Changes in Cadmium Concentration in Muscles, Ovaries, and Eggs of Silver European Eel (Anguilla anguilla) during Maturation under Controlled Conditions

Simple Summary The European eel (Anguilla anguilla) is currently a critically endangered fish species (IUCN list). This is thought to be due to many factors, including pollution of the aquatic environment with heavy metals, especially cadmium (Cd) and mercury (Hg), which may have a negative impact on the condition and abundance of the European eel population. Owing to bioaccumulation, the level of cadmium in the tissues of fish, especially those at the top of the trophic chain, may be significant and endanger the health and effective spawning success of the species due to impairment of the reproductive capacity. In this study, it was found that female eels' muscles contain significantly less cadmium than their ovaries and eggs. This indicates the transfer of cadmium from the maternal organism to the offspring organism. This study determined the contents of cadmium (Cd) in the muscles, ovaries, and eggs of silver female European eels. The analysis of cadmium content was performed on female European eels caught during commercial fishing in freshwater in Warmia and Mazury (Poland), and then subjected to artificial maturation and ovulation processing under controlled conditions. The content of cadmium (Cd) in the tissues was determined by flameless atomic spectrometry using an electrothermal atomizer. The analysis showed statistically significant differences between the cadmium content in the muscles, ovaries, and eggs (p < 0.05) of female European eels. The lowest cadmium content was found in the muscle tissue (0.0012 +/- 0.0001 mg kg(-1) wet weight) and the highest in eggs (after ovulation) (0.0038 +/- 0.0007 mg kg(-1) wet weight). Moreover, a relationship was found between the cadmium content in the muscle tissue and the ovaries (R = 0.673; p = 0.0117) in the same fish. The movement of cadmium from tissues to oocytes may indicate a significant problem concerning this heavy metal content in the reproduction of European eel.

Automated summary

Cadmium pollution is a possible factor contributing to the critically endangered status of the European eel. Research has shown that female eels have lower levels of cadmium in their muscles compared to their ovaries and eggs, indicating a transfer of cadmium from maternal organisms to offspring. This movement of cadmium from tissues to oocytes may pose a significant problem for the reproduction of European eels.