Variation of Chironomidae (Insecta: Diptera) trophic guilds and their relation with trophic state in reservoirs in the semiarid

The Chironomidae larvae are sensitive to variations in aquatic ecosystem conditions. We aim to analyze the variation of Chironomidae trophic guilds and their relation to the trophic state index in reservoirs in the semiarid. The study was conducted from 66 sites, distributed in the littoral zone of three reservoirs of Piranhas-Assu river, during June and December of 2014. The larvae were collected, and after identification, were classified in functional trophic groups. We applied the Trophic Status Index of Carlson, modified by Toledo for trophic classification. Sabugí reservoir was the only classified as mesotrophic (52,60±3,64) in June, where the greatest levels of diversity also occurred in the trophic guilds: gatherer-gollector (9 genera), predator (6 genera) and filterer-collector (1 genus). Higher levels of eutrophication occurred in Passagem das Traíras reservoir (84,99±6,19), the same with the smallest diversity in the guilds: gatherer-collector (3 genera) and 1 genus in the other categories. The variation of trophic guilds has been associated with trophy levels, because higher levels of degradation eliminate sensitive species, reducing the number of taxa. Thus, the Chironomidae trophic guilds demonstrate potential capacity for indicating the degree of impact to which the reservoirs are submitted

Biotic or abiotic factors: which has greater influence in determining the structure of rotifers in semi-arid reservoirs?

ObjectiveThe objective of this study is to evaluate whether the distribution of structural attributes of rotifers in reservoirs in the semiarid region is more strongly influenced by abiotic or biotic environmental factors (density of cyanobacteria).MethodSampling occurred in two reservoirs in the Paraíba Basin, northeastern Brazil (Poções and Camalaú) during April and June 2012. Eight sampling points were distributed at two stations in each reservoir: the region near the entrance of the main tributary and region of the dam and collections were made in the limnetic and littoral zone in every season. To assess the abiotic influence and density of cyanobacteria in the distribution of the structural attributes of rotifers, environmental variables bivariate correlation was conducted in series.ResultsIn Poções reservoir, the distribution of rotifer biomass was negatively related to the density of cyanobacteria; among the environmental variables, chlorophyll-a and total nitrogen were negatively related to all of the tested structural attributes, while the concentrations of total phosphorus were strongly related to the abundance of rotifers. In the Camalaú reservoir, the biomass was a structural attribute with a stronger correlation to the density of cyanobacteria; between the environmental variables and Egeria densa, nitrate was negatively related to all of the attributes tested, while transparency was moderately related to the abundance, biomass and richness as well as Chara sp. with abundance.ConclusionsAssemblages of rotifers are more clearly related to environmental conditions, especially those indicative of trophic conditions, despite the density of cyanobacteria having been a factor that was positively related to the structural characteristics of rotifers and thus indicative of such structural assemblies. This can be used for analysis of local environmental condition factors

Effect of environmental filters on Chironomidae (Insecta: Diptera) assemblages of neotropical watersheds

Environmental filters act at different spatial scales, selecting species with characteristics that allow them to successfully establish and survive under local environmental conditions. We sought to evaluate how environmental filters (physical/chemical, habitat composition, and landscape) and different levels of anthropogenic disturbances affect the abundance of Chironomidae in neotropical semiarid watersheds. Chironomidae larvae were sampled in six reservoirs (112 sites) in the Piranhas-Assu and Paraíba watersheds (NE Brazil) during the dry season. The distribution of Chironomidae larvae was best explained in Least Disturbed sites, with 82.1 % of the total explained variance in the Piranhas-Assu watershed and 64.2 % in the Paraíba watershed. The interactions of filters (physical/chemical, habitat composition, and landscape) best explained the abundance distributions of Chironomidae larvae in the watersheds and sites subjected to different levels of anthropogenic disturbances. The physical/chemical conditions of the water as well as habitat composition depend on landscape characteristics, because anthropogenic activities in watersheds increase nutrient concentrations in the water, promoting the increase of the trophic state of the environment as well as habitat homogenization. This study showed that, independent of the anthropogenic disturbance level, interactions of environmental factors act as strong environmental filters on the distributions of local communities, such as Chironomidae assemblages.Os filtros ambientais atuam em diferentes escalas espaciais selecionando espécies com características adequadas capazes de sobreviver e se establecer sob condições ambientais específicas. Procuramos avaliar como os filtros ambientais (físico/químico, composição do habitat e paisagem) e os diferentes níveis de distúrbios antropogênicos afetam a abundância de Chironomidae em bacias hidrográficas no semiárido neotropical. As larvas de Chironomidae foram amostradas em seis reservatórios (112 locais) nas bacias hidrográficas do rio Piranhas-Assu e do rio Paraíba (NE Brasil) durante a estação seca. A distribuição das larvas de Chironomidae foi melhor explicada nos locais menos perturbados, com 82.1 % da variação total explicada para a bacia hidrográfica do rio Piranhas-Assu e 64.2 % para a bacia hidrográfica do rio Paraíba. As interações entre os filtros (físico/químico, composição do habitat e paisagem) explicaram melhor a distribuição da abundância das larvas de Chironomidae nas bacias hidrográficas e locais sujeitos a diferentes níveis de distúrbio antropogênico. As condições físicas e químicas da água e a composição do habitat dependem das características da paisagem, pois as atividades antrópicas desenvolvidas nas bacias hidrográficas aumentam as concentrações de nutrientes na água, promovendo o aumento do estado trófico do ambiente e a homogeneização dos habitats. Este estudo, mostrou que, independente do nível de disturbio antropogênico, as interações entre os fatores ambientais atuam como fortes filtros ambientais na distribuição das comunidades locais, a exemplo, das assembléias de Chironomidae

Avaliação da abundância e tamanho de Melanoides tuberculatus (MULLER, 1774) no reservatório Engenheiro Ávidos (Cajazeiras-PB)

Melanoides tuberculatus é um molusco exótico que tem se dispersado amplamente em ecossistemas aquáticos do semiárido brasileiro, sendo, em muitos casos, dominante nas comunidades de macroinvertebrados bentônicos. Os objetivos deste estudo foram: i) avaliar a abundância e tamanho de M. tuberculatus no reservatório Engenheiro Ávidos (Cajazeiras-PB); ii) averiguar a relação da abundância e tamanho de M. tuberculatus com variáveis ambientais; iii) avaliar, comparativamente, a classificação dos locais de amostragem – melhor e pior qualidade ambiental – a partir da abundância, tamanho de M. tuberculatus e variáveis físicas e químicas da água; e iv) diagnosticar a qualidade ambiental do ecossistema estudado. Os moluscos foram coletados em dez locais distribuídos na zona litorânea do reservatório Engenheiro Ávidos (Cajazeiras-PB), com auxílio de draga Ekman-Birge. A melhor resposta de classificação dos locais de amostragem foi obtida a partir dos parâmetros físicos e químicos da água. Maiores abundâncias e tamanhos do molusco ocorreram em locais com menor qualidade ambiental. Novos estudos devem ser realizados para acompanhar a dinâmica de M. tuberculatus, como também para avaliar a qualidade ambiental do reservatório.</p

Avaliação da abundância e tamanho de Melanoides tuberculatus (MULLER, 1774) no açude Engenheiro Ávidos (Cajazeiras – PB)

Melanoides tuberculatus é um molusco exótico que tem se dispersado, amplamente, em ecossistemas aquáticos do semiárido brasileiro. Os objetivos desse estudo foram: i) avaliar a abundância e tamanho de M. tuberculatus no açude Engenheiro Ávidos (Cajazeiras – PB); ii) averiguar a relação da abundância e tamanho de M. tuberculatus com variáveis ambientais; iii) avaliar, comparativamente, a classificação dos locais de amostragem - melhor e pior qualidade ambiental - a partir da abundância, tamanho de M. tuberculatus e variáveis físicas e químicas da água; e iv) diagnosticar a qualidade ambiental do ecossistema estudado. Os moluscos foram coletados em dez locais distribuídos na zona litorânea do reservatório Engenheiro Ávidos (Cajazeiras – PB), com auxílio de draga Ekman-Birge. A melhor resposta de classificação dos locais de amostragem foi obtida a partir dos parâmetros físicos e químicos da água. Maiores abundâncias e tamanhos do molusco ocorreram em locais com menor qualidade ambiental. Novos estudos devem ser realizados para acompanhar a dinâmica de M. tuberculatus, como também, para avaliar a qualidade ambiental do reservatório

Climate-associated variation in the drivers of benthic macroinvertebrate species-area relationships across shallow freshwater lakes

&lt;p&gt;&lt;span&gt;The island species-area relationship (ISAR) describes how species richness increases with increasing area of a given island or island-like habitat, such as freshwater lakes. &lt;/span&gt;&lt;span&gt;While the ISAR is one of the most common phenomena observed in ecology, there is variation in both the form of the relationship and its underlying mechanisms.&lt;/span&gt;&lt;/p&gt; &lt;p&gt;&lt;span&gt;We compiled a global dataset of benthic macroinvertebrates from 524 shallow freshwater lakes, ranging from 1 to 293300 ha in area. We used individual-based rarefaction to determine the degree to which ISAR was influenced by mechanisms other than passive sampling (larger islands passively sample more individuals from the regional pool and, therefore, have more species than smaller islands), which would bias results away from expected relationships between rarefied species richness (and other measures that capture relative abundances) and lake area. We also examined how climate may alter the shape of the ISARs. &lt;/span&gt;&lt;/p&gt; &lt;p&gt;&lt;span&gt;We found that both rarefied species richness (the number of species standardized by area or number of individuals) and a measure of evenness emphasizing common species exhibit non-significant relationships with lake area, suggesting that the expected ISARs in these lakes most likely result from passive sampling. &lt;/span&gt;&lt;span&gt;While there was considerable variation among ISARs across the investigated lakes, we found an overall positive rarefied ISAR for lakes in warm (i.e., tropical/subtropical) regions (n = 195), and in contrast, an overall negative rarefied ISAR in cool (i.e., north temperate) lakes (n = 329). This suggested that mechanisms beyond passive sampling (e.g., colonization-extinction dynamics and/or heterogeneity) were more likely to operate in warm lakes. One possible reason for this difference is that the area-dependent intensity of fish predation, which can lead to flatter ISARs, is weaker in warmer relative to cooler lakes.&lt;/span&gt;&lt;/p&gt; &lt;p&gt;&lt;span&gt;Our study illustrates the importance of understanding both the pattern and potential processes underlying the ISARs of freshwater lakes in different climatic regions. Further, it provides a baseline for understanding how further changes to the ecosystem (i.e., in lake area or climate) might influence biodiversity patterns. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;Funding provided by: National Natural Science Foundation of China&lt;br&gt;Crossref Funder Registry ID: https://ror.org/01h0zpd94&lt;br&gt;Award Number: 31971473&lt;/p&gt;&lt;p&gt;Funding provided by: National Natural Science Foundation of China&lt;br&gt;Crossref Funder Registry ID: https://ror.org/01h0zpd94&lt;br&gt;Award Number: 31930074&lt;/p&gt;&lt;p&gt;Funding provided by: Science Fund for Distinguished Young Scholars of Jiangxi Province&lt;br&gt;Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100021183&lt;br&gt;Award Number: 20232ACB215006&lt;/p&gt;&lt;p&gt;&lt;span&gt;We compiled data from studies that used a similar sampling methodology to collect macroinvertebrates from lakes that varied in area.&lt;/span&gt; &lt;span&gt;Our dataset consisted of 524 freshwater lakes from across the globe&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;span&gt;sampled at least once from 1974–2021. Data from 505 lakes was contributed by co-authors of this study and included&lt;/span&gt;&lt;span&gt; lakes in &lt;/span&gt;&lt;span&gt;Denmark (n = 198), China (n =131), Finland (n = 96), USA (n = 48), New Zealand (n = 15), Greece (n =11), Mexico (n = 4) and Russia (n = 2). &lt;/span&gt;&lt;span&gt;Most of these data had been published previously&lt;/span&gt;&lt;span&gt;.&lt;/span&gt; &lt;span&gt;We also included data from an additional 19 lakes identified in a Google Scholar literature review using the search terms "shallow lake" AND "zoobenthos" OR "benthic macroinvertebrate". From this, we identified sources that reported taxonomic-level abundance and nutrient concentrations and met the sampling criteria applied in the other studies (mean depth &lt; 10 m and sampling conducted in offshore zones and warm seasons). These data come from six publications&lt;/span&gt;&lt;span&gt;. See details in paper.&lt;/span&gt;&lt;/p&gt

Climate-associated variation in the drivers of benthic macroinvertebrate species-area relationships across shallow freshwater lakes

&lt;p&gt;&lt;span&gt;The island species-area relationship (ISAR) describes how species richness increases with increasing area of a given island or island-like habitat, such as freshwater lakes. &lt;/span&gt;&lt;span&gt;While the ISAR is one of the most common phenomena observed in ecology, there is variation in both the form of the relationship and its underlying mechanisms.&lt;/span&gt;&lt;/p&gt; &lt;p&gt;&lt;span&gt;We compiled a global dataset of benthic macroinvertebrates from 524 shallow freshwater lakes, ranging from 1 to 293300 ha in area. We used individual-based rarefaction to determine the degree to which ISAR was influenced by mechanisms other than passive sampling (larger islands passively sample more individuals from the regional pool and, therefore, have more species than smaller islands), which would bias results away from expected relationships between rarefied species richness (and other measures that capture relative abundances) and lake area. We also examined how climate may alter the shape of the ISARs. &lt;/span&gt;&lt;/p&gt; &lt;p&gt;&lt;span&gt;We found that both rarefied species richness (the number of species standardized by area or number of individuals) and a measure of evenness emphasizing common species exhibit non-significant relationships with lake area, suggesting that the expected ISARs in these lakes most likely result from passive sampling. &lt;/span&gt;&lt;span&gt;While there was considerable variation among ISARs across the investigated lakes, we found an overall positive rarefied ISAR for lakes in warm (i.e., tropical/subtropical) regions (n = 195), and in contrast, an overall negative rarefied ISAR in cool (i.e., north temperate) lakes (n = 329). This suggested that mechanisms beyond passive sampling (e.g., colonization-extinction dynamics and/or heterogeneity) were more likely to operate in warm lakes. One possible reason for this difference is that the area-dependent intensity of fish predation, which can lead to flatter ISARs, is weaker in warmer relative to cooler lakes.&lt;/span&gt;&lt;/p&gt; &lt;p&gt;&lt;span&gt;Our study illustrates the importance of understanding both the pattern and potential processes underlying the ISARs of freshwater lakes in different climatic regions. Further, it provides a baseline for understanding how further changes to the ecosystem (i.e., in lake area or climate) might influence biodiversity patterns. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;Funding provided by: National Natural Science Foundation of China&lt;br&gt;Crossref Funder Registry ID: https://ror.org/01h0zpd94&lt;br&gt;Award Number: 31971473&lt;/p&gt;&lt;p&gt;Funding provided by: National Natural Science Foundation of China&lt;br&gt;Crossref Funder Registry ID: https://ror.org/01h0zpd94&lt;br&gt;Award Number: 31930074&lt;/p&gt;&lt;p&gt;Funding provided by: Science Fund for Distinguished Young Scholars of Jiangxi Province&lt;br&gt;Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100021183&lt;br&gt;Award Number: 20232ACB215006&lt;/p&gt;&lt;p&gt;&lt;span&gt;We compiled data from studies that used a similar sampling methodology to collect macroinvertebrates from lakes that varied in area.&lt;/span&gt; &lt;span&gt;Our dataset consisted of 524 freshwater lakes from across the globe&lt;/span&gt;&lt;span&gt; &lt;/span&gt;&lt;span&gt;sampled at least once from 1974–2021. Data from 505 lakes was contributed by co-authors of this study and included&lt;/span&gt;&lt;span&gt; lakes in &lt;/span&gt;&lt;span&gt;Denmark (n = 198), China (n =131), Finland (n = 96), USA (n = 48), New Zealand (n = 15), Greece (n =11), Mexico (n = 4) and Russia (n = 2). &lt;/span&gt;&lt;span&gt;Most of these data had been published previously&lt;/span&gt;&lt;span&gt;.&lt;/span&gt; &lt;span&gt;We also included data from an additional 19 lakes identified in a Google Scholar literature review using the search terms "shallow lake" AND "zoobenthos" OR "benthic macroinvertebrate". From this, we identified sources that reported taxonomic-level abundance and nutrient concentrations and met the sampling criteria applied in the other studies (mean depth &lt; 10 m and sampling conducted in offshore zones and warm seasons). These data come from six publications&lt;/span&gt;&lt;span&gt;. See details in paper.&lt;/span&gt;&lt;/p&gt