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RESUMO -(Impactos da construção do Porto de Suape sobre a comunidade fitoplanctônica no estuário do rio Ipojuca, Pernambuco, Brasil). A construção do Complexo Industrial Portuário de Suape, entre os anos de 1979/84, modificou as características ecológicas da área, sendo os maiores impactos observados no estuário do rio Ipojuca. Visando avaliar a ação desses impactos sobre a comunidade fitoplanctônica através da comparação com estudos realizados antes na área, foram analisadas amostras de plâncton coletadas em uma estação, durante um ciclo de 24 horas, nos períodos chuvoso (agosto/90) e seco (janeiro/91). As amostras foram coletadas pela técnica do fracionamento e com rede de plâncton de 65µm de abertura de malha. Coletas de parâmetros hidrológicos foram realizadas concomitantemente. Foram identificados 97 táxons, destacando-se como espécies muito freqüentes nos períodos chuvoso e seco: Gyrosigma balticum, Oscillatoria princeps, Chaetoceros lorenzianus, Climacosphenia moniligera e Licmophora abbreviata. A densidade fitoplanctônica variou entre 142.000 cels.l -1 a 1.789.000 cels.l -1 predominando a fração do nanofitoplâncton. O maior florescimento ocorreu no período seco, nos horários de maior insolação e maré enchente. A diversidade específica foi alta (> 3 bits.cel.l -1 ) explicada pela heterogeneidade ambiental. A comunidade fitoplanctônica apresentou mudanças quali-quantitativas após a implantação do Porto. Agora, predominam espécies marinhas litorais, devido à pequena profundidade e elevado hidrodinamismo na área e um decréscimo de 70% na densidade celular, ao contrário do que ocorria antes da construção do Porto, quando foi detectado a maior ocorrência de espécies marinhas planctônicas e maior número de células/litro. Palavras-chave -Fitoplâncton, ecologia, variação nictemeral, impactoABSTRACT -(Impacts of the construction of the Port of Suape on the phytoplankton community in the Ipojuca River Estuary, Pernambuco, Brazil). The Suape Industrial Port Complex (Pernambuco-Brazil) constructed between 1979/84 modified the ecology of the area, causing great impacts in the Ipojuca River. In order to assess the impacts on the phytoplankton community comparing with previous studies, samples were obtained at one fixed station in August/90 (rainy season) and in January/91 (dry season). Collections were made in a nyctemeral cycle, every 2 hours by the fraction method and with a plankton net 65 µm mesh size. Hydrological data were collected simultaneously. 97 taxa were identified and the most frequent at both studied period were: Gyrosigma balticum,

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In order to address the impact on phytoplankton, sampling was conducted monthly at 4 fixed stations, from April/86 to March/87 at diurnal low and high tide using a plankton net (65 mum mesh size) and a 1 L Van Dorn bottle. Among the 133 taxa identified, marine littoral euryhaline species were most common, outranking Gyrosigma balticum (Ehrenberg) Rabenhorst, Nitzschia sigma (Kützing) Wm. Smith, Licmophora abbreviata Agardh, Climacosphenia moniligera Ehrenberg, Surirella febigerii Lewis, Terpsinoe musica Ehrenberg and Cylindrotheca closterium (Ehrenberg) Reiman and Lewis. The port construction caused significant changes to the phytoplankton community with a strong influence of marine species (mainly dinoflagellate) because of the opening of the reef near the river mouth in 1983. The shallow depth and hydrodynamic brought many littoral species to the water columm. The community was composed by marine euryhaline and limnetic organisms, influenced by the salinity, rain and tide. Species diversity was high (> 3 bits.cel-1) owing to the high environmental heterogeneity (marine, freshwater and benthic interactions). After the port implantation, a strong decrease occurred in phytoplankton density owing to high loads of suspended matter. Lowest values (121,00 cells.l-1) were registered during rainy season. During dry season, when light intensity was higher, phytoplankton presented highest density ( 1,789,000 cells.l-1).

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was investigated. The larval distribution in the channel was analysed based on 187 samples from 9 stations collected from November 1993 to May 1994. 50 of these samples were used to investigate the taxonomic composition. Larval densities varied between 0 and 376 ind. per 50 m³. Seasonal and geographical patterns were found. Both in dry and rainy season larval abundance was low at the inner channel. Except a few hauls, most samples did not exceed densities of 25 or 45 ind./50 m³, respectively. High concentrations beyond 100 ind. per 50 m³ were found at station 2, 3 and once at station 8 in the northern part and at station 7 in the southern part of the channel. Engraulidae larvae and different types of Gobiidae were the dominant groups in the channel. These two families reached almost 76% of the whole ichthyoplankton in the catches. They are followed by Achiridae, Clupeidae, Terapontidae, Sciaenidae, Tetraodontoidei, Carangidae, Syngnathidae, Cottidae (?) and Blennioidei (summing up to 95% of the caught fish larvae in the channel). Nearly all groups are found as adults in the channel. Only five families are represented exclusively by larvae: Achiriidae, Cottidae, Terapontidae, Exocoetidae and Ephippidae. From the latter, only Exocoetidae form an oceanic group. Based on the taxa composition, it is assumed, that the importance of the estuary as nursery ground for shelf and oceanic fish is low. Key words: Ichthyoplankton; estuary; larval distribution;