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Zooplankton richness, abundance and biomass of two hypertrophic shallow lakes with different salinity in central Argentina

Biota Neotropica ◽

10.1590/s1676-06032012000200005 ◽

2012 ◽

Vol 12 (2) ◽

pp. 41-48 ◽

Cited By ~ 5

Author(s):

Santiago Andrés Echaniz ◽

Alicia María Vignatti ◽

Gabriela Cecilia Cabrera ◽

Susana Beatriz José de Paggi

Keyword(s):

Chlorophyll A ◽

Shallow Lakes ◽

Saline Lakes ◽

Fish Predation ◽

Zooplankton Biomass ◽

Planktivorous Fish ◽

Total Biomass ◽

Negative Effects ◽

Low Salinity ◽

Central Argentina

The zooplankton of lakes is controlled by biological and physico-chemical parameters. Among the former, predation by fish can determine the replacement of large-sized species by small-sized ones and among the latter, salinity exerts negative effects on richness and abundance. Since it has been suggested that saline lakes without fishes have higher zooplankton biomass than low salinity ones, the aim of this study was to determine the richness, abundance and biomass of zooplankton in two lakes with different salinity and test the hypothesis that in the presence of zooplanktivorous fishes and at equal concentrations of nutrients and chlorophyll-a, saline lakes have higher biomass than those with low salinity. The study was conducted in two shallow lakes of the Province of La Pampa (central Argentina): a subsaline lake and a hyposaline lake, which shared high concentrations of chlorophyll-a and total phosphorus, reduced transparency and presence of planktivorous fish. Zooplankton richness was different and higher in the subsaline lake, whereas abundance and total biomass were similar, even when the taxonomic groups were considered separately. It is suggested that the presence of a halotolerant planktivorous fish controlled the size of zooplankton due to the predation on larger species and prevented the development of higher biomass in the saline lake, which is an important difference from previously recorded situations. This study shows that, regardless of the differences in salinity, the top-down effect in the food chain may have been a factor that equalized the zooplankton biomass by allowing only the development of small species and highlights the possible importance of fish predation in determining chlorophyll-a concentrations and water transparency.

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Salinity and temperature effects on the growth and chlorophyll-α content of some planktonic aigae

Boletim do Instituto Oceanográfico ◽

10.1590/s0373-55241993000100008 ◽

1993 ◽

Vol 41 (1-2) ◽

pp. 95-103 ◽

Cited By ~ 11

Author(s):

Teresa Cristina Siqueira Sigaud ◽

Elizabeth Aidar

Keyword(s):

Growth Rate ◽

Chlorophyll A ◽

Growth Rates ◽

Maximum Yield ◽

Maximum Growth ◽

Cell Number ◽

Maximum Growth Rate ◽

Salinity Range ◽

Low Salinity ◽

Chlorophyll A Content

The effect of salinity (0-40 %o) and temperature (11-36ºC, at 5ºC intervals) variations on maximum growth rate (div d-1), maximum yield (logio cell number) and chlorophyll-α content (pg cell-1) of four planktonic algae was examined under laboratory conditions. Phaeodactylum tricornutum grew over the entire range of experimental salinities, at 11-26 ºC. The highest maximum growth rates ( 1.6 div d-1) occurred between 9-30 %o and 16-26 ºC. Optimum salinity range for maximum yield (7.0) was found at 9-35 %c, under 16 ºC. Tetraselmis gracilis reproduced from 4 to 40 %o at 11-31 ºC, with the highest values of maximum growth rate ( 1.6 div d-1) and maximum yield (6.1) occurring at salinities between 14-40 %o at 11-21 ºC and 11-16 ºC, respectively. Minutocellus polymorphic and Chaetoceros sp grew between 9-40 %o and 11-31 ºC. Their highest maximum growth rates (2.1 and 2.6 div d-1, respectively) were found at 31ºC, between 20-35 %o and 20-40 %o, respectively. The highest maximum yields for AT. polymorphic (7.2) were recorded between 16-21 ºC at 20-40 %o and for Chaetoceros sp (6.8), between 25-40 %o at 16-31ºC. Chlorophyll-a content per cell was not conspicuously associated to temperature and salinity for the four species. At low salinity extremes, when cell division was inhibited, an increase in the amount of chlorophyll-a per cell was detected.

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High-Resolution electron crystallography of the light-harvesting chlorophyll-a/b protein complex from chloroplast membranes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100181816 ◽

1990 ◽

Vol 48 (1) ◽

pp. 610-610

Author(s):

Werner Kühlbrandt ◽

Da Neng Wang ◽

K.H. Downing

Keyword(s):

High Resolution ◽

Electron Diffraction ◽

Chlorophyll A ◽

Protein Complex ◽

Structural Integrity ◽

Light Harvesting ◽

Lhc Ii ◽

Diffraction Patterns ◽

Difference Fourier ◽

2D Crystals

The light-harvesting chlorophyll-a/b protein complex (LHC-II) is the most abundant membrane protein in the chloroplasts of green plants where it functions as a molecular antenna of solar energy for photosynthesis. We have grown two-dimensional (2d) crystals of the purified, detergent-solubilized LHC-II . The crystals which measured 5 to 10 μm in diameter were stabilized for electron microscopy by washing with a 0.5% solution of tannin. Electron diffraction patterns of untilted 2d crystals cooled to 130 K showed sharp spots to 3.1 Å resolution. Spot-scan images of 2d crystals were recorded at 160 K with the Berkeley microscope . Images of untilted crystals were processed, using the unbending procedure by Henderson et al . A projection map of the complex at 3.7Å resolution was generated from electron diffraction amplitudes and high-resolution phases obtained by image processing .A difference Fourier analysis with the same image phases and electron diffraction amplitudes recorded of frozen, hydrated specimens showed no significant differences in the 3.7Å projection map. Our tannin treatment therefore does not affect the structural integrity of the complex.

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