Aerial map demonstrates erosional patterns and changing topography at Isimila, Tanzania (with corrigendum)

Abstract

Phenological shifts represent one of the most robust bioindicators of climate change. While considerable multidecadal records of plant and animal phenology exist for the northern hemisphere, few noteworthy records are available for the southern hemisphere. We present one of the first phenological records of fish migration for the southern hemisphere, and one of the only phenological records for the southwest Indian Ocean. The so-called ‘sardine run’ – an annual winter migration of sardines, northeast of their summer spawning grounds on the Agulhas Bank off the coast of Durban, South Africa – has been well documented in local newspapers given the importance placed on fishing and fishing-tourism in the region. An analysis of the first arrival dates of sardines reveals a 1.3 day per decade delay over the period 1946–2012. Although this phenological shift reveals a poor association with sea surface temperatures (SST), it coincides with a poleward shift in the position of the 21 °C mean annual SST isotherm – the threshold temperature for sardine populations. The timing of sardine arrivals near Durban corresponds closely with the number of mid-latitude cyclones passing over the Durban coastline during the months of April and May. The strength of the run is strongly associated with ENSO conditions. The complex suite of factors associated with this phenological shift poses challenges in accurately modelling the future trajectory for this migratory event.

Fourteen Years of Archaeological and Heritage Research in the Iringa Region, Tanzania

“…The ESA is best known in our study area from the site of Isimila, documented in the early 1950s (Howell 1961;Howell et al 1962). The site was recently reexamined, using an uncrewed aerial vehicle to document erosion and topographic changes as well as archaeological features (Bergstrom et al 2019). Isimila is a large erosional gully, famous for the hundreds of Acheulean hand axes, picks, and cleavers eroding out of the ravine walls.…”

“…It was one of the first places to be designated as a National Monument by the government of the Republic of Tanzania, which means it receives protection under the Antiquities Act number 10 of 1964. As argued by Bergstrom et al (2019), there is great potential for highly rewarding future archaeological excavations and for research that addresses the impact of erosion and other site formation processes in the area.…”

Geospatial Analysis in African Archaeology: Current Theories, Topics, and Methods

“…And yet, Africanists have excelled in the creative application of geospatial technologies. From GIS (Osei 2014) to geophysics (Fitton and Wynne-Jones 2017;Klehm and Ernenwein 2016;Magnavita 2017; Wynne-Jones 2012) to UAV systems (Bergstrom et al 2019), Africanists have actively collected remote sensing data where they were previously unavailable. The availability, affordability, and reliability of imagery such as Landsat, ASTER, SRTM, and Google Earth showcase how widely available imagery can be used effectively across multiple scales and geographic contexts (e.g., Bubenzer et al 2018;Harrower and D'Andrea 2014;Khalaf and Insoll 2019;Sadr and Rodier 2012;Sampson et al 2015).…”