RESUMO -(Variação temporal do fi toplâncton em três praias urbanas do litoral Sul de Pernambuco, Nordeste do Brasil). Este trabalho teve como objetivo efetuar uma análise comparativa da estrutura da comunidade fi toplanctônica, variação da biomassa e dados ambientais, na zona de arrebentação das praias arenosas de Brasília Formosa (8º04'S; 34º52'W), Boa Viagem (8º07'S; 34º53'W) e Piedade (8º10'S; 34º54 'W) ) no período de estiagem. A morfologia e o hidrodinamismo dos ambientes de praia analisados não favoreceram a formação de manchas por acumulação de microalgas. Palavras-chave: praias arenosas, zona de arrebentação, clorofi la a, diatomáceas, Asterionellopsis glacialis ABSTRACT -(Phytoplankton temporal variation on three urban beaches of Pernambuco's South coast, Brazilian Northeast). This study aimed to make a comparative analysis of phytoplankton community structure, biomass variation and environmental data in the surf-zone of Brasilia Formosa (8º04'S; 34º52'W), Boa Viagem (8º07'S; 34º53'W) and Piedade (8º10'S; 34º54'W) sandy beaches, on the Pernambuco coast. Bottle and net samples were collected during the rainy season (May, June and July/2005) and the dry season (November, December/2005 and January/2006) with simultaneous environmental data collection (water temperature, salinity, suspended material, nitrite, nitrate, phosphate, silicate, rainfall, wind speed and direction). Among the 119 infrageneric taxa identifi ed, diatoms were the most representative group regarding abundance and frequency, notably Asterionellopsis glacialis ( ) in the dry season. Morphology and hydrodynamics were unfavorable to the formation of microalgae patches.

RESUMOO estuário do rio Ariquindá, foi analisado quanto a sua hidrologia, biomassa e produtividade fitoplanctônica entre agosto de 2005 e julho 2006, abrangendo o período chuvoso e de estiagem. As amostras foram coletadas mensalmente em três pontos fixos, na superfície da água durante a baixa-mar e preamar em maré de sizígia. A transparência da água foi menor no período chuvoso, o ambiente variou de oligoalino a eualino, as taxas de oxigênio dissolvido variaram desde zona de baixa saturação a supersaturada, os teores de silicato foram mais elevados no período chuvoso, enquanto os dos demais nutrientes (nitrito, nitrato e fosfato) foram baixos e não apresentaram padrão sazonal, espacial e nem entre os diferentes estágios de maré, o mesmo foi observado para a biomassa e a produtividade fitoplanctônica, exceto em relação aos estágios de maré. O estuário foi classificado como mesotrófico e a fração < 20µm do fitoplâncton foi a mais representativa para o ambiente, com percentual superior a 69% da biomassa fitoplanctônica. Com base nos teores de oxigênio dissolvido, sais nutrientes, biomassa e produtividade fitoplanctônica foi constatado que o estuário não sofre fortes impactos antrópicos, possui uma moderada capacidade produtiva, e a maré foi a forçante física condicionante do ambiente. ABSTRACTThe Ariquindá River estuary of concerning the hydrology, phytoplankton biomass and productivity, in a monthly sampling programme from August 2005 to July 2006, covering the rainy and dry season, at the surface and at three fixed points, during low and high tides in full moon tide. The water transparency was low in the rainy season and the water salinity varied from oligohaline to euhaline. The dissolved oxygen rates varied from low saturated to supersaturated zone. The silicate values were higher in the rainy season, while the concentrations of the other nutrients (nitrite, nitrate and phosphate) were low and did not show seasonal and spatial patterns, nor even between the different tide stages, the some was observed for phytoplankton biomass and productivity, except in relationship the tides stages. The estuary was classified as mesotrophic and the phytoplankton size fraction < 20µm predominated in the environment, representing more than 69% of the microalgae biomass. The ranges of dissolved oxygen rates, nutrients concentrations, phytoplankton biomass and productivity shows that the estuary is not submitted to strong human impacts, it has a moderate productivity, and the tide pattern was the main controlling physical factor of the system.

The contribution of the estuarine channel of Recife harbour to the eutrophication of the Recife coastal area was evaluated by quantifying the instantaneous transport of salt, dissolved inorganic nutrients (PO 4 À , SiOH 4 , NO 3 À , NO 2 À and, NH 4 þ ), material in suspension, Chlorophyll-a, pico-nanoplankton and microplankton during the rainy (June 2007) and dry (November 2007) seasons. The results showed that all of the dissolved nitrogenated nutrients, the silicate and the material in suspension had higher concentrations during the rainy season, whereas the phosphate and Chlorophyll-a (both the total and the pico-nanoplankton and microplankton fractions) showed greater concentrations during the dry season. All of the materials considered were exported to the sea except for Chlorophyll-a (pico-nanoplankton and microplankton fractions) during the dry season, when these materials were imported into the area. The total liquid transport in the rainy season was three times higher than that found for the dry season. Silicate represented nearly 85% of the total exported material during the rainy period, whereas during the dry season, phosphate and silicate represented 79% of the total exported material. The stratification and circulation processes indicated a well mixed environment. The water-renewal rate was low, as demonstrated by the input of phytoplankton biomass during November. The area was characterised as eutrophic during the months investigated.

The aim of this study was to investigate the phytoplankton as indicator of changes in water quality before (2011) during (2012) and after (2012) dredging, covering an interannual variation in the Beberibe River estuary (Brazil). The abiotic variables were examined (temperature, transparency, DO, salinity and BOD 5 ), chlorophyll a and phytoplankton composition. Most species was planktonic marine and despite the dredging, there was an increase in benthic species. Were dominant the cyanobacteria Planktothrix agardhii (rainy season) and the diatom Bellerochea malleus (dry season). The richness and diversity of species were similar before and during the dredging period, showing that the dredging did not cause significant changes; however, there was a progressive increase in planktonic diatoms, especially after the dredging. The short period of dredging was not enough to cause changes in phytoplankton community in the Beberibe River estuary.