Bridging archaeology and marine conservation in the Neotropics.

Anthropogenic impacts on tropical and subtropical coastal environments are increasing at an alarming rate, compromising ecosystem functions, structures and services. Understanding the scale of marine population decline and diversity loss requires a long-term perspective that incorporates information from a range of sources. The Southern Atlantic Ocean represents a major gap in our understanding of pre-industrial marine species composition. Here we begin to fill this gap by performing an extensive review of the published data on Middle and Late Holocene marine fish remains along the southern coast of Brazil. This region preserves archaeological sites that are unique archives of past socio-ecological systems and pre-European biological diversity. We assessed snapshots of species compositions and relative abundances spanning the last 9500 years, and modelled differences in species' functional traits between archaeological and modern fisheries. We found evidence for both generalist and specialist fishing practices in pre-European times, with large body size and body mass caught regularly over hundreds of years. Comparison with modern catches revealed a significant decline in these functional traits, possibly associated with overfishing and escalating human impacts in recent times.

Multi-technique investigation of potshards of a cerrito (earthen mound) from southern Brazil.

The physicochemical investigation of ceramics crafted and managed by ancient humans allows a better understanding of their social, technological, economical, routine and artistic activities. The Brazilian State of Rio Grande do Sul presents the biggest number of registered archaeological sites in the country, and many of them are earthen mounds, locally known as cerritos de indios. This kind of archaeological site is of utmost importance to understand the social development of the biome Pampa - including areas from Brazil, Argentina and Uruguay - and almost nothing is known about the physicochemical composition of the artifacts from the Brazilian portion. In this work we investigated the mineral phases present in archaeological ceramics from the cerrito Pavão I (PSG-20) by means of white light microscopy (petrography), Raman micro-spectroscopy, XRD and XRF spectroscopies, and FTIR-ATR. Different minerals were identified and allowed to propose a firing temperature of ca. 500-650 °C. It was also suggested that the makers used both oxidizing and reducing atmospheres, that more than one clay source was used to prepare the ceramics, and that trace elements are present in different shards. Regarding the multi-analytical technique approach, the results highlight the importance of complementary investigations and underline the role of Raman micro-spectroscopy for these objects.