Positive precipitation–evaporation budget from AD 460 to 1090 in the Saloum Delta (Senegal) indicated by mollusk oxygen isotopes

Effects of Holocene climate change, volcanism and mass migration on the ecosystem of a small, dry island (Brava, Cabo Verde)

“…For instance, taxa such as Euphorbia tuckeyana plot in the bottom left of the CCA graph, where the most influential environmental variables are organic matter and erosion (axis‐1 correlation scores: −0.78, −0.53) (Figure 4). Climate could have also played a role in this process: palaeoclimatological research in Senegal (c. 770 km from Brava) indicates a stable and drought‐free period between 1500 and 900 BP (Azzoug et al, 2012). Further research and integration of palaeoenvironmental records, as well as the study of independent palaeoclimatic lines of evidence could clarify the relationships between volcanism, vegetation change and climate in Cabo Verde.…”

“…For instance, taxa such as Euphorbia tuckeyana plot in the bottom left of the CCA graph, where the most influential environmental variables are organic matter and erosion (axis-1 correlation scores: −0.78, −0.53) (Figure 4). Climate could have also played a role in this process: palaeoclimatological research in Senegal (c. 770 km from Brava) indicates a stable and drought-free period between 1500 and 900 BP (Azzoug et al, 2012).…”

Prehistoric cooking versus accurate palaeotemperature records in shell midden constituents

“…Moreover, mollusc shells or fish otoliths derived from shell middens can provide proxy records such as oxygen isotopes which enable the reconstruction of highest-resolution (sub-seasonal) palaeoenvironmental conditions of ancient coastal environments 5 – 7 . Despite allowing the reconstruction of foraging seasonality 3 , 4 , past upwelling intensities 8 – 10 or seasonal freshwater discharge patterns 11 – 13 , ontogenetic geochemical signatures of shell midden constituents have become an important tool for the reconstruction of ancient water temperature seasonality within coastal areas 14 – 17 . In particular shell midden deposits which cover time spans of up to several millennia allow the long-term reconstruction of environmental change with a sub-seasonal resolution 18 .…”

On the spatial coherence of rainfall over the Saloum delta (Senegal) from seasonal to decadal time scales

“…Their study confirmed that intervals of severe drought lasting for periods ranging from decades to centuries are characteristic of the monsoon and are linked to natural variations in Atlantic temperatures. In the Saloum region, located on the Senegalese Atlantic coast (Figure 1) and highly sensitive to changes in the evaporation-precipitation budget, an exceptional opportunity for paleo-monsoon reconstruction is offered by the presence of fossil shell middens that can be used as high resolution archives (Azzoug et al, 2012a). Mollusks indeed record in the geochemistry of their shells the surrounding environmental conditions.…”