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It is a significant technical challenge to exploit deep-sea polymetallic nodules with high efficiency and low disturbance. The mechanical behavior of seabed nodule collecting is very complicated, which is a multi-physical coupling process involving three-dimensional turbulent flow, discrete particle movement, and fine particle soil failure. In this paper, three main deep-sea hydraulic nodule collecting methods, i.e., the suck-up-based method, the Coandă-effect-based method, and the double-jet hydraulic method, are investigated by numerical simulation on the performance of nodule collecting and environmental disturbance. The realizable K-Epsilon two-layer model and the discrete element method are used to simulate the turbulent flow of the liquid phase and nodule particles in the solid phase respectively. The effect of collection flow qm and drag velocity v on collection rate η, turbulent kinetic energy k, and volume fraction φ of the seawater-sediment mixture in the collecting flow field is analyzed. The flow velocity, pressure, and nodule distribution are explored. The results indicate that, at the same qm and v, the double-jet hydraulic model will achieve the largest η, while the suck-up-based model will achieve the least η. The double-jet hydraulic model has the most significant disturbance to the near-bottom flow field and the most obvious sediment spreading phenomenon. In contrast, the suck-up-based model and the Coandăeffect-based model have less environmental disturbance, which is more conducive to the requirements of environmental protection. The Coandă-effect-based model shows minor sensitivity to qm and v and a good balance between high nodule collecting efficiency and low environmental disturbance. This paper will provide a scie.pngic basis for revealing the nodule collecting mechanism and designing and developing a nodule collecting device.

A well-known problem of visual object tracking is the difficulty of accurately estimating the object trajectory under conditions of environmental disturbances in the bounding box (BB) of a video camera. In this paper, we consider BB variations as Gaussian-Markov colored measurement noise (CMN). In order to perform accurate tracking in the presence of CMN, we use measurement differencing and develop a robust general unbiased finite impulse response (GUFIR) filter and use the general Kalman filter (GKF) as a benchmark. The GUFIR and GKF algorithms are tested by the “Car4” benchmark. It is shown that, in terms of the tracking precision and under the heavy disturbance with the $0.65 \leqslant \Psi \leqslant 0.95$ coloredness factor, the best tracking performance is achieved using the robust GUFIR filter. When $\Psi < 0.6$ , the GUFIR and GKF algorithms perform near equally. In the extreme point of $\Psi = 1.0$ , where the Gauss-Markov CMN loses the stationarity, both algorithms provide zero precision and become inefficient. In general, it is concluded that the GUFIR filter, which ignores any zero mean disturbance and initial values, is much more suitable for applications in visual object tracking than Kalman-like algorithms relying on complete object information.

An incremental deep deterministic policy gradient (IDDPG) algorithm is devised for the trajectory tracking control of a four-wing variable sweep (FWVS) aircraft with uncertainty. The IDDPG algorithm employs the line-of-sight (LOS) method for path tracking, formulates a reward function based on position and attitude errors, and integrates long short-term memory (LSTM) units into IDDPG algorithm to enhance its adaptability to environmental changes during flight. Finally, environmental disturbance factors are introduced in simulation to validate the designed controller’s ability to track climbing trajectories of morphing aircraft in the presence of uncertainty.

Based on the observation data of SS-Y extensometer at Yixian Seismic Station from 2014 to 2021, five typical events disturbed by the environment are analyzed, combined with the tectonic stress background field of Yixian deformation cave and the quantitative calculation of the model. The following conclusions are obtained: ① The load strain caused by the load interference source on the observation data of the extensometer at Yixian Station is related to the distance and load of the interference source and is positively correlated; ② The SS-Y extensometer of Yixian Station is divided into three parts, where the NS test item and the NE test item are subjected to the abnormal amplitude of load disturbance curve. ③ The results of three-dimensional model simulation of interference sources are smaller than those of anomalous variables.

ABSTRACT Global climate change has emerged as a critical environmental problem. Different types of climate extremes drive soil microbial communities to alternative states, leading to a series of consequences for soil microbial ecosystems and related functions. An effective method is urgently needed for buffering microbial communities to tackle environmental disturbances. Here, we conducted a series of mesocosm experiments in which the organic (NOF) and chemical fertilizer (NCF) long-term-amended soil microbiotas were subjected to environmental disturbances that included drought, flooding, freeze-thaw cycles, and heat. We subsequently tracked the temporal dynamics of rare and abundant bacterial taxa in NOF and NCF treatment soils to assess the efficiencies of organic amendments in recovery of soil microbiome. Our results revealed that freeze-thaw cycles and drought treatments showed weaker effects on bacterial communities than flooding and heat. The turnover between rare and abundant taxa occurred in postdisturbance succession of flooding and heat treatments, indicating that new equilibria were tightly related to the rare taxa in both NCF and NOF treatment soils. The Bayesian fits of modeling for the microbiome recovery process revealed that the stability of abundant taxa in NOF was higher than that in NCF soil. In particular, the NOF treatment soil reduced the divergence from the initial bacterial community after weak perturbations occurred. Together, we demonstrated that long-term organic input is an effective strategy to enhance the thresholds for transition to alternative states via enhancing the stability of abundant bacterial species. These findings provide a basis for the sustainable development of agricultural ecosystems in response to changing climates. IMPORTANCE Different climate extremes are expected to be a major threat to crop production, and the soil microbiome has been known to play a crucial role in agricultural ecosystems. In recent years, we have known that organic amendments are an effective method for optimizing the composition and functioning of the soil microbial community and maintaining the health of the soil ecosystem. However, the effects of organic fertilization on buffering bacterial communities against environmental disturbances and the underlying mechanisms are still unclear. We conducted a series of mesocosm experiments and showed that organic fertilizers had additional capacities in promoting the soil microbiome to withstand climate change effects. Our study provides both mechanistic insights as well as a direct guide for the sustainable development of agricultural ecosystems in response to climate change.

Tropical forests have a great potential for the exploitation of natural resources. Among the economic activities that depend on forest resources, timber production is the most important one. Nevertheless, these activities may negatively affect wildlife, the availability of natural resources, and ecosystem process. Here we analysed the effects of low-impact logging on understory bird species richness, number of individuals captured, species composition, and assemblage structure in central Brazilian Amazon. We compared logged and unlogged areas over a period of three years (from August 2014 to May 2017). We captured a total of 180 birds and 42 species (20 families) in the logged area and 226 birds and 49 species (20 families) in the unlogged area. Bird assemblage structure in the logged area changed more intensely over the three years of study and became more similar to the assemblage found in the unlogged area. The degree of similarity (Jaccard’s index) in species composition between logged and unlogged areas increased from 18% in the third year to 39% in the fifth year after logging. The results suggest that the minor effects of low-impact logging were reduced a few years after the disturbance, probably due to ecological succession. The proximity of logged and unlogged areas and the reduced impact in the study site may facilitate the recovery of the bird assemblage after the disturbance.

This study assessed invertebrate response to disturbances in the riparian zone of the Wewe river, using geometric series, rarefaction, Renyi diversity, and CCA models. We sampled 2,077 individuals (dry season) and 2,282 (wet season) belonging to 16 invertebrate orders. The severely disturbed habitat registered the highest individuals (n = 1,999), while the least was the moderately disturbed habitat (n = 740). Seasonal assemblages were not significantly different. Fire, farming, tree felling, and erosion explained 66.8% and 60.55% in the dry and wet seasons, respectively, of variations in invertebrate assemblages. This suggests threats to the invertebrate community and the riparian ecosystem health by anthropogenic interventions.

In this study, basic research was conducted regarding the era of autonomous vessels and artificial intelligence (deep learning, big data, etc.). When a vessel is navigating autonomously, it must determine the optimal route by itself and accurately follow the designated route using route-following control technology. First, the optimal route should be generated in a manner that ensures safety and reduces fuel consumption by the vessel. To satisfy safety requirements, sea depth, under-keel clearance, and navigation charts are used; algorithms capable of determining and shortening the distance of travel and removing unnecessary waypoints are used to satisfy the requirements for reducing fuel consumption. In this study, a reinforcement-learning algorithm-based machine learning technique was used to generate an optimal route while satisfying these two sets of requirements. Second, when an optimal route is generated, the vessel must have a route-following controller that can accurately follow the set route without deviation. To accurately follow the route, a velocity-type fuzzy proportional–integral–derivative (PID) controller was established. This controller can prevent deviation from the route because overshoot rarely occurs, compared with a proportional derivative (PD) controller. Additionally, because the change in rudder angle is smooth, energy loss by the vessel can be reduced. Here, a method for determining the presence of environmental disturbance using the characteristics of the Kalman filter innovation process and estimating environmental disturbance with a fuzzy disturbance estimator is presented, which allows the route to be accurately maintained even under conditions involving environmental disturbance. The proposed approach can automatically set the vessel’s optimal route and accurately follow the route without human intervention, which is useful and can contribute to maritime safety and efficiency improvement.

Abstract Ecosystems are experiencing elevated levels of disturbance, and species with narrower niches are often more vulnerable to disturbances. Niche breadth is often measured in terms of either diet or habitat use but diet and spatial use are infrequently considered in tandem. These different aspects of niche breadth potentially expose species to different types of disturbances; species with narrow dietary niches may be more affected by disturbances that alter trophic relationships, while species with narrow habitat niches may be more vulnerable to habitat loss and point‐source pollutants. We examined dietary and habitat niche breadth of common bottlenose dolphins, Tursiops truncatus truncatus, from three different nearshore sites in the Gulf of Mexico (GoM). Using stable isotopes, we determined proportional contributions of different prey groups to dolphin diets at each site and through time at one site. We used satellite‐linked telemetry at two sites to determine habitat use and site fidelity. Additionally, we examined the literature on cetacean diet, habitat use, movement, and IUCN status to determine relationships between niche breadth and population status for different species. Dolphin diets varied among sites as available prey varied, but Perciformes fish were the most frequently consumed prey. At the site for which we had temporal data, dolphins consumed more cephalopods in 2015 and 2018 but otherwise consumed primarily Perciformes fish. Dolphins had small utilization distributions and exhibited high site fidelity. Data from 31 cetacean species revealed that most species with vulnerable, threatened, or endangered IUCN statuses not only have specialized diets but also exhibit high site fidelity. Dolphins had diet characteristic of flexible generalists but were habitat specialists with high site fidelity. Dolphin populations in the GoM may have altered their diets in response to environmental changes that have altered community composition and trophic dynamics. On the other hand, their high site fidelity has exposed them to point‐source pollutants, such as oil spills, persistent organic pollutants, and freshwater. Our broader analysis of cetaceans confirmed that species with specialized diets and high site fidelity were the most vulnerable to disturbances, providing a framework to predict which nearshore dolphin populations, and cetaceans in general, are most vulnerable to environmental changes.

Abstract Background Mobile organisms in marine environments are expected to modify their behavior in response to external stressors. Among environmental drivers of animal movement are long-term climatic indices influencing organism distribution and short-term meteorological events anticipated to alter acute movement behavior. However, few studies exist documenting the response of vagile species to meteorological anomalies in coastal and marine systems. Methods Here we examined the movements of Eastern brown pelicans (Pelecanus occidentalis carolinensis) in the South Atlantic Bight in response to the passage of three separate hurricane events in 2 years. Pelicans (n = 32) were tracked with GPS satellite transmitters from four colonies in coastal South Carolina, USA, for the entirety of at least one storm event. An Expectation Maximization binary Clustering algorithm was used to discretize pelican behavioral states, which were pooled into ‘active’ versus ‘inactive’ states. Multinomial logistic regression was used to assess behavioral state probabilities in relation to changes in barometric pressure and wind velocity. Results Individual pelicans were more likely to remain inactive during tropical cyclone passage compared to baseline conditions generally, although responses varied by hurricane. When inactive, pelicans tended to seek shelter using local geomorphological features along the coastline such as barrier islands and estuarine systems. Conclusions Our telemetry data showed that large subtropical seabirds such as pelicans may mitigate risk associated with spatially-extensive meteorological events by decreasing daily movements. Sheltering may be related to changes in barometric pressure and wind velocity, and represents a strategy common to several other classes of marine vertebrate predators for increasing survival probabilities.

The aim of this paper was to determine the species diversity and frequency of foraging performed by bees in fragment of degraded forest in a Cerrado-Atlantic Forest ecotone area, also considering the nesting habit of each species. The foraging frequency of each bee species in the main floral sources was recorded for 12 consecutive months. The nesting site was used to sort the bees into guilds: above-ground nesting bees, ground-nesting bees, and both below and above-ground nesting bees. The guild of ground-nesting bees had 24 species and accounted for 17.48 % of the foraging rate, while above-ground nesting bees were represented by 12 species which made 8.89 % of the foraging rate, and both below and above-ground nesting bees comprised five species which made 0.43 % of the foraging rate. Africanized honeybee performed 73.20 % of the foraging flight, and presented a broad food niche. Therefore, in the forest fragment studied, two types of impacts which make difficult the survival and maintenance of the native bee fauna were observed: the dominance over floral resources by the exotic species the Africanized honeybees; the small number of large trees.

In this paper, a differential phase-modulated interferometer (DPMI) is proposed to compensate for the rotational error for precision displacement measurement. In DPMI, a reference interferometer sharing the same reference arm with the measurement interferometer is constructed. Using the two interferometers to differentially measure the displacement, the unbalanced environmental disturbance on the measurement can be minimized. An integrated 2 × 2 array photodetector (APD) is adopted in DPMI. Based on APD with differential wavefront sensing (DWS) technology, the rotation angle can be detected and compensated. Therefore, precision displacement without rotational error and unbalanced environmental disturbance can be achieved. Three confirmatory experiments were performed, and the experimental results show that the maximum displacement drift is reduced from 902.9 nm to 16.3 nm in 100 min stability test, the standard deviations between the pitch and yaw angles obtained by DPMI and Renishaw interferometer are 1.68 × 10−5° and 1.86 × 10−5°, respectively, and the maximum deviation between the measurement result of DPMI and the stage positioning before and after angle compensation is reduced from 5.207 μm to about 0.719 μm.

Since the 1990s, despite the existence of measures to protect the quality of water, in Europe as well as in France, water pollution persists. Agriculture is one of the activities that affect its quality. Thus, despite the existence of policies encouraging the reduction of the use of pesticides and fertilizers, contaminations remain. The gap between the both ancient and weighty legal system and the fact that pressures still impact the water resource incites us to take a closer look: protecting water quality must be included in broader sustainability issues. To this end, we integrate agricultural activity in the overall framework of Food Systems, in particular the processes of resilience put in place in answer to environmental disturbances. Such an approach allows us in the first place to question the temporalities of the processes involved - ecological, political, changes in individual and collective practices - which contribute to the environmental dynamics of Food Systems. More broadly, our results enable us to reconsider the environmental sustainability of these systems.

Sustainable aquaculture needs to be considered when it comes to the utilization of water resources. The aim of this study was to apply biomonitoring using macrobenthic structures on both spatial and temporal applications of monoculture and integrated multi-trophic aquaculture (IMTA) at Tembelas Island, Kepulauan Riau Province, Indonesia. Samples of sediment were taken from three fish farm locations, namely from an IMTA site, a monoculture site, and a reference site. Macrobenthic organisms obtained through rinsing, sieving, and sorting were then identified under a stereo-microscope. Diversity of the macrobenthic assemblages was analyzed with a Shannon-Wiener index (H’). Equitability was expressed through Pielou’s evenness index. Finally, Bray-Curtis’ non-metric multi-dimensional scaling (NMDS) was used for similarities derived from log (X+1) transformed macrobenthic abundance to provide a visual representation of differences in their structure between sites over time. Results showed polychaetes exhibited differences in both variation and abundance of genera between the farm and reference site. The assemblage of macrobenthos at the IMTA site consisted of 9 genera of gastropods, 3 genera of bivalves, 5 genera of polychaetes, and 2 genera of crustaceans. At the monoculture site, 12 genera of gastropods, 4 genera of bivalves, 8 genera of polychaetes, 1 genera of crustaceans, and 1 genera of ophiuroid were observed. A relatively high abundance was observed at the reference site, with 27 genera of gastropods, 11 genera of bivalves, 3 genera of polychaetes, and 1 genera of crustacean. The favorable water conditions and possible absence of waste input from aquaculture resulting in a more suitable habitat for macrobenthic life may explain this relative abundance. Some of them were recognised as opportunistic taxa, i.e., Capitella sp., Heteromastus sp., and Lumbrinereis sp. Based on the diversity and evenness indices and the MNDS ordination, it can be concluded that the application of IMTA systems results in a suppressed or reduced potential impact on environmental disturbance due to aquacultural activities.

The 2011 Great East Japan Earthquake and tsunami wiped out over 1200 shellfish and ascidian culture long-lines and ∼120 salmon farm cages that comprised the entire aquaculture installations in Onagawa Bay, Japan, and severely altered the associated ecosystem. A year later, we launched a coordinated monitoring program to measure the extent of the damage caused by the disaster and monitor the change in the state of the marine ecosystem. As part of this effort, we conducted multi-seasonal sampling to characterize spatio-temporal variation in benthic macrofaunal community and a range of environmental parameters across Onagawa Bay between March 2012 and January 2018. The 492 total macrofaunal species recorded included Polychaeta (38.8%), Bivalvia (13.2%), Amphipoda (10.8%), Decapoda (9.6%), Gastropoda (9.3%), and Echinodermata (4.3%). At the outermost reference site, macrofaunal abundance, biomass, and species diversity were all consistently high throughout the study period. Inside Onagawa Bay, macrofauna metrics increased steadily from the lowest values at the beginning of the study to the highest over time. During the same period, the spatial extent of aquaculture facilities for long-lines and fish cages recovered steadily to within 60.8% and 74.8% of the original state, respectively. The significant variables identified by multivariate analysis to explain spatio-temporal variability in benthic macrofaunal communities were: (1) proximity to the nearest aquaculture facilities; (2) wind fetch length (exposure); (3) sediment grain size; and (4) the total area of aquaculture facilities. This study suggests that coastal aquaculture operations may strongly influence the occurrence and distribution of benthic macrofaunal communities and thereby influence the recovery of seafloor biota at ecosystem scales following a catastrophic natural disaster.

ABSTRACT Wildfire events cause considerable environmental disturbance but few studies have examined changes in soil properties due to fire. This study aimed to assess the effect of a wildfire event on chemical, physical, and biological properties of the soil in a eucalyptus forest in the Pampa biome. Part of a seven-year-old eucalyptus forest was affected by a wildfire event that lasted for two days. Soil and plant litter sampling was performed in three areas: in the forest that was not affected by the fire, in the forest affected by it, and in an adjacent natural pasture area (the original vegetation). Seven samples were collected from the 0.00-0.05 and 0.05-0.20 m layers of each plot for biological analysis, and three samples were collected for chemical and physical analyses. Disturbed soil samples were collected in order to determine pH, organic matter, acidity, and nutrient content. Undisturbed samples were collected to determine soil microporosity, macroporosity, total porosity, and density. Soil macrofauna was assessed through the Tropical Soil Biology and Fertility method, and biological activity was tested through substrate consumption in the bait-lamina test. The fire increased soil pH values, CEC, and base saturation, as well as K, Ca, and Mg content; it decreased potential acidity and P content in the soil. Soil physical properties were not altered by the wildfire. The total abundance of macrofauna and of annelids, arachnids, coleoptera, and isoptera decreased due to the wildfire, resulting in lower soil diversity. Hymenoptera abundance increased because of the fire event. The feeding activity of organisms in the soil surface layer decreased due to the fire. The wildfire in the eucalyptus forest in the Pampa biome altered soil chemical and biological properties.

Constituídas por técnicas simples e baratas, medições de mudanças no desenvolvimento ontogenético mostram-se boas ferramentas de biomonitoramento. Uma das técnicas usualmente utilizadas é a Assimetria Flutuante (AF). Neste estudo foram avaliados os efeitos da retirada de mata ciliar sobre os níveis de AF em caracteres das asas posteriores de Erythrodiplax basalis (Kirby). Os resultados demonstraram que os caracteres apresentam distribuição normal e média zero, permitindo assumir que os níveis de assimetria observados são AF. Também ficou evidenciado que índices de AF não estão correlacionados ao tamanho da asa, e apresentam baixo erro de mensuração. Não há evidência significativa de aumento nos índices de AF em áreas degradadas em detrimento de áreas preservadas para as variáveis (comprimento total da asa, largura da asa na altura no nó, distância do triângulo ao nodus e distância da alça anal ao nodus). A hipótese de que os indivíduos coletados em áreas com alteração ambiental apresentariam maiores níveis de AF em caracteres das asas não foi corroborada. Isto pode decorrer do fato de E. basalis ser uma espécie com boa capacidade de dispersão, e os espécimes amostrados em áreas alteradas podem ter se desenvolvido em outros locais e estavam utilizando as áreas apenas como ponto de forrageio e por isso não foi detectada AF. Outro fator que corrobora essa predição é o fato que outros estudos usando espécies de Zygoptera que possuem capacidade de dispersão menor, níveis significativos de AF tem sido detectados. Environmental Integrity Effect on Fluctuating Asymmetry in Erythrodiplax basalis (Libellulidae: Odonata) (Kirby) Abstract. Constituted by simple and cheaply techniques, measures of changes in ontogenetic development are good biomonitoring tools. One of these techniques commonly used is the Fluctuating Asymmetry (FA). In this study, we explore the effects of riparian vegetation removal on the levels of FA on hind wings traits of Erythrodiplax basalis (Kirby). The results showed that traits present normal distribution and zero mean, which allows us to assume that observe levels of asymmetry are FA. It was also evident that FA indexes are not correlated to the wing length, and present low levels of measurement error. There is no significantly evidence of increase in the FA levels in degraded areas in comparison with preserved areas for the measured variables (wing length, wing width on the nodus level, distance between triangle and nodus and distance between anal loop and nodus). The hypothesis that individuals collected in altered areas present higher levels of FA in wing traits was not corroborated. This may result from the fact that E. basalis is a species with good dispersal capability, and the specimens sampled in disturbed areas may have developed elsewhere and were only using the areas as a point of foraging and therefore was not detected AF. Another factor that corroborates this prediction is the fact that other studies using Zygoptera species that have lower dispersal ability, significant levels of physical activities has been detected.

Constituídas por técnicas simples e baratas, medições de mudanças no desenvolvimento ontogenético mostram-se boas ferramentas de biomonitoramento. Uma das técnicas usualmente utilizadas é a Assimetria Flutuante (AF). Neste estudo foram avaliados os efeitos da retirada de mata ciliar sobre os níveis de AF em caracteres das asas posteriores de Erythrodiplax basalis (Kirby). Os resultados demonstraram que os caracteres apresentam distribuição normal e média zero, permitindo assumir que os níveis de assimetria observados são AF. Também ficou evidenciado que índices de AF não estão correlacionados ao tamanho da asa, e apresentam baixo erro de mensuração. Não há evidência significativa de aumento nos índices de AF em áreas degradadas em detrimento de áreas preservadas para as variáveis (comprimento total da asa, largura da asa na altura no nó, distância do triângulo ao nodus e distância da alça anal ao nodus). A hipótese de que os indivíduos coletados em áreas com alteração ambiental apresentariam maiores níveis de AF em caracteres das asas não foi corroborada. Isto pode decorrer do fato de E. basalis ser uma espécie com boa capacidade de dispersão, e os espécimes amostrados em áreas alteradas podem ter se desenvolvido em outros locais e estavam utilizando as áreas apenas como ponto de forrageio e por isso não foi detectada AF. Outro fator que corrobora essa predição é o fato que outros estudos usando espécies de Zygoptera que possuem capacidade de dispersão menor, níveis significativos de AF tem sido detectados. Environmental Integrity Effect on Fluctuating Asymmetry in Erythrodiplax basalis (Libellulidae: Odonata) (Kirby) Abstract. Constituted by simple and cheaply techniques, measures of changes in ontogenetic development are good biomonitoring tools. One of these techniques commonly used is the Fluctuating Asymmetry (FA). In this study, we explore the effects of riparian vegetation removal on the levels of FA on hind wings traits of Erythrodiplax basalis (Kirby). The results showed that traits present normal distribution and zero mean, which allows us to assume that observe levels of asymmetry are FA. It was also evident that FA indexes are not correlated to the wing length, and present low levels of measurement error. There is no significantly evidence of increase in the FA levels in degraded areas in comparison with preserved areas for the measured variables (wing length, wing width on the nodus level, distance between triangle and nodus and distance between anal loop and nodus). The hypothesis that individuals collected in altered areas present higher levels of FA in wing traits was not corroborated. This may result from the fact that E. basalis is a species with good dispersal capability, and the specimens sampled in disturbed areas may have developed elsewhere and were only using the areas as a point of foraging and therefore was not detected AF. Another factor that corroborates this prediction is the fact that other studies using Zygoptera species that have lower dispersal ability, significant levels of physical activities has been detected.

Unchanging physicochemical conditions and nutrient sources over long periods of time in cave and karst subsurface habitats, particularly aquifers, can support stable ecosystems, termed autochthonous microbial endokarst communities (AMEC). AMEC existence is unknown for other karst settings, such as epigenic cave streams. Conceptually, AMEC should not form in streams due to faster turnover rates and seasonal disturbances that have the capacity to transport large quantities of water and sediment and to change allochthonous nutrient and organic matter sources. Our goal was to investigate whether AMEC could form and persist in hydrologically active, epigenic cave streams. We analyzed bacterial diversity from cave water, sediments, and artificial substrates (Bio-Traps®) placed in the cave at upstream and downstream locations. Distinct communities existed for the water, sediments, and Bio-Trap® samplers. Throughout the study period, a subset of community members persisted in the water, regardless of hydrological disturbances. Stable habitat conditions based on flow regimes resulted in more than one contemporaneous, stable community throughout the epigenic cave stream. However, evidence for AMEC was insufficient for the cave water or sediments. Community succession, specifically as predictable exogenous heterotrophic microbial community succession, was evident from decreases in community richness from the Bio-Traps®, a peak in Bio-Trap® community biomass, and from changes in the composition of Bio-Trap® communities. The planktonic community was compositionally similar to Bio-Trap® initial colonizers, but the downstream Bio-Trap® community became more similar to the sediment community at the same location. These results can help in understanding the diversity of planktonic and attached microbial communities from karst, as well as microbial community dynamics, stability, and succession during disturbance or contamination responses over time.

Nest-site is an important resource for cavity-nesting ants, what limits colony establishment and structures ant community composition through competition. In ecosystems frequently disturbed by firecontinuous establishment of new colonies is crucial to the process of natural succession. Based on this perspective, we tested the hypothesis that fire reduces the amount of cavities for nesting (e.g., hollow branches, dry leaves curled, and galls), with negative impact on ant biodiversity. We searched for natural cavities and added artificial-nests to assess whether the occupancy rate and its consequences for colony growth. We also evaluated the availability of food sources for ants (EFN plants, honeydew-hemipterans and preys). We found that burned areas had less diverse and structurally simple vegetation. The occupation of natural and artificial nests was the same between the areas, but the reduced availability of nesting-sites in the burned area indicates higher limitation after the fire. This effect was even stronger in foliage habitat compared to the ground. In fact, most of the 11 cavity-nesting species found were typically arboreal. Species richness was lower in burned area, possibly due to lower nesting-sites availability, but the abundance was higher, which may be explained by the greater availability of food resources, mainly EFN-bearing plants. The high food availability may also explain the bigger colony size in burned area, since nectar and honeydew boosts colony growth and low richness prevents competition. In summary, our results show that changes in the availability of nesting sites and food resources may be key mechanisms by which fire changes the ant fauna, specifically cavity-nesting ants in the Brazilian Savanna.

Constituídas por técnicas simples e baratas, medições de mudanças no desenvolvimento ontogenético mostram-se boas ferramentas de biomonitoramento. Uma das técnicas usualmente utilizadas é a Assimetria Flutuante (AF). Neste estudo foram avaliados os efeitos da retirada de mata ciliar sobre os níveis de AF em caracteres das asas posteriores de Erythrodiplax basalis (Kirby). Os resultados demonstraram que os caracteres apresentam distribuição normal e média zero, permitindo assumir que os níveis de assimetria observados são AF. Também ficou evidenciado que índices de AF não estão correlacionados ao tamanho da asa, e apresentam baixo erro de mensuração. Não há evidência significativa de aumento nos índices de AF em áreas degradadas em detrimento de áreas preservadas para as variáveis (comprimento total da asa, largura da asa na altura no nó, distância do triângulo ao nodus e distância da alça anal ao nodus). A hipótese de que os indivíduos coletados em áreas com alteração ambiental apresentariam maiores níveis de AF em caracteres das asas não foi corroborada. Isto pode decorrer do fato de E. basalis ser uma espécie com boa capacidade de dispersão, e os espécimes amostrados em áreas alteradas podem ter se desenvolvido em outros locais e estavam utilizando as áreas apenas como ponto de forrageio e por isso não foi detectada AF. Outro fator que corrobora essa predição é o fato que outros estudos usando espécies de Zygoptera que possuem capacidade de dispersão menor, níveis significativos de AF tem sido detectados. Environmental Integrity Effect on Fluctuating Asymmetry in Erythrodiplax basalis (Libellulidae: Odonata) (Kirby) Abstract. Constituted by simple and cheaply techniques, measures of changes in ontogenetic development are good biomonitoring tools. One of these techniques commonly used is the Fluctuating Asymmetry (FA). In this study, we explore the effects of riparian vegetation removal on the levels of FA on hind wings traits of Erythrodiplax basalis (Kirby). The results showed that traits present normal distribution and zero mean, which allows us to assume that observe levels of asymmetry are FA. It was also evident that FA indexes are not correlated to the wing length, and present low levels of measurement error. There is no significantly evidence of increase in the FA levels in degraded areas in comparison with preserved areas for the measured variables (wing length, wing width on the nodus level, distance between triangle and nodus and distance between anal loop and nodus). The hypothesis that individuals collected in altered areas present higher levels of FA in wing traits was not corroborated. This may result from the fact that E. basalis is a species with good dispersal capability, and the specimens sampled in disturbed areas may have developed elsewhere and were only using the areas as a point of foraging and therefore was not detected AF. Another factor that corroborates this prediction is the fact that other studies using Zygoptera species that have lower dispersal ability, significant levels of physical activities has been detected.