Santiago Island Research Articles

Vector competence of the Aedes aegypti population from Santiago Island, Cape Verde, to different serotypes of dengue virus.

BackgroundDengue is an arboviral disease caused by dengue virus (DENV), whose main vectors are the mosquitoes Aedes aegypti and Aedes albopictus. A. aegypti is the only DENV vector in Cape Verde, an African country that suffered its first outbreak of dengue in 2009. However, little is known about the variation in the level of vector competence of this mosquito population to the different DENV serotypes. This study aimed to evaluate the vector competence of A. aegypti from the island of Santiago, Cape Verde, to four DENV serotypes and to detect DENV vertical transmission.MethodsMosquitoes were fed on blood containing DENV serotypes and were dissected at 7, 14 and 21 days post-infection (dpi) to detect the virus in the midgut, head and salivary glands (SG) using RT-PCR. Additionally, the number of copies of viral RNA present in the SG was determined by qRT-PCR. Furthermore, eggs were collected in the field and adult mosquitoes obtained were analyzed by RT-PCR and the platelia dengue NS1 antigen kit to detect transovarial transmission.ResultsHigh rates of SG infection were observed for DENV-2 and DENV-3 whereas for DENV-1, viral RNA was only detected in the midgut and head. DENV-4 did not spread to the head or SG, maintaining the infection only in the midgut. The number of viral RNA copies in the SG did not vary significantly between DENV-2 and DENV-3 or among the different periods of incubation and the various titers of DENV tested. With respect to DENV surveillance in mosquitoes obtained from the eggs collected in the field, no samples were positive.ConclusionAlthough no DENV positive samples were collected from the field in 2014, it is important to highlight that the A. aegypti population from Santiago Islands exhibited different degrees of susceptibility to DENV serotypes. This population showed a high vector competence for DENV-2 and DENV-3 strains and a low susceptibility to DENV-1 and DENV-4. Viral RNA copies in the SG remained constant for at least 21 dpi, which may enhance the vector capacity of A. aegypti and suggests the presence of a mechanism modulating virus replication in the SG.

Assessment and mapping the sensitive areas to desertification in an insular Sahelian mountain region Case study of the Ribeira Seca Watershed, Santiago Island, Cabo Verde

This paper presents the assessment and mapping of the Ribeira Seca catchment, an insular Sahelian mountain region sensitive to desertification, located on the island of Santiago, Cabo Verde. Desertification is a threat to the global environment, representing a serious ecological problem in Cabo Verde. To successfully combat desertification, an evaluation of desertification consequences is required and the building of cartography of the sensitivity for arid and semi-arid ecosystems is required as a first step. The MEDALUS model was the basis for this study in which six quality indicators were used: climate, soil, vegetation, land management, erosion and social factors. Several parameters were defined for each indicator with weights varying between 1 (very low) and 2 (very high). The geometric mean of each of the six quality indicators was employed to produce a map of areas sensitive to desertification. The results of this study show that more than 50% of the watershed show clear evidence of becoming a desertified area.

Functional ultrastructure of the parenchymatic capsules of the cestode Thysanotaenia congolensis (Cyclophyllidea, Anoplocephalidae, Inermicapsiferinae).

Proglottids from adult Thysanotaenia congolensis from naturally infected black rats Rattus rattus from Santiago Island, Cape Verde, were examined by transmission electron microscopy (TEM). The uterus in mature proglottids is composed of an ephemeral transverse tube or sac that breaks down, releasing eggs into the parenchyma where they are sequestered in groups and encapsulated by parenchymatous layers. In gravid proglottids, eggs accumulate in groups of 6-12 at the distal end of sac-like uterine ducts. As eggs accumulate, the end of the uterine ducts expands until it pinches off, releasing groups of eggs into the parenchyma surrounded by remnants of uterine epithelium. These epithelium-bound groups of eggs remain in the parenchyma until they are encapsulated with several parenchymatous layers, forming parenchymatic egg capsules, typical for mature and gravid proglottids of Inermicapsiferinae. The parenchymatic capsules originate from the medullary parenchyma of immature proglottids, which undergoes differentiation into the three layers of gravid proglottids: (1) an outer connective tissue layer composed of long delicate filaments of unknown chemical nature embedded in a granular extracellular matrix; (2) a middle layer appearing as an accumulation of large closely packed PAS-positive mucous goblets that are intensely metachromatic after toluidine blue staining and (3) an inner compact layer composed of lipid-containing cells, muscle cells with elongated muscle fibres and cells of various sizes and shapes forming or containing calcareous corpuscles. The mature hexacanths of T. congolensis are surrounded by reduced oncospheral envelopes consisting of remnants of a very thin membranous layer of degenerating embryophore with long, irregularly shaped cytoplasmic processes and by remnants of uterine epithelium extending as numerous apical microlamellae into the parenchymatic capsule lumen.

Origin of the ‘Ghost Plagioclase’ Signature in Galapagos Melt Inclusions: New Evidence from Pb Isotopes

Olivine-hosted melt inclusions from both Fernandina and Santiago islands in the Galapagos Archipelago have compositions indicating that plagioclase played an important role in the magmatic evolution of these volcanic islands.The major and trace element chemistry of the Santiago melt inclusions indicates simple plagioclase assimilation. In contrast, Fernandina inclusions have compositions for which the plagioclase appears to be present only as a ‘ghost’ trace element signature (i.e. ‘ghost plagioclase’signature).Two competing hypotheses have been proposed to explain this unique signature: (1) incorporation of an ancient recycled plagioclase-rich cumulate into the mantle; (2) shallow-level interaction between melts and plagioclase-rich cumulates in the present-day lower oceanic crust. Here we present new Pb isotope measurements for olivine-hosted melt inclusions from Fernandina and Santiago islands to distinguish between the two models.The new Pb isotope data are within the range previously reported for whole-rock basalts from those islands. Melting and mixing models involving ancient ( 0·5^1 Ga) recycled plagioclase-rich cumulates cannot reproduce the observed trace element and Pb isotopic characteristics of the Fernandina melt inclusions with a ghost plagioclase signature. Shallow-level diffusive interactions between basalt and present-day plagioclase-rich cumulates provide the simplest explanation for the observed trace element compositions and Pb isotope ratios of melt inclusions from Fernandina and Santiago islands.

Fission and fusion in island taxa--serendipity, or something to be expected?

A well-used metaphor for oceanic islands is that they act as 'natural laboratories' for the study of evolution. But how can islands or archipelagos be considered analogues of laboratories for understanding the evolutionary process itself? It is not necessarily the case that just because two or more related species occur on an island or archipelago, somehow, this can help us understand more about their evolutionary history. But in some cases, it can. In this issue of Molecular Ecology, Garrick etal. () use population-level sampling within closely related taxa of Galapagos giant tortoises to reveal a complex demographic history of the species Chelonoidis becki - a species endemic to Isabela Island, and geographically restricted to Wolf Volcano. Using microsatellite genotyping and mitochondrial DNA sequencing, they provide a strong case for C.becki being derived from C.darwini from the neighbouring island of Santiago. But the interest here is that colonization did not happen only once. Garrick etal. () reveal C.becki to be the product of a double colonization event, and their data reveal these two founding lineages to be now fusing back into one. Their results are compelling and add to a limited literature describing the evolutionary consequences of double colonization events. Here, we look at the broader implications of the findings of Garrick etal. () and suggest genomic admixture among multiple founding populations may be a characteristic feature within insular taxa.

17-year change in species composition of mixed seagrass beds around Santiago Island, Bolinao, the northwestern Philippines

Effects of fish culture can alter the adjacent ecosystems. This study compared seagrass species compositions in 2012 with those in 1995, when fish culture was less intensive compared to 2012 in the region. Observations were conducted at the same four sites around Santiago Island, Bolinao: (1) Silaqui Island, (2) Binaballian Loob, (3) Pislatan and (4) Santa Barbara, and by using the same methods as those of Bach et al. (1998). These sites were originally selected along a siltation gradient, ranging from Site 1, the most pristine, to Site 4, a heavily silted site. By 2012, fish culture had expanded around Sites 2, 3 and 4, where chlorophyll a (Chl a) was greater in 2012 than in 1995 by one order of magnitude. Enhalus acoroides and Cymodocea serrulata, which were recorded in 1995, were no longer present at Site 4, where both siltation and nutrient load are heavy.

Lineage fusion in Galápagos giant tortoises.

Although many classic radiations on islands are thought to be the result of repeated lineage splitting, the role of past fusion is rarely known because during these events, purebreds are rapidly replaced by a swarm of admixed individuals. Here, we capture lineage fusion in action in a Galápagos giant tortoise species, Chelonoidis becki, from Wolf Volcano (Isabela Island). The long generation time of Galápagos tortoises and dense sampling (841 individuals) of genetic and demographic data were integral in detecting and characterizing this phenomenon. In C.becki, we identified two genetically distinct, morphologically cryptic lineages. Historical reconstructions show that they colonized Wolf Volcano from Santiago Island in two temporally separated events, the first estimated to have occurred ~199 000 years ago. Following arrival of the second wave of colonists, both lineages coexisted for approximately ~53 000 years. Within that time, they began fusing back together, as microsatellite data reveal widespread introgressive hybridization. Interestingly, greater mate selectivity seems to be exhibited by purebred females of one of the lineages. Forward-in-time simulations predict rapid extinction of the early arriving lineage. This study provides a rare example of reticulate evolution in action and underscores the power of population genetics for understanding the past, present and future consequences of evolutionary phenomena associated with lineage fusion.

Heavy metals of Santiago Island (Cape Verde) top soils: Estimated Background Value maps and environmental risk assessment

In this work we present maps of estimates of background values of some harmful metals (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, V, and Zn) in the soils of Santiago Island, Cape Verde, analyse their relationships with the geological cartography, and assess their environmental risks. The geochemical survey (soil sampling at a spatial resolution of 3 sites per 10km2, sample preparation, geochemical analysis, data treatment, and mapping) was conducted following the guidelines proposed by the International Projects IGCP 259 and IGCP 360. The concentration of the selected elements was determined in the fraction <2mm. Each sample was digested with aqua regia and analysed by ICP-MS.The Estimated Background Value spatial distributions of the studied metals are found to be strongly linked to the geological cartography. These links are identified by a direct comparison of the geochemical maps with the geological cartography, and confirmed by either simple statistics and a Principal Component Analysis. The metals with higher loadings in the first Principal Component, Ni, Cr, Co, Cu, and V, clearly show the influence of a lithology rich in siderophile elements, typical of basic rocks and of its related minerals. The elements with higher loadings in the second Principal Component, Mn, Zn, Pb, As, Hg, and Cd, are chalcophile elements, except for Mn, but an anthropogenic contamination for these elements cannot be discarded.We propose an index to numerically access the environmental risk of one element, which we denominate by Environmental Risk Index, and a Multi-element Index which is simply the average taken over all elements. The occurrence of values greater than 1 in the maps of the Environmental Risk Index shows where the content of the respective element is above the permissible levels according to the available legislation for agricultural and residential purposes. The same applies to the multi-element risk index maps. High values of these risk indices are found, both for agricultural and residential purposes, for Co, Cr, Ni, Cu, and V. These metals are precisely those with higher loadings in PC1, which are demonstrated to be of natural origin in Santiago. This behaviour is also shown in the Multi-element Environmental Risk maps computed with these five metals. The high natural concentration levels of heavy metals at some areas of Santiago should be of concern not only to scientists but also to policymakers. To further evaluate the environmental risks associated with the presence of these metals, their bioavailability should be assessed in future works.

The application of a multi-wavelength Aethalometer to estimate iron dust and black carbon concentrations in the marine boundary layer of Cape Verde

The two-component model (Fialho et al., 2006) was used to decouple the contributions of black carbon (BC) and iron oxides, present in dust, to the aerosol attenuation coefficient, measured with a multi-wavelength Aethalometer. The model results were compared with the elemental carbon (EC) and iron concentrations determined in the laboratory from the analysis of aerosol particles collected with conventional samplers. The comparison was based on one year of data obtained at Praia, Santiago Island, Cape Verde, after side by side operation of the aerosol monitoring instruments. The linear regression equation that best describes the relationship between BC concentrations, derived from the Aethalometer, and EC concentrations, derived from a PM10 high-volume sampler after filter analysis with a thermal optical method, presents a slope of 1.01 ± 0.05 and a correlation coefficient (r) of 0.90, showing that the model worked as intended to describe BC concentrations without interferences from iron dust. On the other hand, the linear regression equation that best describes the relationship between the iron concentrations derived from the Aethalometer and elemental iron concentrations, derived from a PM10 low-volume sampler after filter analysis by k0 – Instrumental Neutron Activation Analysis, presents a slope of 0.495 ± 0.014 and a correlation coefficient (r) of 0.96. These results show that the two-component model underestimated the iron concentrations in dust aerosol, which was explained by differences in the size range of particles sampled with the Aethalometer and the PM10 low-volume sampler together with differences in the size distribution of iron oxides.

Seasonal variability of aerosol concentration and size distribution in Cape Verde using a continuous aerosol optical spectrometer

One year of, almost continuous, measurements of aerosol optical properties and chemical composition were performed at the outskirts of Praia, Santiago Island, Cape Verde, within the framework of CV-DUST (Atmospheric aerosol in Cape Verde region: seasonal evaluation of composition, sources and transport) research project, during 2011. This article reports the aerosol number and mass concentration measurements using a GRIMM Optical Aerosol Spectrometer that provides number size discrimination into 31 size ranges from 0.25 to 32 µm. Time series of 5 min average PM10 concentrations revealed peak values higher than 1000 µg.m-3 during winter dust storm events originating over Northern Africa. The 24 hours average concentrations exceeded the World Health Organization (WHO) guidelines for PM2.5 and PM10 in 20% and 30% of the 2001 days, respectively. Annual average mass concentrations (±standard deviation) for PM1, PM2.5 and PM10 were 5±5, 19±21 and 48±64 µg.m-3, respectively. The annual PM2.5 and PM10 values were also above the limits prescribed by the WHO (10 and 20 µg.m-3, respectively). The aerosol mass size distribution revealed two main modes for particles smaller than 10 µm: a fine mode (0.7-0.8 µm), which possibly results of gas to particle conversion processes; and a coarse mode with maxima at 3-4 µm, which is associated with desert dust and sea salt sources. Within the coarse mode two sub-modes with maxima at 5-6 µm and 10-12 µm were frequently present.

Economic and environmental assessment of renewable energy micro-systems in a developing country

This paper intends to evaluate the impact of the introduction of electricity generation micro-systems based on 100% renewable sources to supply electricity demands of non-electrified rural residential houses in Santiago Island’s energy system (Cape Verde). For that purpose a comparison between three energy scenarios (2011–2030) were studied: a Reference Scenario, where it was assumed that the electricity grid would be expanded to increase households electrification rate and that grid connected renewable energy technologies will be used to increase generation power; a Diesel Scenario, where future electricity requirements would be provided by constructing new diesel power plants; and a Decentralized Scenario that is based on the Reference Scenario but that differs from it for the fact that it considers the installation of off-grid renewable energy micro systems (REMS) to attend electricity requirements of post-2010 electrified rural houses. The electricity supply–demand system of Santiago Island was modeled using an energy planning software and an optimal REMS design was modeled to provide electricity requirements of a typical Santiago’s household. Although it is clear that using renewable energy technologies (Reference Scenario) presents better results from an environmental and economical point of view than installing new diesel power plants (Diesel Scenario), using off-grid REMS to electrify post-2010 rural households (Decentralized Scenario) result to be even more beneficial than generate and distribute on-grid renewable electricity.

The early scientific history of Galapagos iguanas

The oldest known specimen of Galapagos marine iguana (Amblyrhynchus cristatus), now in the University Museum, Oxford, was originally thought to have come from Mexico. A plausible history of its origin with sealers in the Galapagos Islands about 1824 and transportation to and across Mexico is advanced. The naturalists David Douglas and John Scouler, on James (Santiago) Island in January 1825, encountered and attempted unsuccessfully to preserve specimens of the land iguana (Conolophus subcristatus) but only a Scouler specimen of marine iguana made it back to England, and it has since disappeared. Published and previously unpublished journal entries from the voyage of HMS Blonde, which had shore parties at Albemarle (Isabela) and Narborough (Fernandina) islands in March 1825, establish that the specimens on which the original description of Amblyrhynchus (later Conolophus) subcristatus J. E. Gray, 1831 , was based originated in the voyage of the Blonde. Banks Bay, Albemarle Island, is here designated as the type locality for Conolophus subcristatus. Specimens of the marine iguana were also brought back by the Blonde. The published accounts of Scouler and the voyage of the Blonde established the Galapagos as the true home of the marine iguana well before the return of Charles Darwin and HMS Beagle in 1836.

Organic characterisation of PM10 in Cape Verde under Saharan dust influxes

The current study presents, for the first time, a long-term organic speciation of aerosol at the Cape Verde archipelago. The Cape Verde location, in the Atlantic Ocean, provides a unique laboratory to study background aerosol, long-range transport, aerosol mixing with mineral dust, biomass burning and sea surface components. In order to contribute to a better understanding of this environment, a one-year long measurement campaign was performed in Praia City, Santiago Island. PM10 concentrations (20.5–370 μg/m3) and the organic composition of PM10 were influenced by the African dust influxes. The carbonaceous content of PM10 was very low, suggesting that most of the mass has mineral origin. The PM10 composition was essentially characterised by a large variety of organic compounds, which can be grouped into general compound classes, such as n-alkanes, n-alkanols, n-acids and sugars. The n-alkane total concentrations varied from 3.77 to 53.2 ng/m3. The n-alkanols distribution showed a significant biogenic contribution whether from microbial origin or from epicuticular plants during African dust outbreaks. The total concentrations of n-alkanoic acids varied from 0.011 to 4.51 ng/m3. The lower n-alkenoic acids content, obtained during the periods of long-range transport from Africa, indicated a more aged aerosol. The monosaccharide anhydrides were detected in all samples with a range of concentrations from 2.06 to 12.7 ng/m3.

Characterization of the aeolian aerosol from Cape Verde by k 0-INAA and PIXE

Due to its location on West Coast of Africa, Cape Verde is highly influenced by Sahara Desert dust events being an optimum place to observe and study the African aeolian aerosol. During 2011, particulate matter with an aerodynamic diameter lower than 10 μm (PM10) was sampled in Santiago Island and its chemical composition was evaluated by k 0-instrumental neutron activation analysis (k 0-INAA) and particle induced X-ray emission (PIXE). This study showed the existence of a seasonal intrusion of dust from Africa (that occurred from October to March) characterized by significant increases of PM10, mineral elements and anthropogenic particles concentrations. In 2011, the PM10 health-based air quality guidelines defined by WHO, EU and USEPA were exceeded. Cape Verde PM10 composition was characterized essentially by high concentrations of elements originating from the soil (Ca, Ce, Co, Fe, K, Mg, Mn, Rb, S, Sc, Si, Sm, and Ti) and sea (Br, Cl, and Na); and low concentrations of anthropogenic elements (As, Cr, Cu, Ni, Pb, Sb, V, and Zn). k 0-INAA and PIXE were fundamental tools for the determination of airborne chemical elements in Cape Verde. Their multi-elemental capabilities in association with low detection limits made it possible to determine the majority of the element concentrations of environmental interest.

Destination mutant brands: An empirical perspective of tourism professionals and host community to create Mutant Brand Cape Verde

In spring of 2010, as an attempt to compete in the international marketplace, the Ministry of Tourism of Cape Verde embarked on a mission to create Brand Cape Verde. The concept of destination branding is premised on the objective of understanding the key elements of visual communication identity as well as the differentiated attributes of a place. As new technological advances continue to break new grounds and penetrate all sectors of commerce, an innovative branding strategy has been introduced in the destination branding context – Mutant Brands – as a means to visually communicate all the key elements of a place. The present study aims to present the contemporary branding strategy concept of Mutant Brands, highlight the authentic attributes that make Cape Verde a unique destination, provide a new perspective for destination branding, and present insightful empirical research regarding the implementation of Mutant Brand Cape Verde. To accomplish the set objectives, 17 in-depth interviews were conducted on the island of Santiago in Cape Verde, during the months of March and April. Results indicated that Brand Cape Verde failed to aggregate the differentiated characteristics of the islands in the branding strategy. As a result, the implementation of a brand strategy based on the concept of Mutant Brands proved to be adaptable in the context of Cape Verde.

Agama agama: a charter tourist in the Cape Verde Islands?

Agama agama is a successful invader that was recently introduced to Santo Antão Island of the Cape Verde archipelago. The species was then noted to be present also in São Vicente and Santiago Islands but the geographic origin of the introductions remains undetermined. Given its wide range and taxonomic identification problems, we compared new 16S RNA sequences with available Agama agama sequences in order to determine if some geographical structure was present that allowed identification of the country of provenance and number of introduction events on the Cape Verde Islands. Some geographical structure of genetic diversity and reasonably large within-group average divergence were revealed, especially in the countries around the Gulf of Guinea. Results support a single origin for this introduction, as a single 16S haplotype is found among the three Cape Verde Islands, and suggest Liberia as the country with the smallest genetic distance to the individuals found in the Cape Verde archipelago. We suggest that local authorities take action against this exotic species as it is spreading and reproducing and predation on endemic species of reptile has been confirmed.

Uranium Contents in the Lithological Formations of Santiago Island, Cape Verde

We present the uranium contents in the different lithological formations of Santiago. The island is constituted by basaltic-basanite rocks, but phonolitic-trachytic rocks also occur. The highest contents of uranium occur in the phonolitic-trachytics rocks of Ancient Complex and Pico Antónia Formations, and also in other formations of heterogeneous materials, which have phonolitic-trachytics fragments, reaching 62.8μg.g-1 of uranium. These contents are much higher than those of the MORB (0.047-0.18μg g-1) and OIB (1.02μg.g-1) and even higher than those of the upper crust. The source of uranium in the rocks of Santiago is related with the occurrence of zircon

APPRAISING AND SELECTING STRATEGIES TO COMBAT AND MITIGATE DESERTIFICATION BASED ON STAKEHOLDER KNOWLEDGE AND GLOBAL BEST PRACTICES IN CAPE VERDE ARCHIPELAGO

ABSTRACTDesertification is the most disturbing and detrimental cause of rural vulnerability in Cape Verde, affecting families' material and environmental resources. Combating desertification in Cape Verde is complex because it involves addressing a mixture of endogenous (manual agriculture, fuel wood and fodder extraction, land tenure and steep slopes) and exogenous drivers (high rainfall variability, climate change, prolonged drought or heavy rainfall). To address and mitigate the adverse effects of desertification, it is necessary to develop an approach that identifies and brings together all the key stakeholders affected by and acting on the desertification issue, including land users, policy makers, managers, researchers and rural development technicians. This paper presents a hybrid methodology based on global best practices, applied in Cape Verde. It combines experiences and skills of local stakeholders (farmers, local association of land users and local non‐governmental organizations) with scientific knowledge of external stakeholders such as technicians of the Ministry of Rural Development, environmental advisors of Municipalities and researchers. Integration takes place following a participatory process of appraising and selecting desertification control strategies. The paper presents the first results obtained from application of the hybrid methodology to Ribeira Seca, the largest watershed of Santiago Island. The approach was evaluated with local and external stakeholders. Both groups appreciated that they could voice their views and discuss ways to overcome barriers and also to take full advantage of the opportunities offered by jointly selected promising desertification mitigation options. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Estimated Background Values Maps of Uranium in Santiago Island Topsoil and Stream Sediments

We present maps of estimates of background values of uranium in the soils and stream sediments of Santiago Island, Cape Verde, delineate their main sources, relate them with the geology of the island, and assess their environmental risks. We use an index to numerically access the environmental risk of U, which we denominate by Environmental Risk Index. Values of this index higher than one were only found in three soil sampling points, all for agricultural purposes. So, U in Santiago topsoil and stream sediments has a geogenic origin and there is no contamination of uranium in these two sampling media.

Precipitation Patterns in Cape Verde Islands: Santiago Island Case Study

The Cape Verde archipelago is located between 14。N - 18。N and 22。W - 28。W in the Atlantic Ocean. Previous studies associated Cape Verde’s rainfall regime with ITCZ and African squall lines. This hypothesis is revisited here using rainfall time series of the 4 Santiago Island station network of Cape Verde National Institute of Meteorology and Geophysics. Rainfall monthly totals are standardized to produce indices in the 1981-2009 period. Time section plots of zonal and meridional wind components anomalies are made using reanalysis data from ESRL/PSD/NOAA website. Daily outgoing long wave radiation and sea level pressure time section plots are also made as proxies for weather systems propagation. Results show that Santiago presents a seasonal rainfall regime characterized by dry (November-June) and wet (July-October) seasons, with short transition period. In general, rainfall totals increase with altitude. Weather systems within a wet year rainy season were associated with positive anomalies of zonal and meridional wind components of relative short duration, while negative anomalies dominated in dry years. These results suggest that winds coming from southwestern quadrant over warm Atlantic Ocean, associated with frontal systems traveling eastward, are the rain-producing events in wet years, not ITCZ or African squall lines. Winds coming from the northeastern quadrant produce dry years. Apparently, decadal-long wet periods are related to PDO cold phase. In the current PDO cold phase, there is only one year (2002) slightly dry. Considering that each PDO phases lasts 25 to 30 years and the current PDO cold phase started in 1999, it is possible that wet years predominate in the next 10 to 15 years.