Metal effects on germination and seedling development in closely-related halophyte species inhabiting different elevations along the intertidal gradient.

Seed germination and seedling establishment are very sensitive plant stages to metal pollution. Many halophyte species colonizing salt marshes are able to germinate and establish in highly contaminated habitats and low marsh halophyte species seem to show higher tolerance to metals than high marsh species. We analyzed the effects of copper, zinc and nickel in concentrations up to 2000 µM on seed germination and seedling growth in two closely related species of Sarcocornia, S. perennis, a low marsh species, and S. fruticosa, a high marsh species. Germination of both halophytes was not affected by any metal concentration, and their seedling growth, mainly radicle length, was reduced by increasing metal concentrations. Seedlings of S. perennis showed higher tolerance to the three metals than those of S. fruticosa. Our results are useful for designing ecotoxicological bioassays and planning phytoremediation projects in salt marshes.