Wet Season Months Research Articles

Human population movement and behavioural patterns in malaria hotspots on the Thai\u2013Myanmar border: implications for malaria elimination

BackgroundMalaria is heterogeneously distributed across landscapes. Human population movement (HPM) could link sub-regions with varying levels of transmission, leading to the persistence of disease even in very low transmission settings. Malaria along the Thai–Myanmar border has been decreasing, but remains heterogeneous. This study aimed to measure HPM, associated predictors of travel, and HPM correlates of self-reported malaria among people living within malaria hotspots.Methods526 individuals from 279 households in two malaria hotspot areas were included in a prospective observational study. A baseline cross-sectional study was conducted at the beginning, recording both individual- and household-level characteristics. Individual movement and travel patterns were repeatedly observed over one dry season month (March) and one wet season month (May). Descriptive statistics, random effects logistic regressions, and logistic regressions were used to describe and determine associations between HPM patterns, individual-, household-factors, and self-reported malaria.ResultsTrips were more common in the dry season. Malaria risk was related to the number of days doing outdoor activities in the dry season, especially trips to Myanmar, to forest areas, and overnight trips. Trips to visit forest areas were more common among participants aged 20–39, males, individuals with low income, low education, and especially among individuals with forest-related occupations. Overnight trips were more common among males, and individual with forest-related occupations. Forty-five participants reported having confirmed malaria infection within the last year. The main place of malaria blood examination and treatment was malaria post and malaria clinic, with participants usually waiting for 2–3 days from onset fever to seeking diagnosis. Individuals using bed nets, living in houses with elevated floors, and houses that received indoor residual spraying in the last year were less likely to report malaria infection.ConclusionAn understanding of HPM and concurrent malaria dynamics is important for consideration of targeted public health interventions. Furthermore, diagnosis and treatment centres must be capable of quickly diagnosing and treating infections regardless of HPM. Coverage of diagnosis and treatment centres should be broad, maintained in areas bordering malaria hotspots, and available to all febrile individuals.

Surveillance and characterisation of influenza viruses among patients with influenza-like illness in Bali, Indonesia, July 2010\u2013June 2014

BackgroundAlthough Indonesia has high fatality rate of human A/H5N1 cases, epidemiological and clinical data on influenza virus circulation among humans has been limited. Within Indonesia, Bali province is of interest due to high population densities of humans, pigs and poultry. This study aims to characterize and compare the epidemiological and clinical patterns of influenza viruses in humans through surveillance among patients with influenza-like illness (ILI) in Bali, Indonesia.MethodsILI patients were recruited at 21 sentinel health facilities across all nine regencies in Bali, from July 2010 to June 2014. PCR-based assays were used for detection and subtyping of influenza viruses. Demographic, behavioural and clinical data were tested for associations with influenza using chi-squared tests and logistic regression.ResultsOf 2077 ILI patients, 291 (14.0%) tested positive for influenza A, 152 (7.3%) for influenza B, and 16 (0.77%) for both influenza A and B. Of the influenza A isolates, the majority 61.2% were A/H3N2, followed by A/H1N1-pdm09 (80; 26.1%). Two A/H5N1 were identified. Influenza positive rates were significantly higher during wet season months (28.3%), compared with the dry season (13.8%; χ2 = 61.1; df = 1; p < 0.0001). Clinical predictors for infection varied by virus type, with measured fever (≥38 °C) more strongly associated with influenza B (AOR: 1.62; 95% CI: 1.10, 2.39).ConclusionInfluenza circulates year-round among humans in Bali with higher activity during the wet season. High contact rates with poultry and pigs, along with influenza virus detection that could not be subtyped through conventional assays, highlight the need for molecular studies to characterize epidemiological and evolutionary dynamics of influenza in this setting.

Rainfall trend and variability in Southeast Florida: Implications for freshwater availability in the Everglades.

Freshwater demand in Southeast Florida is predicted to increase over the next few decades. However, shifting patterns in the intensity and frequency of drought create considerable pressure on local freshwater availability. Well-established water resources management requires evaluating and understanding long-term rainfall patterns, drought intensity and cycle, and related rainfall deficit. In this study, the presence of rainfall monotonic trends was analyzed using linear regression and Mann–Kendal trend tests. Pettit's single point detection test examined the presence of an abrupt change of rainfall. Drought in Southeast Florida is assessed using the Standardized Precipitation Index (SPI) in 3-, 6-, 12-, and 24-months scale; and the Fast Fourier Transform is applied to evaluate the frequency of each drought intensity. There was an increase of rainfall in most of the wet season months, the total wet season, and the annual total. The wet season duration showed a decrease driven by a decrease in October rainfall. Since 1990, wet season and total annual rainfall exhibited an abrupt increase. The SPI analysis has indicated that extended wetness characterizes the contemporary rainfall regime since 1995, except for the incidence of intermittent dry spells. Short-term droughts have 3-year to 5-year recurrence intervals, and sustained droughts have a 10-year and 20-year recurrence intervals. In Southeast Florida, prolonged drought limits freshwater availability by decreasing recharge, resulting in a longer hydro-period to maintain the health of the Everglades Ecosystem, and to control saltwater intrusion. The increasing dry season duration suggests the growing importance of promoting surface water storage and demand-side management practices.

Development of an acute sediment toxicity test using an endemic benthic macroinvertebrate, Chironomus species to assess the toxicity of Philippines’ Pasig River sediments

In the absence of a sediment quality guideline, mere characterization regarding the identity and levels of the constituents present in sediments, will not contribute much to an effort of establishing the impact of sediment quality to the aquatic environment. Available standard methods for sediment toxicity tests require the use of species that may not be accustomed to a tropical climate such as in the Philippines. In this regard, area of this study was to assess toxicity of the sediment from Pasig River through the use of an endemic midge (order Diptera, family Chironomidae) collected from Los Baños, Laguna, Philippines as test species. Pasig River is one of the most important waterways in the Philippines, traversing six major cities of Metro Manila. Such strategic location of the River, also explains why it is heavily impacted by both point and nonpoint sources of toxicants. Sediment samples were collected in April 2007, month of dry season and November 2007, month of wet season at five sampling stations along the Pasig River—Delpan, Nagtahan, Pandacan, Guadalupe, and Bambang. A modified 96-hour acute toxicity test was adopted in this study in which sediment samples were mixed with “control” sediment, also obtained locally and subsequently and exposed to the test species. Results suggested that the most polluted and most toxic was the Delpan station which yielded the lowest LC50. The LC50 was experimentally determined via probit analysis. Moreover, it was determined that sediment samples collected during the dry season exhibited lower toxicity towards these organisms than those samples collected during the wet season possibly due the effect of runoff. In view of the results obtained, the locally developed ecotoxicological assay performed on sediments of Pasig River can be used to assess and to distinguish sites along Pasig River that could be potentially toxic based upon its response to the locally grown Chironomids species.

Diurnal and Seasonal Variation of Surface Refractivity in Minna and Lapai, North Central Nigeria

Spatial and temporal variations of surface refractivity, Ns, in the troposphere are important parameters in designing terrestrial communication links. This research work examines the effect of variations of meteorological parameters on surface radio refractivity during dry and wet seasons in Minna and Lapai (2011-2013). The data on surface temperature, humidity and pressure collected from the Tropospheric Data Acquisition Network (TRODAN) weather stations installed at the Federal University of Technology, Minna, and at Ibrahim Badamasi Babangida University, Lapai, were used for the computation of radio refractivity. The hourly and monthly averages of radio refractivity during dry and wet seasons were calculated. The results showed that surface refractivity varied diurnally and seasonally in both stations. Refractivity values were high during the early morning and night hours and decreased rapidly during the afternoon hours. Values of refractivity were also generally low during the dry season months and high during the wet season months. It was also observed that refractivity values were higher at Lapai than Minna in dry season months. The result also shows that diurnal refractivity variation is attributed to atmospheric phenomena while seasonal variation is caused by the climatic conditions of the regions. Maximum values of 350 N-units in August in 2011, 343 N-units in July in 2012 and 347 N-units in August in 2013, while the minimum values of 275 N-units in January in 2011, 278 N-units in March in 2012 and 273 N-units were recorded in February for Minna. Surface refractivity has maximum values of 350 N-Units in August (2011), 347 N-Units in August (2012) and 349 N-Units in September (2013), while minimum values of 289 N-Units, 290 N-Units and 297 N-Units occurred in January in 2011, 2012 and 2013 respectively for Lapai.

Groundwater recharge indicator as tool for decision makers to increase socio-hydrological resilience to seasonal drought

Communities in regions with seasonal rainfall face annual dry seasons, during which water shortages and conflicts between different water use sectors may erupt. These difficulties increase following wet seasons with low rainfall, such as in relation to El Niño events in the wet-dry tropics of Central America. Hydrologic data are typically scarce in this region, making the development of drought adaptation strategies challenging. Many communities in the region depend on groundwater as their primary water source. For instance in the Province of Guanacaste in Costa Rica, groundwater supplied 78% of the total domestic water demand in 2015 and groundwater recharge from the wet season provides the primary water supply for the subsequent dry season. In this research we present a ‘groundwater recharge indicator’ that can support water managers in preparing for seasonal droughts. We developed this tool for an aquifer in northwestern Costa Rica where we conducted hydrological monitoring of streams and groundwater levels for 2.5 years, obtained further hydrological data (groundwater levels from 2005 to 2016), and worked with communities to assemble water use data. We combined these datasets in a hydrologic model (the Water Evaluation And Planning system, WEAP) and modelled groundwater recharge from 2005 to 2016, permitting a characterization of the relationship between rainfall and groundwater recharge. The groundwater recharge indicator is based on this relationship, and allows estimating total groundwater recharge for a wet season from cumulative rainfall measured to date. The indicator permits water managers to assess if the current year will likely fall into a low recharge category prior to the end of the wet season. This information can then be used to trigger short-term adaptation strategies with the goal to ‘bank’ groundwater while surface water sources are still available in the wet season. This indicator-based tool was refined through feedback provided in local stakeholder workshops. We also assessed the overall accuracy of predicting end-of-wet-season groundwater recharge with cumulative rainfall to date, and found that after the first 2–3 months of the wet season, prediction accuracies are high, leaving 5–6 months of wet season to respond adaptively to the prediction. The indicator can help water managers to plan ahead, and communicate the need for water conservation (demand management) and consideration of other water sources such as rain and surface water (supply management). This idea is transferable to other communities in regions with seasonal rainfall, and can support decision makers in increasing the socio-hydrological resilience of communities to seasonal droughts.

Wet season cyanobacterial N enrichment highly correlated with species richness and &amp;lt;i&amp;gt;Nostoc&amp;lt;/i&amp;gt; in the northern Australian savannah

Abstract. The Boodjamulla National Park research station is situated in the north-western Queensland dry savannah, where the climate is dominated by summer monsoons and virtually dry winters. Under shrub canopies and in between the tussock grasses cyanobacterial crusts almost entirely cover the flood plain soil surfaces. Seasonality drives N fixation, and in the savannah this has a large impact on both plant and soil function. Many cyanobacteria fix dinitrogen that is liberated into the soil in both inorganic and organic N forms. We examined cyanobacterial species richness and bioavailable N spanning 7 months of a typical wet season. Over the wet season cyanobacterial richness ranged from 6 to 19 species. N-fixing Scytonema accounted for seasonal averages between 51 and 93 % of the biocrust. Cyanobacterial richness was highly correlated with N fixation and bioavailable N in 0–1 cm. Key N-fixing species such as Nostoc, Symploca and Gloeocapsa significantly enriched soil N although Nostoc was the most influential. Total seasonal N fixation by cyanobacteria demonstrated the variability in productivity according to the number of wet days as well as the follow-on days where the soil retained adequate moisture. Based on total active days per month we estimated that N soil enrichment via cyanobacteria would be ∼ 5.2 kg ha−1 annually which is comparable to global averages. This is a substantial contribution to the nutrient-deficient savannah soils that are almost entirely reliant on the wet season for microbial turnover of organic matter. Such well-defined seasonal trends and synchronisation in cyanobacterial species richness, N fixation, bioavailable N and C fixation (Büdel et al., 2018) provide important contributions to multifunctional microprocesses and soil fertility.

Seasonal dynamics of tetracycline resistance gene transport in the Sumas River agricultural watershed of British Columbia, Canada

Environmental transport of contaminants that can influence the development of antibiotic resistance in bacteria is an important concern in the management of ecological and human health risks. Agricultural regions are locales where practices linked to food crop and livestock production can introduce contaminants that could alter the selective pressures for the development of antibiotic resistance in microbiota. This is important in regions where the use of animal manure or municipal biosolids as waste and/or fertilizer could influence selection for antibiotic resistance in pathogenic bacterial species. To investigate the environmental transport of contaminants that could lead to the development of antibiotic resistance in bacteria, a watershed with one of the highest levels of intensity of agricultural activity in Canada was studied; the Sumas River located 60 km east of Vancouver, British Columbia. This two-year assessment monitored four selected tetracycline resistance genes (tet(O), tet(M), tet(Q), tet(W)) and water quality parameters (temperature, specific conductivity, turbidity, suspended solids, nitrate, phosphate and chloride) at eight locations across the watershed. The tetracycline resistance genes (Tcr) abundances in the Sumas River network ranged between 1.47 × 102 and 3.49 × 104 copies/mL and ranged between 2.3 and 6.9 copies/mL in a control stream (located far from agricultural activities) for the duration of the study. Further, Tcr abundances that were detected in the wet season months ranged between 1.3 × 103 and 2.29 × 104 copies/mL compared with dry season months (ranging between 0.6 and 31.2 copies/mL). Highest transport rates between 1.67 × 1011 and 1.16 × 1012 copies/s were observed in November 2005 during periods of high rainfall. The study showed that elevated concentrations of antibiotic resistance genes in the order of 102–104 copies/mL can move through stream networks in an agricultural watershed but seasonal variations strongly influenced specific transport patterns of these genes.

Anomalous Atmospheric Circulation Associated with Recent West African Monsoon Rainfall Variability

The recent West African Monsoon (WAM) wet season (May to October) rainfall’s interannual variability has been examined with emphasis on the rainfall zones of Guinea Coast (GC), Western Sudano Sahel (WSS) and Eastern Sudano Sahel (ESS) in wet and dry years. Rainfall observations from Climate Research Unit (CRU) and Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP), and atmospheric circulation fields from National Center for Environmental Prediction (NCEP) were evaluated from 1979 to 2014. The objectives are to evaluate the trends across the zones and their linear relationship with the identified oceanic pulsations, as well as examine the evolution of the anomalous atmospheric circulation associated with the wet and dry years during the wet season months. The results show remarkable variability across the rainfall zones. The areal averaged rainfall anomalies show significant correlation values of -0.2 with Ocean Nino Index (ONI) only on WSS and ESS respectively, whereas with South Atlantic Ocean Dipole Index (SAODI) it shows significant correlation value of 0.3 only on GC, at 95% Confidence Level from a t-test. The analysis of trends in spatial and temporal patterns of the atmospheric circulation fields has extensively presented attributes associated with the wet seasonal rainfall anomalies in the wet and dry years. FGOALS-s2 model showed an outstanding simulation of the spatial and temporal patterns of these attributes, with the discrepancies noted, hence presenting itself as a viable tool in the prediction of seasonal rainfall extremes over West Africa.

Patterns of human–crocodile conflict in Queensland: a review of historical estuarine crocodile (Crocodylus porosus) management

Context In Queensland, the management of estuarine crocodiles (Crocodylus porosus) by the government is important for ensuring public safety, especially along the populated east coast, where there is a large human population. Aims The present study aimed to determine historical, temporal and spatial patterns of human–crocodile conflict in Queensland. Methods The study used Queensland Government records of estuarine crocodile attacks (1971–2015), sightings by the general public (2003–2015), and removals and relocations for management purposes (1985–2015) to develop General Linear Models describing historical, temporal and spatial patterns. Key results The highest number of attacks, sightings, removals and relocations occurred along the populated east coast between Townsville and the Daintree during wet season months (November–February). There have been 35 crocodile attacks in Queensland since 1971 (total 0.8 per year; fatal 0.3 per year), mostly involving local people or regular visitors (77.1%), specifically adult males (71.4%; mean age 44). There has been an increase in the rate of crocodile attacks over time, with an average of 1.3 per year since 1996, most of which were non-fatal (84%). The number of crocodile sightings has been increasing annually (with a mean of 348 per year since 2011), while the number of crocodiles removed or relocated for management purposes (n = 608) has fluctuating widely each year (range 1–57). Conclusions The level of human–crocodile conflict in Queensland is increasing, and this is likely to be a consequence of increasing human and crocodile populations. While conflict is highest during the wet season, estuarine crocodiles pose a threat to public safety year round. Implications With the increase in conflict, the ongoing management of estuarine crocodiles, through targeted removals in and around areas of higher human habitation and through education, is essential for ensuring public safety into the future.

Spatial Distribution of Elephants versus Human and Ecological Variables in Western Ghana

An elephant survey was conducted in the Bia-Goaso Forest Block in western Ghana during the wet season month of November 2012 to determine the distribution of elephants and assess the human and ecological variables that affect them. One hundred and thirty 1-kilometre transects were systematically distributed in three strata (high, medium, and low density) based on elephant dung pile density recorded in an initial reconnaissance. Elephant activity was concentrated in southern and mid-Bia Conservation Area, the southern tip of Bia North Forest Reserve, and eastern Mpameso Forest Reserve towards the adjoining Bia Shelter belt, indicating a clumped distribution. Secondary forest, water availability, poaching activity, and proximity to roads and settlements explained a high proportion of variance in elephant distribution. Given that the Bia-Goaso Forest Block forms an important biogeographic corridor between Ghana and Cote d’Ivoire, more effort should be directed at mitigating the problems such as poaching activity, vehicular traffic, and impacts of settlements that hinder seasonal movements of forest elephants between western Ghana and eastern Cote d’Ivoire.

Assessment of physico-chemical parameters of River Kaduna and College of Agriculture and Animal Science Dam, (CAAS) Kaduna, Nigeria

River Kaduna is one of the major sources of water to the inhabitants of the communities around the river and also to fish farmers while College of Agriculture and Animal Science Dam (CAAS) is used for fish farming and also for domestic purpose. The study was carried out to assess Physicochemical Parameters of River Kaduna and College of Agriculture and Animal Science Dam, Kaduna. The result of seasonal variation of physicochemical parameters between River Kaduna and College of Agriculture and Animal Science Dam, revealed that the atmospheric temperature (AT) ranged from 32.8 to 33.60C, pH at 7.1, conductivity ranged from 83.7 to 139.7µs/cm, dissolved oxygen ranged from 9.2 to 9.4 mg/l, biological oxygen demand ranged from 5.2 to 5.9 mg/l, water temperature (WT) at 29.20C, total hardness ranged from 37.4 to 58.0 mg/l, alkalinity ranged from 18.8 ton29.7 mg/l, chloride ranged from 14.8 to 15.9 mg/l, nitrate and phosphorus ranged from 0.1 to 0.2 mg/l while transparency ranged from 21.4 to 22.3 cm respectively. The seasonal variation result revealed that both at the Dam and river, AT, pH, DO, WT, Chloride, Nitrate, Phosphorus and Transparency values were not significantly different while conductivity, BOD, TH, Alkalinity and Ammonia were significantly different. However, they were significantly difference from one month to another (wet and dry season months respectively).Keywords: Physico-chemical parameters, River Kaduna, CAAS Dam

No evidence for an elephant-termite feedback loop in Sand Forest, South Africa

Termites and mammalian herbivores might derive mutual benefit from each other through positive feedback loops, but empirical evidence is lacking. One suggested positive feedback loop is between termites and elephant, both ecosystem engineers. Termites, as decomposer organisms, contribute to nutrient cycling and soil enrichment, creating hotspots with increased forage quality. Elephant are known to select these high quality vegetation patches, depositing woody debris when foraging, but it is unknown whether elephant presence might affect termites, and if a feedback loop between these two taxa exists. We tested this hypothesis by measuring termite diversity and activity over three months in the summer wet season, inside and outside a long-term (eight years) elephant exclosure experiment in Sand Forest at Phinda Private Game Reserve, South Africa. Termites were sampled using cellulose baits and woody debris was quantified using line transects. Termite activity was not affected by eight years of elephant absence, despite a greater volume of woody debris where elephant were present. Termite assemblages were similarly unaffected by elephant absence. Apart from Schedorhinotermes, all other termite genera were sampled in both treatments. Therefore, the postulated positive feedback loop between termites and elephant is not supported in Sand Forest. However, this does not contradict findings that areas with high termite activity positively influence herbivore foraging, only that elephant foraging does not affect termite activity. This suggests that elephant disturbance (and elephant management policies) has little to no effect on termites and the fundamental roles they play in ecosystems over at least the short-term.

Surface energy exchange in a tropical montane cloud forest environment: Flux partitioning, and seasonal and land cover-related variations

Relationships between seasonal climate, land cover and surface energy exchange in tropical montane cloud forest environments are poorly understood. The goal of this study was to investigate the seasonality of flux partitioning in lower montane cloud forest (LMCF), shaded coffee (CO) and sugarcane (SU) in central Veracruz, Mexico, as well as to evaluate the changes in surface energy exchange associated with the conversion of LMCF to CO or SU. Sensible (H) and latent heat (λE) fluxes were measured during the late dry and wet seasons using eddy covariance (CO and SU) and sap flow (LMCF) methods. Other measurements included: meteorological parameters, radiation balance, soil heat flux, soil moisture and vegetation characteristics. During the wet-season month of July, average midday Bowen ratios (βs) for sunny conditions were lowest and least variable among land covers: 0.4±0.2 (SE) in LMCF, 0.5±0.1 in SU and 0.7±0.1 in CO. In contrast, during the late dry-season months of March and April, βs were higher (i.e. higher H and lower λE) and more variable. The highest values of β were observed in LMCF, reflecting effects of partial leaf-shedding by dominant deciduous species (2.4±0.8, March) and increased stomatal control (1.4±0.3, April). There was also evidence of stomatal limitation of λE in CO and SU, having βs of up to 1.0±0.1 in April and March, respectively. As compared to LMCF, the average midday available energy (Ae) for sunny conditions was very similar in CO (−3±7%) and 15±8% lower in SU. Although not all results were statistically significant, they suggest that for the wet season conversion of LMCF to shaded coffee or sugarcane led to a decrease of 15±14% or 15±17% in midday λE under sunny conditions, respectively, whereas corresponding values of H increased by 37±38% or remained about the same (−4±40%). In contrast, for the late dry season, conversion of LMCF to shaded coffee or sugarcane appears to have resulted in higher λE and lower H, with changes of, respectively, +79 (±32)%/–45 (±16)% (CO) or +39 (±32)%/–43 (±16)% (SU) for a partially leafless LMCF in March, and +17 (±16)%/–11 (±16)% (CO) for a fully-leafed LMCF in April. In order to more accurately quantify the changes in surface energy fluxes associated with LMCF conversion, future work should focus on reducing the errors in the flux estimates. Nevertheless, for sunny days during the wet season, potential changes in the moisture and heat content of the local atmosphere due to the conversion of LMCF to CO or SU seem to have been in the same direction as those induced by increased greenhouse gases (drying and warming), whereas for the late dry season the effects appear to have been opposite (moistening and cooling).

Flora composition of phytoplankton as bioindicators of water quality in Jakara dam, Kano state, Nigeria

A study on phytoplankton as bioindicators of water quality in Jakara Dam was carried out for a period of 12 months (March, 2013-February 2014). Phytoplankton and water samples were collected and analyzed using standard methods. Sampling sites designated as A, B, C, D, and E were chosen. Physico-chemical parameters showed temperature, secchi disk transparency, pH, and electrical conductivity ranged between 25.3-23.9, 10.7-57.9 cm, 7.9-7.7 and 856.7- 817.9μs/cm respectively, so also dissolved oxygen, biochemical oxygen demand, nitrate and phosphate ranged between 4.5-3.3 mg/l, 2.5-1.7 mg/l, 23.8-14.3 mg/l, and 15.8-12.5mg/l respectively. Cyanophyceae were the most dominant contributing 56.8% of the total flora composition, followed by Bacillariophyceae (23.2%) and Chlorophyceae (23.0%). A combined total of 23 species of phytoplankton were encountered. Cyanophyceae 9, Bacillariophyceae 7 and Chlorophyceae 7. The total flora count obtained was 3255.93 Org/l. The highest phytoplankton density was recorded at site D (870.18 Org/l) and lowest at site A (454.39 Org/l). Oscillatoria spp. had the highest total species count (1131.58) org/l while Anthophysa vegetans had the lowest (10.53 Org/l). High percentages of organic pollution indicators Oscillatoria spp and Microcystis aerogenosa were signs of deteriorating condition of the water quality. Shannon - Weiner’s and Evenness Indices values were higher in the months of wet season than in dry season, while the Simpson’s Index values were low. The total flora counts were higher in dry season. In the wet season, Pearson’s Coefficient analysis showed that there was positive relationship between temperature and nitrate and BOD at P< 0.05. Likewise between DO and phytoplankton, BOD and nitrate and phosphate at P< 0.01. During the period of this study, site A had low secchi disk transparency, high level of nitrate and phosphate. This is due to human activities taking place at the site. Shannon - Weiner’s Index value indicated that the site is more polluted. Government and stakeholders should strengthen their legislation against indiscriminate and improper waste disposal along water-ways, dams inclusive. This will ease inflow and check contamination to a large extent. Keywords : Bioindicators, Indicies, Jakara Dam, Physico-chemical parameters, Phytoplankton

Climatology of the 500-hPa mediterranean storms associated with Saudi Arabia wet season precipitation

The relationship between the Mediterranean 500-hPa storm tracks and wet season (November–April) rainfall over Saudi Arabia is investigated. The analysis is based on the application of an objective tracking scheme to the 6-hourly 500-hPa geopotential height ERA-Interim dataset (0.75° × 0.75°) for the period 1979–2012. The resulting tracks are then associated with the ERA-Interim rainfall events over Saudi Arabia. The association procedure showed that 34 % of the tracks are related to about 70 % of the rainfall. These associated tracks are used to construct climatology. A climatology of these storm tracks revealed that the eastern Mediterranean region is the preferred location for cyclogenesis with a maximum in the southwest parts of the Black Sea. The study also examined the mean radius, average intensity and average depth of the storms. The number of tracks in winter (December–February) is about 60 % of the total number which confirms the major contribution of the Mediterranean storms to rainfall over Saudi Arabia. A significant negative trend was found for storm cyclogenesis over the central Mediterranean, and the Black sea. A significant trend decrease in track density is observed over most of the northern parts of Saudi Arabia. The peaks of storm activities are observed in December and January in 1996, 1997 and 2009. Storm activity generally declines after 2000, especially in the second half of the wet season months (February–April).

Assessment of rainfall variability, rainwater harvesting potential and storage requirements in Odeda Local Government Area of Ogun State in South-western Nigeria

AbstractRainfall variability with periodicity of 5–6 years has been demonstrated for our study area and may be attributed to tropical and extra-tropical factors which operate during different months, seasons and years. Rainfall variability in terms of coefficient of variation ranges from 24 to 39% and 26 to 41% for the seasons and months. The mean increase of 1.63 mm/year and 1.37 mm/year experienced in the dry season months (November–April) and the wet season months (May–October), respectively, is insignificant from a water management perspective. Hoeffding’s D statistics revealed prevalence of non-monotonic trend in all the months and seasons. Recommended minimum and maximum storage capacity requirements for a six-member household to maximize rainwater harvesting are 1 and 6 m3, respectively. The rainwater harvesting potential for the area of study ranges between 18.16 and 27.45 m3 and 15.23 and 30.40 m3 based on the maximum error estimate and coefficient of variation methods. Domestic rainwater harvest...

Feeding ecology and behavioral adjustments: flexibility of a small neotropical primate (Callithrix jacchus) to survive in a semiarid environment

Semiarid environments are known for climate extremes such as high temperatures, low humidity, irregular precipitations, and apparent resource scarcity. We aimed to investigate how a small neotropical primate (Callithrix jacchus; the common marmoset) manages to survive under the harsh conditions that a semiarid environment imposes. The study was carried out in a 400-ha area of Caatinga in the northeast of Brazil. During a 6-month period (3 months of dry season and 3 months of wet season), we collected data on the diet of 19 common marmosets (distributed in five groups) and estimated their behavioral time budget during both the dry and rainy seasons. Resting significantly increased during the dry season, while playing was more frequent during the wet season. No significant differences were detected regarding other behaviors. In relation to the diet, we recorded the consumption of prey items such as insects, spiders, and small vertebrates. We also observed the consumption of plant items, including prickly cladodes, which represents a previously undescribed food item for this species. Cladode exploitation required perceptual and motor skills to safely access the food resource, which is protected by sharp spines. Our findings show that common marmosets can survive under challenging conditions in part because of adjustments in their behavior and in part because of changes in their diet.

COMPARISON OF UNIVARIATE AND BIVARIATE APPROACHES TO MAP PRECIPITATION USING GEOSTATISTICS AND THE KALMAN FILTER

Measured rainfall data are very important in agriculture and environmental science. However, in many cases, the information gathered by existing rain gauges is insufficient for characterizing climatic variation within a study area. Thus, the use of interpolation techniques is necessary to predict values to unsampled sites. In this work, the performances of geostatistical algorithms, such as ordinary kriging and ordinary cokriging, and a proposed Kalman filter method were compared for mapping rainfall. The analysis was performed using both univariate and bivariate approaches. Natural terrain elevation was taken as the auxiliary variable for the bivariate case. The analysis was conducted for specific months of the dry and wet seasons in the Santiago River basin in Mexico. After comparison of the statistical errors, it was established that the geostatistical methods provided excellent results (especially cokriging) for the wet season months, with good correlation of 0.7 or above between rainfall and elevation, but not for the dry season months. Nevertheless, good results were achieved for the dry season months using the proposed Kalman filter methodology, due to the high normality and spatial dependence of the sample in this period.

An Assessment of Diurnal and Seasonal Cloud Cover Changes over the Hawaiian Islands Using Terra and Aqua MODIS*

Abstract A comprehensive understanding of the spatial, seasonal, and diurnal patterns in cloud cover frequency over the Hawaiian Islands was developed using high-resolution image data from the National Aeronautics and Space Administration’s Moderate Resolution Imaging Spectroradiometer (MODIS) sensors aboard the Terra and Aqua satellites. The Terra and Aqua MODIS cloud mask products, which provide the confidence that a given 1-km pixel is unobstructed by cloud, were obtained for the entire MODIS time series (10-plus years) over the main Hawaiian Islands. Monthly statistics were generated from the daily cloud mask data, including mean cloud cover frequency at the four daily overpass times. The derived mean cloud cover frequency showed patterns that were generally consistent with the known distribution of mean rainfall and with the results from previous studies. Cloud cover frequency was the highest over land areas with elevations between the lifting condensation level (~600 m) and the mean height of the trade wind inversion (TWI) base (~2200 m), especially for the windward (northeastern) mountain slopes. Above the TWI, cloud frequency decreased sharply with elevation. Irrespective of season, cloud cover frequency was generally higher in the afternoon than in the morning and higher in daytime than at nighttime although these trends varied spatially. The dry season months (May–October) were less cloudy than the wet season months (November–April) at nighttime. The analysis also revealed a local December–January minimum in the annual cycle of cloud cover frequency. The monthly time series produced in this study is the first high-spatial-resolution cloud cover dataset in Hawaii.