Assessment of water quality and concentration of heavy metals in fishes in the estuary of the Perizes River, Gulf of Maranhão, Brazil.

The present study evaluated physicochemical and microbiological variables of the water in the estuary of the Perizes River in the state of Maranhão, Brazil, heavy metal levels in the muscle tissue of fish species (Genyatremus luteus, Macrodon ancylodon, Sciades herzbergii and Mugil curema). Data were collected bimonthly between Nov 2017 and May 2018. Physicochemical variables of the water (pH, salinity, conductivity, dissolved oxygen and turbidity). The microbiological analysis of the water was performed using the multiple-tube method. Atomic absorption spectrophotometry was used for the determination of heavy metals in muscle tissue of the fishes. The results revealed minor fluctuations in the environmental variables, with the exception of turbidity. The microbiological quality of the water was associated with acceptable bacterial levels. Regarding heavy metals, acceptable concentrations were found of Al, Cu, Fe, Mn, Zn, Ni and Hg, whereas Cr and Pb were found at concentrations higher than the maximum.

Determination of metals in estuarine fishes in a metropolitan region of the coastal zone of the Brazilian Amazon.

The aim of the present study was to determine concentrations of cadmium, copper, chromium, manganese and iron in fishes in the São Marcos (SMB), São Jose (SJB) and Arraial (AB) Bays. Metal concentrations were determined using inductively coupled plasma optical emission spectrometry. Mean Cd and Cr levels were above the permissible limits set by different international or national guidelines in all three bays, whereas copper levels were well below the maximum acceptable limit. High concentrations of iron were found in all species analyzed, whereas high concentrations of manganese were found, especially in specimens caught in SJB. Spatial analysis indicated significant differences among the elements investigated. Copper was correlated more with SMB and AB as well as the species Macrodon ancylodon (carnivore) and Sciades herzbergii (omnivore). Cadmium and iron were strongly associated with AB and SJB, while manganese was only associated with SJB, mainly in carnivorous and herbivorous species.

Stable isotope evidence for dietary diversification in the pre-Columbian Amazon.

Archaeological research is radically transforming the view that the Amazon basin and surrounding areas witnessed limited societal development before European contact. Nevertheless, uncertainty remains on the nature of the subsistence systems and the role that aquatic resources, terrestrial mammalian game, and plants had in supporting population growth, geographic dispersal, cultural adaptations and political complexity during the later stages of the pre-Columbian era. This is exacerbated by the general paucity of archaeological human remains enabling individual dietary reconstructions. Here we use stable carbon and nitrogen isotope analysis of bone collagen to reconstruct the diets of human individuals from São Luís Island (Brazilian Amazon coast) dated between ca. 1800 and 1000 cal BP and associated with distinct ceramic traditions. We expanded our analysis to include previously published data from Maracá and Marajó Island, in the eastern Amazon. Quantitative estimates of the caloric contributions from food groups and their relative nutrients using a Bayesian Mixing Model revealed distinct subsistence strategies, consisting predominantly of plants and terrestrial mammals and variably complemented with aquatic resources. This study offers novel quantitative information on the extent distinct food categories of polyculture agroforestry systems fulfilled the caloric and protein requirements of Late Holocene pre-Columbian populations in the Amazon basin.