ABSTRACT
Testate amoebae have a great potential for use in scientific researches due to their ecological characteristics such as abundance, wealth, and generation time. In this way, this study aimed to present a scientometric analysis to describe the evolution of the different advances in researches on testate amoebae and identify a temporal pattern in this evolution. The literature review was based on papers indexed by Thomson Reuters (www.isiwebofknowledge.com) and SciVerse Scopus (www.scopus.com). In total 562 papers were examined. Results showed a pattern of evolution in scientific studies, most with ecological approach with descriptive and predictive designs. At the global level, researches on testate amoebae progressed in both the number of articles published as well as in the areas studied, especially in Europe and North America. The low number of experimental studies and review articles can characterize the lack of more knowledge to be acquired, both from particular observations (descriptive studies) as well as the observations noted sufficiently predictive of work. In Brazil, studies with testate amoebae are still developing, concentrated in only some regions, but the increased number of studies in recent years allows the prediction of the same overall patterns of advance for Brazilian researches. Thus, we conclude that these organisms are being increasingly used as a tool resp
ABSTRACT
This study evaluated the spatial variations in species richness and abundance of zooplankton over a hydrological cycle, and also verified the influence of physical and chemical water variables and chlorophyll-a concentrations on the abundance of these organisms. The tested hypothesis was that the zooplankton community presents higher species richness in lotic environments and higher abundance in lentic ones. One hundred forty species were identified, distributed among rotifers (88), testate amoebae (35), cladocerans (13) and copepods (4). Higher values of species richness and abundance were observed during the dry period. During both hydrological periods, the copepods presented high abundance values, due to the contribution of young stages, followed by rotifers, cladocerans and testate amoebae. In general, testate amoebae presented high values of species richness and abundance in lotic sampling stations, whereas the other zooplankton groups (rotifers, cladocerans and copepods) presented higher abundances in lentic environments and higher species richness in lotic ones. The Pearson correlation analysis evidenced the importance of physical and chemical water variables and food resource availability influencing the variation of organisms abundance.
This study evaluated the spatial variations in species richness and abundance of zooplankton over a hydrological cycle, and also verified the influence of physical and chemical water variables and chlorophyll- concentrations on the abundance of these organisms. The tested hypothesis was that the zooplankton community presents higher species richness in lotic environments and higher abundance in lentic ones. One hundred forty species were identified, distributed among rotifers (88), testate amoebae (35), cladocerans (13) and copepods (4). Higher values of species richness and abundance were observed during the dry period. During both hydrological periods, the copepods presented high abundance values, due to the contribution of young stages, followed by rotifers, cladocerans and testate amoebae. In general, testate amoebae presented high values of species richness and abundance in lotic sampling stations, whereas the other zooplankton groups (rotifers, cladocerans and copepods) presented higher abundances in lentic environments and higher species richness in lotic ones. The Pearson correlation analysis evidenced the importance of physical and chemical water variables and food resource availability influencing the variation of organisms abundance.
ABSTRACT
The present study evaluated the influence of water level fluctuations and the system type on the structure of planktonic microcrustacean assemblage, in different lagoons on the Upper Paraná River floodplain. Sampling was performed in pelagic region from 15 lagoons associated with three rivers, during flood (February 1999) and dry (October 1999) periods. Forty nine cladoceran species and sixteen copepods species were identified. Null model ANOVA results did not show significant differences in microcrustacean densities among systems. Only B. hagmanni, B. deitersi and Calanoid nauplii densities were significantly different between periods. Differences between periods in each system and among systems in each hydrological period were not significant either. Thus, spatial differences were not superior in microcrustacean structuring. However, some temporal differences were observed for bosminids and Calanoid nauplii
Este estudo avaliou a influência do nível hidrométrico e do tipo de sistema na estrutura da assembléia de microcrustáceos planctônicos, em diferentes lagoas da planície de inundação do alto rio Paraná (PR/MS). As coletas foram realizadas na região pelágica de 15 lagoas associadas a três rios, nos períodos de cheia (Fevereiro/1999) e de seca (Outubro/1999). Foram registradas 49 espécies de cladóceros e 16 de copépodos. Os resultados da ANOVA do modelo nulo não indicaram diferenças significativas das densidades dos microcrustáceos entre os sistemas. Somente as densidades de B. hagmanni, B. deitersi e náuplios de Calanoida foram significativamente diferentes entre os períodos. Diferenças entre períodos hidrológicos em cada sistema e entre sistemas em cada período hidrológico também não foram significativas. Nesse sentido, as diferenças espaciais não foram preponderantes para a estruturação da comunidade de microcrustáceos. Algumas diferenças temporais, no entanto, foram observadas para os bosminídeos e para os náuplios de Calanoida