Search

A series of 10 intra-laboratory bioassays and an inter-laboratory assay involving nine laboratories, were performed to validate the use of Amphibalanus amphitrite larvae as test organisms for ecotoxicological studies. The standardization protocol utilized Cadmium Nitrate as a reference toxicant and larval immobilization (after 24 and 48h) as the end-point. The statistical data analysis showed high homogeneity in intra-laboratory EC50 values among bioassay repetitions (coefficient of variation (CV)=15.8% after 24h and 16.9% after 48h); also CV values obtained in inter laboratory comparison exercise were not higher than the 50%, variation coefficient mentioned in the ISO standards for the precision of inter-laboratory assays. The results demonstrated that the protocol implemented for the balanus larval bioassay comply with the international standards both for intra- and inter-laboratory precision. [Copyright &y& Elsevier]

Abstract: The efficacy of the barnacle Balanus amphitrite as a bioindicator for Cd in the environment was investigated through simulation exercises in an ecotoxicological simulation model based on field data. The study showed in general that B. amphitrite is a good bioindicator to record mean trends of the Cd bioavailability in the environment. The model correct reflected differences between high and low patterns of Cd concentrations in the barnacle in the field, but it did not accurately reflect short-term temporal variations. A model investigation pointed out three issues that must be taken into account when using B. amphitrite as bioindicator for Cd bioavailability in the environment: (1) variations in the mean weight of the sampled population may affect the barnacle''s Cd concentration determination, specially if a size effect for the metal concentration in the organism is not detected; (2) a sampling effort approximately 5 times greater than that of usually applied in such studies would be required to detect an environmental change that caused a realistic increase in the main source of Cd to the barnacle; and (3) barnacle tissue better responds to long-term changes in the Cd level of its sources. [Copyright &y& Elsevier]

Abstract: The barnacle Balanus amphitrite has been used as a biomonitor of metals (As, Cd, Cu, Mn, Hg, Ni, and Zn) in two different littoral habitats in southern Spain: Huelva estuary and Algeciras Bay. Water samples were collected from the same sites as the barnacles to assess metal concentrations and to gain additional information on the environmental conditions. The results clearly showed differences between these two marine habitats. Analysis of variance (ANOVA) showed significant geographic differences in the bioavailability of metals to the barnacles, as reflected in the concentrations of accumulated metals. There was a significant correlation (p<0.05) between the Cu, Mn, Ni, and Zn concentrations found in B. amphitrite and in the dissolved fraction in water from the two areas studied. [Copyright &y& Elsevier]

Abstract: Two three-month sampling programs measuring Cd in the environment and a biomonitor (Balanus amphitrite) were undertaken in the austral winter of 2002 and summer of 2004 in Ross Creek, North Queensland, Australia. The objective was to test whether the burden of Cd in the biomonitor responded to any variation in the dissolved and particulate phase Cd concentrations in Ross Creek, caused by rainfall variation. The barnacles from the most Cd contaminated site were exposed to a total Cd concentration twice that in winter (93.6ngL−1) than in summer (45.6ngL−1). However, no significant variation was identified for the Cd concentration in the biomonitor between winter (8.4mgkg−1) and summer (7.4mgkg−1). A budget analysis based on a bioenergetic kinetic model indicated that Cd flux from food contributes >80% to the Cd concentration in B. amphitrite. A sensitivity analysis showed that physiological characteristics of the biomonitor are the key parameters controlling Cd accumulation in B. amphitrite, rather than the metal concentration in the dissolved or particulate phases. These two model''s outcomes suggest that a tight coupling between Cd in the biomonitor and its availability in the environment does not occur. [Copyright &y& Elsevier]

The barnacle biomonitor Balanus amphitrite, its food sources (two class sizes of suspended particulate material, SPM, and microzooplankton) and water (dissolved phase) were sampled weekly for Cd concentrations along a tidal creek discharging into the Great Barrier Reef lagoon (Ross Creek, Townsville, Queensland). The Cd concentration in the dissolved phase increased upstream, ranging from 1.7 to 283 ng L-1. The Cd concentration in the barnacle''s food sources exhibited the same pattern—ranging, for the small size class of SPM (0.45–50 μm), from <0.01 to 1.15 mg kg-1, for large SPM (50–200 μm) from 0.07 to 1.62 mg kg-1, and for microzooplankton (50–200 μm) from 0.03 to 0.80 mg kg-1. More than 95% of the total Cd in the Ross Creek water (<200 μm) was in the dissolved phase (<0.45 μm). A simple diffusion coefficient model estimated an export during the dry season from Ross Creek into the GBR lagoon of around 6 g Cd d-1. The Cd concentration in two populations of B. amphitrite increased upstream between two sites 2.2 km apart and ranged from 2.15 to 4.69 mg kg-1 and from 5.47 to 12.81 mg kg-1. In addition, their Cd concentrations varied over the three sampling months, exhibiting specific patterns for this variation, which suggests that changing the food sources'' Cd concentration and relative abundance may result in a specific Cd concentration in B. amphitrite. Therefore, for monitoring programs, the interpretation of variations in metal concentration in a biomonitor would be improved by looking at its metal sources and their temporal variability. [Copyright &y& Elsevier]