Sentinel species

According to the different sentinel species analyzed, THg levels in specimens collected downstream from the impacted areas are 10-20 times greater than upstream levels. It clearly points out the relevance of chlor-alkali plants in terms of mercury river pollution. 

This area was the most profusely studied in the AQUATERRA project in terms of biological effects in fish populations. Barbel and bleak were the sentinel species selected in this area and an array of histological and biochemical tests were used to monitor the impact due to three major sources of pollution mercury and OCs at Monzon (with a comparison in one of the papers with Flix) and PBDEs in Barbastro [1—4, 37]. Mercury pollution was directly correlated to an increase of MTprotein in the liver of barbel captured downstream Monzon when compared to samples captured upstream (Fig. 3a). However, mRNA quantitative analyses failed to show any differences between downstream and upstream Monzon, neither correlated with MT protein levels. Further studies showed that MT mRNA in liver is a rather weak marker for chronic metal pollution in liver (see below) [4], The presence of degenerative hepatocytes in barbels and bleaks was also linked to mercury poisoning although it can also reflect the impact by other pollutants, like OCs or PBDEs (Fig. 3e). 

Zelikoff, J.T., Biomarkers of immunotoxicity in fish and other non-mammalian sentinel species predictive value for mammals , Toxicology, 129, 63, 1998. 

In one of the founding studies in immunotoxicology, Friend and Trainer [77] demonstrated that exposure to polychlorinated biphenyls (PCBs) increased mortality of mallard (Anas platyrhynchos) ducklings challenged with duck hepatitis virus. Since then the field of avian immunotoxicology has expanded to show that both the structure and function of the avian immune system often is affected by a diverse array of environmental contaminants, including heavy metals, pesticides, petroleum hydrocarbons, and organic industrial chemicals. Wild birds have proven to be excellent sentinel species for assess-... 

Two sentinel species were caught in the reference and exposure zones in sufficient numbers (at least 12 fish) for statistical interpretation. The data for the white sucker, Catastomus comersoni and longnose sucker, Catastomus catastomus, are listed in Table 7. All endpoints (Beak International, 2000) and comparisons of exposure and reference area data involved appropriate statistical methods. Any significant difference or significant interaction in any endpoint was considered potentially mill-related. 

A LTF rating of 1 ( very low level of effects or no effects observed ) to 5 ( severe level of effects ) was assigned to the fish survey based on the percentage of potentially effluent-related effects relative to all the endpoints measured. Statistically significant differences at a = 0.05 between reference and exposed white sucker (Catastomus commersoni) collected for the Provincial Papers study, including significant interactions from covariate analysis, in either sentinel species and in either sex, were considered to be possibly effluent-related effects (PERE). 

Orlando, E.F., Kolok, A., Binzcik, G.A., Gates, J.L., Horton, M.K., Lambright, C.S., Gray, L.E., Jr., Soto, A.M., Guillette, L.J., Jr. (2004). Endocrine-disrupting effects of cattle feedlot effluent on an aquatic sentinel species, the fathead minnow. Environ. Health Perspect. 112 353-8. 

Human health biomonitoring may also use animal surrogates in the environment to assess potential health hazards to humans - the proverbial canary in the coal mine . For example, chemical and biomarker analysis of bodily fluids or tissue biopsies from family pets, especially dogs, are sometimes used to assess potential chemical exposure and effects in children. This is because dogs often accompany children in the outdoor environment, and both have a tendency to (accidentally or intentionally) consume environmental media such as soil and surface water There has also been an increasing trend to use native animals as sentinel species, that is, fish, wildlife, or invertebrates that are indicators of possible human health risks from environmental hazards. For example, increased incidences of tumors or endocrine disruption in fish may indicate the presence of compounds in the water that may cause cancer or reproductive dysfunction in humans. Concern has also been raised over the increased incidence of deformities in frogs, because these may indicate an increased level of chemicals in the environment, which can cause birth defects in humans. 

Lower, W.R. and R.J. Kendall. 1990. Sentinel species and sentinel bioassay. In Biomarkers of Environmental Contamination, J.F. McCarthy and L.R. Shugart, Eds. Lewis Publishers, Boca Raton, FL, pp. 309-331. 

Ecoassessments focus directly on populations or communities in order to detect if the exposed biocenosis is changing, how it has changed and whether there will be a change. They cover the methodologies related to analysis of biological communities and can be based on different factors such as the structure of the community, the presence and/or status of sentinel species or the use of biological alterations in individuals related to chemical exposure, e.g. crossed-bills in immature cormorants. 

Wirgin, I.I. and Garte, S. (1994) Assessment of environmental degradation by molecular analysis of a sentinel species Atlantic tomcod. In Molecular Environmental Biology, Garte S.J. (ed.), pp. 117—132. Lewis Publishers, Boca Raton, FL. 

Wildlife may be regarded as sentinels for human health. Wildlife sentinel species data may be used for several pvuposes related to exposure and hazard assessment (NRC 1991 van der Schalie et al. 1999), including the following (1) provide additional weight of evidence in a human health risk assessment ... 

Some species of mushrooms have been recommended as sentinel species of mercury contamination because of their ability to accumulate very high concentrations of mercury from the ambient air. In one study, shiitake mushrooms, Lentinus edodus, exposed to Hg vapor at 172.0 xg Hg/m for up to 7 days had grossly elevated concentrations of mercury in caps and stalks. After 3 days caps had 125.0 mg Hg/kg DW and stalks 10.0 mg Hg/kg DW. After 7 days, these values were 310.0 00.0 mg/kg DW in caps and 20.0-30.0 mg/kg DW in stalks. 

Isoforms of various stress proteins have been shown to be expressed under environmental stress in different tissues in many field species such as fish, mollusks, minnows, sea urchins, insects, and nematodes (see review by Sanders 1993). Through carefully controlled laboratory studies, signature or fingerprint changes could be identified for sentinel species such that a particular metal contaminant could be identified in the field based on a similar response. For example, laboratory studies with the crustacean isopod Oniscus asellus demonstrated hsp70 expression in response to heat treatment and lead (lOOmg/kg). In field studies, O. asellus removed from a polluted site in the vicinity of a lead/zinc smelter similarly demonstrated elevated hsp70 expression (Kohler et al. 1992). 

Grove, Robert A., Charles J. Henny, and James L. Kaiser, Worldwide Sentinel Species for Assessing and Monitoring Enviroiunental Contamination in Rivers, Lakes, Reservoirs, and Estnaries, Journal of Toxicology and Environmental Health, Part B Critical Reviews, 12, 25 44 (2008). 

The characteristics of marine bivalves render these organisms ideal for short or long term monitoring of organic and inorganic pollution. As such, bivalves are frequently preferred rather than vertebrate sentinel species and they have been proven along the years to provide robust, reproducible and representative results for sediment or... 

The ubiquitous nature of metals from both natural and anthropogenic sources combined with their necessity in biological processes produce a complex system for study. Metal distributions in abiotic and biotic systems must be examined to accurately assess impact on ecosystems. Wildlife studies of exposure and effect can be challenging, but the results are more complete than evaluation of only metal concentrations. Birds are good sentinel species because they visible, sensitive to toxins, and occupy different trophic positions. Therefore, studies to assess avian population status, reproductive success, and toxicological significance of metal exposures can be extrapolated to other wildlife and possibly humans. 

Monitoring wildlife as sentinel species (e.g., canary in a coal mine)... 

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