Copper ecotoxicology of marine algae: a methodological appraisal

Abstract

The production of accurate and reliable data on copper ecotoxicology of marine algae depends on the use of trace metal clean techniques during experimentation. We reviewed the methodologies used in the literature on copper ecotoxicology of marine macro-and microalgae, specifically the use of trace metal clean procedures such as the labware used (glassware vs. plasticware), methods of cleaning the labware (acid soaking and ultrapure water rinsing), stock solution preparation (copper source and acidification), and measurement and reporting of dissolved copper concentrations. In terms of taxonomic classification, the most studied algal groups were the Phyla Ochrophyta, Bacillariophyta, Rhodophyta, and Chlorophyta. In terms of methodology, ∼50% of the articles did not specify the labware, ∼25% used glassware, and ∼25% plasticware; ∼30% of the studies specified cleaning protocols for labware to remove trace metal impurities; the copper form used to prepare the stock solutions was specified in ∼80% of studies but acidification to stabilise the dissolved copper was performed in only ∼20%; and the dissolved copper concentration was measured in only ∼40% of studies. We discuss the importance of following trace metal clean techniques for the comparison and interpretation of data obtained on copper ecotoxicology in algae. ARTICLE HISTORY

Investigating the fate of copper in a laboratory‐based toxicity test with embryos of Mytilus galloprovincialis: Copper mass balance of a closed bioassay

“…In addition, only approximately 70% of the data used for the marine ambient water criteria derivation in the US Environmental Protection Agency guideline (2016) reported measured [dCu T ] in the test treatments. Given the importance of ecotoxicological bioassays in setting ecological standards of metal pollutants to protect and conserve aquatic ecosystems, the present data indicate the importance of adherence to current guidelines of standardized toxicity tests and data reporting (Leal et al 2016).…”

“…The criteria for guideline derivation of the Organisation for Economic Co‐operation and Development (OECD) and the Australian and New Zealand Environment and Conservation Council (ANZECC) now require bioassay results to be based on measured concentrations, meaning that ecotoxicological studies have to routinely measure and report actual concentrations of a test substance at the start and the conclusion of the exposure (Leal et al ; Warne et al ) to ensure the validity of the toxicity test. Yet, ecotoxicological studies which abide by trace metal–clean protocols and follow current guidelines for the testing of chemicals during bioassays are still mostly lacking (e.g., Maienthal and Becker ; Benoit et al ; Leal et al ). According to Leal et al (), only approximately 25% of toxicity studies regarding marine algae reported actual Cu levels measured in the culture media.…”

“…Three Cu pools are known to be responsible for the loss of [dCu T ] in test solutions over time (Hudson and Morel 1990;Hassler et al 2004;Arnold et al 2005;Jakimska et al 2011;Angel et al 2015;Leal et al 2015): 1) Cu which adheres to the wall of containers (e.g., test tubes) used during the bioassay (Armitage et al 2014;Leal et al 2016); referred to in the present study as Cu tube , 2) Cu which is slowly internalized by exposed organism via an active transport of Cu ions from the cell wall to the inside of the cell (i.e., bioaccumulation) with the help of biotic ligands (e.g., Hudson and Morel 1990;Davis et al 2003;Hassler et al 2004;Arnold et al 2005;Jakimska et al 2011;Angel et al 2015;Leal et al 2016); referred to in the present study as Cu INT , and 3) Cu which is rapidly and reversibly adsorbed (i.e., Cu bound to extracellular proteins [biotic ligands]) to the surface membrane of exposed organisms (e.g., Prasad 2001;Tovar-Sanchez et al 2003;Hassler et al 2004); referred to in the present study as Cu EXT .…”

“…Salinity and DOC are 2 of the main drivers of metal bioavailability as well as associated toxicity (e.g., Arnold et al 2009;Cooper et al 2014;Deruytter et al 2015;Zitoun et al 2018) and are thus highly relevant for evaluating aquatic systems. Particular emphasis was put on the use of trace metal-clean techniques during experimentation and robust data analysis (Leal et al 2016).…”

A unique temperate rocky coastal hydrothermal vent system (Whakaari–White Island, Bay of Plenty, New Zealand): constraints for ocean acidification studies

“…Sample analysis for sulfide was conducted on board. Equipment and sample bottles used for total dissolved trace metals, Hg T and Cu speciation analysis had been cleaned according to conventional trace metal clean protocols (Sander et al 2009;Leal et al 2016).…”