Ecology of Aedes vittatus (Diptera: Culicidae) in rock pools across agroecosystem in Northern Savanna, Nigeria

Background & objectives: This study focuses on modulating dexterity of some ecological variables of Aedes vittatus classically breeding in rocky habitats. The study provides a useful insight into ecological variables that underpin or hinder profuse breeding of Ae. vittatus in rock pools and its probable role in disease transmission. Methods: HANNA HI98129 pH/EC/TDS/TEMP meter was used in situ while standard protocols were used to determine other hydro-chemical variables. Aedes vittatus larvae were obtained with soup ladle and modified ladle dippers. D-frame net was used to capture macroinvertebrates while plankton net was used to obtain samples of microalgae. Tadpoles and water turtles were collected with fine mesh invertebrate net. Macrophytes were uprooted and identified at the Herbarium Unit, Department of Botany, Ahmadu Bello University, Zaria. The influence of physicochemical variables was correlated with distribution of Ae. vittatus using Principal Component Analysis. Regression and ANOVA were used to test for association between predictor variables and mosquito abundance and for the difference amongst inselbergs. Results: Linear larval density of Ae. vittatus in rock pools which tapered across Guinea savanna were obtained from twenty-one sites with average density of 139.6 in Sudan savanna. Guinea savanna had an average larval density of 75.5 with lower subsets of moving average densities compared to Sudan savanna. One hundred and sixty-one aquatic insects belonging to four insect orders cohabited rock pools with Ae. vittatus. Toads and frogs’ tadpoles were of Bufonidae and Pyxicephalidae families while water turtles belong to Emydidae. pH, TDS (ppm), EC (µs/cm) and alkalinity (mg/l) differed significantly (p<0.05) with the abundance of Ae. vittatus in rock pools. Temperature, depth, water hardness and total suspended solid had direct influence on the distribution of Ae. vittatus in rock pools across sites. Significant positive correlation exists between aquatic insects and abundance of Ae. vittatus. Hydroperiod length, concentration of nitrate and pH were determinants that leverage profuse breeding of Ae. vittatus and survival of rock pool biota. Interpretation & conclusion: Results revealed that the bearing influence of rock pool variables is inevitable for breeding of Ae. vittatus. A well defined measure of efficacy incorporating indigenous communities for sustained vector control on inselbergs will go a long way in decimating population of Ae. vittatus and limit the risk of spread of yellow fever hitherto areas not thriving.

Comparative reservoir limnology in Juramento (Salta) and Salí-Dulce (Tucumán) Basins in Argentina / Limnología comparada de los embalses de las cuencas de Juramento (Salta) y Salí-Dulce (Tucumán) en Argentina

Abstract The reservoirs of the upper Juramento basin (Cabra Corral and El Tunal) and the Salí-Dulce basin (El Cadillal, Río Hondo, and Escaba) show certain peculiarities due to their geographical location, basin morphology and limnological features. Such peculiarities were compared during significant algal bloom periods between 2002 and 2008, by analyzing the main physicochemical parameters and ecological attributes of the phytoplankton assemblages using standard methods. Tucumán reservoirs were different in most variables showing higher values of conductivity, nutrients and algal biomass. Regarding the hydrological cycle, El Cadillal exhibited the lowest biomass average (2.74 mg Chl.m-3) during maximum water flows, whereas the Cabra Corral lacustrine zone exhibited the highest biomass average (63.36 mg Chl.m-3) during minimum water flows. For the same period, the Cabra Corral lacustrine zone exhibited lower phytoplankton diversity and richness (1.37 and 9, respectively), in accordance with dinophyte blooms of Ceratium sp. In all reservoirs, the following biological variables showed a significant contrast in the hydrological cycle: highest phytoplankton biomass during minimum water flows (35.68 mg Chl-a m-3) vs. waterfloods (13.68 mg Chl-a m-3) (T = 3.42, P = 0.001). During minimum water flows, richness (14.30 sp.) and equitability (0.51) were lower vs. waterfloods (20.23, 0.59, respectively) (T = 2.36; P = 0.0196), as a result of the allochthonous nutrients provided by the main tributaries. Management of the reservoirs' hydrometric levels during dry season determines the deterioration of the water quality with increased algal blooms. In order to ensure the systems' sustainability, eutrophication must be controlled with programs to reduce diffuse nutrient loads and to treat residential and agroindustrial effluents, particularly in Sali-Dulce basin. Rev. Biol. Trop. 66(1): 415-427. Epub 2018 March 01.

Resumen Los embalses de la Alta Cuenca del Juramento (Cabra Corral y El Tunal) y del Salí-Dulce (El Cadillal, Río Hondo y Escaba) por su ubicación geográfica, morfología y características limnológicas muestran ciertas peculiaridades que son comparadas en el período relevante de proliferaciones algales acaecidas entre 2002 y 2008, mediante análisis de los principales parámetros fisicoquímicos y atributos ecológicos de los ensambles del fitoplancton por empleo de técnicas estandarizadas. Los embalses de Tucumán se diferenciaron en la mayoría de las variables con valores más elevados de conductividad, nutrientes y biomasa de algas. En función del ciclo hidrológico, El Cadillal en aguas altas presentó el promedio más bajo de biomasa (2.74 mg Cl.m-3) y en contraste Cabra Corral el más elevado (63.36 mgCl.m-3) durante los caudales mínimos de agua. En éste último, en el mismo período, también la diversidad y riqueza de especies del fitoplancton fueron menores (1.37 y 9 respectivamente), en concordancia con las proliferaciones de dinófitos (Ceratium sp.). Las siguientes variables biológicas en el conjunto de embalses presentaron un contraste significativo en el ciclo hidrológico: biomasa del fitoplancton más elevada en estiaje (35.68 mg Cl a. m-3) versus crecidas (13.68 mg Cl a. m-3) (T = 3.42; P = 0.001). En estiaje, la riqueza (14.30 sp) y equitatividad (0.51) fueron menores versus crecidas (20.23, 0.59, respectivamente) (T = 2.36; P = 0.0196), debido al aporte alóctono de nutrientes por los tributarios principales. El manejo de los niveles hidrométricos de los embalses durante el estiaje determina el deterioro de la calidad de sus aguas con incremento de proliferaciones algales. Para asegurar la sustentabilidad de los sistemas, es indispensable el control de la eutrofización mediante programas de reducción de cargas difusas de nutrientes y tratamiento de efluentes domiciliarios y agroindustriales, particularmente en la cuenca del Sali-Dulce.

Caracterización espacial y estacional del agua de consumo proveniente de diversas fuentes en una localidad periurbana de Salta / Spatial and seasonal characterization of the drinking water from various sources in a peri-urban town of Salta

El control del agua de consumo es importante, ya sea que esta provenga de sistemas de potabilización o que carezca de tratamiento previo. El acceso creciente a agua potabilizada ha sido monitorizado a lo largo de los últimos anos a fin de alcanzar los denominados «Objetivos de desarrollo del milenio¼, cuyo plazo se cumplió en 2015. De cara al futuro, los llamados «Objetivos de desarrollo sostenible¼, que se han propuesto para el año 2030, buscan garantizar el acceso a agua segura de toda la población mundial. En el marco de estas metas mundiales, es importante la monitorización de los sistemas locales. En este trabajo se estudió una población que cuenta con diferentes sistemas de provisión de agua de consumo, que incluyen o no el tratamiento de aquella. Se realizó la monitorización de todos los indicadores microbiológicos regidos por el Código Alimentario Argentino y de diversas variables fisicoquímicas, a fin de diferenciar los sitios de muestreo de acuerdo con la influencia de la estacionalidad, el tipo de fuente de provisión de agua y la correlación entre las variables microbiológicas y las fisicoquímicas. Se observó que el agua proveniente de fuentes con tratamiento presentó desviaciones en algunas de sus variables en época de lluvias, mientras que las fuentes sin tratamiento no cumplieron con los requerimientos bacteriológicos en forma permanente. Este estudio pone de manifiesto la importancia de reevaluar los sistemas de potabilización, que deberían garantizar su eficacia de manera constante, así como la inmediata necesidad de desarrollar nuevos sistemas de tratamiento para dar solución a la población que aún no cuenta con agua de consumo segura.

Drinking water monitoring plans are important to characterize both treated and untreated water used for drinking purposes. Access to drinking water increased in recent years as a response to the Millennium Development Goals set for 2015. The new Sustainable Development Goals aim to ensure universal access to safe drinking water by 2030. Within the framework of these global goals, it is crucial to monitor local drinking water systems. In this paper, treated and untreated water from different sources currently consumed in a specific town in Salta, northern Argentina, was thoroughly assessed. Monitoring extended along several seasons and included the physical, chemical and microbiological variables recommended by the Argentine Food Code. On the one hand, treated water mostly complies with these standards, with some non-compliances detected during the rainy season. Untreated water, on the other hand, never meets microbiological standards and is unfit for human consumption. Monitoring seems essential to detect anomalies and help guarantee a constant provision of safe drinking water. New treatment plants are urgently needed to expand the water grid to the entire population.

Influence of environmental parameters on fish assemblage of a neotropical river with a flood pulse regime, Central Brazil

This study aims to determine which of twelve environmental parameters (five physicochemical and seven hydromorphological) influence on the fish assemblage structure of the lower Mortes River basin located in the Bananal floodplain of the Araguaia River basin, Central Brazil. Sampling was conducted in six stretches of 1000 m each during the high and low waters. Fish were captured using gill nets and environmental parameters were measured by portable equipment or determined visually. The co-inertia analysis indicated that two physicochemical (dissolved oxygen and water transparency), and four hydromorphological (channel width and depth, riparian vegetation cover and type of the riverside substrate) parameters structure the fish assemblages, both driven by the regional hydrological patterns (flood pulse). These results are explained by fish-environmental parameters relationship characteristic of the aquatic Neotropical systems.(AU)

Este estudo determinou quais entre doze parâmetros ambientais (cinco físico-químicos e sete hidromorfológicos) influenciam na estrutura da assembleia de peixes do baixo rio das Mortes localizado na planície de inundação do Bananal, bacia do rio Araguaia, Brasil Central. As coletas foram realizadas em seis trechos de 1000 m cada durante os períodos de chuva e estiagem, nos quais 1036 peixes foram coletados utilizando-se redes de malhar e medidos os parâmetros ambientais utilizando equipamentos portáteis ou determinados visualmente. A análise de coinércia indicou que dois parâmetros físicos e químicos (oxigênio dissolvido e a transparência da água) e quatro hidromorfológicos (largura e profundidade da calha principal, cobertura da mata ripária e tipo de substrato da margem) estruturam a assembleia de peixes, ambos influenciados pelo regime hidrológico regional (pulso de inundação). Estes resultados são discutidos considerando a interação entre peixes e os parâmetros ambientais característicos dos sistemas aquáticos Neotropicais.(AU)