Taxonomy of common taxa of Chlorophyceae (Chlorophyta) and Zygnematophyceae (Streptophyta) from periphyton of a Neotropical floodplain

Some orders of algal groups such as Chlorophyceae and Zygnematophyceae have been reported as frequent taxa in periphytic communities of wetlands. The present study aimed at submitting these algal members which occurred in high abundance and frequency in the periphyton of 30 environments of the Upper Paraná River floodplain to a taxonomic survey and to present some ecological data concerning their richness. Periphyton were collected from petioles by scraping of Eichhornia azurea (Sw.) Kunth and preserved with Lugol acetic solution in the Upper Paraná River, Brazil, during high water period in March 2010. Taxa were counted in inverted microscope and those higher than 2,500 individuals in density with frequency of occurrence less than 50% simultaneously in the 30 environments sampled were subjected to a detailed taxonomical treatment under optical microscope coupled to a light camera and ocular micrometer under 1000x. Identifications and descriptions were made according to the algal literature. Some abiotic data were shown. Fifteen taxa belonging to the classes Chlorophyceae and Zygnematophyceae were abundant representing 64.6% of the total density. A Procruste analysis within a Detrended Correspondence Analysis showed that distribution pattern of richness of clorophyceans and zygnematophyceans was represented by common species of these communities, highlighting the importance of knowing about these algae taxonomy

Structure of the periphytic algae associated with a floating macrophyte in an open lake on the upper Paraná river floodplain, Brazil / Estrutura das algas perifíticas associadas a uma macrófita flutuante em uma lagoa aberta da planície de inundação do alto rio Paraná, Brasil

We aimed to access the knowledge of the structure of the periphytic algae community on a floating substrate, the macrophyte Ricciocarpus natans (L.) Corda, during two hydrological periods in a connected environment at the Paraná river floodplain. Attached algal was removed from the substrate with the aid of a soft-bristled brush and distilled water jets and was fixed immediately for qualitative and quantitative analysis. The total richness of the periphytic algae was 188 taxa. February showed the highest species richness (154 taxa), while total species density exhibited an inverse pattern, with the highest values occurring in June (273.4 103 ind. cm-2). Bacillariophyceae comprised the largest fraction of density, which was reflected by the abundance of Achnanthidium minutissimum (Kütz.) Czarn. Community structure of periphytic algae in R. natans followed the same pattern of other substrates, as previously determined. This suggests that main factor acting on the structure of periphyton at the Paraná river floodplain is primarily the floodpulses regime. The hydrochoric dispersion of R. natans across the various environments comprising the floodplain favors its communities associated, as the periphytic algae, subject to passive transport via water movement. Floating rhizoids of R. natans also may act as a mesh retainer, promoting the colonization of many metaphytic and planktonic species. However, in order to better understand and delineate patterns of ecosystem functioning, it is recommended that natural substrates be used which have greater stability in the environment, such as rooted or submerged macrophyte species.

Objetivou-se conhecer a estrutura da comunidade de algas perifíticas em um substrato flutuante, a macrófita Ricciocarpus natans (L.) Corda, em dois períodos hidrológicos em um ambiente conectado na planície do alto rio Paraná. O material perifítico foi removido do substrato com ajuda de pincel de cerdas macias e jatos de água destilada e imediatamente fixado para a análise qualitativa e quantitativa. A riqueza total das algas perifíticas foi de 188 táxons. Fevereiro apresentou a maior riqueza (154 táxons), enquanto que a densidade total apresentou um padrão inverso, no qual os maiores valores ocorreram em junho (273,4 103 ind. cm-2). Bacillariophyceae compôs a maior fração da densidade, refletida pela abundância de Achnanthidium minutissimum Czarn (Kütz.). A estrutura da comunidade de algas perifíticas em R. natans seguiu o mesmo padrão de outros substratos, conforme estudos anteriores. Isto sugere que o principal fator atuante sobre a estruturação do perifíton na planície do rio Paraná seja primariamente o regime de pulsos. A dispersão hidrocórica de R. natans ao longo dos vários ambientes que compõem a planície favorece suas comunidades associadas, como as algas perifíticas, sujeito ao transporte passivo através do movimento da água. Os rizóides flutuantes de R. natans também podem atuar como uma malha retentora, promovendo a colonização de muitas espécies metafíticas e planctônicas. No entanto, a fim de melhor compreender e delinear padrões de funcionamento dos ecossistemas recomenda-se o uso de substratos naturais que possuam maior estabilidade no ambiente, tais como espécies de macrófitas aquáticas enraizadas ou submersas.

Structure of the periphytic algae associated with a floating macrophyte in an open lake on the upper Paraná river floodplain, Brazil - doi: 10.4025/actascibiolsci.v35i4.18663

We aimed to access the knowledge of the structure of the periphytic algae community on a floating substrate, the macrophyte Ricciocarpus natans (L.) Corda, during two hydrological periods in a connected environment at the Paraná river floodplain. Attached algal was removed from the substrate with the aid of a soft-bristled brush and distilled water jets and was fixed immediately for qualitative and quantitative analysis. The total richness of the periphytic algae was 188 taxa. February showed the highest species richness (154 taxa), while total species density exhibited an inverse pattern, with the highest values occurring in June (273.4 103ind. cm-2). Bacillariophyceae comprised the largest fraction of density, which was reflected by the abundance of Achnanthidium minutissimum (Kütz.) Czarn. Community structure of periphytic algae in R. natans followed the same pattern of other substrates, as previously determined. This suggests that main factor acting on the structure of periphyton at the Paraná river floodplain is primarily the floodpulses regime. The hydrochoric dispersion of R. natans across the various environments comprising the floodplain favors its communities associated, as the periphytic algae, subject to passive transport via water movement. Floating rhizoids of R. natans also may act as a mesh retainer, promoting the colonization of many metaphytic and planktonic s