Portuguese native Artemia parthenogenetica and Artemia franciscana survival under different abiotic conditions

There are currently only two places in Portugal were native Artemia parthenogenetica can still be found. All other known populations have been eradicated by the invasive species Artemia franciscana, which has caused great losses of Artemia biodiversity in the Mediterranean region. The diploid strains found at the Portuguese salines are therefore of high conservation value. This study aims to assess the survival of these native A. parthenogenetica strains and of A. franciscana under a variety of environmental conditions. The effects of water temperature and salinity, of photoperiod and food supply (shortage) were studied in an experimental setup. The Portuguese parthenogenetic Artemia populations showed great variability in their physiological response to different abiotic conditions, suggesting possible local adaptations in response to different selective pressures experienced. For most of the conditions studied A. franciscana outcompeted the Artemia strain from Aveiro, whereas the strain from Rio Maior was more resistant than the A. franciscana under conditions that were similar to its local habitat. Strain-specific resistance to chemical conditions, related to pollution, are appointed as a potential cause why A. franciscana did not successfully invade Aveiro saline. The saline of Rio Maior has possibly not yet been invaded due to the fitness of its local Artemia strain in combination with its inland location. (C) 2012 Elsevier B.V. All rights reserved.