RESUMO -(Diatomáceas perifíticas em um sistema eutrófi co brasileiro (reservatório do Iraí, estado do Paraná)). O estudo sobre a diversidade das diatomáceas do reservatório do Iraí ampliou o conhecimento da fl ora diatomológica perifítica de ambientes eutrófi cos do estado do Paraná e contribuiu para subsidiar futuros trabalhos que utilizem diatomáceas como bioindicadoras das condições trófi cas da água. Coletas trimestrais foram realizadas no reservatório durante um ano. As amostras perifíticas foram obtidas pela remoção do biofi lme aderido a caules da macrófi ta Polygonum sp. e a lâminas de vidro. Estas foram colocadas em complexos de madeira e deixadas submersas durante 30 dias para colonização. O estudo taxonômico resultou na identifi cação de 11 citações pioneiras para o estado do Paraná entre as 96 espécies de diatomáceas determinadas. Maior diversidade de espécies foi registrada para o substrato macrófi ta. Achnanthidium minutissimum foi dominante na maior parte das amostras analisadas, sendo considerada tolerante às condições eutrófi cas do reservatório do Iraí. Fragilaria rumpens, Fragilaria vaucheriae var. capitellata e Gomphonema gracile foram abundantes. Informações ecológicas sobre as espécies foram obtidas em literatura, sendo 35% características de sistemas aquáticos em processo avançado de eutrofi zação, 18% de ambientes mesotrófi cos e 19% classifi cadas como tolerantes e indiferentes ao estado trófi co dos ambientes. Palavras-chave: algas, Bacillariophyta, bioindicador, eutrofi zação, perifíton ABSTRACT -(Periphytic diatoms in a Brazilian eutrophic system (Iraí reservoir, Paraná state)). This fl oristic survey contributed to our knowledge of periphytic diatoms in a eutrophic reservoir in Paraná state, and provided a basis for future works using diatoms as bioindicators of trophic water conditions. Samples were collected quarterly, over a year, by removing the biofi lm attached to Polygonum sp. stems and to glass slides. The slides were placed in wooden frames and remained submersed for 30 days to colonize. The taxonomic study resulted in 11 new taxonomic records for Paraná state among the 96 identifi ed diatoms. The highest species diversity was found in the macrophyte samples. Achnanthidium minutissimum was dominant in most samples analyzed and considered tolerant of the eutrophic conditions in Iraí reservoir. Fragilaria rumpens, Fragilaria vaucheriae var. capitellata and Gomphonema gracile were abundant. Ecological information on the species was obtained from the literature; 35% of the species were characteristic of aquatic systems in an advanced state of eutrophication, 18% of mesotrophic environments and 19% were classifi ed as tolerant and indifferent to the trophic state of the environment.

-(Periphytic algal community succession in a tropical oligotrophic reservoir (São Paulo, Brazil): comparison between dry and rainy periods). This study aimed at evaluating the time scale influence (successional and seasonal) on the periphyton biomass, diversity, and algal community structure in a tropical oligotrophic reservoir, southeast Brazil. Succession process was followed during dry and rainy periods by every 3-day samplings over 27 days, and included 16 abiotic variables and periphyton properties on artificial substrate. Chlorophyll-a values were low and similar between periods, however, with the highest loss rates observed during the rainy season. Shannon diversity was high (3.4-4.5 bits ind -1 ) and relatively stable among periods and along the entire succession. Chlorophyceae was the most abundant class over succession, mainly represented by Chlamydomonas planctogloea Skuja that contributed with 23% (dry) and 37% (rainy) of the mean total density. Integrated analysis of species and environmental variables revealed climatic period as the main driving force on periphyton structure. Oocystis lacustris Chodat and Gymnodinium sp. were associated with dry period and lower temperature and ammonium values, as well as with higher pH, dissolved oxygen, and total phosphorus levels. Frustulia rhomboides (Ehr.) de Toni var. rhomboides and Cosmarium majae Strom were associated with rainy season and, inversely, to the dry season abiotic variables. Periphyton community was mainly controlled by the climatic period, the autogenic succession being of less importance. Photosynthetic biomass accrual process and periphytic algal species assemblages were more sensitive to such variation. Present results contribute to a better understanding of the periphyton community structuring in oligotrophic reservoirs, providing a reference for changes in degraded tropical systems.

Knowledge of biodiversity in oligotrophic aquatic ecosystems is fundamental to plan conservation strategies for protected areas. This study assessed the diatom diversity from an urban reservoir with oligotrophic conditions. The Piraquara I reservoir is located in an Environmental Protection Area and is responsible for the public supply of Curitiba city and the metropolitan region. Samples were collected seasonally between October 2007 and August 2008. Periphytic samples were obtained by removing the biofilm attached to Polygonum hydropiperoides stems and to glass slides. The taxonomic study resulted in the identification of 87 diatom taxa. The most representative genera regarding the species richness were Pinnularia (15 species) and Eunotia (14 species). Five species were registered for the first time in Brazil and seven in the State of Paraná. Taxonomic and ecological comments of the species registered are provided.

Nut sedge is a weed that releases allelopathic substances in the environment that damage cultivars. This plant is difficult to control and eradicate, causing quantitative and qualitative reductions in the world production of several economically valuable species, among them is roman lettuce (var. mimosa). The objective of this study was to evaluate and compare three biological treatments of lettuce control in an organic agrosystem, determining among them the highest yield of lettuce. The experiment tested the treatments in lettuce cultivation in a consortium with jack beans, sage and soil cover by eucalyptus sawdust. Three replicates were made of each treatment (n=3), and named as C1 (control), C2 (jack beans), C3 (sage) and C4 (sawdust). Ten individuals of lettuce and nut sedge were planted in each plot, and in the C2 and C3 treatments 10 individuals of jack beans and sage were planted, respectively. The quantitative data of all plants, temperature, pH and humidity were measured weekly. After 44 days of the experiment, the lettuce samples were collected and taken to laboratory incubators for drying at ±60°C, obtaining the dry mass. In the C1 (control) treatments there was a growth of 566% of the nut sedge population, in C2 (pork bean) a population increase of 393% and in C3 (sage) a 443% increase of the population. In the C4 plots, where the eucalyptus sawdust cover was used, there was a 64% reduction of the invasive plant. It was concluded that the best method was to cover with eucalyptus sawdust, by reducing the nut sedge population with higher yield of lettuce biomass. Organic agrosystems are characterized by their ecologically balanced and stable production and combine the management of natural resources with the use of modern production technologies. Any artificial method, such as the use of agrochemicals, soluble chemical fertilizers, hormones, transgenic seeds, plant regulators, irradiations and any kind of chemical additive are excluded from this process. These systems are known to be ecologically efficient because they minimally impact minimally the use of renewable and non-renewable resources, with a balance in energy use and conservation

ResumoCom o avanço da tecnologia e da globalização há cada vez mais um aumento das atividades antrópicas sobre o meio ambiente. Com relação aos recursos hídricos, sabe se que a qualidade da água é obtida por um conjunto de parâmetros que podem ser medidos por características físicas, químicas e biológicas. Uma das medidas desenvolvidas para melhorar o controle de qualidade hídrico é o biomonitoramento, a técnica utiliza bioindicadores para diagnosticar impactos a saúde do ecossistema e é considerada uma ferramenta importante na administração dos recursos naturais por fornecer informações que podem dar suporte a legislação. Caracterizados por sua variedade de espécies, dinâmica de nutrientes e ciclo de vida longo, os macroinvertebrados bentônicos se destacam e são os mais utilizados em trabalhos de biomonitoramento.Conhecer e estabelecer novos e melhores bioindicadores de poluição e contaminação da água é de grande importância para facilitar o monitoramento ambiental e torna-lo cada vez mais preciso.Palavras chave: Qualidade da água. Bioindicadores. Água. Biomonitoramento. Use of Bioindicators in water quality monitoring AbstractWith the advancement of technology and globalization the human activities on the environment is growing. With respect to water, the water quality is obtained by a set of parameters that can be measured by physical, chemical and biological properties. One of the measures designed to improve the water quality control is biomonitoring, the technique uses bioindicators to diagnose the impacts on the ecosystem health and is considered an important tool in the management of natural resources by providing information that can support the legislation. Characterized by a variety of species, nutrient dynamics and long life cycle, the benthic macroinvertebrates stand out and are more commonly used in biomonitoring studies. Know and establish new and better