Assessment of sediment toxicity in the Lagoon of Venice (Italy) using a multi-species set of bioassays

Abstract

Within the framework of a Weight of Evidence (WoE) approach, a set of four toxicity bioassays involving the amphipod Corophium volutator (10 d lethality test on whole sediment), the sea urchin Paracentrotus lividus (fertilization and embryo toxicity tests on elutriate) and the pacific oyster Crassostrea gigas (embryo toxicity test on elutriate) was applied to sediments from 10 sampling sites of the Venice Lagoon (Italy). Sediments were collected during three campaigns carried out in May 2004 (spring campaign), October 2004 (autumn campaign) and February 2005 (winter campaign). Toxicity tests were performed on all sediment samples. Sediment grain-size and chemistry were measured during spring and autumn campaigns. This research investigated (i) the ability of toxicity tests in discriminating among sites with different contamination level, (ii) the occurrence of a gradient of effect among sampling sites, (iii) the possible correlation among toxicity tests, sediment chemistry, grain size and organic carbon, and (iv) the possible occurrence of toxicity seasonal variability. Sediment contamination levels were from low to moderate. No acute toxicity toward amphipods was observed, while sea urchin fertilization was affected only in few sites in just a single campaign. Short-term effects on larval development of sea urchin and oyster evidenced a clear spatial trend among sites, with increasing effects along the axis connecting the sea-inlets with the industrial area. The set of bioassays allowed the identification of a spatial gradient of effect, with decreasing toxicity from the industrial area toward the sea-inlets. Multivariate data analysis showed that the malformations of oyster embryos were significantly correlated to the industrial contamination (metals, polynuclear aromatic hydrocarbons, hexachlorobenzene and polychlorinated biphenyls), while sea urchin development to sediment concentrations of As, Cr and organic carbon. Both embryo toxicity tests were significantly affected by high ammonia concentrations found in the elutriates extracted from some mudflat and industrial sediments. No significant temporal variation of the toxicity was observed within the experimental period. Amendments to the set of bioassays, with inclusion of chronic tests, can certainly provide more reliability and consistency to the characterization of the (possible) toxic effects.

Metal Bioaccumulation and Oxidative Stress in Ulva laetevirens in the Venice Lagoon: Early Warning Biomarker for Metal Bioaccumulation

“…Most toxic metal(loid)s (As, Hg, Pb) were abundant, especially at PM, which is continuously exposed to contaminants originating from the industrial area of Porto Marghera and the so-called oil canal for oil transport in the central lagoon. Our results are in accordance with those reported in the recent papers for VL by Masiol et al [31] and Picone et al [43], especially for As and Ni. In surface sediments, the metalloid As showed an increasing concentration trend on a transect from Lido (close to SMM) towards the mainland of VL [44].…”

Assessment of the individual and mixture toxicity of cadmium, copper and oxytetracycline, on the embryo-larval development of the sea urchin Paracentrotus lividus

“…A number of aspects of the sea urchin gamete/embryo biology have been extensively used as a standard acute toxicity bioassay for assessing environmental stress effect (Marin et al 2007;Picone et al 2016;Morgana et al 2016). Among them are egg/sperm binding, fertilization rate, chronology of cell division, and abnormal larval development.…”

Fragrances as new contaminants in the Venice lagoon

“…However, even if these substances are not persistent pollutants in the strictest sense, they are persistently emitted in the environment, and we therefore cannot rule out chronic toxicity, also considering their oestrogenic effects or possible synergistic interactions (Charles and Darbre, 2009;Zhang et al, 2012). It is likely that the urban emissions containing FMs and other PCPs contribute to the overall toxicity of the waters and sediments at a level comparable to that of the industrial area (Picone et al, 2016), causing a decline of the plankton communities, if compared to other areas of the lagoon (Bianchi et al, 2003). Consequently, the main open question is to identify the environmental fate of these substances, namely whether FMs degrade in the aqueous system, accumulate in sediments and biota or volatilize into the atmosphere.…”