Tissue biomarkers as vulnerability indicators in the clam Polymesoda caroliniana

Vulnerability depends on the exposure and sensitivity levels of a system to a specific pressure, together with the capacity to cope, recover, or adapt to this pressure. We propose the use of well-known tissular techniques to measure the components of vulnerability. Immunohistochemistry and histopathology indicate the health status of living organisms and the environment. Therefore, these techniques should provide the necessary information to determine the vulnerability of an organism. Immunohistochemical analysis uses biomarkers to determine the presence of toxic compounds, reflecting the exposure level of an organism. Histopathological analysis reveals the environmental impact of a given toxin, reflecting the sensitivity level of the organism to said toxin. Here, we propose a strategy to use these techniques to assess the vulnerability of clams from Tecolutla, Veracruz. We developed categories for each vulnerability component using semi-quantitative scales. Briefly, we calculated the exposure level based on the average number of positive immunohistochemical biomarkers among several organs of clams. Then, we compared the prevalence of histological alterations with the exposure level to determine the sensitivity level. Finally, to estimate the recovery capacity, we placed the control group in a clean environment for 40 days. These led us to observe the capacity of the clams to reverse the effects of environmental stress. Clams showed a moderate level of exposure, a low sensitivity level, and an effective recovery capacity. In conclusion, these results indicate that clams have a low level of vulnerability. This proposal has the potential to guide future works assessing the vulnerability of organisms and later include them in the estimation of vulnerability from aquatic bodies.