Review The sensitivity of aquatic insects to divalent metals: A comparative analysis of laboratory and field data Kevin V. Brix a, b, ⁎, David K. DeForest c , William J. Adams d a EcoTox 575 Crandon Blvd., #703 Key Biscayne, FL 33149, United States b RSMAS, University of Miami 4600 Rickenback Cswy, Miami, FL 33149, United States c Windward Environmental 200 West Mercer Street, Suite 401 Seattle, WA 98119, United States d Rio Tinto 8315 West 3595 South Magna, UT 84044, United States abstract article info Article history: Received 11 January 2011 Received in revised form 13 June 2011 Accepted 15 June 2011 Available online 4 August 2011 Keywords: Aquatic insects Copper Cadmium Lead Nickel Zinc Laboratory studies have traditionally indicated that aquatic insects are relatively insensitive to metals while field studies have suggested them to be among the most sensitive aquatic invertebrate taxa. We reviewed and synthesized available studies in the literature to critically assess why this discrepancy exists. Despite the intense effort to study the effects of metals on aquatic biota over the past several decades, we found studies specific to insects to still be relatively limited. In general, the discrepancy between laboratory and field studies continues with few efforts having been made to elucidate the ecological and physiological mechanisms that underlie the relative sensitivity (or insensitivity) of aquatic insects to metals. However, given the limited data available, it appears that aquatic insects are indeed relatively insensitive to acute metal exposures. In contrast, we suggest that some aquatic insect taxa may be quite sensitive to chronic metal exposure and in some cases may not be protected by existing water quality criteria for metals. The discrepancy between laboratory and field studies with respect to chronic sensitivity appears to largely be driven by the relatively short exposure periods in laboratory studies as compared to field studies. It also appears that, in some cases, the sensitivity of aquatic insects in field studies may be the result of direct effects on primary producers, which lead to indirect effects via the food chain on aquatic insects. Finally, available evidence suggests that diet is an important source of metal accumulation in insects, but to date there have been no conclusive studies evaluating whether dietary metal accumulation causes toxicity. There is a clear need for developing a more mechanistic understanding of aquatic insect sensitivity to metals in long-term laboratory and field studies. © 2011 Elsevier B.V. All rights reserved. Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4188 2. Methods and materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4188 2.1. Laboratory toxicity data sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4188 2.2. Mesocosm studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4189 2.3. Field bioassessment studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4189 3. Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4189 3.1. Laboratory toxicity data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4189 3.2. Mesocosm studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4190 3.3. Field bioassessment studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4192 4. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4193 4.1. Relative sensitivity of aquatic insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4193 4.2. Mechanisms underlying acute insect sensitivity to metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4194 4.3. Mechanisms underlying chronic insect sensitivity to metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4194 4.4. The importance of dietary metal exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4195 4.5. Are insects protected by current water quality standards? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4195 Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4196 Science of the Total Environment 409 (2011) 4187–4197 ⁎ Corresponding author at: EcoTox 575 Crandon Blvd., #703 Key Biscayne, Florida 33149, United States. Tel.: +1 904 210 6562; fax: +1 305 421 4600. E-mail address: kbrix@rsmas.miami.edu (K.V. Brix). 0048-9697/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.scitotenv.2011.06.061 Contents lists available at SciVerse ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv