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Climate variability and large marine ecosystems in the western South Atlantic315and two years (24 months) to develop negativecorrelations along the NB and EB LMEs, as well aspositive correlations restricted to the southern coast(Fig. 4). The most relevant aspect of thesecorrelations is that this is the only index to presentsome relation with the interannual variability ofSSTA within the SACZ region. The fact thatsignificant correlations also developed with a 24months delay with inverted signals in tropicaland southern Atlantic deserves further attention.This aspect is analyzed through the sequentiallagged correlation maps from lag 0 to 24 months(Fig. 4). Significant positive correlations appearoffshore the southern coast between 25°S and30°S at lag 1 month. Gradually, these correlationsintensify and occupy a large area between 25°Sand 35°S from lag 1 to 9 months. Significantnegative correlations develop along the NB LME bylag 9 months. As these negative correlationsintensify, significant (negative) correlations start todevelop between 15° S and 20° S in the SouthAtlantic, and the positive correlation center between25° S and 40° S splits into two centers by lag17 months. With time, all correlations intensify, withthe strongest values being settled by lag 24 months.This pattern shows, indeed, three main centerswith the largest magnitude of correlation: twonegative centers, one along the NB LME andanother along the EB LME, and one positive centeralong the SB LME.DiscussionThere are striking differences between thecorrelation fields for Niño 3 and the proposedseparation of LMEs along the Brazilian coast. Thisis also the case when the correlation fields for thecold and warm PDO phases are projected onto theseLMEs. We have found that the time lag necessaryfor maximum correlations to be reached is the same(eight months) for both PDO phases, suggesting thatthe mechanisms connecting the Pacific and theAtlantic Ocean are comparable. During the coldPDO phase the boundary between the NB and theEB LMEs intersects a large region where SSTAs arehighly correlated with the tropical Pacific variability(Fig. 3). It is striking, however, the coincidencebetween the significant correlations and the southernlimit of the EB LME. High correlations betweenNiño 3 and SSTA cover the SB LME only partiallyand are mostly centered offshore (at 35°S, 45°W).This contrasts with our results for the NB and EBLMEs, where high correlations are found close tothe coastline. This gives a strong indication thatmarine organisms living on the continental shelf ofthe SB LME, which are sensitive to SSTAs, maytake longer to react the impact of ENSO events. Wedo know, however, that ENSO induced increase inprecipitation in the Patos Lagoon estuary has anegative impact on euryhaline species (Garcia et al.2001). Looking at the warm PDO phase, the EBLME includes areas with high and medium positivecorrelations and also a large area where nosignificant correlation was detected. This means thattrophically related populations in the EB LME maynot respond consistently to a remote climatic forcingsuch as the El Niño because environmentalconditions expressed as SSTAs co-vary differentlyinside this region. This spatial discontinuity ofcorrelations within the EB LME can pose somethreat on pelagic species that rely on the thermalstructure of the west tropical Atlantic, such as thealbacore Thunnus alalunga during their reproductivephase (Frédou et al. 2007). Two other emblematicexamples of the spatial and temporal effects ofclimate on marine pelagic ecosystems are providedby Stenseth et al. (2002), the Peruvian anchovycrash in 1972 and the zonal displacement of thePacific skipjack tuna following the eastwarddisplacement of the warm pool during ENSO events.A further complicating factor is thatecological processes sensitive to long term (e.g.decadal) environmental changes are likely to besubmitted to different regimes (see North et al.2009) within the EB LME. The same complicatingfactor is even more evident in the South Brazil (SB)LME, where high positive correlation with El Niñohas been detected during the PDO cold phase, but nosignify-cant relation was found in the subsequentwarm phase (Fig. 3). So, the PDO-related multidecadaland ENSO-related interannual SSTAvariability along the Brazilian coast exhibit acomplex dynamics against which ecosystemfunctioning should be tested to provide clues as tohow NB, EB and SB LMEs might respond to theseclimate forcings. Besides, if one considers thehypothesis that the PDO can be represented as a rednoise process, then extreme values or rapid shiftsmight occur when fortuitous random phasingcombine contributions of different frequencies(Overland et al. 2010).The TNA and TSA indices are long knownas indicators of the principal modes of TropicalAtlantic Variability (TAV), namely meridionalSSTA gradients, which are important for the climateof the tropical Atlantic and the surrounding landmasses (Enfield et al. 1999). The reason to includethese indices in our analyses is to portray a balancedview of the inter-basin and within-basin influence onthe SSTA of the Brazilian LMEs. The extent towhich the TNA and TSA interact with SSTA alongPan-American Journal of Aquatic Sciences (2010), 5(2): 310-319