Impact of Metalliferous Mining on Salt Marsh Flora

Estuaries within Cornwall, UK have been accepting metal-rich tailings and water from mining for hundreds of years. Over time, saltmarsh ecosystems have developed on metal-rich sediments. Previous work at CSM has indicated that the floristic composition of these saltmarshes varies from characteristic British assemblages. Our hypothesis is metal-sensitive species are unable to colonise,
leading to an abundance of metal-tolerant species. Some saltmarsh species have the ability to accumulate metals without harm. Such plants may be able to indicate availability at metal-rich sites.
This research has classified the floristic communities of a number of saltmarshes in Cornwall. The zones within each marsh have been compared to various environmental factors. The influence of these is currently being assessed but nutrient status, pH and trace metals do not appear to be the prime reasons for community differences.
Metal concentrations within the roots and shoots of Salicornia, taken from one of the most metal-contaminated estuaries in Europe, have been measured over the past year and compared with sediment concentrations to assess seasonal differences in uptake and the relationship to levels in the sediment.
Results so far indicate that metal-rich saltmarshes may contain distinct assemblages of plants which are adapted to the special conditions. These unique ecosystems need more detailed study to assess their role in containing metals within the environment and conserving distinct ecotypes.