Assessing the Impact of Ionizing Radiation on Aquatic Invertebrates: A Critical Review

Abstract

There is growing scientific, regulatory and public concern over anthropogenic input of radionuclides to the aquatic environment, especially given the issues surrounding existing nuclear waste, future energy demand and past or potential nuclear accidents. A change in the approach to how we protect the environment from ionizing radiation has also underlined the importance of assessing its impact on nonhuman biota. This review presents a thorough and critical examination of the available information on the effects of ionizing radiation on aquatic invertebrates, which constitute approximately 90% of extant life on the planet and play vital roles in ecosystem functioning. The aim of the review was to assess the progress made so far, addressing any concerns and identifying the knowledge gaps in the field. The critical analysis of the available information included determining yearly publications in the field, qualities of radiation used, group(s) of animals studied, and levels of biological organization at which effects were examined. The overwhelming conclusion from analysis of the available information is that more data are needed in almost every area. However, in light of the current priorities in human and environmental health, and considering regulatory developments, the following are areas of particular interest for future research on the effects of ionizing radiation on nonhuman biota in general and aquatic invertebrates in particular: (1) studies that use end points across multiple levels of biological organization, including an ecosystem level approach where appropriate, (2) multiple species studies that produce comparable data across phylogenetic groups, and (3) determination of the modifying (i.e. antagonistic, additive or synergistic) effects of biotic and abiotic factors on the impact of ionizing radiation. It is essential that all of these issues are examined in the context of well-defined radiation exposure and total doses received and consider the life stages and life span of the species studied. The review also provides future directions for studies in this stimulating area of research to protect human and environmental health.

The biological effects of ionising radiation on Crustaceans: A review

“…Thus, the observed cytogenetic response in spring biota may have been due to the complex environmental conditions present at the study sites as opposed to the direct effects of ionising radiation. This highlights the inherent difficulties in field radioecology studies (Salbu, 2009) and the importance of quantifying the individual contribution of stressors in environments where abiotic pressures may act synergistically (Dallas et al, 2012). The aforementioned paper represents the only study of natural crustacean populations using mutation as an endpoint.…”

“…Reproductive endpoints are frequently the subject of ecotoxicological and environmental risk assessments studies since perturbations to reproduction may impact upon the long-term survival of a species and hence alter ecosystem dynamics (Anderson & Wild., 1994;Dallas et al, 2012). A large number of publications have focused on radiation-induced effects on reproductive parameters in aquatic invertebrates, with the reported dose level at which significant effects occur varying by at least two orders of magnitude (Harrison & Anderson, 1996).…”

“…This data is often used to calculate lethal dose (LD 50 ) values (Dallas et al, 2012) in order to derive hierarchies of radiosensitivity across taxonomic groups (Blaylock et al, 1996;Harrison & Anderson, 1996). LD 50 values are traditionally used in ecotoxicological studies to determine the ecological risk to species (Stark et al, 2004) and have also been employed in order to determine no observed effect concentration (NOEC) values (Garnier-Laplace et al, 2006) to inform radioprotection and regulatory efforts.…”

“…Within the crustacean subphylum, the dose at which mortality occurs displays remarkable variability (Dallas et al, 2012). Recent work using the harpacticoid copepod Tigriopus japonicus demonstrated tolerance of external gamma radiation doses of up to 600 Gy, with mortality only occurring 5 days after cessation of exposure (Han et al, 2014).…”

“…the Ecological Risk Assessment concept) are well developed (Bréchignac, 2003). An overview of the effects of ionising radiation on aquatic invertebrates has previously been carried out by Dallas et al, (2012). This paper adopts a phyla-specific approach in order to provide a more detailed analysis of effects, and prioritise research needs for the Crustacea, a group of organisms that have been identified as key models for the development of environmental radioprotection frameworks (ICRP, 2008).…”