Anouncement: Kenneth Rijsdijk will present the latest results of the dodo research on the extinction meeting at the Natural History Museum in London!
QRA 1 Day Meeting: Extinction:- The Quaternary Perspective (in association with QUAVER and the Natural History Museum) date(s): 10:00, 19/09/12 – 19/09/12 venue: Natural History Museum, London
Climate induced mass mortality vs. human induced extinction: an interdisciplinary analyses of a dodo mass grave on Mauritius
Kenneth F. Rijsdijk, Perry de Louw, Julian Hume, Hanneke Meijer, John de Vos, Erik de Boer, Henry Hooghiemstra, Leon Claessens, Jens Zinke, Anwar Janoo & the Dodo Research Programme team.
The evidence for human induced extinctions is often controversial: extinction is often a diachronous event which can span several millennia, and the fossil record rarely provides continuous documents of human and pre-human vertebrate mortality events. In addition the effects of climatic change traditionally seen as a causal factor for extinction are spatiotemporary complex. On small (<2000 km2) volcanic islands human causality is clearer; vertebrate species usually become extinct within a few centuries after human settlements irrespective of climatic patterns. There are barely any conclusive cases of pre-human vertebrate extinctions on these islands since the last 1 Ma. This strongly demonstrates the importance of human agency in extinctions on islands. On the other hand the absence of records that register natural extinctions since the last 1 Myr begs the question whether taphonomic factors led to scarcity of sites and removal of pre-human paleontologic evidence, especially on acidic volcanic islands. The case is weakened further by the lack of any site registering the response of insular vertebrates to extreme climatic change events. We present multidisciplinary evidence (paleontology, geohydrology, paleoecology) of a vertebrate mass mortality event from a vertebrate concentration Lagerstätten at the marsh of Mare aux Songes, Mauritius (Rijsdijk et al. 2009). We estimate that within this 2 ha, 4200 year old marsh ca 0.5M individuals died within 150 yrs. We relate this mass mortality to a global mega-drought event that led to hydrological changes within the waterhole depriving the animals of fresh water and inducing water quality change. Our ongoing multiproxy research (geochemistry, stalagmites, palynology, corals) aims to collect independent evidence for mega-drought affecting the Mascarenes. Traditionally it is argued that oceanic islands are relative stable havens during climatic extreme events, however, our multidisciplinary research shows the opposite. Islands, due to their small size, are extremely sensitive to, and may even amplify climatic changes. Our evidence seems to suggest that island species, including the dodo, were highly resilient, enabling the species to survive climatic extremes. However, in spite of the dodo’s resilience, human interference and the multitude of changes humans brought about led to the extinction of multiple Mauritian species that had previously survived millions years of climatic change.
Rijsdijk K.F., J. P. Hume, F. Bunnik, V. Florens, C. Baider, B. Shapiro, J. van der Plicht, A. Janoo, O. Griffiths, L. W. van den Hoek Ostende, H. Cremer, T. Vernimmen, P. De Louw, A. Bholah, S. Saumtally, N. Porch, J. Haile, M. Buckley, M. Collins, E. Gittenberger. 2009. Middle-Holocene Concentration-Lagerstätten on oceanic island Mauritius provides a window into the ecosystem of the dodo (Raphus cucullatus). QuaternaryScience Reviews 21, 14-24.