• An integrated approach to the toxicity assessment of Irish marine sediments. Application of porewater Toxicity Identification Evaluation (TIE) to Irish marine sediments.

      Macken, A; Giltrap, M; Foley, B; McGovern, E; McHugh, B; Davoren, M (Elsevier, 2009)
      An integrated approach to the ecotoxicological assessment of Irish marine sediments was carried out between 2004 and 2007. Phase I Toxicity Identification Evaluation (TIE) of sediment porewaters from two sites on the east coast of Ireland were conducted. Initial Tier I screening of three Irish sites identified the need for TIE after significant toxicity was observed with Tisbe battagliai and the Microtox® assay at two of the assayed sites (Alexandra Basin and Dunmore East). Porewaters classified as toxic were characterised using four manipulations, ethylenediaminetetraacetic acid (EDTA) chelation, sodium thiosulphate addition, C18 Solid Phase Extraction (SPE) and Cation Exchange (CE) SPE. Prior to initial testing, and TIE manipulations, all porewater samples were frozen at -20 ºC for several months until required. After initial Tier I testing Alexandra Basin porewater was classified as highly toxic by both assays while Dunmore East porewater only warranted a TIE with T. battagliai. Results of TIE manipulations for Alexandra Basin porewater and the Microtox® Basic test were inconclusive. The toxicity of the porewater in this assay was significantly reduced after freezing. Three experimental episodes were conducted with one month between each for the Alexandra Basin porewater. After each month of freezing the baseline toxicity was further reduced in the Microtox® assay, therefore it was not possible to draw accurate conclusions on the nature of the active contaminants in the sample. However, toxicity to T. battalgiai did not change after storage of the porewater. The C18 and CE SPE decreased the toxicity of Alexandra Basin porewater to the copepod indicating that both organic and cationic compounds (e.g. metals) were active in the sample. Dunmore East porewater was assayed with T. battalgiai and again a combination of organic and inorganic compounds were found to be partly responsible for the observed toxicity (C18, CE SPE and EDTA reduced toxicity). Results from these TIEs provide insight into the complexity of interpreting marine TIE data from porewater studies where mixtures of unknown substances are present.
    • A Model Compound Study: The ecotoxicological evaluation of five organic contaminants with a battery of marine bioassays

      Macken, A; Giltrap, M; Foley, B; McGovern, E; McHugh, B; Davoren, M (Elsevier, 2008)
      This paper describes the ecotoxicological evaluation of five organic contaminants frequently detected in marine sediments (tributyltin, triphenyltin, benzo[a]pyrene, fluoranthene, and PCB 153) using three marine species (Vibrio fischeri, Tetraselmis suecica, and Tisbe battagliai). The sensitivity of each species varied for all compounds. The triorganotins were consistently the most toxic to all species. The applicability of each test system to assess the acute toxicity of environmental contaminants and their use in Toxicity Identification Evaluation (TIE) is discussed. Suitability of the Microtox and T. battagliai tests for employment in TIE studies were further assessed through spiking experiments with tributyltin. Results demonstrated that the most effective treatment to remove organotin toxicity from the sample was the C18 resin. The results of this study have important implications for risk assessment in estuarine and coastal waters in Ireland, where, at present the monitoring of sediment and water quality is predominantly reliant on chemical analysis alone. Ecotoxicological evaluation of five organic marine sediment contaminants was conducted and the suitability of the test species for marine porewater TIE discussed.
    • A test battery approach to the ecotoxicological evaluation of cadmium and copper employing a battery of marine bioassays

      Macken, A; Giltrap, M; Ryall, K; Foley, B; McGovern, E; McHugh, B; Davoren, M (Springer, 2009)
      Heavy metals are ubiquitous contaminants of the marine environment and can accumulate and persist in sediments. The toxicity of metal contaminants in sediments to organisms is dependent on the bioavailability of the metals in both the water and sediment phases and the sensitivity of the organism to the metal exposure. This study investigated the effects of two metal contaminants of concern (CdCl2 and CuCl2) on a battery of marine bioassays employed for sediment assessment. Cadmium, a known carcinogen and widespread marine pollutant, was found to be the least toxic of the two assayed metals in all in vivo tests. However CdCl2 was found to be more toxic to the fish cell lines PLHC-1 and RTG-2 than CuCl2. Tisbe battagliai was the most sensitive species to both metals and the Microtox® and cell lines were the least sensitive (cadmium was found to be three orders of magnitude less toxic to Vibrio fischeri than to T. battagliai). The sensitivity of Tetraselmis suecica to the two metals varied greatly. Marine microalgae are among the organisms that can tolerate higher levels of cadmium. This hypothesis is demonstrated in this study where it was not possible to derive an EC50 value for CdCl2 and the marine prasinophyte, T. suecica. Conversely, CuCl2 was observed to be highly toxic to the marine alga, EC50 of 1.19 mg l-1. The genotoxic effect of Cu on the marine phytoplankton was evaluated using the Comet assay. Copper concentrations ranging from 0.25 to 2.50 mg l-1 were used to evaluate the effects. DNA damage was measured as percent number of comets and normal cells. There was no significant DNA damage observed at any concentration of CuCl2 tested and no correlation with growth inhibition and genetic damage was found.