Do Methodological Differences in Experiments with Stream Shredders Imply Variability in Outputs? A Microcosm Approach.

Experiments are useful scientific tools for testing hypotheses by manipulating variables of interest while controlling for other factors that can bias or confuse the results and their interpretation. To ensures accuracy and reproducibility, experiments must have transparent and repeatable methodologies. Due to the importance of shredder invertebrates in organic matter processing, carbon cycling, and nutrient cycling, we tested experimentally the effect of different methodological approaches in microcosm experiments on the consumption and survival of shredders. We found that the shredder species, the presence or absence of the case, and the use or non-use of air-pumps in the microcosms did not affect shredder performance (i.e., consumption and survival). Furthermore, the type of water (stream or bottled) did not affect shredder performance. On the other hand, the amount of light had a negative effect on shredder performance, with constant light (i.e., 24 h) reducing shredder consumption and survival. Our results demonstrate that the use of different methodologies does not always result in changes in outcomes, thus ensuring comparability. However, luminosity is a critical factor that deserves attention when conducting microcosm experiments. Our findings provide valuable insights that can assist researchers in designing experiments with shredders from neotropical streams and conducting systematic reviews and meta-analyses.

Seasonal distribution of Calliphoridae and Mesenbrinellidae (Diptera) associated with the decomposition of a clothed animal model in a forest reserve in the Central Amazon.

We evaluated the effects of seasonality on the richness and abundance of dipterans of the families Calliphoridae and Mesembrinellidae associated with the decomposition of a clothed Large White swine Sus scrofa domesticus(Artiodactyla: Suidae) carcass. Experiments were carried out in less rainy, rainy, and intermediate periods between 2010 and 2011 at Reserva Florestal Ducke, Manaus, Amazonas. Two pig carcasses, each weighing approximately 40 kg, were used in each period. A total of 63,872 individuals of 18 species of Calliphoridae and Mesembrinellidae were collected. The abundance and richness of these dipteran families were influenced by the interaction between period and decomposition stage. The compositions of the Calliphoridae and Mesembrinellidae assemblages differed among periods, with the fauna of the less rainy period being less similar to those of the intermediate and rainy periods than they were to each other. Three species were selected as indicators for the less rainy period, namely Paralucilia pseudolyrcea (Mello, 1969) (Diptera, Calliphoridae), Paralucilia nigrofacialis (Mello, 1969) (Diptera, Calliphoridae), and Eumesembrinella randa (Walker, 1849) (Diptera,Mesembrinellidae) while Chloroprocta idioidea (Robineau-Desvoidy, 1830) (Dipetra, Calliphoridae) was selected as an indicator species for the rainy period; no taxon was selected as an indicator of the intermediate period. Among decomposition stages, only fermentation and black putrefaction had indicator taxa, with Hemilucilia souzalopesi Mello, 1972 (Diptera, Calliphoridae and Chysomya putoria(Wiedemann, 1830) (Diptera, Calliphoridae), respectively. Clothes did not prevent the laying of eggs and became a kind of protection for immature stages. The clothed model presented a delay in decomposition compared to other studies developed in the Amazon region.

Do microplastics and climate change negatively affect shredder invertebrates from an amazon stream? An ecosystem functioning perspective.

Pollution and climate change are among the main threats to the biodiversity of freshwater ecosystems in the 21st century. We experimentally tested the effects of microplastic and climate change (i.e., increase in temperature and CO2) on the survival and consumption by an Amazonian-stream shredder invertebrate. We tested three hypotheses. (1) Increased microplastic concentrations and climate change reduce shredder survival. We assumed that the combined stressors would increase toxic stress. (2) Increased concentrations of microplastics have negative effects on shredder food consumption. We assumed that blockage of the digestive tract by microplastics would lead to reduced ability to digest food. In addition, increased temperature and CO2 would lead to an increase in metabolic cost and reduced consumption. (3) The interaction between microplastics and climate change have greater negative effects on survival and consumption than either alone. We combined different concentrations of microplastic and climate change scenarios to simulate in real-time increases in temperature and CO2 forecast for 2100 for Amazonia. We found that both stressors had lethal effects, increasing mortality risk, but there was no interaction effect. Shredder consumption was negatively affected only by climate change. The interaction of microplastics and climate change on shredder consumption was dose-dependent and more intense in the extreme climate scenario, leading to reduced consumption. Our results indicate that microplastic and climate change may have strong effects on the consumption and/or survival of insect shredders in Amazonian streams. In addition, microplastic and climate change effects may affect not only populations but also ecosystem functioning (e.g., nutrient cycling). Integrative approaches to better understand and mitigate the effects of both stressors are necessary because plastic pollution and climate change co-occur in environments.

Ciclo de vida em laboratório de imaturos de Phylloicus elektoros e Phylloicus amazonas (Trichoptera: Calamoceratidae) de um igarapé da Amazônia Central / Immature life cycle of laboratory-reared Phylloicus elektoros and Phylloicus amazonas (Trichoptera: Calamoceratidae) from a central Amazonian stream

Nós criamos massas de ovos dos tricópteros Phylloicus amazonas (n = 2) e Phylloicus elektoros (n = 7) coletadas no campo até a fase adulta. A mediana do tempo de desenvolvimento do primeiro instar larval ao adulto foi de 229 dias para P. amazonas e 275 dias para P. elektoros, incluindo o tempo de desenvolvimento pupal (mediana de 13.5 e 16 dias, respectivamente). Fragmentadores têm sido frequentemente usados em estudos relacionados ao processamento de matéria orgânica em ecossistemas aquáticos. As informações biológicas fornecidas neste estudo podem ser úteis para o planejamento de estudos experimentais em campo ou em condições de laboratório.(AU)

Morphological description of the immature stages of Hermetia illucens (Linnaeus, 1758) (Diptera: Stratiomyidae).

In the dipteran genus Hermetia, only 6 of the 78 valid species have documented immature stages: H. albitarsis Fabricius, 1805, H. aurata Bellardi, 1859, H. concinna Williston, 1900, H. illucens (Linnaeus, 1758), H. panamensis Greene, 1940 and H. pulchra Weidemann, 1830. In particular, H. illucens stands out due to its reported applicability for forensic, medical and economic purposes. Here, we described the morphology of eggs and immature stages of this species, with a view to detecting differences between instars and in the pupal stage, which should eventually help properly identifying larval age. We utilized both optical and scanning electron microscopy tools. The eggs are elliptical and elongated, and color varies from cream white to yellowish. The larvae are apodal, hemichephalic and holopneustic, flattened dorso-ventrally and may be recognized by the head elongated, dorsal and ventral chaetotaxy of the cephalic capsule, thoracic and abdominal segments, and the morphology of the anterior and posterior spiracles. The pupae are adecticous and coarctate, tegument dark brown and pruinescence varying from brown to golden. The overall morphology across instars is similar, but marked variations were observed in the shape of the antennal articuli and the shape of the setae (first instar compared to the others). Our results supplement the biological information on Hermetia illucens and should aid the proper identification and aging of juveniles in the field, as a way to minimize errors in the calculation of the post-mortem interval.

Effects of increasing temperature and, CO2 on quality of litter, shredders, and microorganisms in Amazonian aquatic systems.

Climate change may affect the chemical composition of riparian leaf litter and, aquatic organisms and, consequently, leaf breakdown. We evaluated the effects of different scenarios combining increased temperature and carbon dioxide (CO2) on leaf detritus of Hevea spruceana (Benth) Müll. and decomposers (insect shredders and microorganisms). We hypothesized that simulated climate change (warming and elevated CO2) would: i) decrease leaf-litter quality, ii) decrease survival and leaf breakdown by shredders, and iii) increase microbial leaf breakdown and fungal biomass. We performed the experiment in four microcosm chambers that simulated air temperature and CO2 changes in relation to a real-time control tracking current conditions in Manaus, Amazonas, Brazil. The experiment lasted seven days. During the experiment mean air temperature and CO2 concentration ranged from 26.96 ± 0.98ºC and 537.86 ± 18.36 ppmv in the control to 31.75 ± 0.50ºC and 1636.96 ± 17.99 ppmv in the extreme chamber, respectively. However, phosphorus concentration in the leaf litter decreased with warming and elevated CO2. Leaf quality (percentage of carbon, nitrogen, phosphorus, cellulose and lignin) was not influenced by soil flooding. Fungal biomass and microbial leaf breakdown were positively influenced by temperature and CO2 increase and reached their highest values in the intermediate condition. Both total and shredder leaf breakdown, and shredder survival rate were similar among all climatic conditions. Thus, low leaf-litter quality due to climate change and higher leaf breakdown under intermediate conditions may indicate an increase of riparian metabolism due to temperature and CO2 increase, highlighting the risk (e.g., decreased productivity) of global warming for tropical streams.

Biomass estimation of Triplectides egleri Sattler (Trichoptera, Leptoceridae) in a stream at Ducke Reserve, Central Amazonia

ABSTRACT Biomass is a fundamental measure for understanding the structure and functioning (e.g. fluxes of energy and nutrients in the food chain) of aquatic ecosystems. We aim to provide predictive models to estimate the biomass of Triplectides egleri Sattler, 1963, in a stream in Central Amazonia, based on body and case dimensions. We used body length, head-capsule width, interocular distance and case length and width to derive biomass estimations. Linear, exponential and power regression models were used to assess the relationship between biomass and body or case dimensions. All regression models used in the biomass estimation of T. egleri were significant. The best fit between biomass and body or case dimensions was obtained using the power model, followed by the exponential and linear models. Body length provided the best estimate of biomass. However, the dimensions of sclerotized structures (interocular distance and head-capsule width) also provided good biomass predictions, and may be useful in estimating biomass of preserved and/or damaged material. Case width was the dimension of the case that provided the best estimate of biomass. Despite the low relation, case width may be useful in studies that require low stress on individuals.

Colonization by Chironomidae larvae in decomposition leaves of Eichhornia azurea in a lentic system in Southeastern Brazil.

The objective of this study was to analyze the colonization of Chironomidae (Diptera) larvae during the decomposition of Eichhornia azurea (Swartz) Kunth (Commelinales: Pontederiaceae) leaves in a lake in southeastern Brazil in two seasons of the year. The experiment was conducted from September to November 2007 and February to April 2008. In each period, 21 litter bags were used, each containing 10 g of dried leaves. Three bags were removed after 2, 5, 8, 12, 25, 45, and 65 days of colonization. The decomposition rate of the E. azurea leaves was rapid in both seasons, with no significant difference between them. The Chironomidae showed higher density than the other invertebrates. Goeldichironomus, Tonytarsus, and Corynoneura were the most abundant genera of Chironomidae. The invertebrate density increased during the experiment, differing within days but not between seasons. The faunal composition differed between the decomposition phases (initial and final), but did not differ between the seasons (dry and wet). The taxa Ablabesmyia, Caladomyia, Chironomus, Goeldichironomus, and Parachironomus were the most closely related to the final days of the experiment. Litter was the main food item found in the gut contents of the organisms of all the genera analyzed, both at the beginning and end of the decomposition. We believe that the feeding activity combined with the high larval density is an important factor contributing to the rapid decomposition of the E. azurea leaves. In conclusion, the succession process along the detritus chain of E. azurea was more important in structuring the assemblage of Chironomidae larvae than seasonal variations.

Occurrence of Naididae (Annelida: Oligochaeta) from three gastropod species in irrigation fields in southeastern Brazil / Ocorrência de Naididae (Annelida: Oligochaeta) em três espécies de gastrópodes em campos irrigados no sudeste do Brasil

In the present study we report the occurrence of three Naididae species from three gastropod mollusk species. The species Dero (Dero) righii was found from mollusks of the genus Biomphalaria. Nais communis was found from Biomphalaria sp. and Aplexa rivalis. Chaetogaster limnaei was found from Biomphalaria sp., Aplexa rivalis and Lymnaea columella. In Brazil, previous studies have reported the occurrence of Chaetogaster limnaei from Biomphalaria solely, while Nais communis have been found from Pomacea bridgesii and Dero (Dero) righii in the sediment of aquatic habitats in Mato Grosso do Sul. Our results indicate that, due to their locomotion, naidids are capable of colonizing different substrates in aquatic environments.

No presente estudo, relatamos a ocorrência de Dero (Dero) righii associada a moluscos do gênero Biomphalaria. Nais communis foi encontrada associada a Biomphalaria sp. e Aplexa rivalis. A espécie Chaetogaster limnaei esteve associada à Biomphalaria sp., Aplexa rivalis e Lymnaea columella. No Brasil, estudos anteriores registraram Chaetogaster limnaei associada somente à Biomphalaria, Nais communis à Pomacea bridgesii e Dero (Dero) righii ao sedimento de ambientes aquáticos no Mato Grosso do Sul. Os resultados obtidos confirmam que, devido à capacidade de se deslocar na coluna d'água, os oligoquetos naidideos apresentam habilidade de colonizar diferentes substratos presentes nos ambientes aquáticos.

Oligochaeta (Annelida, Clitellata) of lotic environments at Parque Estadual Intervales (São Paulo, Brazil) / Oligochaeta (Annelida, Clitellata) de ambientes lóticos do Parque Estadual Intervales (São Paulo, Brasil)

Studies on benthic macroinvertebrates of lotic environments usually focus on the occurrence, distribution, and richness of aquatic insects and decapod crustaceans. Only rarely these studies include the Oligochaeta. The aim of the present study was to examine the occurrence and species richness of Oligochaeta in different substrata patches of lotic environments. The studied included seven stream sites at Parque Estadual Intervales (São Paulo, Brazil). Stream sites differed in size and ranged from first to fourth order. In each stream, qualitative collections were made using a D-type net sampler with 0.21 mm mesh. Measures of pH, electrical conductivity, dissolved oxygen, temperature and water turbidity were taken in the studied sites during collections of Oligochaeta. Specimens of the Tubificidae (including Naidinae) and Enchytraeidae families were collected. The Tubificidae Aulodrilus limnobius, Limnodrilus neotropicus and Limnodrilus hoffmeisteri were associated with low-flow habitats containing fine organic material. The most representative species among the Naidinae, Nais communis, was predominantly associated with rocky substrates present in fast current locations. The two other Naidinae species, Pristina osborni and Amphichaeta leydigi, presented low frequency in the studied streams. The Enchytraeidae family was present in only one of the sampled habitats.

Estudos sobre macroinvertebrados bentônicos de ambientes lóticos geralmente focam na ocorrência, distribuição e riqueza de insetos aquáticos e de crustáceos decápodos. Tais estudos apenas raramente incluem Oligochaeta. O objetivo do presente estudo foi examinar a ocorrência e riqueza de espécies de Oligochaeta de diferentes substratos em ambientes lóticos. O estudo incluiu sete riachos do Parque Estadual Intervales (São Paulo, Brasil). Os riachos estudados variaram em tamanho desde primeira até quarta ordem. Em cada ambiente, foram realizadas coletas qualitativas utilizando amostrador do tipo rede em D com malha 0,21 mm. Simultaneamente às coletas de Oligochaeta foram tomadas medidas do pH, condutividade elétrica, oxigênio dissolvido, temperatura e turbidez da água dos ambientes. Foram coletados exemplares das famílias Tubificidae (incluindo Naidinae) e Enchytraeidae. Os Tubificidae Aulodrilus limnobius, Limnodrilus neotropicus e Limnodrilus hoffmeisteri estiveram associados à habitats com pouca correnteza e substrato contendo material orgânico fino. Nais communis espécie mais representativa entre os Naidinae, esteve predominantemente associada a substratos rochosos presentes em locais de correntes rápidas. As duas outras espécies de Naidinae, Pristina osborni e Amphichaeta leydigi apresentaram baixa freqüência nos córregos analisados. A família Enchytraeidae esteve presente somente em um dos ambientes amostrados.