Light intensity can trigger different agonistic responses in juveniles of three cichlid species

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Characterization of a novel freshwater gigartinalean red alga from Belize, with a description of Sterrocladia belizeana sp nov (Rhodophyta)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Quantitative fidelity of recent freshwater mollusk assemblages from the Touro Passo River, Rio Grande do Sul, Brazil

O presente estudo teve como objetivo apresentar uma das primeiras contribuições ao conhecimento sobre a fidelidade quantitativa de associações de moluscos recentes em rios subtropicais. Tanatocenoses e biocenoses foram estudadas em seções retilínea e meandrante tendendo a anastomosada, no curso médio do rio Touro Passo, um tributário de 4ª ordem do rio Uruguai, localizado no extremo oeste do Rio Grande do Sul. As amostragens foram realizadas por meio de quadrats de 5 m², cinco em cada seção, amostrando-se um total de 50 m². Também foram feitas amostragens em um ambiente lêntico, com comunicação intermitente com o Touro Passo, objetivando detectar a existência de transporte de comunidades lênticas para o interior do rio. Os resultados obtidos mostram que, apesar da freqüente oscilação do nível da água, a biocenose do Touro Passo apresenta uma alta fidelidade ecológica e sofre pouca influência de espécies de ambientes lênticos. A composição taxonômica e características de estrutura de comunidades, especialmente as espécies dominantes, refletem, ainda, diferenças ecológicas relacionadas às duas seções amostradas, como a maior complexidade de habitats da estação meandrante. Quanto à fidelidade quantitativa, 60% das espécies encontradas vivas também foram encontradas mortas e 47,3% das espécies encontradas mortas também foram encontras vivas em escala de rio. Porém, 72% dos exemplares coletados mortos são representantes de espécies encontradas vivas. Essa percentagem alta pode estar relacionada à boa correlação entre o ranking de dominância das associações vivas e mortas e, conseqüentemente, as espécies dominantes das tanatocenoses podem ser utilizadas para inferir características ecológicas das biocenoses. Todos os índices analisados variaram muito em escala local (quadrat) e seus valores são mais aproximados aos de outros, registrados em estudos prévios, apenas quando analisados em escala mais ampla (seção, área total).

Rediscovered after 77 years: Odontodiaptomus thomseni - a rare species of calanoid (Crustacea: Copepoda) from South America

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Molecular systematics of Thorea (Rhodophyta, Thoreales) species in Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Nuclear DNA content in 20 species of Siluriformes (Teleostei: Ostariophysi) from the Neotropical region

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phylogenetic relationship of Sirodotia species (Batrachospermales, Rhodophyta) in North and South America

Sequence data from the RUBISCO large subunit (rbcL) plastid gene and nuclear small-subunit ribosomal DNA (SSU rDNA) were examined for five samples of Sirodotia delicatula from southeastern Brazil. Data from six North American samples previously identified as S. huillensis and S. suecica were also included in the analysis. Molecular data supported the continued recognition of these three species as separate entities, although one of the North American collections was misidentified. These results were shown to be congruent with morphology, chromosome number and geographic distribution. S. delicatula is more closely related to S. huillensis, both occurring in tropical-subtropical regions, than either to S. suecica with a temperate-boreal distribution. There was little rbcL variation within S. delicatula from Brazil and Costa Rica (the latter a collection previously identified as S. huillensis), with the six samples sequenced diverging from each other by 0-8 bp (0-0.67%). SSU rDNA data set did not provide sufficient resolution to infer phylogenetic relationships among the species of this group due to the low rates of variation (5 bp). Sirodotia was a well-supported clade (100% bootstrap or 1.00 a posteriori probability) based on rbcL sequences. Thus, the results confirm that Sirodotia is a monophyletic group within the Batrachospermales and we continue to recognize it at the generic level. The species S. delicatula, S. huillensis and S. suecica are morphologically and genetically distinct.

Light-related photosynthetic characteristics of freshwater rhodophytes

Photosynthetic characteristics in response to irradiance were analysed in 21 field and culture populations of thirteen freshwater red algal species applying two distinct techniques (chlorophyll fluorescence and oxygen evolution). Photosynthesis-irradiance (PI) curves indicated adaptations to low irradiances in all species analysed, essentially characterized by occurrence of photoinhibition, low values of the saturation parameter (I-k < 225 mu mol m(-2) s(-1)) and compensation irradiance (I-c < 20 mu mol m(-2) s(-1)) and relatively high values of the effective quantum yield of photosystem II (Delta F/F'(m) >= 45). These characteristics have been reported in freshwater red algae and were confirmed from data based on the two techniques, indicating they are typically shade-adapted plants. on the other hand, some species (e.g. Batrachospermum delicatulum) can tolerate high irradiances (up to 2400 mu mol m(-2) s(-1)), suggesting they have mechanisms that enable them to avoid photodarnage of the photosynthetic apparatus. One of these mechanisms is the increase in dissipation of excessive energy captured by reaction centres after exposure to continuous irradiance, as reflected by the non-photochemical quenching fluorescence parameter in dark/light induction curves. Photo-inhibition occurred in all algae tested by both techniques. Light acclimation was evident particularly in field populations, as revealed by lower values of the saturation parameter (Ik) and the compensation irradiance (I-c) and higher values of Delta F/F'(m) in algae under low irradiances (shaded or heavily shaded stream segments), and vice-versa. Forms living within the boundary layer (e.g. crusts), in a region of reduced current velocity, tended to be more shade-adapted than semi-erect plants (e.g. non-mucilaginous or mucilaginous filaments), as indicated by highest values of photosynthetic efficiency (alpha = 0.31) and effective quantum yield (Delta F/F'(m) = 0.88) under natural conditions. Higher photo- synthetic rates (P-max) for the same species or population were observed under culture than field conditions when measured with the oxygen evolution technique, whereas the opposite trend was observed using chlorophyll fluorescence. (c) 2005 Elsevier B.V. All rights reserved.

SYSTEMATICS OF FRESH-WATER AUDOUINELLA (ACROCHAETIACEAE, RHODOPHYTA) IN NORTH-AMERICA .1. THE REDDISH SPECIES

Multivariate morphometrics and image analysis were used to determine the number of well-distinguished infrageneric taxa of reddish freshwater Audouinella in North America. Three distinct groupings were differentiated from 83 populations collected from Alaska and Labrador in the north to central Mexico and Jamaica in the south. These groupings were statistically related to seven type specimens. The following species were recognized: A. eugenea (SKUJA) JAO, A. hermannii (ROTH) DUBY [syn.: A. violacea (KUTZ.) HAMEL and its varieties, alpina (KUTZ.) RAB., dalmatica (KUTZ.) RAB., expansa (WOOD) SMITH, and hercynica (KUTZ.) KUTZ.] and A. tenella (SKUJA) PAPENFUSS. These species are separated based on dimensions of vegetative cells and monosporangia. A. tenella is found only in California, A. eugenea in warm, alkaline and high-ion waters of the tropical rainforest and desert-chaparral, while A. hermannii occurs widely from the boreal to south temperate and in waters with relatively low temperatures and ion content.

Anindobothrium n. gen. (Eucestoda : Tetraphyllidea) inhabiting marine and freshwater potamotrygonid stingrays

Anindobothrium n. gen. is proposed to accommodate Caulobothrium anacolum inhabiting Himanturu schmardae from Colombia, and 2 new species, one inhabiting Potamotrygon orbigny in Brazil and the other inhabiting Paratrygon aereiba in Venezuela. Members of the new genus resemble members of Pararhinebothroides, Rhinebothroides, and Anthocephalum by having bothridia with poorly differentiated apical suckers and vasa deferentia expanded into external seminal vesicles. It further resembles Pararhinebothroides, Rhinebothroides, and Anthocephalum cairae by having vas deferens inserted near the poral rather than aporal end of the cirrus sac. The 3 species assigned to the new genus form an apparent monophyletic group, based on the possession of 3 putative synapomorphies: (1) genital pores in the anterior 1/4 of the proglottid, a trait that is unusual, but not unique, among phyllobothriids; (2) anteroventral ovarian lobes converging to the center of the proglottid, a character not previously reported for phyllobothriids; and (3) ovarian lobes comprising a loose network of digitiform processes.

Organization of 5S rDNA in species of the fish Leporinus: two different genomic locations are characterized by distinct nontranscribed spacers

To address understanding the organization of the 5S rRNA multigene family in the fish genome, the nucleotide sequence and organization array of 5S rDNA were investigated in the genus Leporinus, a representative freshwater fish group of South American fauna. PCR, subgenomic library screening, genomic blotting, fluorescence in situ hybridization, and DNA sequencing were employed in this study. Two arrays of 5S rDNA were identified for all species investigated, one consisting of monomeric repeat units of around 200 bp and another one with monomers of 900 bp. These 5S rDNA arrays were characterized by distinct NTS sequences (designated NTS-I and NTS-II for the 200- and 900-bp monomers, respectively); however, their coding sequences were nearly identical. The 5S rRNA genes were clustered in two chromosome loci, a major one corresponding to the NTS-I sites and a minor one corresponding to the NTS-II sites. The NTS-I sequence was variable among Leporinus spp., whereas the NTS-II was conserved among them and even in the related genus Schizodon. The distinct 5S rDNA arrays might characterize two 5S rRNA gene subfamilies that have been evolving independently in the genome.

Three new species of Neoplecostomus (Teleostei: Siluriformes: Loricariidae) from the Upper Rio Parana basin of southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Blysmasphaera broennimanni : a new recent allogromiine species (order Foraminiferida, Eichwald, 1830) from Brazil.

Blysmasphaera broennimanni, a new recent allogromiine species from Brazil, is here introduced. This species was mainly found in freshwater and acidic sediments (pH ranged from 4.4 to 5.8). This new species differs from Blysmasphaera brasiliensis Broennimann, 1988 in its wall's outer layer, which is characterized by thin "plates" with everted borders that give the surface an overall net-like appearance. An emendation to the genus Blysmasphaera Broennimann, 1988 incorporating this new observed feature is also proposed.

Fidelity of molluscan assemblages from the touro passo formation (pleistocene-holocene), southern brazil: taphonomy as a tool for discovering natural baselines for freshwater communities

This study is the first assessment of mollusk fossil assemblages relative to the compositional fidelity of modern mollusk living and death assemblages. It also shows that the sedimentary record can provide information on the original, non-human-impacted, freshwater malacofauna biodiversity, based on Late Pleistocene shells. The fossil mollusk assemblage from the Touro Passo Formation (Pleistocene-Holocene) was compared to living and death assemblages of the Touro Passo River, southern Brazil, revealing little resemblance between fossil and live-dead species composition. Although the living and death assemblages agree closely in richness, species composition, and species relative abundances (both proportional and rank), the fossil assemblage differs significantly from both modern assemblages in most of these measures. The fossil assemblage is dominated by the native endemic corbiculid bivalve Cyanocyclas limosa and the gastropod Heleobia aff. bertoniana. These are absent in the living assemblages, and both living and death assemblages are dominated by the alien Asiatic corbiculid C. fluminea, which is absent in the fossil assemblage. The fossil assemblage also contains, overall, a higher proportional abundance of relatively thick-shelled species, suggesting a genuine bias against the thinner- and smaller-shelled species. Our results suggest that contemporary environmental changes, such as the introduction of some alien freshwater mollusk species, together with post-burial taphonomic processes, are the main factors leading to the poor fidelity of the fossil assemblage studied. Hence, the taxonomic composition of the Late Pleistocene mollusks from the Touro Passo Formation probably would show greater similarity to present-day assemblages wherever the mollusk biodiversity is not disturbed by human activities.

Effects of acute heat exposure on respiratory metabolism and blood glucose in freshwater fishes, Prochilodus scrofa (curimbatá) and Cyprinus carpio (carp) acclimatized to tropical winter

1. 1. Routine oxygen consumption and blood glucose were determined from freshwater fishes, Prochilodus scrofa and Cyprinus carpio, exposed at high temperatures for 1 hr. 2. 2. Prochilodus scrofa had a significantly higher rate of oxygen consumption at 30°C than at 25°C, and carp higher at 25°C than at 30°C. 3. 3. Blood glucose was significantly higher for Cyprinus carpio than for Prochilodus scrofa at 25 and 30°C; however, after exposure to these temperatures for 1 hr blood glucose did not change significantly for both species. 4. 4. The results suggest that these interspecific variations may be linked to the differences between native and foreign fishes and their way of life. © 1985.