Analysis of Mercury (Hg) in Four Holothurians Species (Phylum-Echinodermata) From Karachi Coast-Northern Arabian Sea

Abstract

Nowadays metal bioaccumulation in holothuroids is increasing and is a cause of worry owing to toxicity. In the present study the concentrations of mercury (Hg) were measured in holothuroids (Holothuria (Thymiosycia) arenicola Semper, 1868, Holothuria (Lessonothuria) pardalis Selenka, 1867, Holothuria (Lessonothuria) verrucosa Selenka, 1867 and Holothuria (Halodeima) atra Jaeger, 1833) collected during different seasons (pre-monsoon, monsoon, and post-monsoon) in 2015 at Buleji and Sunehri coasts of Karachi, Pakistan. Hg concentrations of tentacles were higher than those in muscle, tentacle and gut tissues of the pre-monsoon, monsoon and post-monsoon. The lowest Hg concentrations were found in muscle tissues at all seasons in Buleji and Sunehri coasts. The mean levels in the muscle tissues were 0.018 mg/kg dry wt. for H. arenicola, 0.024 mg/kg dry wt. for H. verrucosa, 0.026 mg/kg dry wt. for H. pardalis and 0.036 mg/kg dry wt. for H. Atra. The results indicate that according to the European Union legislation the Hg amounts in all tissues of holothurians is much lower than permitted levels. In terms of Estimated Weekly Intakes, this current work also proved that there was no likely health hazard to consumers on account of intake of sea cucumbers under the current consumption rate in Buleji and Sunehri coasts of Karachi, Arabian Sea.

A Review on Heavy Metal Levels in Sea Cucumbers

“…On the other hand, the amounts of Hg in Holothuria (Thymiosycia) arenicola, Holothuria (Lessonothuria) pardalis, Holothuria (Lessonothuria) verrucosa and Holothuria (Halodeima) atra (Ahmed et al, 2018c), and Ohshimella ehrenbergii and Stolus buccalis (Ahmed et al, 2019) (Jinadasa et al, 2014).…”

“…Hg levels in Stichopus herrmanni, Acaudina leucoprocta, Apostichopus japonicus, Actinopyga miliaris, Holothuria arenicola, Stichopus vastus, Ohshimella ehrenbergii, Holothuria atra and Holothuria leueospilota examined by references in Table 2 are low (Ismail et al, 2004;Lin et al, 2018;Jiang et al, 2014;Jinadasa et al, 2014;Ahmed et al, 2018c;Rasyid, 2017;Ahmed et al, 2019) or near the limits of analytical detections (Denton et al, 1999) or non-detectable (Ahmed and Bat, 2020). The highest Hg concentration was found in Stichopus herrmanni species with 3.754 mg / kg wet wt.…”

Concentration of Heavy Metal Hg, Au, and Fe in Sediments, Water, and Tissue Damage of Golden Sea Cucumber Stichopus herrmanni (Semper, 1868) (Holothuroidea; Stichopodidae) in Kayeli Bay, Indonesia

“…If it is associated with how strong a correlation is, then the heavy metals in sediments, intestines, and meat partially have a strong correlation because the value of the correlation coefficient (P-correlation) is almost 1 (Table 3). According to Ahmed et al (2018), heavy metals Hg that enter the marine ecosystems accumulate in sediments so that they can pose risks to benthic biota and further risks to consumers. This means that a high concentration of heavy metals in the sediment is correlated with the concentration of heavy metals in the intestine and meat.…”

“…This means that aquatic biota can be used as an indicator of heavy metal pollution, one of which is a sea cucumber. Currently, sea cucumbers receive attention as the subject of heavy metal pollution research and have been proposed as bioindicators to monitor heavy metal pollution in marine ecosystems (Ahmed et al, 2018). The sea cucumbers of Actinophyga bannwarth and Holothuria impatiens are used as pollution indicator species of heavy metals Cd, Cu, Ni, Mn, Zn, Fe and Pb in the Red Sea, Gulf of Aqaba (Al-Najjar et al, 2018).…”

“…The sea cucumbers have a distinctive morphology with a soft, cylindrical body, extending from the mouth to the anus, and lying on the seafloor (Conand, 2006). Ahmed et al (2018) report that heavy metal Hg dissolves in fat so that it easily accumulates in the body of the biota and can even accumulate in the nerves and brain. Based on this opinion, the pollution of heavy metals due to traditional mining activities in Mount Botak can accumulate in the meat and intestinal tissues of S. herrmanni.…”