Horizontal and seasonal patterns of tropical zooplankton from the eutrophic Prado Reservoir (Colombia (original) (raw)
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Zooplankton community composition and abundance of two Brazilian semiarid reservoirs
2006
Zooplankton community composition and abundance of two Brazilian semiarid reservoirs. Zooplankton communities from Pacajus and Gavião reservoirs of Ceará state (northeast Brazil) were sampled in dry and rainy periods in order to correlate the composition and abundance of zooplankton species with environmental factors. A total of 32 taxa were identified: 19 of Rotifera, 7 of Cladocera and 6 of Copepoda. In the Pacajus reservoir, 25 species were recorded in the dry period and 24 in the rainy period. In the Gavião reservoir, 10 species were recorded in the dry and 24 in the rainy periods. According to Shannon-Weaver index, the diversity of species was lower during the dry season for both reservoirs, which can be related to the higher trophy status presented by these lakes in that time. There was an evident dominance of Copepoda Cyclopoida over Copepoda Calanoida, mainly caused by high densities of Thermocyclops decipiens, particularly in December/ 1998. Diaphanosoma spinulosum and Ceriodaphnia cornuta were important among Cladocera, while Keratella and Brachionus were the most conspicuous genera in the Rotifera assembly. The most abundant rotifer species were Keratella tropica, K. americana, Brachionus calyciflorus, B. havanaensis, and Polyarthra vulgaris. Opportunistic species such as T. decipiens, D. spinulosum, C. cornuta, B. calyciflorus, and K. tropica, found in the two studied reservoirs, can be associated with hypereutrophic waters and disturbed environments.
Zooplankton as an indicator of trophic conditions in two large reservoirs in Brazil
The physical and chemical variables of the water, and the composition and structure of the zooplankton communities, in Três Marias and Furnas Reservoirs in Minas Gerais, Brazil, were compared to characterize these environments in relation to their trophic state. Higher values of electrical conductivity and chlorophyll-a, total solids, suspended organic matter and total nitrogen concentrations were recorded in Três Marias Reservoir. Higher water transparency and nitrite and nitrate concentrations were observed in Furnas (P < 0.000). Higher zooplankton densities were always obtained in Três Marias Reservoir and, during the rainy period (P < 0.000), with mean values in the dry and rainy periods of 23 721 and 90 872 org m )3 , respectively, in Três Marias Reservoir and 9022 and 40 434 org m )3 , respectively, in Furnas Reservoir. Copepoda was the dominant group in both reservoirs, mainly the younger stages (nauplii and copepodids). Based on the absolute and relative values, the contribution of rotifers was higher in Três Marias Reservoir than in Furnas Reservoir. Although the Trophic State Index, based on water transparency and chlorophyll-a and total phosphorus concentrations, indicated an oligotrophic state for both reservoirs, the higher densities of the zooplankton community in Três Marias Reservoir, as well as the predominance of cyclopoids and smaller-sized species such as bosminids, characterized this environment as mesotrophic. Larger-sized species such as calanoids, daphniids and sidids in Furnas Reservoir characterized the better water quality of this reservoir.
Zooplankton assemblages in eutrophic reservoirs of the Brazilian semi-arid
Species composition, density, and temporal dynamics of zooplankton were studied in six reservoirs in a semi-arid region in tropical northeastern Brazil (Rio Grande do Norte state). All the reservoirs are highly eutrophic, with high contents of total nitrogen (minimum of 1200 µg.L -1 ) and total phosphorus (minimum of 10 µg.L -1 ), and extremely high algal biomass was registered (surpassing 20 µg Chl a.L -1 ). All the reservoirs showed an enduring condition of high turbidity and phytoplankton assemblages dominated by cyanobacteria. Zooplankton also showed quantitative patterns suggestive of eutrophic conditions, expressed by high densities, mainly in Passagem das Traíras and Sabugi reservoirs. A spatial differentiation in the composition of the zooplankton community was registered. Rotifers (especially Keratella tropica, Brachionus havanensis, and Keratella americana) were the dominant forms in the zooplankton community of Itans, Passagem das Traíras, and Sabugi reservoirs, while calanoid copepods (mainly Notodiaptomus cearensis) dominated in the Armando Ribeiro, Gargalheiras, and Parelhas systems. The existence of novel relationships in zooplankton community composition in eutrophic reservoirs in this tropical semi-arid region must be considered in designating zooplankton indicators of eutrophic conditions. A composição de espécies, a densidade e a dinâmica temporal do zooplâncton foram estudadas em seis reservatórios de uma região semiárida no nordeste do Brasil (Estado do Rio Grande do Norte). Todos os reservatórios estão altamente eutróficos, com altas concentrações de nitrogênio total (mínimo de 1.200 µg.L -1 ) e fósforo total (mínimo de 10 µg.L -1 ), e biomassa algal extremamente alta (muitas vezes, superando 20 µg.L -1 de Chl a). Todos os reservatórios apresentaram alta turbidez e assembleias fitoplanctônicas dominadas por cianobactérias. O zooplâncton também apresentou padrões quantitativos sugestivos de condições eutróficas, expressas por altas densidades, principalmente nos Reservatórios Passagem das Traíras e Sabugi. Foi registrada uma diferenciação espacial na composição da comunidade zooplanctônica. Rotíferos (especialmente Keratella tropica, Brachionus havanensis e Keratella americana) foram as formas dominantes na comunidade zooplanctônica dos Reservatórios Itans, Passagem das Traíras e Sabugi, enquanto copépodos Calanoida (principalmente Notodiaptomus cearensis) dominaram nos Reservatórios Armando Ribeiro Gonçalves, Gargalheiras e Parelhas. A existência de novas relações na composição da comunidade zooplanctônica em reservatórios eutróficos dessa região semiárida tropical deve ser considerada no estabelecimento de indicadores zooplanctônicos de condições eutróficas.
Caldasia, 2000
Phytoplankton samples were taken at three depths within the photie zone of eaeh of four reservoirs, Punehina, Las Playas, El Penol and San Lorenzo loeated in Antioquia department, Colombia. A total of 77 taxa were identified in the four reservoirs. Diatoms were not included. In all reservoirs, Chlorophyta was the dominant group. Botryococcus braunii was the dominant species at Punchina, Las Playas and El Penol reservoirs; Cosmarium sp. was the dominant at San Lorenzo. Temporal variation in phytoplankton showed two peaks of abundance, apparently related to precipitation. Taxonomic composition among samples from the same reservoir showed little variation. Community structure at different depths showed significant differences only at San Lorenzo reservoir. The inverse of β -diversity showed small values indicating high similarity among the reservoirs. Diversitv showed no significant assoeiation with any morphometric factor evaluated (area, retention time, altitude and age).
Zooplankton biomass in tropical reservoirs in southern Brazil
Hydrobiologia, 2007
In order to test the hypothesis that zooplankton biomass distribution (total and taxonomic groups) was influenced by the nutrient concentration and primary productivity distribution in three tropical reservoirs, subsurface samples were taken in the fluvial, transitional and lacustrine regions of three reservoirs (oligotrophic, mesotrophic and eutrophic) in southern Brazil (Paraná State) in March and September 2002. Zooplankton biomass ranged from 0.04 to 264.47 mg DW m -3 . Higher biomass values were observed for cladocerans (73.60%; 0.01-259.86 mg DW m -3 ), followed by copepods (22.05%; 0.01-69.69 mg DW m -3 ) and rotifers (4.35%; 0.01-11.52 mg DW m -3 ). In general, the total zooplankton, rotifer, cladoceran and copepod biomass, and chlorophyll-a and total nutrient concentrations showed a similar longitudinal distribution within the reservoirs. Total zooplankton, rotifer and cladoceran biomass were related to the chlorophyll-a concentration, and zooplankton biomass was related to the total phosphorus distribution. This may have been due to the significant multicolinearity between the chlorophyll-a and total phosphorus concentrations. Cyanobacteria influenced the taxonomic group biomass results by interfering with the filter feeding in larger zooplankton species, which favoured the dominance of smaller species. As regards the longitudinal distribution of copepod biomass, cyanobacteria biomass determined the displacement of the microcrustaceans to the fluvial region of Iraí Reservoir. Our results supported the hypothesis formulated and the primary productivity was the major predictor of the zooplankton biomass distribution in the reservoirs.
PeerJ, 2020
Background In reservoirs, zooplankton strongly interact with the physical and chemical characteristics of water, and this interaction is mainly influenced by climate variation and the different methods used to manage the dam water level. Therefore, the aim of this study was to evaluate how the distinct operating modes of two cascade reservoirs affected the richness, abundance, and composition of zooplankton, both spatially (intra and inter-reservoirs) and temporally (annual and seasonal). In this study, the upstream reservoir (Salto Santiago) operates using the storage method, with a water retention time (WRT) of 51 days, whereas the downstream reservoir (Salto Osório) operates using the run-of-river method, with a WRT of 16 days. Methods Zooplankton samples were collected for 16 consecutive years from the two reservoirs located on the Iguaçu River, Brazil. A total of 720 samples were collected. Four-way ANOVAs were used to determine the differences in richness and abundance of the zooplankton among years, periods, reservoirs, and environments. Multidimensional non-metric scaling (NMDS) and an analysis of similarities (ANOSIM) were used to describe similarity patterns in species composition. Finally, a canonical correspondence analysis (CCA) was used to select the environmental predictors that best explained the variation in zooplankton abundance data. Results We identified a total of 115 taxa in this study, and rotifers were the richest group. In contrast, the copepods were the most abundant. The four-way ANOVA results showed significant differences in the species richness and abundance of the zooplankton among years, periods, reservoirs, and environments. The NMDS ordination and ANOSIM test indicated that the largest differences in zooplankton species composition were annual and seasonal differences. Finally, the CCA showed that these differences were mainly associated with changes in water transparency, temperature, and the chlorophyll a, phosphorus, and total dissolved solids concentrations. Discussion Inter-annual changes in zooplankton species composition showed that over time, large filters-feeders (e.g., large daphinids and calanoid copepods) were replaced by small cladocerans (e.g., bosminids) and generalist rotifers. The highest species richness was associated with the fluvial environment, whereas the highest abundance was associated with the transitional and lacustrine reservoir environments. Variations in water temperature, nutrients, and food availability explained the annual and seasonal changes in community structure, whereas variations in the water flow characteristics of the environments explained the longitudinal changes in the richness and abundance of zooplankton in reservoirs. The differences in zooplankton structure between the two reservoirs can be explained by the functional differences between the two systems, such as their WRTs and morphometrics.
Zooplanktonic community of six reservoirs in northeast Brazil
Brazilian Journal of Biology, 2009
The aim of the present study was to investigate the zooplankton community at six reservoirs in the state of Pernambuco (Brazil). Zooplankton assemblages were identified using current literature and quantitatively analysed under a microscope and stereomicroscope. Concurrently to the sampling of zooplanktonic and phytoplanktonic communities, in situ measurements of abiotic variables, such as water temperature, dissolved oxygen and pH, were determined using field probes and transparency was determined with a Secchi disk. Total phosphorus concentrations were used for the determination of the Trophic State Index. The reservoirs were classified between eutrophic and hypertrophic, oxygenated, with pH varying from slightly acid to alkaline, high temperatures and low water transparency. A total of 27 zooplankton taxa were identified. Phytoplankton was represented by Cyanophyta, Chlorophyta, Baccilariophyta and phytoflagellates. The highest richness of species was observed for Rotifera (17), ...
Brazilian Journal of Biology, 2021
Zooplankton are widely recognised as being regulated primarily by predators and food availability. In reservoirs, the quantity and quality of food resources are generally affected by the characteristics of the water, which in turn are controlled by the flow pulse generated by operation of the dams. In this study, we investigated the relationship between zooplankton, water quality and food availability (phytoplankton) in eight hydroelectric reservoirs located in Brazil. Samples were collected during the rainy and dry periods between 2008 and 2009. In general, the reservoirs exhibited mesotrophic conditions and Cyanobacteria were the predominant phytoplankton. The results showed that the rotifers Kellicottia bostoniensis, Hexarthra mira, Keratella spp., and Polyarthra vulgaris were present, indicating nutrient-rich environments. In addition, the copepod Thermocyclops decipiens occurred in eutrophic environments. In contrast, the cladoceran Daphnia gessneri and copepod Notodiaptomus henseni were considered indicators of more desirable water quality, owing to their relationship with waters with lower levels of nutrients and suspended solids. The results support the use of these organisms as a useful tool for understanding changes in water quality and in the ecosystem processes involved.