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We employed a new approach linking multivariate and time series analyses to identify common versus unique spatiotemporal components of abundance variation of marine spawning fishes recruiting into a subtropical Western Atlantic estuary. Based on a 10 yr standardized monthly data set, we also investigated patterns of association for local and regional factors with annual and inter-annual variation in abundance of 5 dominant marine estuarine-dependent fishes. The total amount of variation in fish abundance explained by environmental variables was 22.4%. After factoring out shared spatiotemporal variation (0.8%), our analysis showed that temporal components had an almost 5-fold greater contribution (28.0%) than spatial components (6.4%) in explaining the variation in abundance of the 5 species. Most of the variation across the temporal scale (58.5%) was associated with annual (from 0.5 to 1.3 yr) rather than multi-year oscillations (> 2 yr). Such annual patterns were probably associated with adaptations of marine estuarine-dependent fishes for exploiting predictable pulses in seasonal productivity typically found in subtropical estuaries. In contrast, inter-annual variation in abundance occurring at a scale of 3 to 7 yr could be attributed to rainfall anomalies associated with El Niño Southern Oscillation (ENSO) events, whereas those occurring at a scale of 2 yr could be influenced by the Southern Annular Mode (SAM). Our findings corroborate the hypothesis that prevalent annual patterns of variation in the abundance of marine estuarine-dependent fishes are associated with predictable productivity pulses linked to the annual temperature regime, whereas inter-annual variations in fish abundance are associated with the influence of large-scale climatic phenomena.

Trawling is the most common method of shrimp harvesting. This technique causes a negative impact on the fauna due to the high bycatch rates and to the animals that are accidentally caught and generally returned to the sea dead. The consequences of this technique and the biological aspects of the involved species are poorly studied, specially in the Brazilian northeast. The objective of this study was to show some aspects of the population biology of Isopisthus parvipinnis (Bigtooth corvina) captured as bycatch during sea-bob (Xiphopenaeus kroyeri) shrimp fishing in the region of Ilhéus, in the state of Bahia in Brazil. A total of 1290 individuals were caught in a monthly sampling at three different stations, from March, 2003 to February, 2005. The standardized Morisita index of dispersion suggests that this species has a clumped distribution in the studied area. The number of individuals showed a significant variation (p < 0.0001) between the seasons, being higher during the winter. The estimated first maturation length (L 50 ) was about 159 mm, and 95% of the captured individuals were below this value. The sexual ratio found was 1.5 males for each female. Concerning to diet, 10 feeding categories were identified, and Decapoda Dendobranchiata was the most important in numeric frequency and occurrence. This fact suggests that Isopisthus parvipinnis is a carnivorous species, with a tendency toward crustacean-eating at least in the younger individuals.A pesca de arrasto é o método mais comum de captura de camarão. Esta técnica causa impactos negativos na fauna demersal devido ao grande número de animais que são capturados acidentalmente e que geralmente são devolvidos mortos ao mar. As conseqüências desta metodologia de pesca e os aspectos biológicos das espécies envolvidas são pouco estudados, especialmente no Nordeste do Brasil. Este estudo tem como objetivo mostrar aspectos biológicos de Isopisthus parvipinnis (tortinha) capturada como fauna acompanhante da pesca do camarão sete barbas (Xiphopenaeus kroyeri) na região de Ilhéus, no estado da Bahia, Brasil. Um total de 1290 indivíduos foram capturados em coletas mensais, em três pontos de coleta distintos, de março de 2003 a fevereiro de 2005. O índice de dispersão de Morisita padronizado sugere que a espécie, na área analisada, apresenta uma distribuição agregada. O número de indivíduos variou significativamente entre as estações do ano (p < 0,0001), sendo maior durante o inverno. O comprimento estimado de primeira maturação (L 50 ) foi de 159 mm, sendo que 95% dos indivíduos capturados estavam abaixo deste valor. A razão sexual encontrada foi de 1,5 machos para cada fêmea. Quanto à dieta, foram identificadas 10 categorias alimentares, sendo que Decapoda Dendobranchiata foi a mais importante em freqüência numérica e de ocorrência. Este fato sugere que Isopisthus parvipinnis é uma espécie carnívora, com tendência a carcinofagia, ao menos nos indivíduos jovens.

We used long-term juvenile abundance data (2000 to 2010) of dominant fish species in 2 coastal habitats of Southern Brazil to test a novel adaptation of traditional multivariate analyses, as an alternative for evaluating the lag in species response relative to the changes in environmental variables. We investigated the hypothesis that the recruitment response to changes in environmental variables is not immediate. This new approach consisted of traditional multivariate analysis (e.g. canonical redundancy analysis) using an explanatory matrix composed of original and lagged environmental variables, and the performance of this analysis was assessed by comparison with traditional univariate time-lag analysis. Both the univariate and multivariate time-lag analyses showed similar results, but the multivariate approach had advantages and is presented as a useful and uncomplicated alternative to conduct time-lag analysis using a multivariate ecological dataset. Marine and estuarine recruitment processes were better explained by lagged temperature (predominant lags of 1 and 2 mo, respectively) than by in-phase (i.e. time lag = 0) temperature. In contrast, other environmental variables (transparency, salinity and freshwater outflow) did not show significant delays. Hence, our findings show that the species response to environmental variables is not immediate, especially for temperature. Rather, the time lag elapsed between the changes in abiotic factors and juvenile abundance is mediated by ecological and hydrological processes. Our study reaffirms the importance of time-lag analyses as a tool for better understanding of the temporal dynamics of estuarine and marine recruitment.

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