Seagrass Cymodocea nodosa and seaweed Ulva lactuca as tools for trace element biomonitoring. A comparative study

Abstract

This study compared the capacity of the seagrass Cymodocea nodosa and the green alga Ulva lactuca to sequester the trace elements Cd, Cr, Cu, Ni, Pb and Zn, in seawater and benthic sediments, under the same environmental conditions. Samples of C. nodosa leaves and U. lactuca thalli were collected in four sites off the coast of Sicily (Italy), with varying degrees of anthropogenic impact. C. nodosa accumulated generally higher levels of trace elements, suggesting a better performance in marine phytoremediation. In turn, C. nodosa and U. lactuca showed a similar performance regarding the bioindication of trace elements. Since salinity, temperature and pH had relatively constant values, their role in the accumulation processes in both species should be considered as secondary. Although C. nodosa and U. lactuca fulfill several criteria as bioindicators, including widespread distribution, abundance and tolerance to toxicity, their regular use in biomonitoring programs is still limited.

Keywords: Little Neptune grass; Marine pollution; Mediterranean Sea; Metals; Sea lettuce; Sicily.