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Aim In this study, we investigated the effects of secondary PET microplastics (< 53 µm) on the Daphnia similis basic life-history parameters survival, age at first reproduction and total offspring number. We also analyzed D. similis enzymatic activity (superoxide dismutase, catalase and glutathione-S-transferase) at sub-effect concentrations. Methods We performed acute and chronic toxicity tests using six PET microplastics concentrations (0, 102, 103, 104, 105 and 106 part. mL-1). We also applied an exposure test to analyze superoxide dismutase, catalase and glutathione-S-transferase activities at sub-effect concentrations. Results D. similis mortality increased (LC50 = 1 x 105 part. mL-1), reproduction decreased (EC50 = 105 part. mL-1) and time to first offspring was delayed by 5 days at the highest microplastic concentration after 21 days exposure. Neither mortality nor alterations in superoxide dismutase, catalase or glutathione-S-transferase activities were detected after 48 h exposure. Microplastics adhered to D. similis body appendages, causing altered swimming behavior. Conclusions Lack of acute toxicity but occurrence of chronic effects serve as a warning for caution when concluding about microplastics non-toxicity in short-term tests. Microplastics had unexpected effects with important ecological implications. Our results contribute to fill the knowledge gaps on the effects of microplastic pollution on aquatic ecosystems, especially under long-term exposure.

The distribution of aquatic insects is influenced by several environmental features, especially water quality and substrate. Diversity and distribution of the aquatic community and the distribution...

Species diversity can be a result of environmental and spatial constrains that act at small and large spatial scales. An important question in community ecology is to know the contribution of each one in studies with multiple spatial scales. We examined aquatic insect assemblages in small streams from the Atlantic Forest in a mainland-island scenario, with the aim of measuring which variables explain the β-diversity of insects at three spatial scales (streams, ecoregions, mainland-island). We sampled 20 streams across four ecoregions, two on the mainland and two on the island. Spatial distribution of streams was hierarchical and ecoregions were isolated. The β-diversity decreased with increasing spatial scale, where higher values were found among streams and not among ecoregions or mainland-island. Our results indicate that the contribution of environmental and spatial predictors to the β-diversity of aquatic insect varies according to the scale of observation. Environmental variables of water and riparian forest had a greater effect on β-diversity among stream sites, while spatial and landscape (physical barriers) variables seem to be key factors at larger scales (ecoregions and mainland-island, respectively), which can prevent dispersal. Our study shows that local environmental heterogeneity had a great importance for maintaining regional diversity of aquatic insects.

Indexación: Web of Science; Scopus. Food web studies provide a useful tool to assess the organization and complexity of natural communities. Nevertheless, the seasonal dynamics of food web properties, their environmental correlates, and potential association with community diversity and stability remain poorly studied. Here, we condensed an incomplete 6-year community dataset of a subtropical coastal lake to examine how monthly variation in diversity impacts food web structure over an idealized time series for an averaged year. Phytoplankton, zooplankton, macroinvertebrates, and fish were mostly resolved to species level (n = 120 trophospecies). Our results showed that the seasonal organization of the food web could be aggregated into two clusters of months grouped here as ‘summer’ and ‘winter’. During ‘winter’, the food web decreases in size and complexity, with the number of trophospecies dropping from 106 to 82 (a 22.6% decrease in the number of nodes) and the trophic interactions from 1,049 to 637 between month extremes (a 39.3% drop in the number of links). The observed simplification in food web structure during ‘winter’ suggests that community stability is more vulnerable to the impact of any change during this period. http://onlinelibrary.wiley.com/doi/10.1002/ece3.3031/epdf

Temporal and spatial variations of organic and inorganic forms of phosphorus in the sediments of a subtropical oligo-mesotrophic shallow lake were investigated in relation to water column parameters, sediment characteristics and benthic fauna. The main results found were: 1) Phosphorus (P) concentration varied seasonally, with organic P and total P increasing in the sediments in warmer periods; 2) Sediment spatial variation, in terms of grain size composition and organic matter content, influenced P concentrations; 3) quantities and qualities of P in the sediments were positively correlated with water parameters, especially DO and NO3, Chl-a, water temperature, pH, and total P. Negative correlations were observed between %OP and DO in sites 1, 3 and 4, and with NO3 in sites 2, 3 and 4; 4) benthic functional feeding groups showed significant relationships with temporal variation in sediment P concentration, including gathering-collectors, shredders, filterers and filtering-collectors. The results suggest a high importance of temperature mediated control of sediment-P release, both directly, through its direct effects on primary production and decomposition rates, and indirectly through its effects on other water and sediment parameters, especially dissolved oxygen concentration.

In lakes, the littoral habitat and its invertebrate communities are often exposed to water-level fluctuations. We examined the effects of seasonal changes on water level, substrata availability and benthic fauna in the littoral zone of Peri Lake, a shallow lake that has experienced a strong reduction in water level due to changes in rainfall. In this study, we also examined whether the abundance and composition of aquatic invertebrates differed among the four substrata. Our main objective was to assess the effect of seasonal changes on water level and benthic invertebrates inhabiting the different types of substrata. Benthic invertebrates were sampled four different substrata (Schoenoplectus californicus, sand and stones, allochthonous leaf litter, and macrophyte stands), and we also measured meteorological, physical and chemical variables. We found that complex habitats, such as allochthonous leaf litter and aquatic macrophyte, stand to be colonised by a larger number of macroinvertebrates because they provide more habitats or potential niches for colonisation by different species. In addition, we observed that during periods of low water level, the presence of substrata in the littoral zone decreased, as did the associated biota. Therefore, our results suggest that water level changes have a major functional impact on the littoral zone of the lake, and can affect substratum availability, which also impacts invertebrate communities.

Taxonomic inventories are the basis of several ecological studies and they enable a better understanding of the local and regional biodiversity. This paper aimed to survey the aquatic insect fauna in a subtropical island, as well as to generate information on the habitats used by the taxa found. Two regions showing a good state of environmental conservation in the Santa Catarina Island, in Santa Catarina, Brazil, were selected: “Lagoa do Peri” Municipal Park and “Desterro” Environmental Protected Area. Aquatic invertebrates were collected by using a Surber sampler (in a lotic environment) and an Eckman-Birge dredger (in a lentic environment) between 2009 and 2012. Sixty taxa were found, belonging to eight taxonomic orders. Thus, there were 19 new registers of aquatic insect families for Santa Catarina. At the sites of this study, 13 families already known for Santa Catarina were not observed, according to a comparison with articles published until July 2014. As for the habitat, richness differed between the types of the habitats sampled, with lower richness in the substrate “sand”. The study represents a significant contribution to knowledge on aquatic insects in Santa Catarina, especially regarding the biodiversity in islands. Inventários taxonômicos são a base de diversos estudos ecológicos e possibilitam conhecer melhor a biodiversidade local e regional. O objetivo deste trabalho foi inventariar a fauna de insetos aquáticos de uma ilha subtropical, bem como gerar informações sobre os hábitats utilizados pelos táxons encontrados. Foram selecionadas duas regiões em bom estado de conservação na Ilha de Santa Catarina, estado de Santa Catarina (SC), o Parque Municipal da Lagoa do Peri e a Unidade de Conservação Ambiental Desterro. Os invertebrados aquáticos foram coletados com amostrador de Surber (em ambiente lótico) e draga de Eckman-Birge (ambiente lêntico) entre 2009 e 2012. Foram encontrados 60 táxons compreendidos em oito ordens taxonômicas. Com isso, foram realizados 19 novos registros de famílias de insetos aquáticos para SC. Nos locais deste estudo não foram observadas 13 das famílias já conhecidas para SC, conforme comparativo com artigos publicados até julho/2014. Quanto ao hábitat, a riqueza diferiu entre os tipos de habitats amostrados, com riqueza menor no substrato “areia”. O estudo representa uma importante contribuição para o conhecimento de insetos aquáticos no estado de Santa Catarina, especialmente para a biodiversidade de ilhas.

We collected leaf litter monthly and analysed how the temporal dynamics of litterfall affect the breakdown rates, microbial and fungal biomass and aquatic invertebrate community in a tropical stream in southern Brazil. The results showed that total annual litterfall varied over time and was negatively associated with rainfall. Litter fell mostly in the spring months, but other peaks occurred throughout the year. In all, 122 tree species were identified; however, only seven represented >70% of the total of leaf litter vertical input. Leaf decomposition was higher in February and April (wet, warm months) than during the wet season. Fungal biomass was high in decomposing leaves (460±28μgg–1 of ash-free dry mass, AFDM), with a maximum of 655μgg–1 AFDM in July. Microbial biomass in decomposing leaves was lower (326±27 nmol g–1 AFDM), with a maximum of 504 nmol g–1 AFDM in October. Monthly variability in the fungal and microbial biomass and aquatic invertebrate colonisation were associated with litter quality. The results suggested that litterfall is the result of regional environmental factors and characteristics of the riparian vegetation and that modifications in the quality, quantity and timing of the delivery of litter input to the stream affect activity in the decomposer community, which then affects monthly litter-breakdown rates.

Aquatic insects are important elements in the ecological dynamics of lotic systems and their distribution in these environments can be driven by several environmental factors. Based in this assumption the aim of this study was to evaluate which environmental variables act as structural driver of the Ephemeroptera, Plecoptera and Trichoptera (EPT) community. We hypothesize that community structure will display strong temporal alterations due to characteristics in subtropical regions. We evaluated the effect of water temperature, conductivity, dissolved oxygen, depth, current velocity and rainfall on the distribution of EPT community. The insects were sampled using the litter bags incubation in a third-order subtropical stream located on Santa Catarina Island, Southern Brazil. The abundance of EPT was monitored for 24 months between January 2012 and December 2013. We identified 530 EPT specimens belonging to 11 families and 20 genera. The community showed a significant variation along the monitored time, mainly attributed to Trichoptera order. In addition to the results of this work the Ecnomidae family, Austrotinodes and Neotrichia genera represent new records for Santa Catarina State. Environmental variables varied significantly during the study time and depth and rainfall were the mainly environmental drivers acting under the community structure. We also observed a negatively correlation among rainfall and EPT community, especially to Trichoptera, which showed a strong temporal variation. In this study the EPT community displays a strong temporal variation along the monitored time, mainly attributed to rainfall events, characteristic of subtropical region. We also suggest that body adaptations also have an influence in the EPT community structure, once under flood event conditions these adaptations may offer advantage or disadvantage to invertebrate establishment, as pointed in the Trichoptera order.

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 Eckman-Birge 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. OBJETIVO: O objetivo deste estudo foi avaliar a influência das características da água e sedimento na abundância, diversidade e riqueza da comunidade de invertebrados bentônicos na lagoa do Peri, uma lagoa costeira de água doce localizada em Santa Catarina. MÉTODOS: Foram realizadas 60 coletas para análise de invertebrados, e 45 para sedimento entre abril, maio e junho de 2009, em 5 diferentes pontos da lagoa com draga Eckman-Birge. Variáveis físicas e químicas da água também foram medidas. A influência dos fatores ambientais na comunidade foi medida através de uma Análise de Correspondência Canônica (CCA), e foram feitas regressões lineares para as principais correlações; RESULTADOS: Um total de 5,535 espécimes foram coletados, identificados em 18 táxons. Tanaidacea foi o mais abundante representando 54% da abundância relativa, seguido de Diptera (23%) e Ostracoda (17%). A família mais rica em gêneros foi Chironomidae (6 táxons). Os resultados da CCA revelaram correlação positiva entre Chaoborus e Stenocypris com a profundidade local, e negativa entre Odonata, Gastropoda, Cytheridella e Coleoptera com grãos finos, assim como entre Tanaidacea, Lopescladius, Annelida e Nematoda com a quantidade de matéria orgânica (MO) no sedimento e profundidade local. Regressões lineares demonstraram uma relação inversa de Tanaidacea em resposta a MO (y = 0.6 - 0.62.MO) e areia grossa (y = 0.6 - 0.6.are) assim como de Lopescladius em relação a MO (y = 0.37 - 0.41.MO) e areia grossa (y = 0.37 - 0.46.are). O fato da lagoa do Peri não ter influência do mar e ter Tanaidacea como táxon mais abundante, um grupo não esperado em ambientes de água doce, lhe confere destaque entre demais lagoas costeiras do Brasil. Através deste estudo concluímos que as características de sedimento e profundidade local foram mais importantes que variáveis da água na determinação da estrutura da comunidade de invertebradoss bentônicos na lagoa do Peri, que variou de acordo com características ambientais locais.

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.