Tropical Freshwater Research Articles

Ecotoxicological assessment of synthetic and biogenic surfactants using freshwater cladoceran species

Surfactants have been continuously detected within aquatic environments as a consequence of their use on a global scale. Lipopeptides are biosurfactants naturally produced by Bacillus subtilis that have been explored as green alternatives. The assessment of ecotoxicological parameters of synthetic and biogenic surfactants are required for evaluating toxicity values and to verify the eco-friendly behaviour of the biological compounds. This study aimed to conduct toxicity testing for different surfactants – sodium dodecyl sulphate and Triton X-100 - and biosurfactants – surfactin, iturin and fengycin - at different concentrations using Daphnia magna as model organism and Dendrocephalus brasiliensis as alternative test species for monitoring of pollutants in tropical freshwaters. According results, both species showed high sensitivity for the anionic compound SDS concerning the recommended dosage use, exhibiting EC50–48h values of 24.1 and 15.4 mg/L for D. magna and D. brasiliensis, respectively. Although the biological source, surfactin showed the lower safety behaviour among the biogenic surfactants, while iturin and fengycin revealed very low toxicity effects on both organisms. Besides, data exhibited a higher responsiveness of D. brasiliensis for all tested compounds in comparison to D. magna, highlighting the importance of this species for monitoring of pollutants in tropical and subtropical environments.

Perceptions and Attitudes of Urucum Settlement Residents about Local Wildlife

ABSTRACTThis study aimed to evaluate perceptions and attitudes of local people about wild fauna and was carried out in the Urucum settlement, in the Brazilian Pantanal. We sought to: (1) identify which species of wild animals were most frequently chosen by residents of the Urucum settlement based on their familiarity; (2) identify the values associated with this fauna and the implications for conservation; and (3) test the effect of gender, age, and level of education of the residents on their attitudes. We used a structured questionnaire with open and closed questions to interview the residents. Distributions of responses about perceptions were analyzed using the chi-square test, and differences between the values associated with each species were analyzed using the Kruskal-Wallis test. The effect of gender, age, and level of education on attitudes toward the most chosen species was tested using generalized linear models (GLM). Among 61 residents interviewed, we found that the nine-banded armadillo (Dasypus novemcinctus), toucan (Ramphastos toco), monk parakeet (Myiopsitta monachus), rhea (Rhea Americana), and rattlesnake (Crotalus durissus) were the most frequently chosen species. These species were followed by tropical freshwater fish (a fish of the genus Astyanax sp.) and the blue morpho butterfly (Morpho sp.), both chosen with equal frequency. Most perceptions and attitudes were positive apart from those for the rattlesnake. Attitudes toward the rattlesnake were associated with the age of respondents, and the most common value associated with conserving the selected animals was “Anthropocentric.” As demonstrated by other studies, contact with environmental education activities could help to promote tolerance to rattlesnakes. Likewise, this tool can also broaden our understanding of the ecological importance of wild species, facilitating their conservation.

The complete mitochondrial genome of Hemibagrus spilopterus (Teleostei: Siluriformes)

Hemibagrus spilopterus is a tropical freshwater fish with high nutritional value. Here, we present the complete mitogenome of H. spilopterus. It was a circular molecule with 16,521 bp in length and contained 22 tRNA genes, 13 protein-coding genes, 2 rRNA genes, and a control region. The overall base composition was 31.68% A, 26.55% T, 26.77% C, and 15.01% G, with an AT content of 58.23%. The phylogenetic analysis showed that it was closely related to Hemibagrus sp. RCH and the genus Hemibagrus was not a monophyletic group.

Rethinking resting eggs decapsulating

Abstract Aim Temperature and light have been recognized as important factors for ephippia hatching in temperate and tropical freshwater systems. Oddly some authors suggested that decapsulation of resting eggs would be a pro when it comes to ex situ hatching studies, exposing those eggs to a greater amount of light. This study aimed to compare the difference in the hatching rate between resting eggs decapsulated and intact ephippia of Daphnia laevis, a zooplankton that occurs at lakes, in tropical freshwaters (Cladocera). Methods The ephippia used in this work were collected at the sediment of a reservoir, in Belo Horizonte city (Minas Gerais, Brazil). We set up the laboratory experiment with two distinct groups: intact ephippia and decapsulated resting eggs. For that, we manually decapsulated 120 ephippia and kept 120 others intact (six replicas with 20 ephippia each), then incubated them all with culture water at 22ºC (12h photoperiod) for 30 days with daily monitoring. Results The results showed that decapsulation influenced negatively the hatching success, as the intact ephippia had a hatching rate of 22%, while those decapsulated only had 6%. In addition, Daphnia hatchlings were observed for intact ephippia group up to the twenty-seventh day, while for the decapsulated the last hatching occurred on the tenth day. Decapsulated eggs are subject to high exposure to light and it may jeopardize the embryo development. Conclusions In this context, we suggest that removing the protective capsule from the eggs needs to be done with caution, since in some species this can damage the resting eggs, which alters the viability and compromise the accuracy of the hatching rates studies.

The challenge of restoring tropical freshwater ecosystems

Abstract We are living a growing worldwide process of degrading the bases of sustaining life. In Brazil, this threat is intensified by the growing fragility of environmental protection structures. Ecological restoration is an alternative to face the degradation of aquatic environments. It has been employed on a larger scale in the developed regions of the planet, but with little convincing results. In Brazil, the experiences are few and specific, limited mainly by complexity and costs. It is necessary to think in a more agile way and act within the possibilities. The restoration with its classic strategies should give way to an “urgent restoration”. This approach considers that we have the basic ecological information and professionals able to act in the resumption of control of the ecological processes that have been altered. Restoration in the condition of urgency implies beginning to think of protection, as a first step, turning attention to the management of the watershed. The way to regain control of the process where it was lost is the integrated management that involves the rational use and protection of the ecosystem. Brazil’s commitment to the Paris climate agreement to restore 12 million hectares of forests and the restoration liabilities on private properties because of the recent Native Vegetation Protection Law are excellent opportunities to act in the integrated management of the river basin and to promote the protection of freshwaters by the restoration of native forests. The restoration of tropical freshwaters and especially the Brazilian ones is something urgent. However, possible solutions must be thought of and can only be constructed when one get involved most people related to the issue. The idea to be nurtured is that restoration involves thinking about the watershed because the threats are beyond the aquatic environment itself, the restoration then also needs to go beyond the aquatic environment itself.

Efek Penambahan Vitamin C Terhadap Laju Pertumbuhan Spesifik Ikan Pelangi Merah (Glossolepsis incisus Weber)

Ikan pelangi merah (Glossolepsis incisus Weber) merupakan salah satu ikan hias tropis di perairan tawar Indonesia yang bernilai ekonomis tinggi. Akan tetapi laju pertumbuhan yang sangat lambat menyebabkan ikan ini jarang ada di pasar. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh penambahan vitamin C terhadap laju pertumbuhan spesifk ikan ini. Metode penelitian yang digunakan adalah metode eksperimen dengan 5 perlakuan dan 2 ulangan pada ikan ukuran 2 cm dan 6 cm. Dosis vitmin C yang digunakan yaitu 0 mg/kg pakan, 500 mg/kg pakan, 1000 mg/kg pakan, 1500 mg/kg akan dan 2000 mg/kg pakan. Hasil penelitian menunjukkan bahwa penambahan vitamin C sangat mempengaruhi SGR dan FCR serta berpengaruh nyata terhadap pH dan DO media namun tidak berpengaruh nyata terhadap SR dan Suhu. Hubungan vitamin C dengan SGR dan FCR adalah kuadratik dan diperoleh dosis terbaik dengan penambahan vtamin C sebesar 1666mg/kg pakan pada ukuran 2 cm dan dosis 1111 mg/kg pakan pada ukuran 6 cm. Peningkatan SGR dipengaruhi oleh meningkatnya dosisvitamn C demikian pula nilai FCR, namun akan terjadi penurunan SGR dan FCR jika vitamin C yang dibutuhkan berlebihan atau tidak sesuai.

Pollution menacing Lake Victoria: Quantification of point sources around Jinja Town, Uganda

Lake Victoria is Africa's largest tropical freshwater lake, important as a source of drinking water and as a source of food for the population in the surrounding region. Due to increased human activities in agriculture and industry during the past decades a continuously increasing inflow of agricultural runoff has been observed, and lately there have also been increased discharges of municipal effluents and industrial wastewater into Lake Victoria. This paper summarises the results of a one-year (1997 to 1998) environmental and ecological study of industrial wastewater point sources in the Jinja (Uganda) catchment area. Main industries concern food processing, textile, leather and paper production and metallurgy. One fish- filleting factory showed the highest annual nutrient loads with 0.13 t NO3-N, 0.20 t NH4-N and 0.77 t PO4-P, while another disposed of annual loads that amounted to 0.10 t NH4-N and 0.49 t PO4-P. From food-processing industries, the highest annual load of organic matter (COD) discharged to the lake amounted to 36.8 t. A tannery in Jinja released effluent with an extremely high mean concentration of the very toxic chromium+6 of 264 mg·l-1, which results in an estimated annual load of 2.2 t of Cr+6. Concentrations of nitrogen and phosphorus from fish-filleting industries and chromium+6 from the tannery were far above the allowed effluent limits in Uganda, leading to enhanced eutrophication and bioaccumulation of Cr+6 in Napoleon Gulf, Lake Victoria. The study provides information on point sources of effluent derived from Jinja's industrial sector in an effort to force resource users to move towards a more sustainable pattern of environmental management. The most appropriate way to reduce the ongoing eutrophication and pollution of Lake Victoria would be to reduce the releases of nitrogen, phosphorus, organic compounds and chromium into Napoleon Gulf by on-site pretreatment, so that they remain within non-critical levels. Industries must be required to monitor their effluents before these are discharged into Kirinya National Water and Sewerage Corporation oxidation ponds and finally into Kirinya West urban wetlands.

Diet of Hemigrammus marginatus (Characiformes: Characidae) in the Upper Contas River, Diamantina Plateau (Bahia, Brazil)

ABSTRACT Studies on the composition of fish diet and on how species exploit food resources are especially relevant in tropical freshwater systems, where dietary plasticity is a commonly used strategy. In this study, we analysed the food spectrum and the environmental, seasonal and ontogenetic variations in the diet of a characid species [Hemigrammus marginatus Ellis, 1911 (Characidae)] in the region of the Upper Contas River, in the Diamantina Plateau, Brazil. We verified an omnivorous/invertivorous and opportunistic food habit, with predominance of insects and microcrustaceans, followed by filamentous algae. Seasonality did not alter the food resources used by the species. However, differences were detected in the dominant categories when comparing the two sampled rivers, as well as in the food consumption throughout the development of the species. These data increase the knowledge about the biology of H. marginatus and allow understanding the influence of the characteristics of the rivers and their surroundings in the trophic ecology of the species, as our findings have shown that, although insects have been expressive in both studied localities, microcrustaceans exhibit a greater relative importance in the more lentic environment, which is probably related to the variation in the availability of these resources in the environment.

Occurrence and distribution of viruses and picoplankton in tropical freshwater bodies determined by flow cytometry

This study aimed to examine the drivers in shaping the occurrence and distribution of total viruses and picoplankton in tropical freshwater ecosystems. Flow cytometry was used to quantify the concentrations of total viruses, picoheterotrophs, picophytoplankton, and picocyanobacteria. Three land use patterns (urban-, agriculture- and parkland-dominated) were evaluated using ArcGIS. Significant correlations were observed between water-borne microbial targets and water quality parameters (0.175 ≤ |r| ≤ 0.441), nutrients (0.250 ≤ r ≤ 0.570) and land use factors (0.200 ≤ |r| ≤ 0.460). In particular, the concentrations of total viruses and picoheterotrophic cells were higher in catchments whereas the abundances of picophytoplankton and picocyanobacteria were higher in reservoirs. Total viruses and picoplankton had higher concentrations in urban- and agriculture-dominated areas, probably due to anthropogenic inputs and agricultural inputs, respectively. Although surface water is a complex matrix influenced by niche-based (i.e., physicochemical properties, nutrients, land use impact etc.) and neutral-based factors (i.e., ecological drift, dispersal and species), land use patterns could help to elucidate the occurrence and distribution of the total microbial community at the macroscopic level. Meanwhile, inter-correlations among viruses, picoplankton and picoheterotrophs (0.715 ≤ r ≤ 0.990) also substantiates their mutual interactions in influencing the microbial community. Furthermore, the relationships between total microbial cells and bacterial and viral indicators were also investigated. Concentrations of total viruses, picoplankton and picoheterotrophs were positively correlated with bacterial indicators (0.427 ≤ r ≤ 0.590) and viral indicators (0.201 ≤ r ≤ 0.563). These results indicated that faecal and viral contamination could contribute to the numbers of total viruses and bacteria.

The complex study of complexes: The first well-supported phylogeny of two species complexes within genus Caridina (Decapoda: Caridea: Atyidae) sheds light on evolution, biogeography, and habitat

Atyid shrimps, a key component of tropical freshwater ecosystems, face multiple anthropogenic threats and thus need special attention. With more than 300 described species, the genus Caridina is the most speciose of all the Caridea infra-order. Caridina spp. occupy diverse habitats in tropical freshwaters of the Indo-West Pacific region. Several species complexes have been recognized, based on common morphological features, but little is known about how well these morphological characteristics align with phylogenetic characteristics. Furthermore, no phylogeny of the genus Caridina published so far has provided well-resolved and supported relationships among different species, thus impeding the possibility of proposing evolutionary hypotheses. In this study we used next generation sequencing (NGS) to provide new insights into the phylogenetic relationships among the genus Caridina, focusing on two complexes: ‘Caridina nilotica’ and ‘Caridina weberi’. We collected 92 specimens belonging to these two groups from most of their known geographical range, representing 50 species, for which we sequenced seven mitochondrial genes and two nuclear markers using ion torrent NGS. We performed a phylogenetic analysis, which yielded the first well-supported tree for the genus Caridina. On this tree were mapped the geographic ranges and the habitats used by the different species, and a time calibration was tested. We found the driving factors that most likely account for separation of clades are differences in habitat and to a lesser extent geography. This work provides new insights into the taxonomy of this group and identifies opportunities for further studies in order to fill knowledge gaps that currently impede the management and conservation of atyid species.

Grazing and growth rate of a cyclopoid copepod fed with a phytoplankton diet constituted by a filamentous cyanobacterium

Many tropical freshwaters experience persistent cyanobacterial blooms throughout the year. However, to date, most of the cyanobacteria–zooplankton interaction studies focused on temperate regions using large generalist grazers, which rarely coexist with cyanobacteria. Here a short-term (3 h) laboratory experiment was conducted to examine the grazing rate of Thermocyclops decipiens exposed to different combinations of phytoplankton (T1 = 100% Nitzschia-0% Cylindrospermopsis, T2 = 75% Nitzschia-25% Cylindrospermopsis, T3 = 50% Nitzschia-50% Cylindrospermopsis, T4 = 25% Nitzschia-75% Cylindrospermopsis and T5 = 0% Nitzschia-100% Cylindrospermopsis). In addition, an 8-day experiment was performed to determine the effect of the diet treatments on Thermocyclops survivorship and growth. The total biomass of phytoplankton in treatments with higher proportion of Nitzschia (i.e., T1 and T2) showed abrupt decline (i.e., down to 61% and 71%, respectively) over time when compared to other treatments. While Thermocyclops largely excluded Cylindrospermopsis when Nitzschia is abundant, they were capable of shortening the longer filaments of Cylindrospermopsis into significantly smaller fragments and ingesting them when provided as a sole food. This, however, negatively influenced their survivorship and growth. Our results generally suggest that dominantly occurring selective grazers in tropical and warmer-temperate lakes may shift the phytoplankton community composition to favor cyanobacteria by grazing on the alternative food source, at least before the cyanobacteria becomes dominant.

Mitochondrial Genetic Diversity of the Freshwater Snail Melanoides tuberculata.

According to geological history, Peninsular Malaysia and Borneo formed at different times and were once connected during Quaternary glaciations. To determine how this history has influenced phylogeography, our study examined the population genetic structure of the tropical freshwater gastropod Melanoides tuberculata across Peninsular Malaysia and Borneo using the sequences from mitochondrial DNA 16S rRNA and cytochrome oxidase subunit I genes (1168bp). In total, 104 specimens were collected from seventeen populations. All mtDNA haplotypes were identified as belonging to two highly divergent lineages, and these lineages were almost allopatric in their distributions. Our study found that the freshwater fauna in Malaysia might be divided into four regions: northeast Peninsular Malaysia, northwest Peninsular Malaysia, south Peninsular Malaysia, and Borneo. The phylogeography of M. tuberculata in Malaysia was shaped by the landforms of Peninsular Malaysia and by the paleo-river systems in the Sunda continental shelf. In addition, our study found that these two lineages in Malaysia have invaded the globe. These results suggest that Malaysia is located in important shipping lanes throughout the world, and the populations of M. tuberculate might be widely distributed throughout the world by shipping.

Integrating laboratory and field studies to assess impacts of discharge from a uranium mine and validate a water quality guideline value for magnesium.

Magnesium (Mg) is a primary contaminant in mine water discharges from the Ranger Uranium Mine (north Australia). Site-specific water quality guideline values (WQGVs) for Mg have been derived from laboratory and field studies. Contaminated groundwater with elevated electrical conductivity and metals (Mg, Mn, U, SO4 , and Ca) was detected flowing from the mine site into adjacent surface waters. This provided an opportunity to investigate the protectiveness of the Mg WQGV by conducting an integrated laboratory and field study. A direct toxicity assessment (DTA) of the groundwater was conducted with local tropical freshwater species: duckweed (Lemna aequinoctialis), green hydra (Hydra viridissima), and the aquatic snail Amerianna cumingi. An in situ toxicity assessment was carried out in the creek receiving diluted groundwater by use of the same species of snail, to aid interpretation of laboratory-derived data. The toxicity of the contaminated groundwater was higher than Mg-only toxicity testing for H. viridissima, with other elevated metals and major ions contributing to toxicity. However, for duckweed and snail, the contaminated groundwater was less toxic than the Mg-only testing. In situ snail monitoring supported laboratory exposures, showing no effect on reproduction of A. cumingi exposed to an average of approximately 5 mg/L Mg; however, a very small effect was noted closer to the groundwater source, probably associated with other contaminants. The minimal toxicity observed for L. aequinoctialis and A. cumingi, despite the elevated Mg, can be explained by the high calcium (Ca) concentration of the water and the potential amelioration of metal toxicity. The extent of Ca amelioration of Mg toxicity was organism dependent. This study affirms the proposed environmental rehabilitation standard of 3 mg/L Mg for surface waters with a Ca concentration typical of water from this mine site. Integr Environ Assess Manag 2019;15:64-76. © 2018 SETAC.

Transgenerational effects of cyanobacterial toxins on a tropical micro-crustacean Daphnia lumholtzi across three generations

Climate change and human activities induce an increased frequency and intensity of cyanobacterial blooms which could release toxins to aquatic ecosystems. Zooplankton communities belong to the first affected organisms, but in tropical freshwater ecosystems, this issue has yet been poorly investigated. We tested two questions (i) if the tropical Daphnia lumholtzi is capable to develop tolerance to an ecologically relevant concentration of purified microcystin-LR and microcystins from cyanobacterial extract transferable to F1 and F2 generations? And (ii) would F1 and F2 generations recover if reared in toxin-free medium? To answer these questions, we conducted two full factorial mutigenerational experiments, in which D. lumholtzi was exposed to MC-LR and cyanobacterial extract at the concentration of 1 μg L−1 microcystin continuously for three generations. After each generation, each treatment was spit into two: one reared in the control (toxin free) while the other continued in the respective exposure. Fitness-related traits including survival, maturity age, body length, and fecundity of each D. lumholtzi generation were quantified. Though there were only some weak negative effects of the toxins on the first generation (F0), we found strong direct, accumulated and carried-over impacts of the toxins on life history traits of D. lumholtzi on the F1 and F2, including reductions of survival, and reproduction. The maturity age and body length showed some inconsistent patterns between generations and need further investigations. The survival, maturity age (for extract), and body length (for MC-LR) were only recovered when offspring from toxin exposed mothers were raised in clean medium for two generations. Chronic exposure to long lasting blooms, even at low density, evidently reduces survival of D. lumholtzi in tropical lakes and reservoirs with ecological consequences.

Toxicity of copper oxide nanoparticles to Neotropical species Ceriodaphnia silvestrii and Hyphessobrycon eques

The increase of production and consumption of copper oxide nanostructures in several areas contributes to their release into aquatic ecosystems. Toxic effects of copper oxide nanoparticles (CuO NPs), in particular, on tropical aquatic organisms are still unknown, representing a risk for biota. In this study, the effects of rod-shaped CuO NPs on the Neotropical species Ceriodaphnia silvestrii and Hyphessobrycon eques were investigated. We also compared the toxicity of CuO NPs and CuCl2 on these species to investigate the contribution of particles and cupper ions to the CuO NPs toxicity. Considering the low copper ions release from CuO NPs (<1%), our results revealed that the toxicity of CuO NPs to C. silvestrii and H. eques was mainly induced by the NPs. The 48 h EC50 for C. silvestrii was 12.6 ± 0.7 μg Cu L−1 and for H. eques the 96 h LC50 was 211.4 ± 57.5 μg Cu L−1 of CuO NPs. There was significant decrease in reproduction, feeding inhibition and increase in reactive oxidative species (ROS) generation in C. silvestrii exposed to CuO NPs. In fish H. eques, sublethal exposure to CuO NPs caused an increase in ROS generation in gill cells and an increase in cells number that were in early apoptotic and necrotic stages. Our results showed that CuO NPs caused toxic effects to C. silvestrii and H. eques and ROS play an important role in the toxicity pathway observed. Data also indicated that C. silvestrii was among the most sensitive species for CuO NPs. Based on predicted environmental concentration in water bodies, CuO NPs pose potential ecological risks for C. silvestrii and H. eques and other tropical freshwater organisms.

Response surface methodology applied to tropical freshwater treatment

ABSTRACTThis paper presents the profits and disadvantages of the chemometrics approach instead of the one-factor-at-a-time (OFAT) coagulation diagram approach for tropical water physicochemical treatment. Central composite design associate to response surface methodology (CCD-RSM) is used to find the real best conditions for coagulant dosage and pH aiming at high-turbidity removal. The number of experiments needed to chemometrics model construction (12) is comparatively smaller than that used in the coagulation diagram (84), saving financial and environmental resources. Arguments for Water Treatment Plants (WTP) considering the replacement of coagulation diagram approach by the CCD-RSM approach in drinking water treatment are presented. Chemometrics models are all constructed on a free software platform, providing the best pH within the range 7.7–8.1, and the best coagulant dosage (polyaluminium chloride, PAC) between 2.0 and 3.1 mg Al2O3 L−1 (equivalent in mass). CCD-RSM provides a faster, lower-cost and more reliable alternative tool for WTP decision-making instead of the OFAT model, mainly for waters more affected by seasonal effects as can be seen in tropical and subtropical countries.

Carga de combustibles leñosos en humedales costeros de la Reserva de la Biosfera La Encrucijada, Chiapas, México

Introduction: The quantity and quality of forest fuels determine the frequency, intensity and impact of a fire. Despite the ecosystem services they provide, little is known about coastal wetlands such as mangroves and tropical freshwater forested wetlands. Objective: To determine the woody fuel load in wetlands of the La Encrucijada Biosphere Reserve (EBR). Materials and methods: Woody fuels were quantified in three sites where there is an association of mangroves and tropical freshwater forested wetlands. Four sampling units were established by vegetation type at each site. The planar intersect technique was adapted for this evaluation. The fuel load was quantified and compared by type of vegetation, site and diameter class of the woody material. Results and discussion: Tropical freshwater forested wetlands accumulated dead fuels in a range from 63.19 to 151.87 t·ha-1, while mangroves accumulated between 88.81 to 152.38 t·ha-1; the load difference was not statistically significant (F = 1.05; P = 0.31). Regarding the diameter class, the fine fuel loads (from 0.01 to 0.60 cm) were significantly different among the mangrove sites (F = 3.05; P = 0.04), and the medium fuels (from 2.51 to 7.50 cm) were different among the swamp sites (F = 9.93; P = 0.006). Conclusion: The quantification of forest fuels was possible in coastal wetlands, such as mangroves and tropical freshwater forested wetlands, finding loads up to three times higher than in other temperate zone ecosystems. The information obtained will support the prioritization of fire-prone areas.

Assessing the effects of Awba dam sediment (Nigeria) on the steroidogenesis of H295R cells using different extraction methods

In the present study, H295R human cells were used to investigate the endocrine disruptor potential of three different sediments extracts taken from a Nigerian tropical freshwater dam (Awba Dam), using three extraction methods that allowed a selective consideration of contaminants based on their binding affinity, which is mainly driven by polarity, to sediment particles. After exposure to different concentration of each extract, H295R cells were evaluated for the expression profiles of 10 steroidogenic enzyme genes and estradiol (E2) and testosterone (T) levels. Our results showed a comparable concentrated-related increase in the expression of 17β-hsd1, 3β-hsd2 and cyp21 in cells treated with the polar and non-polar extracts. The star, hmgr, cyp11b2 and 17β-hsd4 were slightly decreased, in an apparent concentration-specific manner, after treatment with the polar extract and decreased in the non-polar treatment. The cyp11a and cyp17 showed an opposite trend in the polar and non-polar treatments. E2 was significantly higher in cell treated with the non-polar extract. Elutriate exposure produced less pronounced variation in mRNA and hormones levels. Overall the extract with non-polar compounds produced the most severe effects in H295R cells. Thus, direct ingestion of detritus and mud from fishes and other benthonic organisms represent possible transfer of contaminants in the trophic web, and mainly account for alteration of the endocrine system previously observed in fish from the same study site.

Prevalence of Schistosoma haematobium and Its Intermediate Hosts in Makurdi Metropolis

Introduction: Urinary Schistosomiasis (US) is a chronic water-borne infection caused by digenetic trematode belonging to the genus schistosoma, it is generally caused by Schistosoma haematobium. Bulinus globosus is a species of a tropical freshwater snail that acts as an intermediate host of Schistosoma haematobium. Aim: The study was aimed at ascertaining the prevalence of Schistosoma haematobium infection and to describe its intermediate hosts among school children in Makurdi.&#x0D; Methodology: Snails were collected by hand picking and scooping net methods. An epidemiological survey research on urinary Schistosomiasis was undertaken from September to November 2017 among students that volunteered in the selected schools within Makurdi metropolis. A total of 97 freshwater snails were collected and 200 urine samples involving pupils aged between 5 to 18 years were collected and analyzed for the eggs of Schistosoma haematobium by microscopy using Urine Syringe Filtration Technique (USFT). Statistical analysis was performed using SPSS 20. Chi-square test was used to determine the significant difference between variables.&#x0D; Results: Out of the 97 species of freshwater snails that were caught 41(42.3%) was Bulinus spp. Of the 200 urine samples analyzed, 49(24.5%) were found to be infected with ova of S. haematobium. The infection was higher among males 30(25.6%) than females 19(22.9%) although the difference was not statistically significant (χ2CAL=0.19, χ2TAB=3.84). The prevalence of Schistosoma haematobium infection among school children in relation to age showed that ages 15-19 years had the highest prevalence 13(38.2%) and ages 5-9 had the lowest prevalence 3(8.5%). The statistical analysis also revealed that there is no significant difference (8.302) in Schistosoma haematobium infection among the four schools in the study area. The presence of many snail species especially the Bulinus spp and increased contact time with the Schistosoma haematobium infested freshwater habitat was thought to be responsible for the prevalence of the disease in the area. Finding of this study shows that urinary Schistosomiasis was found to have a low prevalence in the area studied and there is the need to intensified integrated control measures to reduce or completely eradicate the disease.

Short-term deleterious effects of standard isolation and cultivation methods on new tropical freshwater microalgae strains.

Algae with potential biotechnological applications in different industries are commonly isolated from the environment in order to obtain pure (axenic) stocks that can be safely stored for long periods of time. To obtain axenic cultures, antibiotics are frequently employed, and cryopreservation is applied to preserve standing stocks. However, many of these now standard methods were developed using strains derived from pristine to near-pristine environments and cold to temperate regions. The potential effect of the said methods on the life cycle and biochemical profile of algae isolates from hyper-eutrophic and constant high-temperature tropical regions is not well understood. These effects could potentially render them unsuitable for their intended biotechnological application. In this study, we conducted a genetic characterization (18S rRNA) and evaluated the effect of purification (the use of the antibiotic chloramphenicol, CAP) and cryopreservation (dimethyl sulfoxide; DMSO–sucrose mix and glycerol) on the growth rate and lipid content of three new tropical freshwater algal isolates: Chorella sp. M2, Chlorella sp. M6, and Scenedesmus sp. R3, obtained from the Ecuadorian coast. The genetic and morphological characterization revealed a clear discrimination between these strains. All strains cultured with CAP exhibited a lower growth rate. Subsequent to cryopreservation, Chorella sp. M2, Chlorella sp. M6, and Scenedesmus sp. R3 presented no significant difference in growth rate between the cryopreservants. Further, a significantly higher lipid content was observed in the biomass cryopreserved with glycerol in relation to the DMSO–sucrose, with Chorella sp. M2 and Chlorella sp. M6 having twice as much as they had in the first treatment. These results highlight the relevance of selecting an appropriate method for storage, as the materials used can affect the biological performance of different tropical species, although it is still to be determined if the effects observed in this study are long lasting in subsequent cultures of these algae.