Environmental quality assessment of Grand Harbour (Valletta, Maltese Islands) : a case study of a busy harbour in the Central Mediterranean Sea

Abstract

Contamination levels by plastic debris, trace elements and persistent organic pollutants were assessed

and related to macrobenthic diversity within soft bottoms of Grand Harbour (Malta, Central Mediterranean). Sediment toxicity was evaluated by ecotoxicological method, deploying Bacteria (Vibrio fischeri), Echinodermata (Paracentrotus lividus) and Crustacea (Corophium orientale). Univariate analysis (Pearson’s test) was used to test relationships between biodiversity

indices, pollutants and grain size. A multivariate approach (PERMANOVA) was applied to investigate for

any significant differences among sampling stations

concerning plastic abundances and to test the relationship between infaunal abundances and pollutant concentrations (the BIOENV test). Significant differences

in the plastic abundances were found between sampling

stations. The lowest value for Shannon-Wiener biodiversity index was associated to the highest sediment

pollution level. Multivariate analyses suggest that MBT and TBT were factors that most influenced

macrozoobenthic abundance and biodiversity. The bivalve Corbula gibba and the introduced polychaete

Monticellina dorsobranchialis were the most abundant found species.