Diversidade e variação espaço-temporal da comunidade de macroinvertebrados bentônicos em uma lagoa costeira subtropical no sul do Brasil

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas, Programa de Pós-Graduação em Ecologia, Florianópolis, 2010Visando entender a estrutura da comunidade de macroinvertebrados aquáticos presente em uma lagoa costeira subtropical, foi desenvolvido um estudo envolvendo dois aspectos apresentados nesta dissertação em forma de capítulos, sendo os objetivos do capítulo 1: Identificar a estrutura da comunidade de macroinvertebrados aquáticos com base na composição, abundância, riqueza e preferência de habitat das espécies; investigar a distribuição espaço-temporal e relacionar o padrão de distribuição da comunidade de macroinvertebrados aquáticos com as variáveis ambientais e, do capítulo 2: Identificar os itens alimentares predominantes no conteúdo digestório das larvas de Chironomidae; verificar se ocorrem modificações sazonais quanto ao alimento ingerido e discutir como interações biológicas e/ou características ambientais interferem na organização espacial e nos padrão de co-ocorrência das guildas tróficas identificadas. Para a realização deste estudo, cinco regiões com diferentes características espaciais foram amostradas com o auxílio de uma draga Eckman-Birge. Procedimentos padrão de triagem e identificação dos organismos coletados foram realizados em laboratório. No geral, obteve-se os seguintes resultados referentes ao capítulo 1: Foram coletados 29.085 espécimes de macroinvertebrados aquáticos distribuídos em 47 táxons e 7 classes, com Insecta dominando em número de espécies e Crustácea em número de indivíduos. Diferenças quanto à densidade total e riqueza de espécies foram observados entre as regiões amostradas e as estações do ano. Regiões marginais com sedimentos mais heterogêneos e presença de vegetação aquática apresentaram uma maior diversidade de organismos quando comparados as regiões centrais, com sedimentos homogêneos e com ausência de vegetação aquática. Outono, primavera e verão foram às estações do ano que apresentaram as maiores densidades totais e diversidade de espécies. Com relação ao capitulo 2, obteve-se os seguintes resultados: os itens alimentares mais frequentes na dieta de Chironomidae foram compostos principalmente por detritos vegetais, seguidos por microalgas coloniais e filamentosas. Tanypodinae e Caladomya cf. ortoni foram os únicos a ingerirem além de fragmentos vegetais, fragmentos de animais, enquanto Lopescladius ingeriram partículas microinorgânicas e microalgas. Os resultados obtidos com as análises de conteúdo digestivo revelaram uma variação quanto ao tamanho do item alimentar ingerido por todas as larvas de Chironomidae durante as estações do ano, porém, não foi evidenciado mudanças no tipo do alimento ingerido. Modelos nulos evidenciaram diferenças nos padrões de co-ocorrência dos itens alimentares na dieta das larvas durante o período de estudo, estando os fragmentos de animal com uma coocorrência menor do que o esperado ao acaso e os itens vegetais apresentando uma coocorrência maior do que o esperado ao acaso. O valor do c-score observado para a coocorrência das espécies pertencentes tanto a guilda dos predadores quanto a dos herbívoros, revelou uma maior coocorrência das espécies dentro de cada guilda. Acredita-se que as diferentes estratégias de obtenção dos recursos alimentares entre as espécies, a heterogeneidade do hábitat e a disponibilidade do recurso no ambiente foram os fatores responsáveis pelos resultados encontrados neste estudo

Avaliação dos efeitos temporais no processamento da matéria orgânica alóctone em Riachos tropicais

Tese (doutorado)—Universidade de Brasília, Programa de Pós-Graduação em Ecologia, 2014Mudanças temporais na quantidade e na qualidade de detritos foliares provenientes de diferentes espécies vegetais interferem no processo de decomposição foliar devido às modificações na comunidade decompositora. Este estudo teve como objetivo foi quantificar a queda do detrito foliar ao longo de um ciclo anual e avaliar se mudanças na quantidade e na qualidade do detrito modifica as taxas de decomposição foliar. Foram estudados riachos inseridos na bacia hidrográfica da lagoa do Peri, na cidade de Florianópolis, SC. No capítulo 1, foi realizado um estudo anual com o objetivo de quantificar o aporte vertical de detritos foliares em um pequeno riacho tropical e avaliar se mudanças na quantidade e na qualidade do detrito foliar que entra no riacho influenciam as taxas de decomposição foliar. Como resultados, foi encontrado uma variação temporal no aporte de detritos foliares, estando esta variação relacionada com a intensidade de chuvas (diminuição no aporte) e ventos (aumento no aporte) na região. Da mesma forma, observou-se uma variação química na qualidade do detrito foliar como resultado das mudanças no tipo de detrito entregue para o riacho. Detritos contendo menores concentrações de lignina e celulose e maiores concentrações de nitrogênio apresentaram taxas de decomposição foliares mais elevadas. Variações temporais na química do detrito apresentaram uma relação direta com a colonização microbiana e de invertebrados aquáticos e, consequentemente com as taxas de decomposição encontrada. Como conclusão, as modificações temporais na quantidade e na qualidade dos detritos foliares para o riacho influenciaram na comunidade decompositora interferindo nas taxas de decomposição foliar. No capítulo 2, a taxa de decomposição foliar foi avaliada como uma medida de integridade ecológica. Para isto selecionou-se dois riachos com diferentes graus de preservação ambiental (referência e impactado) em um fragmento de mata Atlântica no sul do Brasil. Folhas senescentes oriundas da vegetação ripária do riacho Cachoeira Grande (experimento 1) foram coletadas e incubadas em ambos os riachos por um período de 30 dias. Os resultados demostraram que as taxas de decomposição foliar foram mais rápidas no riacho referência quando comparado ao impactado. A biomassa dos fungos foi mais siginificativa no riacho referência enquanto a comunidade microbiana (principalmente bactérias) teve uma maior contribuição no impactado. Análises de regressções múltiplas indicaram que os fragmentadores influenciaram nas taxas de decomposição no riacho referência, que apresentou uma maior riqueza, porém uma menor abundância de invertebrados aquáticos quando comparado ao riacho impactado. Uma relação negativa foi observada entre os valores de fósforo na água e as taxas de decomposição foliar nos dois riachos. Diferenças nos valores de oxigênio podem ter influenciado as taxas de decomposição foliar no riacho impactado, como consequência de mudanças na comunidade decompositora. Nossos resultados destacam a sensibilidade dos ambientes aquáticos às modificações ambientais e demostraram que a decomposição foliar foi uma medida eficiente para detectar, mesmo que moderadas, modificações antrópicas no riacho impactado indicando seu uso em programas de biomonitoramento. ______________________________________________________________________________ ABSTRACTTemporal changes in the quantity and quality of leaf litter from different plant species interfere in the leaf litter breakdown process due to changes in the decomposers community. The aim of this study was to quantify the litterfall over a yearly cycle and assess if changes in their amount and quality modify the litter breakdown rates. We study streams inserted the watershed pond Peri in the city of Florianópolis, SC. Chapter 1, it was realized an annual study for to quantify the contribution of allochthonous litter leaf in a small tropical stream and assess whether changes in the quantity and quality of leaf detritus delivery the stream influence of litter breakdown rates. The results showed a temporal variation in leaf litter input to the stream and this variation can be explained by local variations in precipitation (decrease in input) and winds (increase in input). Similarly, we observed a temporal variation in quality of leaf litter as a result of the type of litter delivered to the stream. Litter containing lower concentrations of lignin and cellulose, and higher concentrations of nitrogen showed a higher litter breakdown rates when compared to leaf litter with lower concentrations of nitrogen and a higher concentration of lignin and polyphenols. Temporal changes in the chemistry of detritus showed a direct relationship with the microbial and aquatic invertebrate colonization and consequently in the litter breakdown rates found. As conclusion we found a monthly variation in the input of organic matter to the stream as a result of regional climatic factors and riparian vegetation characteristics and we concluded that changes in the input of litter leaf breakdown influence in the decomposers community interfering in the litter breakdown rates. Chapter 2, we use the litter leaf breakdown rates as a measure of functional integrity and wondered whether even moderate level of anthropogenic impact may interfere in the processing of leaf litter. For this, we selected the two streams (reference and impacted) with different levels of environmental preservation in a fragment of Atlantic Forest in southern Brazil. We collected senescent leaves from the riparian vegetation in the reference streams and incubated in both streams for 12 months. Our results showed that leaf breakdown rates were faster in the reference stream when compared to impacted. The fungal biomass was most important in the reference stream while the microbial community (mainly bacteria) was more important in the impacted stream. Multiple regression analyzes indicated that the shredders influenced in the litter breakdown rates in the reference stream that showed higher taxa richness, but a lower abundance compared to the impacted stream. A negative relationship was observed between the values of phosphorus in water and leaf decomposition rates in the two streams. The differences in the oxygen concentration may have influenced the rates of leaf decomposition in stream impacted as a result of changes in decomposers community. Our results highlight the sensitivity of aquatic environments at environmental change and have demonstration that leaf decomposition was an effective measure to detect anthropogenic changes in the impacted stream indicating its use in biomonitoring programs

Influence of piers on functional groups of benthic primary producers and consumers in the channel of a subtropical coastal lagoon

Hábitats artificiais têm se tornado comum em áreas costeiras no mundo todo, podendo influenciar a estrutura e funcionamento de ecossistemas bênticos. Nós analisamos a influência de trapiches nos grupos morfofuncionais bênticos de algas associadas a substrato consolidado e de macrofauna em substrato inconsolidado, no canal da Lagoa da Conceição (sul do Brasil). O principal impacto da presença de trapiches é a redução da irradiação disponível para atividade fotossintética, o que está diretamente relacionado com o decréscimo na biomassa microfitobentônica no sedimento e de macroalga de formas de vida mais complexas. Contrário ao esperado os morfotipos com alto potencial de produtividade de biomassa, como macroalgas calcárias articuladas, corticadas e coriáceas, em geral foram menos abundantes, sendo que macroalgas foliáceas e filamentosas de menor biomassa foram encontradas exclusivamente em áreas controle. Os efeitos do trapiche nos grupos funcionais de epifauna e infauna foram específicos ao ponto de coleta e provavelmente relacionados com redução generalizada de produtores primários e com o novo hábitat criado. A infauna discretamente móvel foi o único grupo funcional capaz de prosperar embaixo dos trapiches, devido à sua mobilidade reduzida e frágil estrutura morfológica, beneficiando-se do abrigo oferecido pelos hábitats artificiais. Nossos resultados mostraram que os trapiches podem ter um efeito negativo sobre os organismos da base da cadeia trófica, responsáveis pelo controle bottom-up.Artificial habitats have become common in coastal areas worldwide and may influence the structure and functioning of benthic ecosystems. We analyze the influence of piers on the benthic morphofunctional groups of rocky seaweeds and of soft bottom macrofauna in the channel of Conceição Lagoon (southern Brazil). The main impact is a reduction in the luminosity available for photosynthetic activity which is directly related to a decrease in the biomasses of sediment microphytobenthos and of more highly structured macroalgae life-forms. Contrary to expectations, the morphotypes of potentially high biomass productivity, such as articulated coralline, corticated and leathery macroalgae, were in general less abundant and the low biomass foliose and filamentous macroalgae occurred in reference areas but not under the piers. The piers' effects on motile epifauna and infauna functional groups were site-specific and probably related to the general reduction in primary producer organisms in the new habitats. The discretely motile infauna was the only functional group able to thrive under the piers due to their reduced motility and fragile morphological structures, being benefited by the shelter provided by the artificial habitats. Our results showed that the piers might have a negative effect on the base-trophic level organisms responsible for bottom-up controls

Macro-scale (biomes) differences in neotropical stream processes and community structure

The definition of conservation strategies and ecological assessment schemes requires understanding ecosystem patterns over multiple spatial scales. This study aimed to determine if macro-scale structural and functional (processes) patterns associated with stream ecosystems differed among three neotropical biomes (Cerrado, Amazon, Atlantic Forest). We compared the aquatic communities (benthic invertebrates and hyphomycetes) and processes (decomposition rates, primary production and biofilms growth and aquatic hyphomycetes reproduction rates-sporulation) of Cerrado stream sites (neotropical savannah) against those of stream sites in the connecting biomes of the Atlantic Forest and Amazon (rainforests). We expected that, contrary to the biome dependency hypothesis the community structure and processes rates of streams at the biome-scale would not differ significantly, because those ecosystems are strongly influenced by their dense riparian forests, which have a transitional character among the three biomes. Fifty-three stream sites were selected covering a wide range of geographic locations (Table 1), from near the Equator (2° S) in the Amazon, to intermediate latitudes in the Cerrado (12-19° S), and latitudes closer to the tropic of Capricorn in the Atlantic Forest (19º-25° S). We found that: 1) at the abiotic level, the aquatic ecosystems of the three biomes differed, which was mostly explained by large-scale factors such as temperature, precipitation and altitude; 2) functional and structural variables did not behave similarly among biomes: decomposition and sporulation rates showed larger differences among biomes than invertebrate and aquatic hyphomycete assemblages structure; 3) invertebrate assemblages structure differed between the rainforests and Cerrado but not between rainforests (Amazon and Atlantic Forest) whereas aquatic hyphomycetes were similar among all biomes; 4) biofilm growth and algae concentration in biofilms of artificial substrates were highly variable within biomes and not significantly different between biomes. Overall, aquatic ecosystem processes and community structure differed across biomes, being influenced by climatic variables, but the variation is not as pronounced as that described for terrestrial systems. Considering the potential use of these functional and structural indicators in national-wide ecological assessments, our results indicate the need to define different reference values for different biomes, depending on the variable used. The approach followed in this study allowed an integrative analysis and comparison of the stream ecosystems across three tropical biomes, being the first study of this kind. Future studies should try to confirm the patterns evidenced here with more sites from other areas of the three biomes, and especially from the Amazon, which was the least represented biome in our investigation. © 201

Plant litter dynamics in the forest-stream interface: Precipitation is a major control across tropical biomes

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. © 2017 The Author(s)

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

First island species of Hyalella (Amphipoda, Hyalellidae) from Florianópolis, state of Santa Catarina, Southern Brazil

Rangel, Carolina, Silva, Aurea Luiza Lemes Da, Siegloch, Ana Emília, Limberger, Márcio, Castiglioni, Daniela Da Silva (2022): First island species of Hyalella (Amphipoda, Hyalellidae) from Florianópolis, state of Santa Catarina, Southern Brazil. Zootaxa 5116 (1): 40-60, DOI: 10.11646/zootaxa.5116.1.