Laurent Londeix

Understanding deep-time marine biodiversity change under the combined effects of climate and connectivity changes is fundamental for predicting the impacts of modern climate change in semi-enclosed seas. We quantify the Late Miocene–Early Pliocene [11.63 to 3.6 million years (Ma)] taxonomic diversity of the Mediterranean Sea for calcareous nannoplankton, dinocysts, foraminifera, ostracods, corals, molluscs, bryozoans, echinoids, fishes, and marine mammals. During this time, marine biota was affected by global climate cooling and the restriction of the Mediterranean’s connection to the Atlantic Ocean that peaked with the Messinian salinity crisis. Although the net change in species richness from the Tortonian to the Zanclean varies by group, species turnover is greater than 30% in all cases, reflecting a high degree of reorganization of the marine ecosystem after the crisis. The results show a clear perturbation already in the pre-evaporitic Messinian (7.25 to 5.97 Ma), with patterns differing among groups and subbasins.

Massive salt accumulations, or salt giants, have formed in highly restricted marine basins throughout geological history, but their impact on biodiversity has been only patchily studied. The salt giant in the Mediterranean Sea formed as a result of the restriction of its gateway to the Atlantic during the Messinian Salinity Crisis (MSC) 5.97 to 5.33 million years ago. Here, we quantify the biodiversity changes associated with the MSC based on a compilation of the Mediterranean fossil record. We conclude that 86 endemic species of the 2006 pre-MSC marine species survived the crisis, and that the present eastward-decreasing richness gradient in the Mediterranean was established after the MSC.

We present a summary of two round-table discussions held during two subsequent workshops in Montreal (Canada) on 16 April 2014 and Ostend (Belgium) on 8 July 2015. Five species of the genus Achomosphaera Evitt 1963 Evitt WR . 1963. A discussion and proposals concerning fossil dinoflagellates, hystrichospheres, and acritarchs, I. National Academy of Sciences, Washington, Proceedings. 49(2):158–164. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] and 33 of the genus Spiniferites Mantell 1850 emend. Sarjeant 1970 Sarjeant WAS . 1970. The genus Spiniferites Mantell, 1850 (Dinophyceae). Grana. 10(1):74–78. [Taylor & Francis Online] , [Google Scholar] occuring in Pliocene to modern sediments are listed and briefly described along with remarks made by workshop participants. In addition, several holotypes and topotypes are reillustrated. Three species previously assigned to Spiniferites are here considered/accepted as belonging to other genera: Impagidinium inaequalis (Wall and Dale in Wall et al. 1973 Wall D , Dale B , Harada K . 1973. Descriptions of new fossil dinoflagellates from the Late Quaternary of the Black Sea. Micropaleontology. 19(1):18–31. [Crossref] , [Google Scholar] ) Londeix et al. 2009 Londeix L , Herreyre Y , Turon J-L , Fletcher W . 2009. Last Glacial to Holocene hydrology of the Marmara Sea inferred from a dinoflagellate cyst record. Rev Palaeobot Palynol. 158(1-2):52–71. [Crossref], [Web of Science ®] , [Google Scholar] , Spiniferites? rubinus (Rossignol 1962 Rossignol M . 1962. Analyse pollinique de sédiments marins quaternaires en Israël II. - Sédiments pleistocènes. Pollen et Spores. 4:121–148. [Google Scholar] ex Rossignol 1964 Rossignol M . 1964. Hystrichosphères du Quaternaire en Méditerranée orientale, dans les sédiments Pléistocènes et les boues marines actuelles. Revue de Micropaléontologie. 7:83–99. [Google Scholar] ) Sarjeant 1970 Sarjeant WAS . 1970. The genus Spiniferites Mantell, 1850 (Dinophyceae). Grana. 10(1):74–78. [Taylor & Francis Online] , [Google Scholar] , and Thalassiphora balcanica Balteş 1971. This summary forms the basis for a set of papers that follows, where points raised during the workshops are explored in greater detail.