Exploratory data analysis of the Mediterranean component of the BEEP programme.

Work Package 3 (WP3) uses the data generated by ecotoxicologists from 11 laboratories who sample twice per year at four sites (France, Italy, Spain and Greece) to conduct the Mediterranean portion of the BEEP programme (Biological Effects of Environmental Pollution in marine coastal ecosystems). The WP3 data have been compiled into files using a data base structure (one record=one measurement) that eases statistical analysis and importation of new data. Here we present our first attempt of exploratory analysis based on a subset of data from the campaigns in May and September of 2001 and 2002. For most biomarkers, data plot revealed a strong station*campaign interaction, confirmed by two-way ANOVAs. This could be "true" variability with biomarkers responding to contaminant inputs that have changed among the four sampling times. Alternatively it could betray analytical problems and inadequate sampling designs or a lack of stability in the biomarkers themselves whereby they change in random ways unrelated to environmental factors.