Norma Catarina Bueno

Bimodality in stable isotope composition facilitates the tracing of carbon transfer from macrophytes to higher trophic levels

Even though the suitability of macrophytes to act as a carbon source to food webs has been questioned by some studies, some others indicate that macrophyte-derived carbon may play an important role in the trophic transfer of organic matter in the food web of shallow lakes. To evaluate the importance of macrophytes to food webs, we collected primary producers—macrophytes and periphyton—and consumers from 19 South American shallow lakes and analyzed their carbon stable isotopes composition (δ13C). Despite the diversity of inorganic carbon sources available in our study lakes, the macrophytes’ δ13C signatures showed a clear bimodal distribution: 13C-depleted and 13C-enriched, averaging at −27.2 and −13.5‰, respectively. We argue that the use of either CO2 or HCO3− by the macrophytes largely caused the bimodal pattern in δ13C signals. The contribution of carbon from macrophytes to the lake’s food webs was not straightforward in most of the lakes because the macrophytes’ isotopic composition was quite similar to the isotopic composition of periphyton, phytoplankton, and terrestrial carbon. However, in some lakes where the macrophytes had a distinct isotopic signature, our data suggest that macrophytes can represent an important carbon source to shallow lake food webs.

Diatoms (Bacillariophyceae) of Iguaçu National Park, Foz do Iguaçu, Brazil

This study represents a taxonomic survey of class Bacillariophyceae diatoms found in samples collected in the Iguacu River (Iguacu National Park, municipality of Foz do Iguacu, in the state of Parana, Brazil) between August 2007 and July 2008. Two sampling stations were utilized, the first located upstream of Iguacu Falls (Cais Bananeiras Station) and second downstream of the falls (Cais Macuco Safari Station). The study resulted in the identification of 86 taxa, including 74 at the specific level and seven taxonomic varieties. Two of these had never before been documented in the state of Parana: Gomphonema gibberum Hustedt and Pinnularia meridiana Metzeltin & Krammer. Nine are first-time records for Brazil: Cymbella charrua Metzeltin, Lange-Bertalot & Garcia-Rodriguez, Placoneis ovillus Metzeltin, Lange-Bertalot & Garcia-Rodriguez, Gomphonema affinopsis Metzeltin, Lange-Bertalot & Garcia-Rodriguez, , Gomphosphenia lingulatiformis (Lange-Bertalot & Reichardt) Lange-Bertalot, Luticola aequatorialis (Heiden) Lange-Bertalot & Ohtsuka, Sellaphora garciarodriguezii Metzeltin & Lange-Bertalot, Eolimna submuralis (Hustedt) Lange-Bertalot Kulikovskiy, Geissleria neosubtropica Metzeltin, Lange-Bertalot & Garcia-Rodriguez and Stauroneis cf. sylviabonillae Metzeltin, Lange-Bertalot & Garcia-Rodriguez.

Desmidiaceae (exceto Cosmarium) de um tributário do reservatório de Itaipu, Paraná, Brasil

Survey of genera Desmidiaceae (except Cosmarium) in a tributary of Itaipu Reservoir. It carried out it qualitative analysis of 60 samples collected in the period from July 2003 to June 2004. Forty-one species, ten varieties which are not the typical of its respective species and an another not typical species were also identified. The Desmidiaceae were represented by the genera: Actinotaenium (1), Closterium (3), Euastrum (5), Micrasterias (5), Octacanthium (1), Onychonema (1), Penium (1), Pleurotaenium (2), Spondylosium (2), Staurastrum (14), Staurodesmus (5) and Xanthidium (1). Staurastrum was the most presented genus, contributing with 34% of the total wealth. The least presented genera were: Actinotaenium, Octacanthium, Onychonema, Penium and Xanthidium, with one species each totaling 12%. Micrasterias truncata (Corda) Brebisson ex Ralfs var. pusila G.S. West was found in all stations of collection.

Closterium Nitzsch ex Ralfs (Desmidiaceae) em um lago artificial urbano, Paraná, Brasil

An investigation of the genera Closterium from an artificial lake of Cascavel city, Parana, Brazil was undertaken. The samples were collected from January/2002 to November/2003, in the lake littoral zone. Seventeen taxa of the genera Closterium were identified, where 13 of them were typical and four of them non-typical varieties. C. cynthia De Notaris var. cynthia, represented 25% of total samples, followed by C. moniliferum (Bory) Ehrenberg ex Ralfs var. moniliferum (17%). Taxa such as C. ehrenbergii Meneghini ex Ralfs var. ehrenbergii, C. leibleinii Kutzing ex Ralfs var. leibleinii e C. lunula (Muller) Nitzsch ex Ralfs var. biconvexum Schmidle were less frequent in the analysis representing 3% of the taxon total records.

Phytoplankton functional groups in a subtropical Brazilian reservoir: responses to impoundment

The discontinuity in rivers caused by the construction of reservoirs disrupts the longitudinal gradient and decreases the natural connectivity of lotic systems. We evaluated the dynamics of Reynolds functional groups (RFGs) in response to the formation of a subtropical reservoir, in relation to the environmental changes between the pre- and post-impoundment periods. We hypothesized that the disruption of longitudinal connectivity and the changes in the light and mixing regime after the impoundment would directly influence the phytoplankton functional structure. Significant changes in the light and mixing regimes were observed after the impoundment, with the formation of a lacustrine zone, influencing the dynamics of RFGs. Fourteen RFGs were recorded. RFG C (diatoms) dominated in the pre-impoundment period. In the post-impoundment period, RFGs C, P (diatoms), and J (chlorophyceans) codominated with the highest mean values of biovolume. RFGs MP, N, H1, W2, F, E, A, W1, B, X1, and S1 contributed relatively little to the biovolume, although with higher values in the post-impoundment period. RFGs F and S1 were recorded only after the impoundment. This study revealed the important roles of physical processes and nutrients in the spatial and seasonal gradient, and in the selection of phytoplankton functional groups in a subtropical reservoir.

Desmídias (Zygnemaphyceae) do Rio São João, Parque Nacional do Iguaçu, Paraná, Brasil

Desmids (Zygnemaphyceae) of the Sao Joao River, Iguacu National Park, Parana, Brazil). This paper is a characterization of the desmid florula of the Sao Joao River, Iguacu National Park, Foz do Iguacu, Parana, Brazil. Samples were collected in the period from June 2008 to May 2009 in three sampling stations of the Sao Joao river. The samples were obtained with a 25 µm nylon plankton net was immediately fixed on Transeau solution. 44 taxa were identified distributed among the genera Actinotaenium (1), Bambusina (1), Closterium (7), Cosmarium (11), Desmidium (1), Euastrum (2), Gonatozygon (3), Micrasterias (5), Netrium (1), Octacanthium (1), Pleurotaenium (1), Spondylosium (2), Staurastrum (4), Staurodesmus (2), Teilingia (1), and Xanthidium (1). Cosmarium Corda ex Ralfs was the most representative genus in the study, with 25% of the local documented taxa.

Chlorococcales (Chlorophyceae) de um tributário do reservatório de Itaipu, Paraná, Brasil

This work aimed the taxonomic knowledge of the order Chlorococcales (Chlorophyceae) from Sao Francisco Falso River, one of the Itaipu reservoir tributaries located at the municipal district of Santa Helena, Parana State, Brazil. Samples were collected from July 2003 to June 2004 at five sample stations located in the litoral region of the river. The phytoplanktonic material, obtained with plankton net (25 µm net) and by passing open flasks on water surface, were immediately fixed in Transeau solution. The qualitative sample analysis allowed the identification of 21 taxa belonging to the families: Palmellaceae, Hydrodictyaceae, Botryococcaceae, Chlorellaceae, Coelastraceae and Scenedesmaceae. The most representative genus was Desmodesmus with seven taxa. Hydrodictyon reticulatum (L.) Lagerheim and Coelastrum astroideum De Notaris var. astroideum were firstly cited in the Parana State.

Coscinodiscophyceae and Fragilariophyceae (Diatomeae) in the Iguaçu River, Paraná, Brazil

A taxonomic survey was carried out on Coscinodiscophyceae and Fragilariophyceae found in the Iguacu River catchment area within Iguacu National Park, in the state of Parana, Brazil. Between September 2007 and August 2008, we collected 24 samples from two stations on the Iguacu River, upstream and downstream of the falls. We identified 37 taxa, including 22 specific and infraspecific taxa of Coscinodiscophyceae, together with 15 specific and infraspecific taxa of Fragilariophyceae. Melosira ruttneri Hustedt and Fragilaria alpestris Krasske ex Hustedt represent new records for Brazil.

Desmidioflórula (Zygnemaphyceae, Desmidiales) do rio Cascavel, oeste do estado do Paraná, Brasil

This study aimed to perform the taxonomic survey of desmids of an important lotic ecosystem in the western region of Parana State. Samples were collected monthly (July 2010 to June 2011), in three sampling stations from the Cascavel River, resulting in the identification of 60 taxa, belonging to 10 genera. The Cosmarium Corda ex Ralfs (29) and Closterium Nitzsch ex Ralfs (10) obtained the largest number of inventoried species. A total of 14 new citations were recorded for the Parana State, distributed among genera Actinotaenium (Nageli) Teiling (2), Cosmarium (7), Closterium (1), Micrasterias C. Agardh ex Ralfs (1), Pleurotaenium Nageli (1), Staurastrum Meyen (1) and Staurodesmus Teiling (1). At the end of the study was observed that the total number of species identified, 83.9% were common to all three stations collected, 13.3% were recorded in the sampling stations 2 and 3, and 3.3% only at station 3.

New Records of Chara (Chlorophyta, Characeae) for Subtropical Southern Brazil

Abstract Twelve taxa of the genus Chara (Characeae, Chlorophyta) are decribed and illustrated based on specimens from southern Brazil. The taxonomic survey in the states of Paraná, Santa Catarina and Rio Grande do Sul recorded seven, one, and nine species for each state, respectively. Chara guairensis was the most common species in the area, followed by C. rusbyana. The species Chara guairensis, C. martiana, C. rusbyana, Chara hydropitys, C. braunii and its varieties were recorded for the first time in Rio Grande do Sul, and the following six for Paraná: C. angolensis, C. diaphana, C. guairensis, C. kenoyeri, C. martiana, and C. zeylanica.