Susicley Jati

Interannual variability of phytoplankton in the main rivers of the Upper Paraná River floodplain, Brazil: influence of upstream reservoirs

The interannual variation of phytoplankton communities in the three main rivers of the Upper Paraná River floodplain is evaluated in relation to changes in the hydrosedimentological regime. These changes are a result of climatic variability and the formation of Porto Primavera Reservoir, located at the upper Paraná River. Phytoplankton species richness and density were investigated in rivers during a prior period (1993-1994) and eight years after reservoir impoundment (2000-2007). Multiple analyses were conducted to test the differences between these time periods in order to find predictor variables for phytoplankton attributes. A total of 454 phytoplanktonic taxa were found. The regression analysis revealed significant differences between periods. In the years following construction of the Porto Primavera dam, species richness was lower in the Paraná River and density was higher in the three rivers. In general, the algal density decreased from 2005 to 2007. Diatoms and cyanobacteria contributed significantly to the total density during the period from March 1993 to February 1994. The years 2000-2007 presented the lowest diatom contribution to species richness and the highest cyanobacteria contribution. From 2000 on, cryptomonads and cyanobacteria dominated. The interannual variability of phytoplankton was probably influenced by changes in hydrosedimentological regime due to climatic variations (La Niña and El Niño-Southern Oscillation events--ENSO) and the operational procedures associated with an upstream reservoirs. Studies on climatic variability and its effects on hydrosedimentological regimes of the Paraná, Baía and Ivinhema rivers and the biota therein are necessary to obtain subsidies for management, including decisions related to the operation of dams upstream and downstream of the study area, with the purpose of minimizing risks to the Environmental Protection Area.

Functional diversity and adaptative strategies of planktonic and periphytic algae in isolated tropical floodplain lake

Functional diversity and adaptative strategies of planktonic and periphytic algae in isolated tropical floodplain lake. This study aimed to test the hypothesis that after a great magnitude and high duration of flood pulse in floodplain, functional diversity of phytoplankton and phycoperiphyton communities will be higher during high water. The strategies’ dynamics evaluated during high and low water periods consisted of size classes, life forms, and functional groups. For the phytoplankton, the adaptations to floating, and for phycoperiphyton, the intensity and structure for attachment to substrate were also analyzed. Functional diversity was calculated from functional dendrograms of species. Functional diversity, richness, and density of both communities presented the greatest values during the high waters. In the high waters, Cryptomonas marsonii Skuja was dominant in plankton and Pseudoanabaena skujae Claus in periphyton, while in the low water, Merismopedia tenuissima Lemm. was dominant in plankton and Fragilaria capucina Desm. was dominant in periphyton. Thus, the flood pulse promoted the dominance of free-floating species in plankton, during the high water, and of metaphytic species in periphyton. In the low water, we observed the dominance of species with higher surface/volume ratio in plankton, and strongly attached in periphyton. We concluded that, in isolated floodplain lake, possibly the flood pulse directs the functional diversity of phytoplankton and phycoperiphyton.

Phytoplankton functional and morphological groups as indicators of environmental variability in a lateral channel of the Upper Paraná River floodplain

AIM: Models of phytoplankton functional classification based on functional (FGs) and morphological (MBFGs) traits can be an important tool in aquatic monitoring. In this long-term study on phytoplankton, the goal was to use these two approaches to explain the changes in this community in an active channel of the Upper Parana River floodplain, depending on the environmental conditions imposed by the hydrosedimentological regime. METHODS: Samples were taken between 2000 and 2013. RESULTS: 196 taxa were identified. Bacillariophyceae and Cyanobacteria showed higher contribution to biovolume. Were recorded 11 FGs (A, C, E, H1, J, Lo, M, MP, N, P and X1). The FGs C, Lo, M, MP, P and X1 were common to both periods. Already the FGs A, E, H1 and J occurred only in limnophase, while the FG N occurred only in potamophase. Were recorded seven MBFGs (I, II, III, IV, V, VI e VII). All seven MBFGs occurred in both hydrological periods, however the MBFGs III, VI and VII contributed with high biovolume values mainly in the limnophase. The FG P and MBFG VI were indicator of eutrophic status, while the FG M and MBFG VII were indicators of mesotrophic status. Only FGs reflected the environmental variability. CONCLUSION: The classification of phytoplankton in FGs and MBFGs represented an important tool for understanding of the behavior and dynamics of the species in relation to environmental conditions. However, the FGs appear to be more related to environmental variation this lotic channel than MBFGs. Probably this is related to the refinement of this classification, which reflected the changes in the community, in long-term scale, influenced by local and regional characteristics imposed by the hydrosedimentological regime of the Parana River.

Drivers of phytoplankton richness and diversity components in Neotropical floodplain lakes, from small to large spatial scales

Understanding the distribution patterns of species and how spatial and environmental factors drive the structure of communities is crucial to the preservation of biodiversity. We evaluate, during the low and high water periods, the phytoplankton diversity in lakes of four Brazilian floodplain systems (FPs): Amazon, Araguaia, Pantanal, and Paraná. We hypothesized that (i) species variation/replacement among floodplains (β2) is the predominant mechanism in shaping phytoplankton gamma diversity; (ii) the variation in phytoplankton taxonomic composition within each floodplain (β1) is mainly governed by local environmental conditions due to the high dispersal ability of phytoplankton at small spatial scales; and (iii) variation in the phytoplankton taxonomic composition among floodplains (β2) is mainly influenced by dispersal limitation. Variation partitioning was used to evaluate the influence of spatial and environmental factors on species richness. Higher γ diversity was found in the Araguaia and Amazon FPs. The high contribution of β2 (large scale) to γ diversity revealed the high degree of environmental heterogeneity in each floodplain. β1 (small scale) was more influenced by environmental variables, and β2 by both spatial and environmental factors. Our findings showed that γ diversity was explained by the interaction between the two factors, and that these processes influencing variation were scale dependent.

Functional approach based on morphology as a model of phytoplankton variability in a subtropical floodplain lake: a long-term study

Long-term phytoplankton dynamics in a floodplain lake, between periods of limnophase and potamophase was studied using the morphology-based functional classification (MBFG). The work was carried out to test the hypothesis that the temporal distribution of MBFGs is influenced by the hydrosedimentological regime of the Paraná River, and that these differences can be registered by analyzing the dominant MBFGs in the two periods. Samples were taken in an isolated floodplain lake on the Upper Paraná River floodplain, Brazil, from 2000 to 2012, and water level, water temperature, conductivity, pH, dissolved-oxygen, euphotic zone, maximum depth, and nutrients were used to explain the distribution of MBFGs. 478 taxa were identified and distributed in seven MBFGs (I–VII). MBFG V (flagellates algae) and VI (diatoms) showed 100% frequency of occurrence. MBFG II was associated exclusively with the limnophase; MBFG IV and VII were associated with limnophase periods with higher pH and dissolved-oxygen content; and MBFG I, III, V, and VI were associated with limnophase and potamophase, mainly associated with transparency, nutrients, and conductivity. The MBFG approach represented the trends of each group in terms of its occurrence and biovolume, according to the hydrosedimentological regime, providing broad-scale information on changes in the phytoplankton.

First record of the occurrence of Ceratium furcoides (Levander) Langhans (Dinophyceae) in the Upper Paraná River Floodplain (PR/MS), Brazil

(With 1 figure)Genus Ceratium Schrank (Dinophyta) is among the plankton species regarded as exotic in Brazil. The species presents asymmetry and flattening mesophyll cell, as well as an elongated apical horn and two to three antapical and cingulate equatorial with spiral dislocation. Ceratium furcoides (Levander) Langhans differ from the remaining best represented species due to its conical apical horn formed with four plates, these three extending to the apex, whereas the fourth plate (4’) has its reduced size and does not reach the apex (Popovský and Pfiester, 1990).This taxon was detected in samples of total and net phytoplankton. These samples were collected at several lotic and lentic environments of the Upper Parana River Floodplain (53°10´W 22°40´S – 53°21´W – 22°50´S), as part of the Ecological Long-Term Research Programme (CNPq/PELD - site 6) sampling, in December 2012 and June 2013 (Table 1). The individuals identified presented metric thresholds, morphology and tabulating of the thecal plates (Figure 1) in accordance with the diagnosis by Popovský and Pfiester (1990). The measurements recorded for the specimens were 147.6 to 184.5 μm long and 36.9 to 49.2 μm wide.The occurrence of this genus is regarded as rare in the country (Oliveira et al., 2011), although the genus dispersion and development in several Brazilian watersheds have already been recorded, indicating an expansion process of geographical distribution. The occurrence of taxon Ceratium furcoides in Brazil was recorded in studies by Santos-Wisniewski et al. (2007) and Silva et al. (2012), for the Furnas reservoir in Minas Gerais, Matsumura-Tundisi et al. (2010), for Billings Dam, state of Sao Paulo, Oliveira et al. (2011), in rivers and reservoirs of the states of Alagoas, Bahia, Pernambuco and Sergipe, and Cavalcante et al. (2013), for rivers and reservoirs of Parana and Rio Grande do Sul.Since the Upper Parana River Floodplain is the last stretch free of impoundments in this river, there are preservation areas with high aquatic biodiversity. The record of this species in natural environments and in conservation areas is unprecedented and a cause for concern. Although it occurred in low densities and biomass, its monitoring is necessary for a better understanding of the dynamics of its population in order to prevent and manage potential environmental issues.

Limnoperna fortunei Dunker, 1857 larvae in different environments of a Neotropical floodplain: relationships of abiotic variables and phytoplankton with different stages of development

Limnoperna fortunei Dunker, 1857 is an Asian invasive freshwater bivalve. Although there need to contain their spread, studies about the biology of the larvae are scarce. We correlated the larval stages of L. fortunei with biotic factors such as phytoplankton and main abiotic variables in lotic environments of the Upper Paraná River floodplain. The four samples were taken quarterly during the year 2012. The Principal component analysis (PCA) showed only spatial differences, as did a Canonical Correspondence Analysis (CCA). High densities of larvae were recorded in all samples the Paraná River and Baía River only in December, especially those in their initial stage. In the biovolume of Class of algae, Bacillarophyceae showed the highest value, but Chlorophycea who was strongly correlated with the density of D-stage larvae. The large variety of phytoplankton, especially microplankton Chlorophyceae, high values of PO4, NH4 and temperature were positively correlated with high densities of D-stage larvae. We conclude that high temperature, and food availability, indicated by phytoplankton community, favored the reproduction of L. fortunei and enhance the ability of specie dispersion due to the increase in the emission of propagules. Therefore, studies that address the biology of golden mussel larvae should be performed in order to prevent its spread.

Composition and species richness phytoplankton in a subtropical floodplain lake: a long-term study

OBJETIVO: A diversidade de especies fitoplanctonicas em lagos de inundacao e influenciada pelas diferentes condicoes impostas pelo regime hidrossedimentologico do canal principal. Foram avaliados quais os fatores preditores da composicao e riqueza de especies fitoplanctonicas, em escala de longa duracao, em um lago de inundacao diretamente conectado ao rio Parana. Nos hipotetizamos que a riqueza de especies do lago de inundacao esta diretamente relacionada ao indice de conectividade com o canal principal. METODOS: Amostragens trimestrais foram realizadas entre fevereiro de 2000 e marco de 2013 (exceto em 2001 e 2003), a sub-superficie, na regiao limnetica do lago. Dados foram analisados atraves de correlacao de Spearman, PCA, DCA, ANOVA e analise de regressao. RESULTADOS: Foram inventariados 397 taxons com alta contribuicao de especies raras (72%). Cloroficeas e diatomaceas foram os grupos mais frequentes. Observou-se uma tendencia de aumento de diatomaceas e decrescimo de cianobacterias. A DCA mostrou diferencas na composicao fitoplanctonica. Os maiores valores medios de riqueza foram registrados em anos com alto numero de dias de potamofase. Diferencas significativas para a riqueza total de especies e primeiro eixo da DCA foram observadas entre os anos. A analise de regressao evidenciou que os fatores preditores da riqueza de especies foram Zeu e Zmax. CONCLUSAO: A riqueza de especies fitoplanctonicas do lago de inundacao esta diretamente relacionada ao indice de conectividade com o canal principal.