Seasonal changes in water quality and macrophytes and the impact of cattle on tropical floodplain waterholes

The present study indicates the critical role of hydrologic connectivity in floodplain waterholes in the wet–dry tropics of northern Australia. These waterbodies provide dry-season refugia for plants and animals, are a hotspot of productivity, and are a critical part in the subsistence economy of many remote Aboriginal communities. We examined seasonal changes in water quality and aquatic plant cover of floodplain waterholes, and related changes to variation of waterhole depth and visitation by livestock. The waterholes showed declining water quality through the dry season, which was exacerbated by more frequent cattle usage as conditions became progressively drier, which also increased turbidity and nutrient concentrations. Aquatic macrophyte biomass was highest in the early dry season, and declined as the dry season progressed. Remaining macrophytes were flushed out by the first wet-season flows, although they quickly re-establish later during the wet season. Waterholes of greater depth were more resistant to the effects of cattle disturbance, and seasonal flushing of the waterholes with wet-season flooding homogenised the water quality and increased plant cover of previously disparate waterholes. Therefore, maintaining high levels of connectivity between the river and its floodplain is vital for the persistence of these waterholes.

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Assessment of Spatio-temporal Variations of Selected Water Quality Parameters of Lake Ziway, Ethiopia Using Multivariate Techniques

10.21203/rs.3.rs-1102595/v1 ◽

2021 ◽

Author(s):

Dessie Tibebe ◽

Feleke Zewge ◽

Brook Lemma ◽

Yezbie Kassa

Keyword(s):

Water Quality ◽

River Mouth ◽

Temporal Variations ◽

Quality Parameters ◽

Dry Season ◽

Water Quality Parameters ◽

Quality Data ◽

Nutrient Concentrations ◽

Wet Season ◽

Water Quality Data

Abstract Lake Ziway is shallow freshwater located in Northern part of Ethiopian Rift Valley. It is characterized as semi-arid to sub-humid type of climate. Expansions of the flower industry, widespread fisheries, intensive agricultural activities, fast population growth lead to deterioration of water quality and depletion of aquatic biota. In this study, spatial and temporal variations of selected water quality parameters of Lake Ziway were evaluated using multivariate statistical techniques in the study periods of 2014 and 2015. Monthly water quality data were collected from nine sampling stations during dry and wet seasonal basis for analysis of 15 water quality parameters. Mean nutrient concentrations showed increasing trend and were higher in Floriculture effluent (Fb) and Floriculture effluent after mixing in the lake (Fa) in all seasons. These sites were also characterized by high electrical conductivity (EC) and total dissolved solid (TDS). All the nine sampling sites were categorized into three pollution levels according to their water quality features using cluster analysis (CA). Accordingly, sampling sites Fb and Ketar River (Kb) are highly and moderately polluted in both seasons, respectively. On the other hand, sampling sites at the center (C), Meki river mouth (Ma), Ketar river mouth (Ka), Meki River (Mb), Korekonch (Ko) and Fa in dry season and Ka, C, Ma, Ko, Bulbula river mouth (B) and Fa during wet season were less polluted. Principal component analysis (PCA) analysis also showed the pollutant sources were mainly from Fb during dry season Mb and Kb during wet season. The values of comprehensive pollution index illustrated the lake is moderately and slightly polluted in dry and wet seasons, respectively. Comparatively, the pollution status of the lake is high around floriculture effluent discharge site and at the two feeding rivers (Kb and Mb) due to increasing trends in agrochemical loads. This may lead to long term ecological changes in the lake unless possible measures taken.

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The seasonal changes of the gut microbiome of the population living in traditional lifestyles are represented by characteristic species-level and functional-level SNP enrichment patterns

BMC Genomics ◽

10.1186/s12864-021-07372-0 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Xue Zhu ◽

Jiyue Qin ◽

Chongyang Tan ◽

Kang Ning

Keyword(s):

Gut Microbiome ◽

Seasonal Changes ◽

Dry Season ◽

Urban Setting ◽

Snp Analysis ◽

Wet Season ◽

Human Gut ◽

Human Gut Microbiome ◽

Genome Level ◽

Prevalent Species

Abstract Background Most studies investigating human gut microbiome dynamics are conducted on humans living in an urban setting. However, few studies have researched the gut microbiome of the populations living traditional lifestyles. These understudied populations are arguably better subjects in answering human-gut microbiome evolution because of their lower exposure to antibiotics and higher dependence on natural resources. Hadza hunter-gatherers in Tanzania have exhibited high biodiversity and seasonal patterns in their gut microbiome composition at the family level, where some taxa disappear in one season and reappear later. Such seasonal changes have been profiled, but the nucleotide changes remain unexplored at the genome level. Thus, it is still elusive how microbial communities change with seasonal changes at the genome level. Results In this study, we performed a strain-level single nucleotide polymorphism (SNP) analysis on 40 Hadza fecal metagenome samples spanning three seasons. With more SNP presented in the wet season, eight prevalent species have significant SNP enrichment with the increasing number of SNP calling by VarScan2, among which only three species have relatively high abundances. Eighty-three genes have the most SNP distributions between the wet season and dry season. Many of these genes are derived from Ruminococcus obeum, and mainly participated in metabolic pathways including carbon metabolism, pyruvate metabolism, and glycolysis. Conclusions Eight prevalent species have significant SNP enrichments with the increasing number of SNP, among which only Eubacterium biforme, Eubacterium hallii and Ruminococcus obeum have relatively high species abundances. Many genes in the microbiomes also presented characteristic SNP distributions between the wet season and the dry season. This implies that the seasonal changes might indirectly impact the mutation patterns for specific species and functions for the gut microbiome of the population that lives in traditional lifestyles through changing the diet in wet and dry seasons, indicating the role of these variants in these species’ adaptation to the changing environment and diets.

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Seasonal feeding plasticity can facilitate coexistence of dominant omnivores in Neotropical streams

Reviews in Fish Biology and Fisheries ◽

10.1007/s11160-021-09648-w ◽

2021 ◽

Author(s):

Mayara P. Neves ◽

Pavel Kratina ◽

Rosilene L. Delariva ◽

J. Iwan Jones ◽

Clarice B. Fialho

Keyword(s):

Seasonal Variation ◽

Fish Species ◽

Resource Availability ◽

Seasonal Changes ◽

Dry Season ◽

Diet Overlap ◽

Isotopic Niche ◽

Neotropical Streams ◽

Feeding Plasticity ◽

The Impact

AbstractCoexistence of ecomorphologically similar species in diverse Neotropical ecosystems has been a focus of long-term debate among ecologists and evolutionary biologists. Such coexistence can be promoted by trophic plasticity and seasonal changes in omnivorous feeding. We combined stomach content and stable isotope analyses to determine how seasonal variation in resource availability influences the consumption and assimilation of resources by two syntopic fish species, Psalidodon aff. gymnodontus and P. bifasciatus, in the Lower Iguaçu basin. We also tested the impact of seasonality on trophic niche breadth and diet overlap of these two dominant omnivores. Seasonal changes in resource availability strongly influenced the consumption and assimilation of resources by the two fish species. Both species exhibited high levels of omnivory, characterized by high diversity of allochthonous resources in the wet season. Terrestrial invertebrates were the main component of diet during this season. However, in the dry season, both species reduced their isotopic niches, indicating diet specialization. High diet overlap was observed in both seasons, but the isotopic niche overlap was smaller in the dry season. Substantial reduction in the isotopic niche of P. bifascistus and a shift toward aquatic invertebrates can facilitate coexistence during this season of resource shortage. Feeding plasticity allows omnivorous fish to adjust their trophic niches according to seasonality, promoting the exploitation of different resources during periods of greater resource diversity. This seasonal variation could be an important mechanism that contributes to the resource partitioning and coexistence of dominant omnivores in Neotropical streams.

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Analysis of the distribution of domestic wastewater in the Brantas river area of Malang city

MATEC Web of Conferences ◽

10.1051/matecconf/201819505004 ◽

2018 ◽

Vol 195 ◽

pp. 05004

Author(s):

Prihatiningsih Bekti ◽

Zaenal Kusuma ◽

Agus Suharyanto ◽

Amin Setyoleksono

Keyword(s):

Water Quality ◽

Domestic Wastewater ◽

Sampling Technique ◽

Dry Season ◽

Wastewater Management ◽

The Public ◽

Pollution Levels ◽

Momentary Sampling ◽

Control And Management ◽

The Impact

The degradation of water quality has become a major problem today. In Indonesia, the decline in water quality is caused by domestic wastewater which is a non-point source. In an effort to reduce the occurrence of environmental degradation due to domestic wastewater, it is necessary to give an idea and convince the public and the relevant parties of the importance of domestic wastewater management. Efforts are made by informing the pattern of distribution of domestic wastewater in a region and the impact of its distribution for its control and management. The research method uses a momentary sampling technique in accordance with SNI 6989.59:2008. The location of the water sampling is determined purposively. Sampling was conducted in two periods; the dry season in September and the rainy season in January. The observed parameters included BOD5 and E.coli. Determination of the distribution of domestic wastewater uses GIS. The distribution of domestic wastewater is determined based on pollution levels expressed as IP. The results show that pollution levels in Sawojajar and Sumbersari were lightly polluted with average IPs of 4.09 and 4.02 (dry season). While Kedungkandang is in the good category, IP = 0.32 (dry season).

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Diet selection by cattle grazing Stylosanthes-grass pastures in the seasonally dry tropics: effect of year, season, stylo species and botanical composition

Australian Journal of Experimental Agriculture ◽

10.1071/ea9960781 ◽

1996 ◽

Vol 36 (7) ◽

pp. 781 ◽

Cited By ~ 12

Author(s):

DB Coates

Keyword(s):

Cattle Grazing ◽

Diet Selection ◽

Dry Season ◽

Major Influence ◽

Botanical Composition ◽

Wet Season ◽

Seasonally Dry ◽

Dietary Preference ◽

Dry Tropics ◽

Opportunity For Selection

The dietary preference of cattle grazing Stylosanthes-based pastures in the seasonally dry tropics of North Queensland was studied using faecal carbon ratios (S13C) to determine grass-legume proportions. Estimates were made at monthly intervals for several years in 1 experiment to determine the effect of year, season and botanical composition on dietary stylo proportions. In another experiment, the effect of stylo cultivars (Verano and Seca) on dietary preference was monitored for 17 months. Where pastures provided ample opportunity for selection, cattle showed a strong preference for grass in the early wet season and in the late dry season. The proportion of stylo in the diet increased during the wet season and reached peak proportions (as high as 80%) in the late wet season or early dry season. Dietary stylo proportions decreased as pastures dried off and as the stylo shed leaf or became more stemmy. The length of the wet season and the amount and distribution of rainfall had a major influence on the seasonal pattern of diet selection. Stylo rarely fell below 20% in the diet. On an annual basis, stylo accounted for about 45% of the diet which was appreciably higher than the proportion of stylo in the pasture. Dietary stylo proportions were higher on Seca-based pasture than on Verano-based pasture. The avoidance of stylo in the early wet season was less pronounced with Seca compared with Verano. Later in the season Seca was the dominant dietary component for a much longer period than Verano. The effect of botanical composition on dietary grass-legume proportions varied between and within years. Correlations between grass-legume proportions in the pasture and in the diet were highest in the late dry season and early wet season when preference for grass was strongest. At the end of the wet season when cattle preferred stylo, dietary stylo was not related to pasture stylo content except in a drought year. Averaged over the full year, dietary stylo content was significantly correlated with pasture stylo content in all years and the correlation was highest in a drought year when there was a high level of utilisation and less opportunity for selection. A simple model relating dietary stylo to pasture stylo was developed and is discussed.

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Seasonal diet preferences of chital deer in the northern Queensland dry tropics, Australia

The Rangeland Journal ◽

10.1071/rj20015 ◽

2020 ◽

Vol 42 (3) ◽

pp. 211

Author(s):

Kurt Watter ◽

Greg Baxter ◽

Michael Brennan ◽

Tony Pople ◽

Peter Murray

Keyword(s):

Dry Season ◽

Wet Season ◽

Variable Environment ◽

Dry Tropics ◽

Plant Groups ◽

Axis Axis ◽

Plant Group ◽

Diet Preference ◽

Dry Seasons

Chital deer (Axis axis) were introduced to the Burdekin dry tropics of north Queensland, Australia, in the late 1800s. Here rainfall and plant growth are highly seasonal and a nutritional bottleneck for grazing animals occurs annually before the wet season. This study describes the seasonal changes in diet and diet preference of chital in this seasonally-variable environment. Rumen samples were taken from 162 deer from two sites over the wet and dry seasons of two consecutive years and sorted macroscopically for identification. Relative seasonal availability of plant groups was estimated using step point sampling of areas grazed by chital. Chital alter their diet seasonally according to availability and plant phenology. Chital utilised 42 plant genera including grasses, forbs, subshrubs, shrubs, trees and litter. Grass consumption ranged from 53% of biomass intake during the dry season to 95% during the wet season. The predominance of grass in the wet season diet exceeded relative availability, indicating a strong preference. Although grass contributed more than half of the dry season diet it was the least preferred plant group, given availability, and the least actively growing. Shrubs were the preferred plant type in the dry season, and least subject to seasonal senescence. Composition and quantity of seasonal pastures vary markedly in north Queensland, and chital alter their diet by consuming those plants most actively growing. The increased dry season intake of non-grass forage appears to be a strategy to limit the detriment resulting from the progressive deterioration in the quality of grass.

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Seasonal Distribution and Abundance of Dugongs in the Western-Gulf-of-Carpentaria

Wildlife Research ◽

10.1071/wr9890141 ◽

1989 ◽

Vol 16 (2) ◽

pp. 141 ◽

Cited By ~ 7

Author(s):

P Bayliss ◽

WJ Freeland

Keyword(s):

Relative Density ◽

Relative Abundance ◽

Coastal Waters ◽

Seasonal Changes ◽

Aboriginal People ◽

Dry Season ◽

Seasonal Distribution ◽

Wet Season ◽

Aerial Surveys ◽

The 1960S

Aerial surveys of coastal waters (27 216 km2) in the western Gulf of Carpentaria during the dry season of 1984 and wet season of 1985 indicated no major seasonal changes in distribution and relative abundance of dugongs. Minimum population size in the dry season was estimated as 16 816 � 2946 (standard error), with a relative density of 0.62 k 0.11 km-2, and that for the wet season 16 846 + 3257, with a relative density of 0.62 � 0.12 km-2. The estimates exclude 5% of observations which could have been either dugongs or Irrawaddy dolphins, and were corrected for submerged dugongs and those missed on the surface. Dugongs were unevenly distributed over the study area, and neither mean group size nor proportion of calves varied between seasons. Dugong abundance was correlated with area of available seagrass. The catch rate of dugongs by Aboriginal people off Numbulwar decreased six-fold between the 1960s and 1985 (60 to 10 p.a.), possibly due to excessive hunting.

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A Comparative Frequency Analysis of Maximum Daily Rainfall for a SE Asian Region under Current and Future Climate Conditions

Advances in Meteorology ◽

10.1155/2017/2620798 ◽

2017 ◽

Vol 2017 ◽

pp. 1-16 ◽

Cited By ~ 7

Author(s):

Velautham Daksiya ◽

Pradeep Mandapaka ◽

Edmond Y. M. Lo

Keyword(s):

General Circulation ◽

Daily Rainfall ◽

Circulation Model ◽

Dry Season ◽

Wet Season ◽

Climate Conditions ◽

Rainfall Extremes ◽

Annual Maximum Daily Rainfall ◽

The Impact ◽

Maximum Daily Rainfall

The impact of changing climate on the frequency of daily rainfall extremes in Jakarta, Indonesia, is analysed and quantified. The study used three different models to assess the changes in rainfall characteristics. The first method involves the use of the weather generator LARS-WG to quantify changes between historical and future daily rainfall maxima. The second approach consists of statistically downscaling general circulation model (GCM) output based on historical empirical relationships between GCM output and station rainfall. Lastly, the study employed recent statistically downscaled global gridded rainfall projections to characterize climate change impact rainfall structure. Both annual and seasonal rainfall extremes are studied. The results show significant changes in annual maximum daily rainfall, with an average increase as high as 20% in the 100-year return period daily rainfall. The uncertainty arising from the use of different GCMs was found to be much larger than the uncertainty from the emission scenarios. Furthermore, the annual and wet seasonal analyses exhibit similar behaviors with increased future rainfall, but the dry season is not consistent across the models. The GCM uncertainty is larger in the dry season compared to annual and wet season.

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Seasonal Variation of Phthalate Esters in Urban River Sediments: A Case Study of Fengshan River System in Taiwan

Sustainability ◽

10.3390/su14010347 ◽

2021 ◽

Vol 14 (1) ◽

pp. 347

Author(s):

Kuan-Nan Lin ◽

Chiu-Wen Chen ◽

Chih-Feng Chen ◽

Yee Cheng Lim ◽

Chih-Ming Kao ◽

...

Keyword(s):

Phthalate Esters ◽

River Sediments ◽

Aquatic Organisms ◽

River System ◽

Dry Season ◽

Ecological Risks ◽

Total Risk ◽

Wet Season ◽

Potential Risks ◽

The Impact

The Fengshan River system is one of the major rivers in Kaohsiung City, Taiwan. This study investigated the concentration of eight phthalate esters (PAEs) in sediments of the river and the impact of potential ecological risks during the dry and wet seasons. The potential risk assessment of sediment PAEs was evaluated by adopting the total risk quotient (TRQ) method. The total PAEs concentrations (∑PAEs) in the sediments of the Fengshan River system are between 490–40,190 ng/g dw, with an average of 8418 ± 11,812 ng/g dw. Diisononyl phthalate (38.1%), bis(2-ethylhexyl) phthalate (36.9%) and di-isodecyl phthalate (24.3%) accounted for more than 99.3% of ∑PAEs. The concentration of ∑PAEs in sediments at the river channel stations is higher during the wet season (616–15,281 ng/g dw) than that during the dry season (490–1535 ng/g dw). However, in the downstream and estuary stations, the wet season (3975–6768 ng/g dw) is lower than the dry season (20,216–40,190 ng/g dw). The PAEs in sediments of the Fengshan River may have low to moderate potential risks to aquatic organisms. The TQR of PAEs in sediments at the downstream and estuary (TQR = 0.13) is higher than that in the upstream (TQR = 0.04). In addition, during the wet season, rainfall transported a large amount of land-sourced PAEs to rivers, leading to increased PAEs concentration and potential ecological risks in the upper reaches of the river.

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Investigating the liquid water path over the tropical Atlantic with synergistic airborne measurements

10.5194/amt-2019-18 ◽

2019 ◽

Cited By ~ 1

Author(s):

Marek Jacob ◽

Felix Ament ◽

Manuel Gutleben ◽

Heike Konow ◽

Mario Mech ◽

...

Keyword(s):

Water Vapor ◽

Liquid Water ◽

Critical Role ◽

Dry Season ◽

Passive Microwave ◽

Variable Component ◽

Wet Season ◽

Liquid Water Path ◽

Water Path ◽

Airborne Measurements

Abstract. Clouds are a strongly variable component of the climate system and several studies have identified especially marine low level clouds to play a critical role for the climate. Liquid water path (LWP) is an important quantity to characterize clouds. Passive microwave satellite sensors provide the most direct estimate on global scale, but suffer from high uncertainties due to large footprints and the superposition of cloud and precipitation signals. Here, we use high spatial resolution airborne microwave radiometer (MWR) measurements together with cloud radar and lidar observations to better understand LWP of warm clouds over the tropical North Atlantic. The nadir measurements were taken by the German High Altitude and Long range research aircraft (HALO) in December 2013 (dry season) and August 2016 (wet season) during two Next generation Advanced Remote sensing for VALidation campaigns (NARVAL). Microwave retrievals of integrated water vapor (IWV), LWP and rain water path (RWP) are developed using artificial neural network techniques and a unique database based on cloud-resolving model simulations with 1.25 km grid spacing. The IWV and LWP retrievals share the same eight MWR frequency channels as their sole input. The comparison of retrieved IWV with coincident dropsondes and water vapor lidar measurements shows root-mean-square deviations below 1.4 kg m−2 over the range from 20 to 60 kg m−2. This comparison raises the confidence in LWP retrievals which can only be assessed theoretically. The theoretical analysis shows the dependency of the uncertainty on LWP itself as the error is below 20 g m−2 for LWP below 100 g m−2 and below 20 % above. The identification of clear sky scenes by ancillary measurements, here backscatter lidar, is crucial for thin clouds (LWP < 12 g m−2) as the microwave retrieved LWP uncertainty is higher than 100 %. The RWP retrieval combines active and passive microwave observations and is able to detect drizzle and light precipitation. The analysis of both campaigns reveals that clouds were more frequent in the dry than in the wet season and their LWP and RWP were higher, but microwave scattering of ice was observed more frequently in the wet season (1.6 % vs. 0.5 % of the time). As to be expected, the observed IWV clearly shows that the wet season (mean IWV = 41 kg m−2) is more humid than the dry season (mean IWV = 28 kg m−2). The results reveal that the observed frequency distributions of IWV are strongly affected by the choice of the flight pattern. Therefore, the airborne observations need to be used carefully to mediate between long-term ground-based and spaceborne measurements to draw statistically sound conclusions.

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