Sílvio José de Macêdo

Influence of the Amazon and Para Rivers on Water Composition and Phytoplankton Biomass on the Adjacent Shelf

Abstract In the context of the REVIZEE programme, an extensive sampling cruise was carried out in the northern section of the Brazilian Exclusive Economic Zone on board O.V. Antares (Operation North III). Several parameters were surveyed along the Amazon continental shelf during this cruise, such as horizontal and vertical distributions of temperature, salinity, dissolved oxygen, pH, dissolved inorganic nutrients, and phytoplankton biomass. Water with salinity below 33 psu and high silicate content was observed throughout the shelf, indicating the influence of the Amazon River plume up to a distance of 147 km from the coast; pH always remained alkaline. Water temperature was relatively homogeneous at the surface, with an average of 28°C. A permanent thermocline was detected in oceanic regions. Coastal waters were eutrophic, well oxygenated (maximum of 6.54 mL O2 L−1), and presented high chlorophyll a (maximum of 9.8 mg chlorophyll a m−3) and nutrient concentrations (up to 9.54 μmol L−1 NO3−, 0.89 μmol L−1 PO42−, and 108.59 μmol L−1 Si044−). Oceanic waters adjacent to the Amazon shelf presented high transparency (Secchi depth up to 35 m) and chlorophyll a (mean: 0.1 mg m−3) and low nutrient concentrations (maximum of 1.58 μmol L−1 NO3−, 0.18 μmol L−1 PO42−, and 5.92 μmol L−1 Si044−). Cluster analysis performed with all data showed a clear separation between coastal and oceanic waters at the surface layer and at 1% light penetration layers. This separation into two groups of stations clearly represents areas with different degrees of influence from the discharges of the Amazon Basin. The Amazon River is very important to the nutrient budgets of the shelf.

Impactos da construção do Porto de Suape sobre a comunidade fitoplanctônica no estuário do rio Ipojuca (Pernambuco-Brasil)

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: Oscillatoria princeps, Chaetoceros lorenzianus, Climacosphenia moniligera and Licmophora abbreviata. Phytoplankton densities ranged from 142,000 cells.l-1 to 1,789,000 cells.l-1 predominating the nanoplankton fraction, being higher in the dry season, during periods of intense sunlight and flood tide. Species diversity was high (> 3 bits.cel.l-1), explained by the environment heterogeneity. The phytoplankton community changed after port construction. Now, there are many littoral species due to the shallow depth and high hydrodinamism of the area and a decrease of 70% in cell density compared to the results obtained before port construction where predominated planktonic species and higher number of cells liter.

Impacts of the construction of the Port of Suape on phytoplankton in the Ipojuca River estuary (Pernambuco-Brazil)

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 mm 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 (Kutzing) 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).

Hydrology and phytoplankton community structure at Itamaracá-Pernambuco (Northeast Brazil)

Estudos hidrologicos e fitoplanctonicos foram realizados em dois perfis perpendiculares a costa, em frente a Ilha de Itamaraca-PE (perfis Orange e Catuama), durante a Expedicao do Navio de Pesquisas Victor Hensen, dentro do acordo de cooperacao bilateral celebrado entre o Departamento de Oceanografia da UFPE e o Centro de Ecologia Marinha Tropical (ZMT-Bremen-Alemanha). A camada superficial esta caracterizada por uma zona de estabilidade termica e salina. As concentracoes de nutrientes foram geralmente mais baixas na superficie e mais elevadas em profundidades acima de 100m. Foram identificados 102 taxons, incluindo 49 diatomaceas, 49 dinoflagelados, 3 cianoficeas e 1 euglenoficea. A diversidade especifica e equitabilidade foram elevadas, indicando um equilibrio ambiental. A associacao das amostras evidenciou 2 grupos, um caracterizado por dinoflagelados e diatomaceas, englobando a maioria das estacoes e outro, compreeendendo as estacoes 32 e 38, caracterizadas pelo predominio de Oscillatoria erythraeum. A associacao de especies evidenciou 4 grupos, sendo o maior caracterizado por 49 especies marinhas oceânicas e 31 especies costeiras e eurialinas. A densidade fitoplanctonica variou de 50.000 cels.l-1 a 590.000 cels.l-1 denotando um ambiente oligotrofico.

Chlorophyll a and nutrient distribution around seamounts and islands of the tropical south-western Atlantic

Data collected on two large-scale surveys around the seamounts and islands off north-eastern Brazil during 1997 and 1998 provided information on the distribution of Chlorophyll a and inorganic nutrients. During both surveys, the concentrations of Chlorophyll a and nutrients were highly patchy. The highest measurement of Chlorophyll a was 3.91 µg L–1 during 1997. A wide range of nutrient concentrations were found, from undetectable values to a maximum of 17.52 µm L–1 (Si), 1.37 µm L–1 (PO4), 10.02 µm L–1 (NO3) and 0.72 µm L–1 (NO2). In 1998, concentrations of Chlorophyll a and nutrients (nitrite and nitrate) were far more uniform, with Chlorophyll a concentrations lower and phosphate concentrations generally higher than in 1997. Topography–flow interaction on thermohaline structures was observed around Saint Peter and Saint Paul Archipelago and in the Fernando de Noronha Chain, creating a patchy pattern around the island and seamounts. Nutrients exhibited an inverse linear relationship with temperature and salinity and an exponential decay relationship with Chlorophyll a.

Diurnal and spatial variation of the mesozooplankton community in the Saint Peter and Saint Paul Archipelago, Equatorial Atlantic

The aim of this study is to assess small-scale variations in and spatial comparisons among the composition, distribution and abundance of the main zooplankton groups in the Saint Peter and Saint Paul Archipelago (SPSPA). Plankton samples were collected in May 2008 by net with a 300 µm mesh size. Sampling was carried out at two stations, Inner and Outer, during five consecutive days in the early morning and late afternoon. A total of 153 zooplankton taxa were identified. Copepoda was the most abundant and frequent group (with 49 species identified). Exocoetidae (Teleostei) eggs were also present in large numbers. No significant differences were found between stations or between day and night samples. The observed biomass was low; however, it was superior to that observed in the open ocean. The density of zooplankton was also low, but it increased slightly during the night. Indicator species for upwelling, such as Phaenna spinifera and Flaccisagitta hexaptera , were observed. We conclude that physical factors are important for structuring the SPSPA zooplankton community.

Urban secondary sewage: an alternative medium for the culture of Tetraselmis chuii (Prasinophyceae) and Dunaliella viridis (Chlorophyceae)

The effect of different concentrations (10, 20, 30 and 40%) of urban secondary sewage on the growth of Tetraselmis chuii (Prasinophyceae) and Dunaliella viridis (Chlorophyceae) was examined to verify the possibility of its use as an alternative culture medium for these species. Stocks and 700mL duplicate batch cultures were maintained under controlled laboratory conditions. 30% and 40% additions were the most efficient for the growth of both species. Statistical analysis of the adjusted growth (cell.mL-1) and biomass (µg chlorophyll-a.mL-1) curves performed using the Chi-square test (p<0.05) demonstrated significant differences between the nutritive medium f/2 and the 40% addition used for these two species. The results suggested that some of the concentrations tested here yielded satisfactory cell densities and growth rates when compared with other culture media (macroalgae, bovine and chicken manure extracts). Thus it could be used by semi intensive aquaculture systems.

Heavy metal concentrations in sediments of the Capibaribe River Estuary in the Metropolitan Region of Recife, Pernambuco-Brazil

The objective of this research was to assess the heavy metal concentration in sediments from the Capibaribe river estuary located in Recife City (Pernambuco, Brazil). Sampling was carried out in the rainy and dry seasons in six fixed stations along the river estuary during the rainy/2002 and dry/2003 seasons. Superficial sediment samples were collected between 0 – 10 cm deep, during low tide. 14 traps were also used and the settled sediment collected 24 hours later. Dissolved oxygen, pH, salinity, temperature and water transparency data were obtained in the same stations. To quantify cadmium, cobalt, copper, chromium, iron, lead, manganese, nickel and zinc metals an Atomic Emission Spectrometer with Inductive Coupled Plasma (ICP-AES) method was used. No cobalt, lead or nickel were detected, all of them below the quantifying limit. The obtained results to both sediments and sedimentary material showed concentration levels above “background” indicating a high level of contamination in the study area. The pH, salinity, temperature and water transparency parameters results are as expected to estuarine areas. The dissolved oxygen content indicated that pollution is threatening the water quality in the area studied.

N:Si:P atomic ratio in the Santa Cruz Channel, Itamaracá-PE (Northeast Brazil): a nyctemeral variation

Estudos nas Barras Orange e Catuama do Canal de Santa Cruz, Itamaraca-PE, foram realizados durante os periodos chuvoso e seco, num ciclo nictemeral, com intervalo de 3 horas entre as coletas, numa seccao transversal. O objetivo foi a determinacao da variacao espacial e temporal da relacao N:Si:P, suas possiveis inter-relacoes e dependencias, bem como a influencia das condicoes hidrodinamicas locais, influenciadas pela variacao das mares em diferentes periodos do ano. Nitrito-N e nitrato-N, foram mais elevados no periodo chuvoso, enquanto que amonia-N, fosfato-P e silicato-Si, foram no periodo seco, sendo este resultado diferente de pesquisas anteriores. A relacao N:P foi menor que 16:1, nos diferentes periodos e estacoes, sendo porem, mais elevada no periodo chuvoso e na barra Orange, enquanto que a relacao Si:P esteve sempre superior a 15:1. Neste estudo, o nitrogenio foi o nutriente limitante para o fitoplâncton nesta area. Durante os ciclos nictemerais observados, os principais fatores que influenciaram a composicao dos parâmetros fisicos, quimicos e biologicos foi o ciclo de mares e parâmetros meteorologicos.

Series temporales de variables hidrobiológicas en un estuario tropical (Brasil)

Este trabajo muestra los resultados de series temporales en el estuario de Barra de Jangadas en el Noreste de Brasil. El estudio fue realizado durante siete dias consecutivos desde una marea de sicigia a una de cuadratura, en una estacion fija durante el periodo seco (enero) y lluvioso (julio), en 2001. Se analizaron parametros meteorologicos (precipitacion pluviometrica, evaporacion, intensidad de los vientos), hidrologicos (temperatura, salinidad, pH, oxigeno disuelto-OD y tasa de saturacion, DBO5, nutrientes (NH3 +NH4, NO2 -, NO3 -, PO4 -3, SiO2)), batimetria, intensidad de las corrientes y clorofila-a. El analisis de componentes principales (ACP), explico el 80% de la varianza total, mostrando una relacion inversa entre nutrientes y OD, salinidad y pH. Este analisis mostro una correlacion positiva entre la bajamar y los nutrientes, indicativo de polucion de origen antropogenica. La temperatura del agua vario poco estacionalmente, similar a la clorofila-a que caracterizo un ambiente eutrofico con valores superiores a 20 mg m-3. Mayores concentraciones de sal ocurrieron en el mes estival y sin mostrar estratificacion vertical. El oxigeno disuelto vario significativamente entre ambos periodos. Los valores totales de nitrogeno y fosforo inorganico disuelto en julio fueron en promedio 2 y 5 veces superiores a los de enero, respectivamente. Las medias de N:P variaron de 35:1 en enero a 8:1 en julio, siendo ambos, el fosfato y el nitrogeno limitantes para el crecimiento del fitoplancton. Diferencias dia/noche evidenciaron que, en enero, el amonio decrecio en mayor proporcion que el resto de los compuestos nitrogenados, indicativo de la asimilacion por los organismos autotroficos durante el dia.