Explosive demographic expansion by dreissenid bivalves as a possible result of astronomical forcing

[摘要] Human induced range expansions of invasive dreissenid bivalves are of greatconcern. However, the underlying biological processes are only poorlyunderstood, partly due to the lack of information on natural expansionevents. Here we use the extinct bivalve species Sinucongeriaprimiformis as a model organism for testing natural (i.e. pre-Anthropocene)blooms of dreissenid species in a lacustrine system of Lake Pannon during theTortonian (~ 10.5 Myr; late Miocene). A total of 600 samples from a consecutivecore were evaluated for the relative abundance of this pavement-formingmollusc, which cover about eight millennia of late Miocene time with a decadalresolution.

Our data indicate that the settlement by bivalves in the offshoreenvironment was limited mainly by bottom water oxygenation, which followspredictable and repetitive patterns through time. These populationfluctuations might be related to solar cycles: successful dreissenidsettlement is recurring in a frequency known as the lower and upperGleissberg cycles with 50–80 and 90–120 yr periods. These cycles appearto control regional wind patterns, which are directly linked to water mixingof the lake. This is modulated by the even more prominent 500 yr cycle,which seems to be the most important pacemaker for Lake Pannon hydrology.

[学科分类] 地球化学与岩石