Life history and physiological responses of native and invasive brine shrimps exposed to zinc

Although a substantial amount of research exists on pollution and biological invasions, there is a paucity of understanding of how both factors interact. Most studies show that pollution favours the establishment of invasive species, but pollution may also promote local adaptation of native species and prevent the establishment of new incomers. However, evidence for this is extremely limited because most studies focus on successful invasions and very few on cases where an invasion has been resisted. Here we provide evidence of local adaptation of native species to pollution combining life history and physiological data. We focused on the invasion of the North American brine shrimp Artemia franciscana, which is causing a dramatic biodiversity loss in hypersaline ecosystems worldwide, and one of the last native Artemia populations in SW Europe (A. parthenogenetica from the historically polluted Odiel estuary, SW Spain). Life table response experiments were carried out in the laboratory to compare the demographic responses of A. parthenogenetica and a nearby A. franciscana population to long-term Zn exposure (0.2 mg L−1). We also evaluated oxidative stress by measuring antioxidant defences (catalase, glutathione reductase and superoxide dismutase) and lipid peroxidation (thiobarbituric acid reactive substances). A high concentration of Zn induced strong mortality in A. franciscana, which also showed high levels of lipid peroxidation, suggesting relatively poor physiological resistance to pollution compared with A. parthenogenetica. The age at maturity was shorter in A. parthenogenetica, which may be an adaptation to the naturally high mortality rate observed in the Odiel population. Exposure to Zn accelerated age at first reproduction in A. franciscana but not in A. parthenogenetica. In contrast, Zn had a stimulatory effect on offspring production in A. parthenogenetica,which also showed higher reproductive parameters (number of broods, total offspring and offspring per brood) than A. franciscana. Overall, the results of this study strongly suggest that native Artemia from Odiel estuary is locally adapted (at both, reproductive and physiological levels) to Zn contamination and that A. franciscana is highly sensitive. This is a good example of how pollution may play a role in the persistence of the last native Artemia populations in the Mediterranean.This work was funded by the Spanish Ministry of Economy and Competitiveness research project CGL2013-47674-P. Financial support was also provided by the Portuguese ‘Fundação para a Ciência e a Tecnologia’ (FCT) through MARE (UID/MAR/04292/2013), from the programs POPH (Portuguese Operational Human Potential Program) and QREN (Portuguese National Strategic Reference Framework) (FSE and national funds of MEC), through the PhD grants of A.J.P.C. (SFRH/BD/108224/2015) and P.A.V. (SFRH/BD/74524/2010). I.V. is supported by Generalitat Valenciana (GV-2014/085 PROMETEO-II). M.M.H. was supported by the Spanish Ministry of Economy and Competitiveness' (MINECO) and 'Universidad de Castilla-La Mancha' (UCLM) through a ‘Juan de la Cierva – Incorporación’ (IJCI-2014-20171) contract, and currently is funded by Junta de Comunidades de Castilla-La Mancha and the European Regional Development Fund (SBPLY/17/180501/000514). M.I.S. was supported by a Ramón y Cajal postdoctoral contract from the Spanish Ministry of Science and Innovation (MICINN).Peer reviewe