Rainy Period Research Articles

Importance of pneumatophore fringe-mudflat continuum for an estuary-dependent fish species

ABSTRACT Shallow estuarine habitats are well recognized for providing a positive correlation to the abundance and diversity of juvenile fish species. This has been associated with the hypotheses of refuge from predators and the availability of food. Therefore, this study aimed to evaluate the importance of two adjacent habitats to mangrove fringes (area adjacent to pneumatophore zone and mudflat) as an ecological habitat for Diapterus auratus juveniles. Sampling was carried out in the rainy (January–July 2016) and dry (August–December 2016) periods. This study indicated that D. auratus juveniles did not show significant differences in abundance and biomass between adjacent habitats. However, univariate analyses found there was a significant increase in fish abundance in the dry season, due to influx of young-of-the-year. Further, the size-frequency of D. auratus showed a recruitment pattern recorded between August and January, suggesting a broad spawning period between the end of the rainy season and a recovery period between March and May. There were distinct changes in the diet between seasons for D. auratus, according to the dendrogram of the food eaten by the fish. The combined results from the distribution and feeding ecology suggest a connectivity among adjacent areas, and indicate that both habitats provide critical foraging and refuge habitat for D. auratus in this tropical estuary.

Trophic distribution of mercury from an abandoned cinnabar mine within the Záskalská reservoir ecosystem (Czech Republic).

The distribution of mercury species was studied in all aquatic ecosystem components (i.e., water, sediment, emergent aquatic plants, invertebrates and omnivorous and piscivorous fish) of the Záskalská water reservoir (Central Bohemia, Czech Republic) which is in the vicinity of an abandoned cinnabar mine. The results indicate that the transport of mercury from the cinnabar mine is the major source of mercury in the Záskalská reservoir. The legal maximum limit (0.07μg/L) for total mercury concentration in water samples was exceeded only during rainy periods. The total mercury concentration in the surface sediments was in the range from 0.22 to 9.19mg/kg in dry matter (up to 0.2% CH3Hg+) and was sample site-specific. The dominant form of mercury in sediments was mercury sulphide (22.9-79.2%). The emergent macrophytes accumulated mercury primarily by the roots from sediments, and no significant translocation of mercury to leaves was observed. The legal maximum limit for mercury content in fish muscle (0.5mg/kg in the fresh matter) was exceeded up to 4.48 times for piscivorous fish. Hazard index values indicate a health risk concern for children and for people consuming more than 100g of fish muscle per day. Our results emphasise the need to implement legal restrictions on the consumption of piscivorous fish caught in ecosystems downstream of abandoned cinnabar mines.

Water security threats and challenges following the rupture of large tailings dams

The rupture of mine-tailings dams can severely contaminate rivers, because released tailings can interact with water for years keeping contaminant concentrations high. The general purpose of this study was to examine the rupture of B1 tailings dam in Ferro-Carvão stream (municipality of Brumadinho, state of Minas Gerais, Brazil), which occurred in 25 January 2019 and contaminated the main water course (Paraopeba River) with 2.8 Mm3 of metal-rich tailings. The specific purpose was to assess the percentage of non-conforming concentrations following the event, considering the Normative Deliberation COPAM/CERH-MG no. 1. The results showed non-conforming aluminum, iron, manganese, lead, phosphorus and turbidity concentrations, clearly above pre-rupture averages, especially in the rainy period. The catastrophe triggered the suspension of Paraopeba River as drinking water source to the Metropolitan Region of Belo Horizonte (BHMR; 6 million people). Since then, the supply to the BHMR became an everyday challenge to water management authorities, because the Paraopeba source represented a 30% share. Mitigation measures are therefore urgently needed. As complementary objective to this study, we aimed to verify the possibility to restore drinking water supply through conventional treatment. The treatability of Paraopeba River water was assessed by the Raw Water Quality Index considering the rainy and dry periods in separate. The results suggested the possibility to lift up the suspension in the dry period, improving the regional water security. Considering the huge dataset on which this study is standing, our results are generalizable to similar events with sparser information.

Water quality assessment and pollution threat to safe water supply for three river basins in Malaysia

Pollution in raw water poses increasing threats to safe water supply in many developing countries. Therefore, a comprehensive water quality assessment is essential to provide various stakeholders the information to deal with this problem. This study applies chemometrics to interpret a recent 10-year water quality data from three major river basins (Selangor River basin, Langat River basin, and Klang River basin) frequented by water supply disruptions in Selangor, Malaysia. We present the application of selected chemometrics approaches, namely agglomerative hierarchical cluster analysis, principal component analysis, factor analysis and Man-Kendall trend analysis. The results showed three spatial groups of monitoring stations with similar land use practices and pollution characteristics. Besides spatial differences, periodic variations were observed when similar pollutants exhibited different pollution loads during rainy and dry periods. We found that nitrogen species, total suspended solids, and dissolved solids represented the major pollution loads in the studied basins. The results further confirmed a significant increasing trend in ammonia pollution. Our study demonstrates how ammonia pollutant is likely to pose a threat to water supply and highlights the vulnerability of Selangor's water resource system to water pollution. The results of this study could facilitate decision making towards more holistic strategies, specifically, incorporating ammonia treatment facilities into the conventional water treatment plant will help achieve smooth water supply operations.

Off-flavor detection in tilapia reared in cages in tropical lakes

Aquaculture activity in the aquatic ecosystem can intensify the presence of the semi-volatile compounds geosmin (GSM) and 2-methylisoborneol (MIB). These metabolites are the leading cause of off-flavor in fish from aquaculture facilities, even at small concentrations. Thus, this study aimed at evaluating the influence of tilapia production in cages on the availability and production of the metabolites GSM and MIB in water and sediment. Samples were obtained from two Brazilian natural tropical lakes (Palmas and Palminhas) in alternate months, in both dry and rainy periods. The physicochemical parameters of water and sediment samples were measured in situ and in the laboratory. Water samples were collected for quantitative analysis of the phytoplankton community, and fresh tissue samples from ten tilapia (Oreochromis niloticus) to analyze semi-volatile compounds (GSM, MIB, and β-ionone). Samples from fish farms in Palminhas Lake present higher aqueous concentrations of phosphorus and ammonia, a higher abundance of Cyanophyceae, and the presence of GSM and MIB in sediment and fish flesh. Conversely, Palmas Lake presented low nutrients and a higher abundance of Chlorophyceae, with GSM presence and MIB absence. Therefore, eutrophication caused by fish farming in these tropical lakes with long water retention time coupled with inadequate governmental policies leads to negative feedback that leads to off-flavors in fish products.

Rainfall-driven nutrient loading affects coastal phytoplankton in the southwestern Indian Ocean: a lagoon at Mauritius Island

This study aimed to test the effects of rainfall-driven nutrient loading on the microphytoplankton dynamics in the shallow water at Trou aux Biches lagoon on the northwest coast of Mauritius. Changes in density, diversity and estimated productivity of microphytoplankton were monitored in three zones—coast, lagoon and reef—during two rainfall periods of 4 and 3 days’ duration, respectively, in March–April 2017. The average nutrient loading from terrestrial runoff was 15.5% and the salinity decreased by 2.5%. Following the two rainfall events, a 3-fold increase in total microphytoplankton density (TMPD), with a dominance of diatoms, was noted within a week at the coast and lagoon, while it remained relatively unchanged at the reef. These changes in microphytoplankton densities were concomitant with adequate levels of silicate (>2 µM) and high nitrate:silicate ratios (2.84–6.93). During this study, the numbers of genera of diatoms, dinoflagellates and cyanobacteria observed were 28, 12 and 3, respectively. The Shannon–Wiener, equitability and evenness indices showed high diversity values for diatoms and cyanobacteria prior to the rainfall events and for dinoflagellates after the events. The chlorophyll a content, relative electron transport rate, and estimated productivity of microphytoplankton increased during and after the rainy periods. TMPD and chlorophyll a were correlated significantly and positively with nutrients, salinity and temperature. Toxic algal species such as the dinoflagellates Alexandrium, Dinophysis and Tripos were recorded, although not in bloom densities. These findings indicate that rainfall-driven nutrient loading led to an increase in microphytoplankton density and estimated productivity, and a change in its diversity.

EVALUATION STUDY OF FLOOD DISASTERS IN KELAPA GADING

Kelapa Gading is one of the sub-districts in North Jakarta that is often hit by floods, so it is necessary to analyze the causes of flooding and how to overcome them. According to the calculations performed using the Manning Formula, whose results then compared with the planned discharge calculated using the Rational Method, it is established that there are 18 channels from 33 drainage channels which are unable to accommodate runoff discharge that may occur within a 5-year period. Thus, for a period of 10 years, there are 20 channels that are unable to accommodate the existing runoff discharge. Furthermore, from 10 Pumping Stations in a ten years rainy period, there are four pumps that are unable to accommodate runoff discharge with the assumption of 0.2 m inundation. Meanwhile, assuming a 0.5 m inundation, there are seven pumps that cannot accommodate the existing runoff discharge. Therefore, suggestions that can be given to reduce flooding in Kelapa Gading are to enlarge the existing drainage channel and add pumps according to the recommendations. Lack of land infiltration also causes flooding therefore, it is necessary to build 617infiltration wells which are constructed at various points in Kelapa Gading thus making flooding does not occur again.

Temporal analysis of desertification vulnerability in Northeast Brazil using Google Earth Engine

AbstractIntensive agricultural production has negative environmental impacts, increasing predisposition to desertification in areas with inadequate soil management. To evaluate the effects of agriculture, we aimed to perform a temporal analysis and analyze the development of desertification in Northeast Brazil. Initially, the region was separated into four climatic zones, grouping the locations with similar characteristics of air temperature and rainfall. In the analyses, images of the northeast region acquired from the Landsat 5 (1989, 1999, and 2009) and Landsat 8 (2019) satellites were processed using the Google Earth Engine platform. The periods were separated into dry and rainy periods, according to the climatic zones. The evaluation of vegetation index, characterization of the remaining vegetation cover, landscape pattern, and meteorological conditions were performed, respectively, through the Normalized Difference Vegetation Index, Modified Soil‐Adjusted Vegetation Index, and albedo of the terrestrial surface. The desertification index showed an increase in susceptible areas when comparing the interval from 1989 to 2019. In general, our results showed that there is less predisposition for desertification to occur during the rainy season. Also, when the results of our study were compared to official data released by the National Program of Action to Combat Desertification and Mitigate the Effects of Drought, there was disagreement regarding the classification of areas.

Occurrence and distribution of microplastics in wastewater treatment plant in a tropical region of China

Wastewater Treatment Plants (WWTPs) are one of the main contributors to microplastics (MPs) in the environment. However, most of the current studies only reported the occurrence of MPs in WWTPs and rarely focused on the transfer and removal of MPs at each process unit. This work explores the MPs removal efficiency of a tropical urban WWTP during dry and rainy periods. The sewage and sludge samples were collected and analyzed to measure the MPs characteristics using a stereo-microscope and μ-FTIR techniques. Results showed the secondary treatment step eliminated most of the MPs, with an average concentration of 12.98 n/L in the effluent, indicating a 94.09% of total MPs removal rate. Throughout the sewage treatment stage, the most common MPs were black, small in size (25–380 mm), and identified as fibers. Moreover, the concentration of MPs in the effluent was higher in the rainy period compared to the dry period and some control strategies for MPs pollution in WWTPs are offered according to the results of this study.

Improving GSMaP V06 precipitation products over the Upper Tocantins River basin in the Brazilian Cerrado, based on local rain-gauge network

Gridded precipitation products from remote sensing are currently available and could potentially enhance the use of precipitation data in regions with sparse network of ground rain gauges. Thus, this study aimed to evaluate the performance and propose correction models for Global Satellite Mapping of Precipitation (GSMaP) use in the Upper Tocantins River basin, a key area for food and electricity production in central Brazil, but with sparse network of ground rain gauges, challenging water resources and agriculture decision makers. GSMaP data were compared with data from a rain gauge network between 2000 and 2019. Evaluations were made at daily and monthly temporal scales. In general, GSMaP products show an overestimate bias for drizzle (0.1 ~ 1 mm day−1) and underestimate for rainfalls above 10 mm day−1. The use of monthly scale data significantly reduces the bias observed in the daily scale, but with an underestimation trend of -28.3% and -39.7% for the dry and rainy periods, respectively. Categorical indices showed that the GSMaP system had better hit rates for rain detection in the rainy season (October–April) than in the dry season (May–September). For the studied region, the use of GSMaP data on daily and monthly scales should be preceded by a bias analysis as a function of rain gauge network data. The use of bias coefficient corrected observed rainfall data underestimation on daily and monthly scales, improved correlation between GSMaP and observed rainfall data and reduced errors associated with rainfall network data within the basin influence area. The findings of this study indicate how decision makers could adjust and apply GSMaP products to estimate rainfall for water resources, agriculture and drought management challenges in the Upper Tocantins River basin.

Long-term precipitation events in the eastern part of the Baltic Sea region

Precipitation anomalies have a significant impact on both natural environmental and human activity. Long lasting drought analysis has received great attention on a global and regional scale while prolonged rainy periods so far have been much less studied. However, long-term precipitation events are also important and threatening. The situation around the Baltic Sea in 2017 revealed that such periods could cause significant losses in agriculture.The rainy periods of 30, 60, and 90 consecutive days in a given year during which the maximum precipitation amount was recorded in the eastern part of the Baltic Sea region were analysed in this study. Daily precipitation amount data from the E-OBS gridded dataset was used. The investigation covered a period from 1950 to 2019. The changes in magnitude and timing of such rainy periods were evaluated.It was found that the annual precipitation in the eastern part of the Baltic Sea region increased significantly during the analysed period. Positive changes were observed throughout the year except during April and September. The amounts of precipitation during rainy periods of different duration also increased in most of the investigated areas but changes were mostly insignificant. Consequently, a decrease in the ratio of precipitation amount during the rainy period to annual precipitation was observed. It was also found that the rainy periods occurred earlier, especially in the case of the rainy periods of 60- and 90-days durations. Such tendencies pose an increasing threat to agriculture.

Spatiotemporal evaluation of organochlorine pesticide residues in bottom sediments of the Rio de Ondas hydrographic basin, western Bahia, Brazil.

The Rio de Ondas Hydrographic Basin (ROHB), Bahia state, Brazil, is located in a region with abundant water resources and is highly impacted by intense agricultural activity. In such a scenario, the use of organochlorine pesticides can represent a potential risk to the aquatic environments, due to their persistence, high bioaccumulation capacity, and high toxicity. Thus, organochlorine pesticide residues in bottom sediment samples from rivers on eighteen sites distributed along the ROHB in the dry and rainy periods were analyzed by gas chromatography coupled with mass spectrometry. The validated method showed no matrix effect, recoveries ranging from 82% (β-HCB) to 118% (DDD), limits of detection between 0.003ngg-1 (α-HCH) and 0.011ngg-1 (DDT), limits of quantification of 0.010ngg-1 (α-HCH) to 0.036ngg-1 (DDT), repeatability with the highest relative standard deviation of 0.97% (α-hexachlorocyclohexane at 2.000ngg-1), and inter-day precision ranging from 10% (aldrin at 0.050ngg-1 and 0.600ngg-1 and α-endosulfan at 0.600ngg-1) to 25% (β-endosulfan at 0.050ngg-1). Although most compounds were banned since 1985, it was observed that their residues were widely distributed in the ROHB, with the total concentrations varying from 3.242ngg-1 (P02) to 12.052ngg-1 (P17) and from 0.313ngg-1 (P14) to 30.861ngg-1 (P13) in the dry and rainy periods, respectively, which may be related to historical contamination and/or prohibited use. Moreover, the spatiotemporal variation showed the highest concentrations of organochlorine pesticide residues in the rainy season, coinciding with the planting period.

Avaliação das Mudanças Climáticas Usando o índice de Humidade da Classificação Climática Thornthwaite no Bioma Pantanal

Abstract Thornthwaite climate classification indices are essential to interpret climate types in the state of the pantanal biome (Mato Grosso do Sul), simplifying calculation process and interpretation of climatological water balance by farmers. However, there are few studies found in the literature that characterize the climate of pantanel biome in different climatic scenarios. We seek to assess climate change using humidity index of Thornthwaite climate classification in pantanal biome. We used historical series of climate data from all 79 municipalities of Mato Grosso do Sul between 1987 and 2017, which were divided into microregions. Air temperature and precipitation were collected on a daily scale. Precipitation and potential evapotranspiration data allowed calculating water balance by the Thornthwaite and Mather method. We characterized all locations as wet and dry using aridity indices proposed by Thornthwaite. The global climate model used was BCC-CSM 1.1 developed at the Beijing Climate Center (BCC) with a resolution of 125 x 125 km. We used the scenarios RCP-2.6, RCP-4, RCP-6 and RCP-8.5 for analyzing 21st century projections (2041-2060 and 2061-2080 periods). Maps were generated from climate indices of Mato Grosso do Sul using kriging interpolation method with spherical model, one neighbor, and 0.25° resolution. The microregions showed different patterns regarding water balance components and humidity index. Humidity index had a mean of 15.94. The prevailing climate in the state of Mato Grosso do Sul is C2 (moist subhumid). The state of Mato Grosso do Sul has two well-defined periods during the year: a dry and a rainy period. Three climate types predominate in Mato Grosso do Sul and, according to the Thornthwaite classification, are B1 (humid), C2 (moist subhumid), and C1 (dry subhumid). Water characterization in Mato Grosso do Sul showed 234.78 mm year−1 of water surplus, 80.8 mm year−1 of water deficit, and 1,114.8 mm year−1 of potential evapotranspiration. Water deficit and potential evapotranspiration decrease as latitude increases. The climatic projections show, in all scenarios, reduce the area classified as umida in the state (B1, B2 and B3), besides adding the dry subhumid class (C1). The Scenario RCP 8.5 in 2061 - 2080 is the most worrisome situation of all, because the state can undergo major changes, especially in the pantanal biome region.

Evapotranspiration, crop coefficient and water use efficiency of onion cultivated under different irrigation depths

ABSTRACT This study aimed to determine crop evapotranspiration through the soil water balance, the crop coefficient and water use efficiency of the onion (Allium cepa L.) in a system with four irrigation regimes, cultivated in the semiarid region of northeastern Brazil. Two field experiments were carried out during the rainy and dry periods of the region in 2018, using the treatments of 100% (T1), 75% (T2), 50% (T3) and 25% (T4) of the reference evapotranspiration for daily water replacement and five replicates for each treatment. It was verified that crop evapotranspiration varies according to the water availability in the soil; however, the highest water use efficiency occurred for the T3 treatment. The T1 treatment obtained the highest estimated yield, 43.86 tons ha-1, while T4 obtained 13.47 tons ha-1, the lowest estimated yield among the treatments, and this difference was statistically significant (p ≤ 0.05) by F test. The crop coefficients obtained were 0.68, 0.89, 0.99 and 0.73 for the initial, vegetative, bulbing and maturation stages, respectively.

Short-term rainfall limits cyanobacterial bloom formation in a shallow eutrophic subtropical urban reservoir in warm season

The global increase in dominance of toxic blooms of cyanobacteria has severely impacted aquatic ecosystems and threatened human health for decades. Although it has been shown that high levels of rainfall may inhibit the growth of bloom-forming cyanobacteria, it is still unclear how cyanobacteria respond to short-term rainfall events. Based on five-year (2016–2020) high-frequency (half-week) sampling data from a shallow eutrophic urban reservoir in subtropical China, we explored the short-term effects of rainfall events on cyanobacterial biomass (CBB) by constructing generalized additive models of CBB in rainy periods during warm (April to September) and cool (December and January) months, respectively. We find evidence in support of the hypotheses that short-term rainfall events significantly reduce CBB in warm months, but the opposite response was observed in the cool months. We also highlight a difference in the factors explaining CBB decreases in warm months (precipitation, air temperature, relative humidity, dissolved oxygen and total phosphorus) compared with factors explaining the response of CBB in cool months (sunshine hours, pH and total carbon). In particular, meteorological factors (precipitation, wind speed and sunlight) might drive changes in water temperature and hydro-dynamics of the reservoir, thereby causing a rapid reduction of CBB after rainfall events in warm months. This varying response of cyanobacteria to short-term rainfall events in the shallow eutrophic subtropical reservoir may also be expected in temperate or cool lakes as climate change effects become stronger.

Influence of seasonality on wing morphological variability in populations of Mansonia amazonensis (Theobald) (Diptera: Culicidae).

Mansonia amazonensis (Theobald, 1901) is one of 15 species of the subgenus Mansonia Blanchard, 1901. It is essentially a Neotropical species, recorded in Bolivia, Peru and Brazil. In the highly seasonal Amazon region, Mansonia species find ideal environmental conditions for reproduction, development and establishment. Considering that climate significantly influences the size and behavior of mosquitoes, and insects in general, we analyzed the influence of seasonality on wing morphological variability in populations of Ma. amazonensis. Captures were carried out near the banks of the Madeira River in Rondnia State, Brazil during the dry, rainy and transition periods between seasons during 2018 and 2019. Morphometric characters of 181 wings were analyzed using morphological methods. The results show that wing size of Ma. amazonensis increases following a relatively gradual trend, from smaller wings during the dry period to larger ones in the rainy season. This study provides the first evidence, detected using geometric morphometry, of seasonally associated phenotypic variability in the wing conformation of Ma. amazonensis.

Identification of varied soil hydraulic properties in a seasonal tropical rainforest

In forest areas, seasonal ecosystem changes may affect soil hydraulic properties and ultimately alter the pattern of soil moisture dynamics. A National Ecological Station in a tropical rainforest of Xishuangbanna located in southern China collected in-situ measurements of meteorological forcing, soil moisture content, litterfall, leaf area index (LAI), and water and carbon flux from 2003 to 2008, which provided an ideal dataset for a detailed investigation on how the soil hydraulic properties would vary in response to seasonal ecosystem changes. Methodologically, the Marquardt Levenberg optimization algorithm was integrated in an unsaturated flow model to inversely estimate the soil hydraulic parameters based on unvaried, seasonally varied, and monthly varied parameterization strategies, respectively. The results indicated that the simulated soil moisture using seasonally varied and monthly varied parameters were more accurate than that with unvaried parameters. Moreover, the statistical analysis of monthly varied soil hydraulic parameters suggested that the temporal variations in soil hydraulic properties were tightly related to the seasonal ecosystem changes in terms of LAI, litterfall, and heterotrophic respiration. In deciduous periods, a significant reduction of LAI was accompanied with abundant litterfall that replenished organic matter to the topsoil. In contrast, during the hot rainy periods, the high heterotrophic respiration rate indicated that the soil organic matter underwent intensive decomposition under the condition of high air temperature and wet soil moisture– leading to strong seasonal cycles in soil hydraulic properties. The seasonal ecosystem change led to a significant increase in saturated hydraulic conductivity Ks from less than 100 cm/day in hot rainy season to over 150 cm/day in cool dry season. Moreover, the inversely estimated soil hydraulic parameters of saturated water content θs and field capacity θf at the topsoil layer were also featured with clear seasonal cycles (ranging from 0.32 to 0.42 and 0.23 to 0.27 respectively). In comparison with unvaried soil hydraulic parameter, inclusion of varied soil hydraulic properties provided more accurate simulations of soil moisture dynamics, which in turn, benefited the hydro-ecological modeling in vegetated areas.

Distribution of physical and chemical variables in the water column and characterization of the bottom sediment in a macrotidal estuary on the Amazon coast of the state of Maranhão, Brazil

The objective of this research was to characterize the distribution of dissolved nutrients at six sampling stations in the estuary of the Anil River (ARE) and characterize the bottom sediment. The study area is influenced by a tropical climate and semidiurnal macrotidal regime. Sampling of the surface water and sediment was performed in the main channel at six sampling stations distributed along the estuary in the rainy period (May 9th) and dry period (October 5th) during the spring. Physical variables were collected with the aid of a HANNA HI-8424 multi-parameter probe (water temperature, salinity, pH, dissolved oxygen, and turbidity) and YSI CTD (conductivity, temperature, and depth) probe. A van Veen dredge was used for the collection of bottom sediment from the main channel. The sedimentological results were heterogeneous. Grain size ranged from very fine to medium sand. Dissolved nutrients in the ARE had different sources depending on the season. Continental and fluvial inputs, evidenced by salinity values, governed the distribution of nutrients in the rainy period (January to June), whereas nutrient concentrations were related to the recycling of organic material in the estuary in the dry season (July to December). The considerable presence of sand in the main channel indicates that the sediments available in ARE are exposed to intense hydrodynamics. The distribution of nutrients and the grain size revealed the occurrence of different sources in the estuary according to the rainfall regime and the intense hydrodynamics of tidal currents (semidiurnal macrotidal).
 Keywords: dissolved nutrients, estuarine environment, sedimentology.

The influence of protected fat in supplements on the performance and carcass characteristics of Nellore beef bulls in tropical pasture.

The finishing stages for uncastrated Nellore beef cattle on tropical pasture often produce high yielding carcasses with minimal fat cover. This study aimed to evaluate the performance and carcass characteristics of uncastrated Nellore beef bulls fed a diet containing rumen-protected fat during the rainy period for 210days. Eighty Nellore beef bulls with 28months of age, and an initial live weight of 416kg ± 16kg, were allocated into eight paddocks (7.0ha), totaling 56ha, at 10 animals/paddock, in a continuous-grazing system. The pasture characteristics, performance production, loin-eye area (cm2), subcutaneous fat thickness (mm), and rump fat thickness were evaluated. There was no effect (P > 0.05) on the average total weight gain (203.00kg) and average daily gain (0.98kg/day). On the other hand, the subcutaneous fat thickness and rump fat thickness were 42.8% and 49.5% greater, respectively, when the animals were fed a diet containing rumen-protected fat inclusion (P < 0.05). Supplementation with rumen-protected fat provided a thicker fat layer in the carcass of Nellore beef bulls grazing on tropical pasture during the rainy period.

Metagenomics indicate that public health risk may be higher from flooding following dry versus rainy periods.

Urban floodwater could lead to significant risk for public and environmental health from mobilization of microbial pathogens and overflow of wastewater treatment systems. Here, we attempted to assess this risk by obtaining metagenomic profiles of antibiotic resistance genes (ARGs), virulence factors (VFs) and pathogens present in floodwater samples collected in urban Atlanta, GA that were categorized in two distinct groups: floods that occurred after periods of drought and those after regular (seasonal) rain events. Even though no major (known) pathogens were present at the limit of detection of our sequencing effort (~3 Gbp/sample), we observed that floodwaters after drought showed a 2.5-fold higher abundance of both ARGs and VFs compared to floodwater after rainy days. These differences were mainly derived by several novel species of the Pseudomonas genus, which were more dominant in the former versus the latter samples and carried several genes to cope with osmotic stress in addition to ARGs and VFs. These results revealed that there are previously undescribed species that become mobilized after flooding events in the Southeast US urban settings and could represent an increased public health risk, especially after periods of drought, which warrants further attention.