Shallow lakes are an essential component of the Argentine Pampean wetlands. The Sauce Grande shallow lake is a typical water body of the Argentine Pampean wetlands, based on its shallow characteristics and its homogeneity in terms of physical, chemical, and biological characteristics. Phytoplankton is dominant in the turbid shallow lake and is sensitive to internal fluctuations in the water body and prevailing environmental conditions that affect its abundance and distribution.
We conducted a temporal and spatial analysis of the distribution and abundance of the phytoplankton community in the Sauce Grande shallow lake (province of Buenos Aires, Argentina), from April to September 2012, in order to study the influence of physicochemical variables of the water on phytoplankton.
Download Lagu Dj Plankton
DOWNLOAD 🔥 https://ssurll.com/2y67Eu 🔥
The multivariate analysis showed that certain water physico chemical factors (conductivity, depth, pH, turbidity, and temperature) profoundly influenced the phytoplankton dynamics, giving rise to a seasonal succession of community species, with a clear dominance of Cyanobacteria. The Spearman correlation showed that Cyanobacteria relate positively and significantly to conductivity whereas Chlorophyta and Bacilla riophyta relate negatively and significantly to temperature, pH, conductivity, and salinity. Chlorophyta was the group with the highest number of recorded taxa while Cyanobacteria constituted the largest group, the most abundant species being Synechocystis salina Wislouch.
The results obtained in this study demonstrate that the phytoplankton com munity of the Sauce Grande shallow lake is highly susceptible to changes in water environmental conditions, in particular to water level fluctuations, and to conductivity, pH, and temperature.
Las lagunas son el componente esencial del humedal pampeano argentino. La laguna Sauce Grande es un t pico cuerpo de agua pampeano en base a sus caractersticas someras y su homogeneidad en las caractersticas fsicas, qu micas y biolgicas. El fitoplancton se muestra dominante en las lagunas turbias, y es sensible a las fluctuaciones internas del cuerpo de agua y a las condiciones ambientales prevalecientes, vindose afectadas su abundancia y distribucin.
Los resultados obtenidos en esta investigacin demostraron la alta susceptibili dad de la comunidad fitoplanctnica de la laguna Sauce Grande a los cambios en las variables ambientales, en particular, a las fluctuaciones en el nivel del agua y luego, a la conductividad, pH y temperatura.
Shallow lakes are an essential component of the Argentine Pampean wetlands, one of the most extensive wetland areas in South America. Lakes on the plain are shallow with brief periods of thermal stratifica tion (Quirs, 2005). Shallow lakes often alternate between two states: a turbid one, in which phytoplankton dominates productivity; and a re latively clearer vegetated state, in which rooted vegetation dominates productivity (Scheffer et al., 1993; Scheffer et al., 2003). There is a third state of shallow lakes found in the Argentine Pampean wetlands, which also corresponds to turbid lakes, in which turbidity is mostly due to suspended inorganic material (Torremorell et al., 2007). Bilotta & Bra zier (2008) defined turbidity as a measure of the light scattering pro perties of water, and their readings were influenced by the particle size and shape of suspended solids, the presence of phytoplankton, and the presence of dissolved matter and mineral substances. These systems normally show a high sequential phytoplankton population variability with frequent changes in the composition and relative abundance of species as a result of the interactions between the physical, chemical, and biological variables (Calijuri et al., 2002) that have a notable in fluence on the structure of the phytoplankton community (Rojo et al., 2000; Phlips et al., 2002). The Sauce Grande shallow lake is a typical shallow Pampean lake (Ringuelet, 1972), given its shallow nature and the homogeneity of its physicochemical and biological parameters. This homogeneity is frequently affected by both extreme drought and in tense rainfall, which produce drastic changes within its structure and performance (Quirs et al., 2002a, b). Shallow lakes, which are globally the most common and widespread inland water bodies (Downing et al., 2006), are particularly vulnerable to drought and unbalanced ratios between evaporation and precipitation (Jeppesen et al., 2009; Moss et al., 2011) due to their large surface:volume ratio (Coops et al., 2003). In this sense, Izaguirre et al. (2015) demonstrated the vulnerability of most Pampean shallow lakes to water level fluctuations. Moreover, the struc ture and dynamics of the phytoplankton community may be susceptible to climatic changes that alter the level of the lake water through eva poration and changes in the flow of the stream network in the water supply basin (Coops et al., 2003).
The Sauce Grande shallow lake was recently characterized as a murky water body dominated by phytoplankton (Ferrer et al., 2012). In the fall of 2010 it was found to be in a eutrophic condition based on measurements of chlorophyll a and water transparency (Ferrer et al., 2012) and even hypertrophy was recorded during 2012-2013 (Cony et al., 2014).
Qualitative samples, subsurface mode, were taken with a plankton net of 30 m mesh aperture, one from each sampling site, and were fixed, in situ, with 4% formaldehyde. Observations were made with two microscopes, a Leitz SM Lux and a Zeiss Axiolab. We identified the sam ples with specialized literature for the dominant algal groups (Bourrely, 1966; Hindk, 1977, 1984, 1988, 1990; Komrek & Anagnostidis, 1999, 2005; Komrek & Fott, 1983) and with similar studies conducted in the Pampean wetlands (Guarrera et al., 1968, 1972).
Phytoplankton qualitative analysis. The phytoplankton composition was similar for both groups and species at both sampling sites. Of 54 taxa identified, 30 were Chlorophyta (55.5 %), 14 belonged to Cyano bacteria (26 %), and 10 to Bacillariophyta (18.5 %). From the latter, seven (70 %) were pennate and three (30 %) centric (Fig. 3). Table 2 shows the species identified at both sites: Dictyosphaerium ehrem bergianum Negeli and Oocystella borgei (J.Snow) Hindk were only found in August 2012 at site 2; Oocystis eremosphaeria G.M. Smith appeared in May, July, and August only at site 2; Pediastrum borya num (Turp.) Meneghini in August at site 2 and Planctonema lauterbor nii Schmidle were only found in May 2012 at both sites; Staurastrum planctonicum (Teiling), Tetraedron caudatum (Corda) Hansgirg, and T. minimun (A. Braun) Hansgirg were only identified at site 1. Meanwhile, the Cyanobacteria Aphanotece clathrata (West et G.S.West) was found in September 2012, only at site 1. Among diatoms, Chaetoceros mue lleri Lemmermann only appeared in April 2012 at site 2, Navicula aff. gregaria Donkin was found at site 1 in April, August, and September; Pseudostaurosira brevistriata var. inflata (Pantocsek) Hartley only in July and September, and Surirella striatula Turpin in August 2012, at both sites 1 and 2.
Phytoplankton quantitative analysis. The ANOVA performed on phytoplankton abundance did not detect differences between sampled sites (F = 0.005, p >0.05). However, significant differences between months (F = 6.36, p
At site 1, total abundance showed values of 3.6x106 ind.ml-1 in September and 5.4x106 ind.ml-1 in July 2012 (Fig. 5). At site 2, abun dance ranged from 4.0x106 to 5.1x106 ind.ml-1 in April and May 2012, respectively. The total average phytoplankton abundance was 4.4x106 ind.ml-1 at both sites, and Cyanobacteria were the most abundant group, followed by Chlorophyta and Bacillariophyta (Fig. 5). Synecho cystis salina Wislouch was the dominant species throughout the entire period, reaching a relative representation of 47% of the total abundan ce in September at site 1 and 45% in August at site 2. Chroococcus minimus (Keissler) Lemmermann, Aphanocapsa elachista W. West et G.S. West and A. nubilum Komrek et Kling were the species with the second highest abundance at both sites.
Figure 5 Monthly variation of the abundance of the phytoplankton taxonomic groups and the percentage of the dominant species (Synechocystis salina) during the study period at both Sauce Grande study sites (Argentine Pampean wetland).
Principal Component Analyses (PCA). The PCA-1 included the abun dance of the represented taxonomic groups (Cyanobacteria, Chlorophyta, and Bacillariophyta) during the entire study period in conjunction with the physicochemical variables for each sampling site shown in Figure 7. The turbidity was included in the analysis, but did not show correlation with any axis, so the variable was removed from the graphic result. For S1, the first two ordination axes explain 85.5% of the total variance (Fig. 7A), the positive portion of the first axis represents the conductivity, salinity, and abundance of Bacillariophyta, and the negative portion relates to the pH and the abundance of Cyanobacteria. The second axis is related to the temperature, the depth (positive portion), and the abundance of Chloro phyta (negative portion). April was characterized by the highest salinity and conductivity and less phytoplankton abundance, especially of Cya nobacteria, whereas samples from May and June showed a high density of Chlorophyta and Bacillariophyta individuals, as well as lower pH and depth records. July had the highest phytoplankton abundance, in particu lar Cyanobacteria, and the lowest temperature and depth records. During August and September the highest pH and depth records and the lowest phytoplankton abundance of Chlorophyta and diatom representatives oc curred (Fig. 7A). For site 2 (Fig. 7B), the first two ordination axes explained 82.9%, the positive portion of the first axis represents the abundance of Bacillariophyta and Chlorophyta, and the negative portion relates to the abundance of Cyanobacteria, temperature, conductivity, and salinity. The second axis is related to the pH (positive portion) and depth (negative portion). June showed the highest abundance of Chlorophyta and Baci llariophyta. July and August showed high pH, salinity, conductivity, and a significant abundance of Cyanobacteria. September had high temperatu re and depth records and lower abundances of green algae and diatoms (Fig. 7B). 17dc91bb1f
ak gun aa kalam meri full song download
how to download notes from save my exams