Cintia Yamashita

Assessment of the health quality of Ria de Aveiro (Portugal): Heavy metals and benthic foraminifera

This work analyses the distribution of heavy metals in the sediments of Ria de Aveiro (Portugal) assessed by total digestion and sequential chemical extraction of the sediments. The influence of environmental parameters on the living benthic foraminiferal assemblages was studied. The most polluted parts in the Ria de Aveiro are areas where the residence time is high and cohesive sediments are deposited. Organic matter, which is an excellent scavenger for a number of metals, is in general more abundant in the finer deposits of this lagoon, which act as sinks of anthropogenic pollutants. This condition is observed in Aveiro canals and Murtosa channel where sediments with the highest concentrations of Zn, Pb, Cu, and Cr are found. The sediments of Murtosa channel are also enriched in As, Co and Hg. In Aveiro canals the enrichment of heavy metals is mostly related to the past industrial production at their margins (ceramic and metallurgy), whereas in Murtosa channel with effluent discharges of the Chemical Complex of Estarreja. Foraminiferal density and diversity reach higher values near the lagoon mouth under higher marine influence and decline in general under very low-oxygen conditions. Some species seems to be indifferent to the increasing of TOC (e.g. Haynesina germanica and Ammonia tepida) and some have an opportunistic behaviour in areas with very depressed levels of oxygen (e.g. A. tepida and Quinqueloculina seminulum) whereas other species can better tolerate sulphide/reducing conditions (e.g. H. germanica, Bolivina ordinaria, Buliminella elegantissima, Bulimina elongata/gibba and Nonionella stella) a widespread condition in this lagoon. Foraminiferal density and some species are negatively correlated with concentrations of heavy metals. A most sensitive group of species to higher concentrations of heavy metals is identified (such as B. ordinaria, B. pseudoplicata and B. elongata/gibba) and another one of more tolerant species (such as H. germanica A. tepida and Q. seminulum). Foraminifera are more tolerate higher available concentrations (AC) of Zn in any phase than higher AC of Cu adsorbed do clay minerals (F1) and associated with Fe and Mn oxides (F2) and of Pb in F2; the phase F2, probably the most mobile phase, and even phase F1 seems to be more toxic than the increasing of metals in organic matter (F3).

Seasonal variation in abundance of the developmental stages of Euterpina acutifrons (Copepoda: Harpacticoida) from the São Sebastião Channel, southern Brazil

The annual variation in abundance of all developmental stages of the harpacticoid copepod Euterpina acutifrons (Dana) was studied in plankton samples collected fortnightly from May 1971 to May 1972 in the São Sebastião Channel, Brazil. The species occurred throughout the year, becoming scarce during the summer. Three distinct peaks of abundance were evident (July, December and April), the most pronounced being in July (winter). Generation time in the field (26°–27°C) was calculated as approximately two weeks. Small males were always more abundant that large males but densities peaked during the coldest months when the highest populational breeding peak occurred. Males usually outnumbered females, and young members (nauplii and copepodites) outnumbered adult forms. Results are compared with tropical, northern hemisphere and New Zealand data.

Aglauropsis kawari (Limnomedusae: Olindiasidae), a new species from the South Atlantic Ocean

A new species of Limnomedusae belonging to the genus AglauropsisF. Müller, 1865, is described from the coastal waters off Rio Grande do Sul, Brazil. The new species belongs to the family Olindiasidae. It is named Aglauropsis kawari sp. n. and differs from the other species of the genus by the number of tentacles and statocysts and, mainly, by the shape and position of the gonads. The possibility of Aglauropsis agassiziMüller, 1865 and A. kawari sp. n. being synonyms is discussed. The vague description of the former does not permit this assumption.

Associações de Foraminíferos em Resposta a Variações Ambientais da Laguna de Aveiro – Portugal

This study is based on the characterization of the sedimentary environment in selected sites, located in Aveiro canals and salt-pans, in the eastern-central and northern part of Aveiro Lagoon. Results of physicochemical parameters measured in water and sediment, as well as grain size, geochemical and microfaunal (benthic foraminifera) data are analyzed. The determinants factors of spatial and seasonal variability of living and dead foraminiferal assemblages were analyzed in two sampling periods, late summer and late winter, in order to study the response of these organisms to the impact caused by pollution and sazonal variation of physicochemical parameters. Biotic and abiotic results are analyzed to discriminate sites with different degree of environmental stress. The conditions of salinity, temperature, pH and Eh in the studied sites vary spatially and seasonally. The sediment in these locations is generally poorly oxygenated, suboxic or even anoxic a few millimeters below the surface. Some of the sites are affected by chemicals derived from industrial effluents and urban contaminants. The most polluted areas by heavy metals such as As, Cr, Cu and Zn are Porto de Salreu, Largo do Laranjo and some locals in the city of Aveiro. Foraminiferal assemblages in the studied sites integrate common lagoonal and estuarine euryhaline and eurythermic species, most of which tolerant to the oxygen reduction. The size of the living foraminiferal communities is reduced and their structure affected by increasing concentrations of heavy metals such as As, Cr, Cu and Zn, as well as by the high variability of environmental parameters such as low Eh, related to depressed levels of oxygen in the sediment, leading to the death of many species. The results also indicate a greater tolerance of some opportunistic species to the Pb enrichment, since the environment offer them abundance and quality of food.