Cave benthic invertebrates in south-eastern Brazil: are there 'key' factors structuring such communities?

2018 ◽  
Vol 69 (11) ◽  
pp. 1762 ◽  
Author(s):  
T. G. Pellegrini ◽  
P. S. Pompeu ◽  
R. L. Ferreira
Keyword(s):  
Aquatic Insect ◽  
Physicochemical Characteristics ◽  
Hydraulic Characteristics ◽  
Key Factors ◽  
Stream Channels ◽  
Insect Communities ◽  
Eastern Brazil ◽  
Physical Features ◽  
Local Variability ◽  
Insect Assemblage

The aim of this study was to determine the effects of microhabitat traits related to water quality and physical features of stream channels (substrate, channel morphology and hydraulic characteristics) on the richness and structure of the aquatic insect assemblage in cave streams. Sampling was conducted in three subterranean streams in Brazil. Aquatic insect richness was significantly and positively related to water depth and the presence of shelters for invertebrates. These shelters are directly related to channel heterogeneity, a factor that determined the surface area of habitats suitable for colonisation, refuges and the amount and variety of nutrients in streams where resources are extremely limited. Furthermore, analyses of community composition revealed that aquatic insect assemblages in each cave were structured by distinct factors (including physicochemical characteristics of the water or hydraulic features of the channel). Together, these findings highlight that different factors are responsible for structuring the assemblages in each cave, which may reflect their local variability, and that silting of cave streams would likely have deleterious effects on aquatic insect communities through reductions in overall habitat heterogeneity.

scholarly journals Effects of experimental multi-season drought on abundance, richness, and beta diversity patterns in perennially flowing stream insect communities

Hydrobiologia ◽  
2021 ◽  
Author(s):  
P. Saffarinia ◽  
K. E. Anderson ◽  
D. B. Herbst
Keyword(s):  
Beta Diversity ◽  
Aquatic Insect ◽  
Flow Regimes ◽  
Surface Flow ◽  
Insect Community ◽  
Stream Channels ◽  
Insect Communities ◽  
Threshold Response ◽  
Small Streams ◽  
Flow Loss

AbstractFreshwater systems are projected to experience increased hydrologic extremes under climate change. To determine how small streams may be impacted by shifts in flow regimes, we experimentally simulated flow loss over the span of three summers in nine 50 m naturally fed stream channels. The aquatic insect community of these streams was sampled before, during, and after experimental drought treatments as well as following one unforeseen flood event. Abundance, richness, and beta diversity were measured as indicators of biotic effects of altered flow regimes. Abundance declined in proportion to flow loss. In contrast, we observed a threshold response in richness where richness did not decrease except in channels where losses of surface flow occurred and disconnected pools remained. The flood reset this pattern, but communities continued their prior trajectories shortly thereafter. Beta diversity partitions suggested no strong compositional shifts, and that the effect of drought was largely experienced uniformly across taxa until flow cessation. Pools served as a refuge, maintaining stable abundance gradients and higher richness longer than riffles. Upon flow resumption, abundance and richness returned to pre-treatment levels within one year. Our results suggest that many taxa present were resistant to drought conditions until loss in surface flow occurred.

Behavioral Responses of Drunella coloradensis (Ephemeroptera) Nymphs to Short-Term pH Reductions

1993 ◽  
Vol 50 (12) ◽  
pp. 2692-2697 ◽  
Author(s):  
Christopher M. Pennuto ◽  
Frank deNoyelies Jr.
Keyword(s):  
Acute Stress ◽  
Aquatic Insect ◽  
Behavioral Responses ◽  
Activity Levels ◽  
Stream Channels ◽  
Insect Communities ◽  
Stream Insects ◽  
Community Monitoring ◽  
Behavior Frequency ◽  
Passive Drift

Behavioral responses of Drunella coloradensis nymphs were examined in outdoor experimental stream channels after pH reductions of 1 and 2 pH units below ambient. The severity of pH decline below the ambient of 7.8 influenced the behavior patterns displayed by nymphs. At pH 7.01 (an intermediate pH decline) nymphs sat less frequently and burrowed more than controls. Burrowing behavior frequency returned to control levels and drifting and crawling behaviors increased relative to controls at pH 6.02. Ventilatory behaviors increased with pH decline, but were independent of the severity of acidity increases. These results suggest that individual behaviors may offer a more sensitive indicator of sub-acute stress in aquatic insect communities than population or community monitoring. Behaviors leading to increased activity levels in stream insects may have community-level effects via changes in predator–prey encounter rates or increased susceptibility to passive drift. These potential changes are discussed in reference to monitoring for acidification effects.

Spatial and seasonal variability of emergent aquatic insects and nearshore spiders in a subtropical estuary

2019 ◽  
Vol 70 (4) ◽  
pp. 541 ◽  
Author(s):  
Martha J. Zapata ◽  
S. Mažeika P. Sullivan
Keyword(s):  
Aquatic Insects ◽  
High Salinity ◽  
Aquatic Insect ◽  
Freshwater Ecosystems ◽  
Dispersal Ability ◽  
Insect Community ◽  
Insect Communities ◽  
Low Salinity ◽  
Subtropical Estuary ◽  
Adult Aquatic Insects

Variability in the density and distribution of adult aquatic insects is an important factor mediating aquatic-to-terrestrial nutritional subsidies in freshwater ecosystems, yet less is understood about insect-facilitated subsidy dynamics in estuaries. We surveyed emergent (i.e. adult) aquatic insects and nearshore orb-weaving spiders of the families Tetragnathidae and Araneidae in a subtropical estuary of Florida (USA). Emergent insect community composition varied seasonally and spatially; densities were lower at high- than low-salinity sites. At high-salinity sites, emergent insects exhibited lower dispersal ability and a higher prevalence of univoltinism than low- and mid-salinity assemblages. Orb-weaving spider density most strongly tracked emergent insect density rates at low- and mid-salinity sites. Tetragnatha body condition was 96% higher at high-salinity sites than at low-salinity sites. Our findings contribute to our understanding of aquatic insect communities in estuarine ecosystems and indicate that aquatic insects may provide important nutritional subsidies to riparian consumers despite their depressed abundance and diversity compared with freshwater ecosystems.

scholarly journals Physicochemical Differentiation of the Muskau Arch Pit Lakes in the Light of Long-Term Changes

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2368 ◽  
Author(s):  
Małgorzata Oszkinis-Golon ◽  
Marcin Frankowski ◽  
Leszek Jerzak ◽  
Andrzej Pukacz
Keyword(s):  
Physicochemical Characteristics ◽  
Key Factors ◽  
Physicochemical Conditions ◽  
Morphometric Features ◽  
Temporal Differentiation ◽  
Pit Lakes ◽  
Negative Effect ◽  
Oxygen Profiles ◽  
Lake Stratification

Thirteen pit lakes of the Muskau Arch (Western Poland) were studied in the summer season of 2016. The lakes display great geomorphological and hydrochemical diversity. The aim of the study was to characterize temporal changes in the physicochemical conditions of the pit lakes over the last 30 years (1986–2016) and to determine the main factors influencing their evolution. All the lakes were characterized in terms of the same set of physicochemical parameters measured and used for comparative analysis with literature data from the years 1986 and 1992. The results showed significant temporal differentiation in terms of morphometric features and most of the physicochemical characteristics. pH, EC, Ca2+, Mg2+ and total Fe were among the most significantly differentiating parameters. A similar pattern of changes was found for most of the lakes, suggesting natural fluctuations. Despite the differences in values of thermal and oxygen profiles, there were also similarities in lake stratification. Additionally, meromictic conditions were found in 4 lakes. In some of the lakes a negative effect of neutralization and fertilization of the water was observed. Our results showed that the Muskau Arch lakes are subject to dynamic hydrogeological and hydrochemical changes. In addition to natural changes, human-caused transformations were among the key factors responsible for the differentiation of the physicochemical conditions.

scholarly journals Graphene Hybrid Materials for Controlling Cellular Microenvironments

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4008
Author(s):  
Cheol-Hwi Kim ◽  
Tae-Hyung Kim
Keyword(s):  
Stem Cell ◽  
Hybrid Materials ◽  
Hybrid Composites ◽  
Stem Cell Differentiation ◽  
Physicochemical Characteristics ◽  
Key Factors ◽  
Cell Functions ◽  
Graphene Derivatives ◽  
Cytoskeletal Dynamics ◽  
Cellular Microenvironments

Cellular microenvironments are known as key factors controlling various cell functions, including adhesion, growth, migration, differentiation, and apoptosis. Many materials, including proteins, polymers, and metal hybrid composites, are reportedly effective in regulating cellular microenvironments, mostly via reshaping and manipulating cell morphologies, which ultimately affect cytoskeletal dynamics and related genetic behaviors. Recently, graphene and its derivatives have emerged as promising materials in biomedical research owing to their biocompatible properties as well as unique physicochemical characteristics. In this review, we will highlight and discuss recent studies reporting the regulation of the cellular microenvironment, with particular focus on the use of graphene derivatives or graphene hybrid materials to effectively control stem cell differentiation and cancer cell functions and behaviors. We hope that this review will accelerate research on the use of graphene derivatives to regulate various cellular microenvironments, which will ultimately be useful for both cancer therapy and stem cell-based regenerative medicine.

Trait patterns of aquatic insects across gradients of flow-related factors: a multivariate analysis of Canadian national data

2008 ◽  
Vol 65 (4) ◽  
pp. 670-680 ◽  
Author(s):  
Nelli Horrigan ◽  
Donald J Baird
Keyword(s):  
Dissolved Oxygen ◽  
Large Scale ◽  
Aquatic Insect ◽  
Adult Life ◽  
Taxonomic Composition ◽  
Medium Size ◽  
Insect Communities ◽  
Related Factors ◽  
Adult Life Span ◽  
Consistent Manner

Large-scale comparisons of aquatic bioassessment metrics based on taxonomic composition are currently constrained by the biogeographic limitations of taxon occurrence. The use of species trait patterns offers a possibility to overcome this constraint. We examine the assertion that the trait composition of aquatic insect communities changes in a consistent manner along similar environmental disturbance gradients by evaluating relationships between traits and three flow-related variables (velocity, water temperature, and dissolved oxygen) in 13 independently collected Canadian data sets. Certain trait states such as low crawling rate, common occurrence in drift, short adult life span, erosional rheophily, medium size at maturity, and cold or cool thermal preference were consistently sensitive to all three flow-related factors, velocity in particular, despite biogeographic differences in faunal composition. Trait modalities exhibiting the highest mean correlation with velocity, temperature, and dissolved oxygen were identified, and the potential confounding effect of trait “syndromes” was addressed by restricting the selection of flow-sensitive traits to those with high evolutionary lability. The results of the study provide a basis for the future development of flow bioassessment metrics at the national Canadian scale and potentially at the international scale.

scholarly journals Unravelling the Environmental Application of Biochar as Low-Cost Biosorbent: A Review

2020 ◽  
Vol 10 (21) ◽  
pp. 7810 ◽  
Author(s):  
Antía Fdez-Sanromán ◽  
Marta Pazos ◽  
Emilio Rosales ◽  
María Angeles Sanromán
Keyword(s):  
Low Cost ◽  
Value Added ◽  
Physicochemical Characteristics ◽  
The Novel ◽  
Key Factors ◽  
Biomass Waste ◽  
Environmental Application ◽  
Adsorption Mechanisms ◽  
Points Of Interest ◽  
Interesting Approach

In this age, a key target for enhancing the competitiveness of the chemical, environmental and biotechnology industries is to manufacture high-value products more efficiently and especially with significantly reduced environmental impact. Under this premise, the conversion of biomass waste to a high-value added product, biochar, is an interesting approach under the circular economy principles. Thus, the improvements in the biochar production and its new and innovative uses are hot points of interest, which are the focus of vast efforts of the scientific community. Biochar has been recognized as a material of great potential, and its use as an adsorbent is becoming a reliable strategy for the removal of pollutants of different streams, according to its high adsorption capacity and potential to eliminate recalcitrant compounds. In this review, a succinct overview of current actions developed to improve the adsorption capability of biochar, mainly of heavy metal and organic pollutants (dyes, pharmaceuticals and personal care products), is summarized and discussed, and the principal adsorption mechanisms are described. The feedstock and the production procedure are revealed as key factors that provide the appropriate physicochemical characteristics for the good performance of biochar as an adsorbent. In addition, the modification of the biochar by the different described approaches proved their feasibility and became a good strategy for the design of selective adsorbents. In the last part of this review, the novel prospects in the regeneration of the biochar are presented in order to achieve a clean technology for alleviating the water pollution challenge.

Sign in / Sign up

Export Citation Format

Share Document