Body size descriptor of Cymodocea nodosa indicates anthropogenic stress in coastal ecosystems

Abstract

1 - We studied skewness (asymmetry) of log-transformed relative frequencies of Cymodocea nodosa leaf length (SkLnRfLL) as an easily measurable indicator of anthropogenic stress in selected biotopes of Eastern Macedonia, North Aegean, Greece. 2 - Since the spatial variation of the skewness coefficient was not known, a random nested sampling design within a hierarchy of spatial scales ranging from 10’s of metres (area) to 100’s of metres (site) to kilometres (biotope) was implemented. Three Cymodocea nodosa biotopes of the eastern Kavala Gulf coasts (Nea Karvali, Erateino, Agiasma), with that of Nea Karvali being the most degraded (close to an industrial area), were sampled during the main seagrass growth season in July 2004. Fifty five quantitative samples with 60 or more Cymodocea leaves were analysed in total, using non-parametric and parametric nested ANOVA. 3 - Statistically significant variation (p<0.01) was observed at the biotope scale, showing maximum mean value in the most degraded biotope of Nea Karvali (3.7) and minimum mean values in the less impacted biotopes of Agiasma (2.3) and Erateino (2.7). This pattern was also confirmed by post-hoc comparison. 4 - SkLnRfLL, based on the theory of normal population distribution and metabolic theory of ecology, seems to be a promising indicator of anthropogenic stress in North Aegean coastal ecosystems.