Hyperaccumulation of metals in the shoot
system of plants is uncommon, yet taxonomically and geographically
widespread. It may have a variety of functions,
including defense against herbivores. This study investigated
the effects of hyperaccumulation on metal concentrations
across trophic levels. We collected plant material,
soil, and invertebrates from Portuguese serpentine outcrops
whose vegetation is dominated by the nickel hyperaccumulator
Alyssum pintodasilvae. Samples were analyzed for
nickel, chromium, and cobalt. Grasshoppers, spiders, and
other invertebrates collected from sites where A. pintodasilvae
was common had significantly elevated concentrations
of nickel, compared to nearby sites where this hyperaccumulator
was not found. Chromium and cobalt, occurring in
high concentrations in the serpentine soil but not accumulated
by A. pintodasilvae, were not elevated in the invertebrates.
Therefore, it appears likely that a flux of nickel to
herbivore and carnivore trophic levels is specifically facilitated
by the presence of plants that hyperaccumulate this
metal. The results may be relevant to the development of
phytoremediation and phytomining technologies, which use
plants to extract metals from the soil.
