Pacific Type Research Articles

Interdecadal change of interannual variability and predictability of two types of ENSO

A significant interdecadal climate shift of interannual variability and predictability of two types of the El Nino-Southern Oscillation (ENSO), namely the canonical or eastern Pacific (EP)-type and Modoki or central Pacific (CP) type, are investigated. Using the retrospective forecasts of six-state-of-the-art coupled models and their multi-model ensemble (MME) for December–January–February during the period of 1972–2005 along with corresponding observed and reanalyzed data, we examine the climate regime shift that occurred in the winter of 1988/1989 and how the shift affected interannual variability and predictability of two types of ENSO for the two periods of 1972–1988 (hereafter PRE) and 1989–2005 (hereafter POST). The result first shows substantial interdecadal changes of observed sea surface temperature (SST) in mean state and variability over the western and central Pacific attributable to the significant warming trend in the POST period. In the POST period, the SST variability increased (decreased) significantly over the western (eastern) Pacific. The MME realistically reproduces the observed interdecadal changes with 1- and 4-month forecast lead time. It is found that the CP-type ENSO was more prominent and predictable during the POST than the PRE period while there was no apparent difference in the variability and predictability of the EP-type ENSO between two periods. Note that the second empirical orthogonal function mode of the Pacific SST during the POST period represents the CP-type ENSO but that during the PRE period captures the ENSO transition phase. The MME better predicts the former than the latter. We also investigate distinctive regional impacts associated with the two types of ENSO during the two periods.

CMIP5 model simulations of the impacts of the two types of El Niño on the U.S. winter temperature

CMIP5 model simulations of the impacts of the two types of El Niño on the U.S. winter temperature

Different impacts of the two types of El Niño on Asian summer monsoon onset

In this study, we investigate the features of Asian summer monsoon onset during the decaying phases of central Pacific (CP) and eastern Pacific (EP) types of El Niño. The Asian summer monsoon onset is late during the EP El Niño while it is generally normal during the CP El Niño. Compared to the CP El Niño, the EP El Niño exerts a stronger impact on the climate over the Indian Ocean and the western North Pacific. Warmer sea surface temperature (SST) develops in boreal spring in the southern Indian Ocean and thus forms a large cross-equatorial SST gradient during the EP El Niño, which induces asymmetric patterns of winds and precipitation over the Indian Ocean. The asymmetric precipitation and circulation patterns contribute to a late monsoon onset. In addition, the anomalous anticyclone over the western North Pacific during the EP El Niño also contributes to late onset of the monsoon.

North American Climate in CMIP5 Experiments. Part II: Evaluation of Historical Simulations of Intraseasonal to Decadal Variability

This is the second part of a three-part paper on North American climate in phase 5 of the Coupled Model Intercomparison Project (CMIP5) that evaluates the twentieth-century simulations of intraseasonal to multidecadal variability and teleconnections with North American climate. Overall, the multimodel ensemble does reasonably well at reproducing observed variability in several aspects, but it does less well at capturing observed teleconnections, with implications for future projections examined in part three of this paper. In terms of intraseasonal variability, almost half of the models examined can reproduce observed variability in the eastern Pacific and most models capture the midsummer drought over Central America. The multimodel mean replicates the density of traveling tropical synoptic-scale disturbances but with large spread among the models. On the other hand, the coarse resolution of the models means that tropical cyclone frequencies are underpredicted in the Atlantic and eastern North Pacific. The frequency and mean amplitude of ENSO are generally well reproduced, although teleconnections with North American climate are widely varying among models and only a few models can reproduce the east and central Pacific types of ENSO and connections with U.S. winter temperatures. The models capture the spatial pattern of Pacific decadal oscillation (PDO) variability and its influence on continental temperature and West Coast precipitation but less well for the wintertime precipitation. The spatial representation of the Atlantic multidecadal oscillation (AMO) is reasonable, but the magnitude of SST anomalies and teleconnections are poorly reproduced. Multidecadal trends such as the warming hole over the central–southeastern United States and precipitation increases are not replicated by the models, suggesting that observed changes are linked to natural variability.

Phylogenetic relationships of selected genera of Lutjanidae inferred from mitochondrial regions, with a note on the taxonomic status of Pinjalo pinjalo

Phylogenetic relationships of 43 species in 11 genera, representing four subfamilies of the family Lutjanidae and two genera of the family Caesionidae, were inferred using mitochondrial DNA (mtDNA) cytochrome c oxidase subunit I (COI). Further assessment using the mtDNA control region (CR) was carried out to infer the relationship between the Indian and western Pacific types of Lutjanus russellii collected from the coast of Peninsular Malaysia. A total of 11 and 12 species were sequenced for COI and CR genes, respectively. Clade formation reflects, to some extent, the species groupings based on morphological characteristics and their biogeography. The close phylogenetic relationship between Pinjalo pinjalo and the Lutjanus red snappers (Lutjanus malabaricus and Lutjanus sebae) warrants a taxonomic revision of the former as the two genera are currently separated based on non-exclusive morphological characters. A sequence divergence of 4.2% between the Indian and western Pacific types of L. russellii as well as the morphological and biogeographical differences may suggest two separate species.

West Pacific-type convergent boundaries and their role in the formation of the Central Asian Fold Belt

The type of convergent boundaries forming in the area of mantle plumes is considered. These convergent boundaries (West Pacific type) are characteristic of the western margin of the Pacific. West Pacific-type boundaries are a regular succession of structures from ocean to continent: island arcs, marginal basins, rift basins, and associated OIB-type volcanics at the continental edge. The convergence zones are up to a thousand kilometers wide.Studies of the history of the part of the Central Asian Fold Belt forming the folded periphery of the Siberian continent have shown that the continent drifted above the African plume or corresponding low-velocity mantle province for most of the Phanerozoic (up to the Early Mesozoic inclusive). This fact determined the West Pacific type of convergent boundaries for the accretionary structures of the Central Asian Fold Belt. The drift of Siberia from African to Pacific province in the Late Cenozoic determined the structure and development of the convergent boundary in the western Pacific, including extensive intraplate magmatism in continental Asia in the Late Mesozoic and Cenozoic.

‘Endangered species turned dangerous’: Rena Owen and celebrity in Aotearoa/NZ

This article argues that Rena Owen’s star persona has been constrained, and ultimately undermined, by essentialist definitions of her status as Māori on the part of print media, in particular women’s magazines, in response to her role as Beth in Once Were Warriors (Lee Tamahori, 1994), a role that thrust her into the international limelight. These ancillary texts served to emphasise two stereotypes, positioning her either in relation to the traditional Pacific Island female type of the ‘dusky maiden’ or focusing on her criminal past and current scandalous behaviour. These representations of the actress detracted from her considerable talents and were undoubtedly a factor in determining a career trajectory that failed to fulfil its early promise. The scandal mongering of the tabloids expressed the uneasiness with which Aotearoa/New Zealand viewed public personalities that embraced a cultural past that included both Māori and European identities. Unlike the international press, which compared Owen’s performance to that of a range of film stars noted for their dramatic and charismatic capacities and presence, from Bette Davis to Anna Magnani, the New Zealand press portrayed her as ‘Beth’—as a social victim rather than an accomplished thespian.

Surface thermal centroid anomaly of the eastern equatorial Pacific as a unified Niño index

By analyzing the variability of global SST (sea surface temperature) anomalies, we propose a unified Nino index using the surface thermal centroid anomaly of the region along the Pacific equator embraced by the 0.7°C contour line of the standard deviation of the SST anomalies and try to unify the traditional Nino regions into a single entity. The unified Nino region covers almost all of the traditional Nino regions. The anomaly time series of the averaged SST over this region are closely correlated to historical Nino indices. The anomaly time series of the zonal and meridional thermal centroid have close correlation with historical TNI (Trans-Nino index) indices, showing differences among El Nino (La Nina) events. The meridional centroid anomaly suggests that areas of maximum temperature anomaly are moving meridionally (although slightly) with synchronous zonal movement. The zonal centroid anomalies of the unified Nino region are found helpful in the classification of the Eastern Pacific (EP)/Central Pacific (CP) types of El Nino events. More importantly, the zonal centroid anomaly shows that warm areas might move during a single warming/cooling phase. All the current Nino indices can be well represented by a simple linear combination of unified Nino indices, which suggests that the thermal anomaly (SSTA) and thermal centroid location anomaly of the unified Nino region would yield a more complete image of each El Nino/La Nina event.

Impacts of the central and eastern Pacific types of ENSOon sea surface temperature in the South Pacific

The present study examines the relationship between two types of El Nino–Southern Oscillation (ENSO), the central Pacific (CP) ENSO and the eastern Pacific (EP) ENSO, and the sea surface temperature (SST) variability over the South Pacific (SP) (20° S–60° S, 145° E–70° W) using NOAA OI SST for the period 1982–2006. The SP SST variability associated with the two types of ENSO varies with season. These two types of ENSO can excite different atmospheric patterns associated with the Pacific–South American mode, through which they influence the SP SST variability. Both the surface turbulent air–sea heat fluxes and the heat advection by Ekman currents (i.e., Ekman heat fluxes) have an important impact on the SST variability. An analysis of the surface mixed layer heat budget indicates that the heat fluxes (the sum of turbulent heat fluxes and Ekman heat fluxes) can effectively explain much of the SST variability related to the two types of ENSO.

Lesser Himalayan sequences in Eastern Himalaya and their deformation: Implications for Paleoproterozoic tectonic activity along the northern margin of India

Substantial part of the northern margin of Indian plate is subducted beneath the Eurasian plate during the Caenozoic Himalayan orogeny, obscuring older tectonic events in the Lesser Himalaya known to host Proterozoic sedimentary successions and granitic bodies. Tectonostratigraphic units of the Proterozoic Lesser Himalayan sequence (LHS) of Eastern Himalaya, namely the Daling Group in Sikkim and the Bomdila Group in Arunachal Pradesh, provide clues to the nature and extent of Proterozoic passive margin sedimentation, their involvement in pre-Himalayan orogeny and implications for supercontinent reconstruction. The Daling Group, consisting of flaggy quartzite, meta-greywacke and metapelite with minor mafic dyke and sill, and the overlying Buxa Formation with stromatolitic carbonate-quartzite-slate, represent shallow marine, passive margin platformal association. Similar lithostratigraphy and broad depositional framework, and available geochronological data from intrusive granites in Eastern Himalaya indicate strikewise continuity of a shallow marine Paleoproterozoic platformal sequence up to Arunachal Pradesh through Bhutan. Multiple fold sets and tectonic foliations in LHS formed during partial or complete closure of the sea/ocean along the northern margin of Paleoproterozoic India. Such deformation fabrics are absent in the upper Palaeozoic–Mesozoic Gondwana formations in the Lesser Himalaya of Darjeeling-Sikkim indicating influence of older orogeny. Kinematic analysis based on microstructure, and garnet composition suggest Paleoproterozoic deformation and metamorphism of LHS to be distinct from those associated with the foreland propagating thrust systems of the Caenozoic Himalayan collisional belt. Two possibilities are argued here: (1) the low greenschist facies domain in the LHS enveloped the amphibolite to granulite facies domains, which were later tectonically severed; (2) the older deformation and metamorphism relate to a Pacific type accretionary orogen which affected the northern margin of greater India. Better understanding of geodynamic evolution of the northern margin of India in the Paleoproterozoic has additional bearing on more refined model of reconstruction of Columbia.

West Pacific-type convergent boundaries: Role in the crust growth history of the Central-Asian orogen

Convergent plate boundaries like that between the present western Pacific and eastern Asia constitute a special type related to subduction in provinces of mantle superplumes. The West Pacific-type convergent boundaries may reach thousands of kilometers across and consist of several structures that regularly grade one to another from ocean to continent: island arcs, marginal and back-arc basins, and continent-margin rifts with OIB volcanism.Convergent boundaries of the West Pacific type contributed to Phanerozoic crust growth in Central Asia as accretionary structures of the Central Asian orogen on the southern periphery of Siberia belonged to such a convergence zone. The lithosphere of Siberia interacted with hot mantle as the continent moved over the African superplume, or over the respective large low shear velocity province (LLSVP), from the Vendian to the Early Mesozoic. In the Late Cenozoic, Siberia left the African LLSV province and shifted to the Pacific LLSVP. The influence of the latter has controlled the structure and evolution of the convergent boundary in the western Pacific, namely, widespread within-plate magmatism in continental Asia in Late Mesozoic and Cenozoic time.

Understanding the ENSO–CO2 Link Using Stabilized Climate Simulations

Abstract The influence of atmospheric CO2 concentration on the El Niño–Southern Oscillation (ENSO) is explored using 800-yr integrations of the NCAR Community Climate System Model, version 3.5 (CCSM3.5), with CO2 stabilized at the a.d. 1850, 1990, and 2050 levels. Model mean state changes with increased CO2 include preferential SST warming in the eastern equatorial Pacific, a weakening of the equatorial trade winds, increased vertical ocean stratification, and a reduction in the atmospheric Hadley and oceanic subtropical overturning circulations. The annual cycle of SST strengthens with CO2, likely related to unstable air–sea interactions triggered by an increased Northern Hemisphere land–sea temperature contrast. The mean trade wind structure changes asymmetrically about the equator, with increased convergence in the Northern Hemisphere and divergence in the Southern Hemisphere leading to corresponding deepening and shoaling of the thermocline. The proportion of eastern versus central Pacific–type El Niño events increases with CO2, but the significance of the changes is relatively low; ENSO amplitude also increases with CO2, although the change is insignificant at periods longer than 4 yr. The 2–4-yr ENSO response shows an enhancement in equatorial Kelvin wave variability, suggesting that stochastic triggering of El Niño events may be favored with higher CO2. However, the seasonal cycle–ENSO interaction is also modified by the asymmetric climatological changes, and forcing by the Southern Hemisphere becomes more important with higher CO2. Finally, higher-resolution CCSM4 control simulations show that ENSO weakens with CO2 given a sufficiently long integration time. The cause for the difference in ENSO climate sensitivity is not immediately obvious but may potentially be related to changes in westerly wind bursts or other sources of high-frequency wind stress variability.

Seasonal evolution of dominant modes in south pacific SST and relationship with ENSO

A season-reliant empirical orthogonal function (S-EOF) analysis was applied to the seasonal mean SST anomalies (SSTAs) based on the HadISST1 dataset with linear trend removed at every grid point in the South Pacific (60.5°-19.5°S, 139.5°E-60.5°W) during the period 1979–2009. The spatiotemporal characteristics of the dominant modes and their relationships with ENSO were analyzed. The results show that there are two seasonally evolving dominant modes of SSTAs in the South Pacific with interannual and interdecadal variations; they account for nearly 40% of the total variance. Although the seasonal evolution of spatial patterns of the first S-EOF mode (S-EOF1) did not show remarkable propagation, it decays with season remarkably. The second S-EOF mode (S-EOF2) showed significant seasonal evolution and intensified with season, with distinct characteristics of eastward propagation of the negative SSTAs in southern New Zealand and positive SSTAs southeast of Australia. Both of these two modes have significant relationships with ENSO. These two modes correspond to the post-ENSO and ENSO turnabout years, respectively. The SEOF1 mode associated with the decay of the eastern Pacific (EP) and the central Pacific (CP) types of ENSO exhibited a more significant relationship with the EP/CP type of El Nino than that with the EP/CP type of La Nina. The S-EOF2 mode contacted with the EP type of El Nino changing into the EP/CP type of La Nina showed a more significant connection with the EP/CP type of La Nina.

A change in the relationship between tropical central Pacific SST variability and the extratropical atmosphere around 1990

A newly released reanalysis dataset covering the period 1979–2009 is analyzed to show that the sea surface temperature (SST) variability in the tropical central Pacific is more closely related to the SST variability in the tropical eastern Pacific before 1990 but more closely related to sea level pressure (SLP) variations associated with the North Pacific Oscillation (NPO) after 1990. Only during the period after 1990 can the NPO excite large SST variability in the tropical central Pacific. Related to this change, El Niño Southern Oscillation (ENSO) SST anomalies tend to spread from the eastern to central tropical Pacific before 1990 in a pattern resembling that associated with the Eastern Pacific (EP) type of ENSO, but are more closely connected to SST variability in the subtropical north Pacific after 1990 with a pattern resembling that of the Central Pacific (CP) type of ENSO. This study concludes that the increased influence of the NPO on the tropical Pacific is a likely reason for the increasing occurrence of the CP type of ENSO since 1990. An analysis of the mean atmospheric circulation during these two periods suggests that the increased NPO influence is associated with a strengthening Hadley circulation after 1990.

Different types of La Niña events and different responses of the tropical atmosphere

Historical La Nina events since 1950 are divided into Eastern Pacific (EP) type and Central Pacific (CP) type, and the SSTA developing features as well as the different responses of the tropical atmosphere are further analyzed by using multiple datasets. Classification of different types La Nina is based on the normalized Nino3 and Nino4 indices and the SSTA distribution pattern during the mature phase. The minimum negative SSTA for CP La Nina is located over the equatorial central Pacific near the dateline, more westward than that of EP La Nina. It has stronger intensity and larger east-west zonal difference of SSTA over the equatorial Pacific than EP La Nina. Influenced by the different SSTA distribution pattern, CP La Nina induces more westward location of the anomalous sinking motion and the anomalous low-level divergent and high-level convergent winds over the equatorial eastern Pacific. The different response of the tropical atmospheric circulation between EP and CP La Nina is more significant in the upper troposphere than in the lower troposphere. However, the tropical precipitation patterns during the mature phase of EP and CP La Nina are much similar, except the less (more) precipitation over the equatorial central Pacific (eastern Indian Ocean-western Pacific) during CP La Nina than during EP La Nina.

Examination of the Two Types of ENSO in the NCEP CFS Model and Its Extratropical Associations

Abstract Two types of El Niño–Southern Oscillation (ENSO) simulated by the National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFS) model are examined. The model is found to produce both the eastern Pacific (EP) and central Pacific (CP) types of ENSO with spatial patterns and temporal evolutions similar to the observed. The simulated ENSO intensity is comparable to the observed for the EP type, but weaker than the observed for the CP type. Further analyses reveal that the generation of the simulated CP ENSO is linked to extratropical forcing associated with the North Pacific Oscillation (NPO) and that the model is capable of simulating the coupled air–sea processes in the subtropical Pacific that slowly spreads the NPO-induced SST variability into the tropics, as shown in the observations. The simulated NPO, however, does not extend as far into the deep tropics as it does in the observations and the coupling in the model is not sustained as long as it is in the observations. As a result, the extratropical forcing of tropical central Pacific SST variability in the CFS model is weaker than in the observations. An additional analysis with the Bjerknes stability index indicates that the weaker CP ENSO in the CFS model is also partially due to unrealistically weak zonal advective feedback in the equatorial Pacific. These model deficiencies appear to be related to an underestimation in the amount of the marine stratus clouds off the North American coasts inducing an ocean surface warm bias in the eastern Pacific. This study suggests that a realistic simulation of these marine stratus clouds can be important for the CP ENSO simulation.

Sea surface chlorophyll signature in the tropical Pacific during eastern and central Pacific ENSO events

Recent analyses of physical measurements show the existence of a central Pacific type of El Niño (CPEN) with a sea surface temperature warming pattern distinct from that of the “classical” eastern Pacific El Niño (EPEN). In this study, we analyze the surface chlorophyll signature of El Niño‐Southern Oscillation (ENSO), using monthly maps of satellite‐derived chlorophyll anomalies between September 1997 and December 2010. We identify five typical ENSO structures. The first structure describes the lonely 1997–1998 EPEN of the period, the second and third represent La Niña, the fourth illustrates intermediate conditions, and the fifth characterizes CPEN. During the 1997–1998 EPEN, a large eastward shift of the oligotrophic warm pool and a reduction of equatorial upwelling result in negative chlorophyll anomalies east of 170°E between 10°S and 10°N. During the four CPEN events, a reduced eastward shift yields negative chlorophyll anomalies in the equatorial band, within about 160°E and 160°W only. Westward surface current in the central basin limits the expansion of the anomaly core. Negative chlorophyll anomalies that extend eastward from the equatorial anomaly core probably result from reduced upward iron fluxes linked to the deepening of the Equatorial Undercurrent. During La Niña, the westward expansion of the equatorial upwelling results in positive chlorophyll anomalies west of the date line. Away from the equatorial band, advection of oligotrophic warm pool waters by enhanced eastward countercurrents drives negative anomalies within 8–10°N and toward the Marquesas Islands during CPEN, while reduced countercurrents lead to positive chlorophyll anomaly during La Niña.

Geochemistry of basaltic lavas from the southern Lau Basin: input of compositionally variable subduction components

We present new major element, trace element, and Sr–Nd–Pb isotope data for 18 basaltic lavas and six glasses collected in situ from the Eastern Lau Spreading Centre (ELSC) and the Valu Fa Ridge (VFR). All lava samples are aphanitic and contain rare plagioclase and clinopyroxene microlites and microphenocrysts. The rocks are sub-alkaline and range from basalt and basaltic andesite to more differentiated andesite. In terms of trace element compositions, the samples are transitional between typical normal mid-ocean ridge basalt (MORB) and island arc basalt. Samples from the VFR have higher large ion lithophile element/high field strength element ratios (e.g. Ba/Nb) than the ELSC samples. VFR and ELSC Sr–Nd isotopic compositions plot between Indian MORB and Tonga arc lavas, but VFR samples have higher 87Sr/86Sr for a given 143Nd/144Nd ratio than ELSC analogues. The Pb isotopic composition of ELSC lavas is more Indian MORB-like, whereas that of VFR lavas is more Pacific MORB-like. Our new data, combined with literature data for the Central Lau Spreading Centre, indicate that the mantle beneath the ELSC and VFR spreading centres was originally of Pacific type in composition, but was displaced by Indian-type mantle as rifting propagated to the south. The mantle beneath the spreading centres also was variably affected by subduction-induced metasomatism, mainly by fluids released from the altered, subducting oceanic crust; the influence of these components is best seen in VFR lavas. To a first approximation, the effects of underflow on the composition and degree of partial melting of the mantle source of Lau spreading centre lavas inversely correlate with distance of the spreading centres from the Tonga arc. Superimposed on this general process, however, are the effects of the local geographic contrasts in the composition of subduction components. The latter have been transferred mainly by dehydration-generated fluids into the mantle beneath the Tonga supra-subduction zone.

Morphology and Molecular Phylogeny ofChordaria okhotskensissp. nov. (Ectocarpales, Phaeophyceae) from the Sea of Okhotsk

Three Chordaria species were reported from the Russian Far East, viz. C. chordaeformis, C. flagelliformis, and C. gracilis. Chordaria flagelliformis and C. gracilis are common and widely distributed in the Bering Sea and Kamchatka, Kuril Islands, and the Sea of Okhotsk, while C. chordaeformis was only reported from the Avacha Bay (southeast Kamchatka). We describe a new species, Chordaria okhotskensis, from the Taujskaya Bay (northern Sea of Okhotsk, Russia). The external morphology of C. okhotskensis is similar to C. chordaeformis in having unbranched or sparsely branched thalli with branches borne at acute angles. The new species differs from C. chordaeformis in having large elongate medullary cells and thalli that are entirely flattened. Phylogenetic analysis based on rbcL gene data showed that this new species from the Sea of Okhotsk is distinct from the Atlantic and Pacific types of C. chordaeformis. Based on the phylogenetic results, the Kamchatka specimens of C. chordaeformis were also attributed to a new taxon, C. okhotskensis.

Occurrence of Banana bunchy top virus in banana and plantain (Musa sp.) in Benin

Banana bunchy top virus (BBTV; genus Babuvirus, family Nanoviridae), is one of the most serious pathogens of banana (AAA genome) and plantain (AAB genome) (Musa spp). BBTV is well established in central and southern sub-Saharan Africa (Kumar et al., 20011). It is transmitted by the banana aphid, Pentalonia nigronervosa (Homoptera: Aphididae), in a persistent manner. In July 2011, banana and plantain that displayed stunting and leaf symptoms typical of banana bunchy top disease were observed to be widespread in Dangbo Commune, Oueme Department, Benin. To identify the cause of the disease, a roving survey was conducted in December 2011 in nine locations in Avrankou, Dangbo, Akpro-Misserete and Porto-Novo Communes, in Oueme (Fig. 1). In each location, incidence of symptom-bearing plants was estimated from counts of 15 mats, and samples were collected for BBTV assessment. About 60% of the 94 banana mats assessed had plants exhibiting typical symptoms of BBTV infection - chlorotic leaf margins, dark green streaks on petioles, narrow leaves that bunched at the top and severe stunting (Fig. 2). Total DNA was extracted from 25 leaf samples collected from plants with symptoms; they were then tested for BBTV by polymerase chain reaction (PCR) according to the published protocols. Two oligonucleotide primer pairs, mREP-F and mREP-R, specific for a ~240 bp conserved domain of BBTV DNA-mRep segment (Mansoor et al., 2005), and Scp-F and Scp-R specific for a ~1075 bp BBTV DNA-S that encodes coat protein gene (Amin et al., 2008) were used for PCR amplification. The amplicons of expected size were obtained from 23 of the 25 samples analysed suggesting the presence of BBTV in the affected plants (Fig. 3). The PCR products of DNA-mRep segment amplified from the BBTV-infected banana samples collected in Zoungue (GenBank Accession No. JQ437548) and Mitro (JQ437549) were sequenced in both directions directly from the purified PCR products. These two sequences showed 100% nucleotide sequence identity with a BBTV isolate from Cameroon (FJ580970) and 99-100% identity with several other BBTV isolates from the GenBank database belonging to the South Pacific group, comprised of BBTV isolates from Africa, Australia, India and South Pacific (Fig. 4). This finding confirmed that the virus isolate associated with the diseased plants in Benin indeed was of the BBTV South Pacific type. This finding constitutes the first report of BBTV in Benin. The disease is widespread in all the four communes surveyed (Fig. 1). Further surveys are necessary to assess the extent of BBTV occurrence in Benin. Until now, Cameroon was the western most frontier of BBTV presence in sub-Saharan Africa (Oben et al., 2009). This finding confirms spread of the disease into West Africa, and underscores an urgent need for intensive surveys in neighbouring countries and implementation of strict phytosanitary measures to prevent movement of planting material from the infected zones and to prevent further spread of BBTV.