Short-term effects of wildfire on Patagonian headwater streams

2018 ◽  
Vol 27 (7) ◽  
pp. 457 ◽  
Author(s):  
Emilio A. Williams Subiza ◽  
Cecilia Brand
Keyword(s):  
Headwater Streams ◽  
Taxonomic Composition ◽  
Specific Conductance ◽  
Functional Feeding Groups ◽  
Short Term ◽  
Argentine Patagonia ◽  
Nothofagus Forest ◽  
Periphyton Biomass ◽  
Abundance And Diversity ◽  
Quality Assessments

In March–April 2015, the El Cristo fire burned 1228 ha of mixed Nothofagus forest in Los Alerces National Park (Argentine Patagonia). We compared physicochemical variables and community structure of burned and unburned headwater streams. Sampling began shortly after the fire was extinguished and comprised periodic water quality assessments and four visits to collect periphyton and invertebrate samples (May, August, October and December). Water temperature, total dissolved solids, total suspended solids and specific conductance were significantly higher in burned sites, whereas nutrient and oxygen concentrations exhibited no major differences. Chlorophyll a (used as a surrogate for autotrophic periphyton biomass) also did not differ significantly. Macroinvertebrate richness, abundance and diversity showed no differences across sites, but taxonomic composition and densities of sensitive taxa were markedly lower at burned streams. Oligochaetes and amphipods, however, were significantly more abundant in the disturbed reaches. Analysis of functional feeding groups revealed that the relative abundances of shredders and collector-filterers were lower at burned sites, possibly reflecting a shift in detrital input.

scholarly journals Dynamics of Bacterial and Viral Communities in Paddy Soil with Irrigation and Urea Application

Viruses ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 347 ◽  
Author(s):  
Yuting Li ◽  
Hao Sun ◽  
Weichao Yang ◽  
Guanxiong Chen ◽  
Hui Xu
Keyword(s):  
Bacterial Abundance ◽  
Nitrogen Addition ◽  
Nitrogen Fixing ◽  
Short Term ◽  
Nitrogen Fixing Bacteria ◽  
Ecological Processes ◽  
N Accumulation ◽  
Natural Systems ◽  
Viral Communities ◽  
Abundance And Diversity

Viruses are ubiquitous in natural systems. By influencing bacterial abundance (BA) and community structure through lysis-lysogenic conversion, viruses are involved in various ecological processes. In agricultural management, nitrogen addition and irrigation should be considered as important factors that can modify soil viral dynamics but have been ignored. In our study, short-term dynamics of autochthonous soil viral and bacterial abundance and diversity after irrigation and urea application were examined in a long-term experimental paddy field. Urea addition delayed the emergence of peak viral abundance for three days, suggesting that viruses are sensitive to N addition. Under short-term eutrophic conditions through urea application, viruses undertake a lysogenic-biased strategy. Moreover, nitrogen-fixing bacteria were most likely specifically lysed in urea-treated soil, which suggests that soil viruses block N accumulation by killing nitrogen-fixing bacteria. To the best of our knowledge, this study is the first to investigate dynamic changes in autochthonous viruses in paddy fields.

The effects of copper and zinc on biomass and taxonomic composition of algal periphyton communities from the River Gharasou, Western Iran

2009 ◽  
Vol 38 (3) ◽  
Author(s):  
Islam Atazadeh ◽  
Martyn Kelly ◽  
Mozafar Sharifi ◽  
John Beardall
Keyword(s):  
Taxonomic Composition ◽  
Short Term ◽  
Western Iran ◽  
Artificial Streams ◽  
Copper And Zinc

The effects of copper and zinc on biomass and taxonomic composition of algal periphyton communities from the River Gharasou, Western IranIndoor artificial streams were used to evaluate the short-term (24 day) influence of copper and zinc, individually and in combination, on the biomass and taxonomic composition of algal periphyton communities. The effects of Cu (50 μg 1

Testing temporal stability of the larval digenean community in Heleobia conexa (Mollusca: Cochliopidae) and its possible use as an indicator of environmental fluctuations

Parasitology ◽  
2010 ◽  
Vol 138 (2) ◽  
pp. 249-256 ◽  
Author(s):  
M. J. MERLO ◽  
J. A. ETCHEGOIN
Keyword(s):  
Environmental Changes ◽  
Temporal Stability ◽  
Host Community ◽  
Buenos Aires Province ◽  
Short Term ◽  
Environmental Disturbances ◽  
Preferred Habitat ◽  
Environmental Fluctuations ◽  
Abundance And Diversity ◽  
Potential Use

SUMMARYLarval digeneans have been proposed as indicators of abundance and diversity of vertebrate and other hosts as well as environmental disturbances. To evaluate its response to environmental changes and its potential use as an indicator of environmental fluctuations, the temporal stability of the community of larval digeneans in Heleobia conexa was comparatively analysed in 4 separate years (1996, 1999, 2004 and 2005) in Mar Chiquita coastal lagoon (Buenos Aires province, Argentina). In total, 4579 specimens of H. conexa were collected and 22 digenean species were observed. Overall prevalence presented inter-annual and seasonal differences. These differences correlate with seasonal changes in composition of the vertebrate definitive host community and with the elimination of the preferred habitat of H. conexa in 1999. In general, the larval digenean community of H. conexa showed a yearly re-establishment following the annual cycle of H. conexa and the presence of definitive hosts. This annual restructuring allowed inferences about the effects of short-term environmental changes in the lagoon. According to these observations, the larval digenean community of H. conexa could be considered as a good bio-indicator with quick response to environmental disturbances.

scholarly journals Colonisation of leaf litter by aquatic invertebrates in an Atlantic Forest stream

2014 ◽  
Vol 74 (2) ◽  
pp. 267-273 ◽  
Author(s):  
VC. Oliveira ◽  
EA. Gonçalves ◽  
RG. Alves
Keyword(s):  
Leaf Litter ◽  
Atlantic Forest ◽  
Riparian Vegetation ◽  
Aquatic Invertebrates ◽  
Dry Weight ◽  
Taxonomic Composition ◽  
Β Diversity ◽  
Forest Stream ◽  
Α Diversity ◽  
Abundance And Diversity

Riparian vegetation along streams in the Atlantic Forest in Brazil contributes to the formation of a highly heterogeneous leaf litter in streambeds. To investigate the structure and composition of the aquatic invertebrate community during the process of leaf decomposition of two plant species present along the banks of the stream studied, 21 plastic mesh bags containing 2.5g (dry weight) of leaf matter from each species (Alchornea glandulosa (Vell) and Cabralea canjerana End. and Poeppig), for a total of 5.0g, were placed in the streambed. Three bags were removed after 3, 6, 9, 12, 24, 48 and 96 days. The taxonomic density was negatively correlated with the remaining weight. The high density of collector organisms, such as Chironomidae, Oligochaeta and Amphipoda, on the last day of incubation, probably occurred due to the increased amount of fine organic matter in the more advanced decomposition stages. The highest α diversity (Shannon-Wiener) values were observed for the 3rd and 96th days of the experiment, while the β diversity values showed that these days presented the highest variation in the taxonomic composition, thus presenting a different faunistic composition. This study showed that the trophic structure and composition of aquatic invertebrates changes during the decomposition of leaf litter. The faunistic abundance and diversity observed in this study indicate that the entrance of material from plants growing along streams provides favorable conditions for the colonisation and establishment of invertebrates in lower-order streams, and thus points to the need to preserve riparian vegetation.

Short-term recolonization of stones in a tropical island stream

2002 ◽  
Vol 53 (6) ◽  
pp. 993 ◽  
Author(s):  
Luz Boyero ◽  
Jose Luis DeLope
Keyword(s):  
Significant Variation ◽  
National Park ◽  
Taxonomic Composition ◽  
Total Density ◽  
Community Characteristics ◽  
Tropical Stream ◽  
Short Term ◽  
Taxa Richness ◽  
Abiotic Variables ◽  
Community Evenness

The recolonization of stones by macroinvertebrates in streams can occur at very small temporal scales, an often-neglected factor in recolonization studies. In a tropical stream in Coiba National Park, Panama, 36 stones were washed and brushed and each one was subjected to four different periods of exposure in a riffle (1, 3, 9, 27 h). Ephemeroptera, together with Diptera, Trichoptera, Coleoptera, Lepidoptera and Hydracarina, were the main recolonizers. Total density of individuals, and density and relative abundance of the most common taxon (Baetidae : Ephemeroptera), showed significant variation over the four recolonization periods, partially explained by some abiotic variables (water depth, current velocity and stone shape). Taxa richness, community evenness and taxonomic composition did not vary significantly over the four periods. The recolonization of stones in the tropical stream began immediately after the disturbance, although only some community characteristics varied significantly over the first hours.

scholarly journals Long-term dysbiosis promotes insulin resistance during obesity despite rapid diet-induced changes in the gut microbiome of mice

2017 ◽  
Author(s):  
Kevin P. Foley ◽  
Emmanuel Denou ◽  
Brittany M. Duggan ◽  
Rebecca Chan ◽  
Jennifer C. Stearns ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Glucose Tolerance ◽  
Glucose Intolerance ◽  
Intestinal Microbiota ◽  
Fecal Microbiota ◽  
Taxonomic Composition ◽  
Short Term ◽  
Fecal Microbiome ◽  
Induced Changes

AbstractThe intestinal microbiota and insulin sensitivity are rapidly altered in response to a high fat diet (HFD). It is unclear if gut dysbiosis precedes insulin resistance or vice versa. The initial triggers of diet-induced insulin resistance can differ from mechanisms underlying chronic dysglycemia during prolonged obesity. It is not clear if intestinal dysbiosis contributes to insulin resistance during short-term or long-term HFD-feeding. We found that diet-induced changes in the composition of the fecal microbiome preceded changes in glucose and insulin tolerance at both the onset and removal of a HFD in mice. Dysbiosis occurred after 1-3 days of HFD-feeding, whereas insulin and glucose intolerance manifested by 3-4 days. Antibiotic treatment did not alter glucose tolerance during this short-term HFD period. Conversely, antibiotics improved glucose tolerance in mice with protracted obesity caused by long-term HFD feeding for over 2 months. We also found that microbiota transmissible glucose intolerance only occurred after prolonged diet-induced dysbiosis. Germ-free mice had impaired glucose tolerance when reconstituted with the microbiota from long-term, but not short-term HFD-fed animals. Our results are consistent with intestinal microbiota contributing to chronic insulin resistance and dysglycemia during prolonged obesity, despite rapid diet-induced changes in the taxonomic composition of the fecal microbiota.

scholarly journals Effects of Grazing Enclosures on Species Diversity, Phenology, Biomass, and Carrying Capacity in Borana Rangeland, Southern Ethiopia

2021 ◽  
Vol 8 ◽  
Author(s):  
Yeneayehu Fenetahun ◽  
You Yuan ◽  
Xu Xinwen ◽  
Wang Yongdong
Keyword(s):  
Species Diversity ◽  
Carrying Capacity ◽  
Shannon Index ◽  
Southern Ethiopia ◽  
Short Term ◽  
Vegetation Height ◽  
Grazing Intensities ◽  
Abundance And Diversity ◽  
Index Value

A grazing enclosure (GE) is one of the most effective techniques for restoring degraded rangelands by modifying the composition, abundance, and diversity of species. However, the effect of GEs on different grazing intensities and durations compared to open-grazing (OG) rangelands is not well known. We aimed to assess the effect of GE on the characteristics of plant species. We established five plots in a short-term enclosure, a long-term enclosure, and an OG treatment to examine the effect of GE on vegetation species’ height, abundance, diversity, phenology, biomass, heterogeneity, and the carrying capacity (CC) of rangeland under grazed and enclosed conditions. We found that GE significantly (P < 0.05) increased vegetation height, abundance, biomass, CC, phenological period, and species diversity. However, the increase in height, diversity, and phenological periods were not consistent with enclosure duration, and higher increments were recorded at the short-term enclosure site. The highest Shannon index value recorded at StGE (2.45) was 28.6 and 12.2% greater than the LtGE (1.75) and OG (2.15) sites, respectively. The advanced phenological periods were higher at the StGE site and showed 22.6 and 60.3% higher values than the LtGE and OG sites, respectively. The highest carrying capacities of 23.4 and 114.3% for livestock were observed at the LtGE compared to the StGE and OG grazing sites. In addition, the heterogeneity of the plants’ community was significantly higher in the long-term GE, due to the decrease in species’ diversity. In conclusion, this paper further contributes to the development of the theoretical basis on the effects of GEs and recommends strategies like rotational grazing and reseeding to be used in tandem with a GE for sustainable management of rangelands.

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