Riparian plant litter is a major energy source for forested streams across the world and its decomposition has repercussions on nutrient cycling, food webs and ecosystem functioning. However, we know little about plant litter dynamics in tropical streams, even though the tropics occupy 40% of the Earth’s land surface. Here we investigated spatial and temporal (along a year cycle) patterns of litter inputs and storage in multiple streams of three tropical biomes in Brazil (Atlantic forest, Amazon forest and Cerrado savanna), predicting major differences among biomes in relation to temperature and precipitation regimes. Precipitation explained most of litter inputs and storage, which were generally higher in more humid biomes (litterfall: 384, 422 and 308 g m−2 y−1, storage: 55, 113 and 38 g m−2, on average in Atlantic forest, Amazon and Cerrado, respectively). Temporal dynamics varied across biomes in relation to precipitation and temperature, with uniform litter inputs but seasonal storage in Atlantic forest streams, seasonal inputs in Amazon and Cerrado streams, and aseasonal storage in Amazon streams. Our findings suggest that litter dynamics vary greatly within the tropics, but point to the major role of precipitation, which contrasts with the main influence of temperature in temperate areas.

Abstract:Aim: The objective of this study was to evaluate the influence of water and sediment characteristics on the abundance, richness and diversity of the benthic invertebrate community in Peri lagoon, a freshwater coastal lagoon located in central coast of Santa Catarina State; Methods: Samplings were performed in April, May and June 2009, in five different sites of Peri lagoon. The samples were taken with an EckmanBirge drag, totalizing 60 for the invertebrate community, and 45 for sediment. Water physicochemical variables were also measured. Environmental influences in benthic community have been measured using a Canonical Correspondence Analysis (CCA). Linear regressions were also plotted for main correlations; Results: A total of 5,535 specimens were collected, identified into 18 taxa. Tanaidacea was the most abundant representing 54% of relative abundance, followed by Diptera (23%), and Ostracoda (17%). The richest family was Chironomidae with 6 taxa. CCA results indicated positive correlation between Chaoborus and Stenocypris with local depth, and negative correlation between Odonata, Gastropoda, Cytheridella and Coleoptera with the finest grains of sediment, as well as between Tanaidacea, Lopescladius, Annelida and Nematoda with both organic matter (OM) content in sediment and local depth. Linear regression analysis demonstrated inverse relation of Tanaidacea in response to OM (y = 0.6 -0.62.OM) and sand (y = 0.6 -0.6.sand), and of Lopescladius in response to OM (y = 0.37 -0.41. OM) and sand (y = 0.37 -0.46.sand). The fact that Peri lagoon has no marine influence and has Tanaidacea as the most abundant taxa, a group not expected in freshwaters, gives to this lagoon a particular relevance among coastal lagoons. The study concluded that sediment characteristics and local depth are more significant than water variables in determining the benthic community structure in Peri lagoon, which varied in accordance with different local conditions.

Allochthonous organic matter is a major energy source for headwater stream ecosystems. Therefore, examinations of how energy flows throughout these streams requires knowledge of mechanisms driving leaf input, retention and export. In this study we quantified the major input pathways and retention dynamics of coarse particulate organic matter (CPOM) in an Atlantic Rainforest stream in southern Brazil. We hypothesised that much of the temporal variability in the CPOM budget would be driven by precipitation, and thus we focus especially on the importance of vertical v. lateral input pathways, precipitation-driven inputs v. stocks, and composition of CPOM throughout 1 year. Most leaf litter entered the stream by the lateral input pathway (70.5gm–2month–1±108s.d.) compared with the vertical (32.4gm–2 month–1 ±17.5s.d.), and lateral input was correlated with precipitation and bank slope. In addition, torrential rainfall caused a net decrease in CPOM by reduction in the benthic stocks. Finally, six species represented 52.9% of total leaf input, where the most important (~25% of total input) was Schizolobium parahyba. Overall, this research confirms our prediction that the CPOM budget of this Atlantic Rainforest stream is driven in large part by precipitation.

ResumoA Lagoa da Conceição é um dos principais focos turísticos da Ilha de Santa Catarina, sendo conseqüente alvo de modificações de origem antrópica. Pesquisas têm caracterizado e avaliado a gravidade de seus principais contaminantes. Neste trabalho foi feita uma revisão da disponibilidade de dados relacionada à ecologia da Lagoa, visando direcionar novas pesquisas e estudos complementares para compreensão da dinâmica do ambiente e para seu uso sustentável. A Lagoa recebe influencia de esgotos domésticos, metais pesados e ocupação desordenada. A influência das águas marinhas é mais observada nas regiões próximas ao canal da Barra, que leva a diminuição das concentrações de alguns nutrientes e alterações das comunidades. Averiguou-se a falta de dados contínuos e de longa duração sobre a dinâmica das comunidades aquáticas, produtividade do ambiente, ciclos do nitrogênio e fósforo e das concentrações de clorofila. O padrão de circulação da Lagoa, assim como a influência do Canal da Barra, são informações importantes para compreensão do funcionamento do ecossistema. Nota-se extrema necessidade de um programa de monitoramento periódico e contínuo de dados físicos, químicos e biológicos para avaliar as alterações no ambiente. Estas informações serão muito importantes para futuras propostas de educação ambiental, recuperação e para a preservação da Lagoa. Unitermos: Lagoa da Conceição, conservação, qualidade de água, lagoas costeiras, síntese ecológica AbstractConceição Lagoon: a review on the availability of ecological data aiming new researches on the ecosystem. Conceição Lagoon is one of the major touristic centers on Santa Catarina Island and, as a consequence, it has been subjected to great changes by anthropogenic actions. Research has characterized and evaluated the magnitude of the main contaminants in the Lagoon. A review on the availability of data concerning the ecology of the Lagoon was made, aiming at the development of new researches and complementary studies to better understand the dynamics of this ecosystem and to achieve its sustainable use. The Lagoon receives the influence from sewage waste, heavy metals and disordered land occupation. The effect of sea water is strongest nearby Barra Channel, which generates a decrease in the concentration of some nutrients and a disturbance in

O aumento do contingente populacional, bem como da demanda pelo recurso hídrico, têm intensi¿ cado as ações humanas na região da bacia da Lagoa do Peri. Este trabalho realizou uma revisão da disponibilidade de dados ecológicos da Lagoa do Peri, visando o direcionamento de novas pesquisas para a compreensão do funcionamento do ambiente. Estas informações podem contribuir na elaboração de uma futura proposta de conservação e uso sustentável da Lagoa. Alta densidade de cianobactérias Cylindrospermopsis raciborskii foi diagnosticada nas águas da Lagoa, e apresenta-se como situação de risco para a saúde do ecossistema e conseqüentemente da população. Destacam-se lacunas a respeito da dinâmica, funcionamento e estruturação das comunidades aquáticas, suas relações com o entorno e a inÀ uência de fatores abióticos. Séries de dados contínuos ao longo do tempo também são informações ausentes. Percebe-se a necessidade de medidas educacionais, políticas e sociais na conservação do ambiente, voltadas para o manejo e uso sustentável da bacia da Lagoa do Peri. Estas práticas garantirão a qualidade e disponibilidade do recurso hídrico para esta e as futuras gerações.