Reproducibility of bacterial and copepod density assessment in bathing and artisanal fishing water of the Eastern Mediterranean

Faecal bacteriological indicators and copepod density assessment are used to predict the environmental health of seawater for recreational bathing and artisanal fishing, respectively. The reproducibility of bacterial culture-count and copepod-microscopic density assessment after respective capturing of the sampled seawater on 0.22 m Millipore filter and 150 m mesh sieve copepod net, is determined. The paired t-test was performed to evaluate the reproducibility of each obtained parameter-mean in first and second simultaneous water samplings of a total of 10 sites selected along a 200 km distance, at about 500 - 1000 m offshore. The means of each bacterial indicator in colony forming units/100 ml of sea water in first versus (vs.) second sampling of the 10 sites, followed by the P values were: total bacterial count (6.3 × 10² vs. 6.2 × 10², P = 0.958), Coliform count (3.9 × 10² vs. 2.6 × 10², P = 0.212), Staphylococcus aureus (3.0 × 10² vs. 2.4 × 10², P = 0.551), and Clostridium perfringens (1.4 × 10 vs. 0.4 × 10, P = 0.298). However, the average copepod density in five microscopic fields at magnification of 100× in sample 1 vs. sample 2 were: (1.40 vs. 1.60 respectively, P = 0.267). This sampling design along the 200 km coast, the used technique for capturing the indicators, and the quantitative laboratory assessment of the indicator densities resulted in high reproducibility with a non-significant difference between the first and second sampling within the 95% confidence limits (P > 0.05), a data in support of future monitoring protocol of the environmental health of the coastal water of the Mediterranean sea.