Seasonal variation of trace metal (Mn, Zn, Cu, Pb, Co, Cd) concentrations in compartments of the seagrass Cymodocea nodosa

• Published in: Botanica marina Vol. 56; no. 2; pp. 169 - 184
• Main Authors: Malea, Paraskevi, Kevrekidis, Theodoros, Potouroglou, Maria
• Format: Journal Article
• Language: English
• Published: 01.04.2013
• ISSN: 0006-8055; 1437-4323
• DOI: 10.1515/bot-2012-0138

Abstract The concentrations of six trace metals (Mn, Zn, Cu, Pb, Co and Cd) in five compartments (blades, sheaths, vertical rhizomes, main axis plus additional branches and roots) of the seagrass Cymodocea nodosa from the Gulf of Thessaloniki, Greece were determined monthly, together with potential associated variables (climate variables, sediment metal concentrations, plant compartment biomass, size and age). Uni- and multivariate data analyses were applied. Univariate analyses showed that leaf blades displayed the highest annual mean concentration of most metals (Mn, Zn, Pb, Co, Cd) analyzed, whereas sheaths had the highest Cu concentration; metal concentrations in blades generally showed a wider monthly variability than those in the other plant compartments, and especially roots. The multivariate pattern of metals in leaf blades showed a seasonal periodicity that appeared to be governed by the cumulative effect of plant growth dynamics and sediment metal content. In particular, most metal concentrations increased from April onwards, with enhancement of blade biomass, size and age, and remained high throughout the blade growing season, whereas Cu concentration showed the opposite pattern; an additional increase in blade Zn concentration during early winter coincided with a marked increase in sediment Zn content. The multivariate patterns of metals in the other plant compartments showed no distinct seasonality and were not markedly related to the examined variables. These findings are not consistent with the assumption that metals in seagrass tissues display an overall seasonal trend of markedly higher levels during the cold period. The present study stresses the need for more knowledge on metal seasonality in seagrass compartments and on the associated variables.