Assessment of Hg in Holothuria (Mertensiothuria) leucospilota (Brandt, 1835) from Karachi coasts, Pakistan

Abstract

The aim of the present study was to determine mercury levels in sediments, surface sea water and Holothuria leucospilota muscles and skin in two selected sites from Karachi coast. Samples were collected during two seasons south-west monsoon (August-September) and north-east monsoon (December-January). The concentrations of Hg in sediment ranged from 0.0012 to 0.0023 mg kg -1 , and in surface water from 0.00018 to 0.00034 (µg l -1 ), while in muscle and skin of black sea cucumber ranged from LOD to 0.0034 and LOD to 0.0046 mg kg-1 dry wt., respectively. Moreover, Hg showed the highest accumulation rate in the skin tissue with BSAF values ranging between 2 in Buleji and 2.69 in Sunehri at north-east monsoon. The BSAF values in the muscles of the black sea cucumber ranged from 1.44 at south-west monsoon in Buleji to 1.63 at north-east monsoon in Sunehri, respectively. Since BSAF value is higher than 2 on the skin of sea cucumber, it is evaluated as macro-concentrator. However, the BSAF value varies between 1 and 2 in muscle, it has been determined as micro-concentrator. Hg in the black sea cucumbers from Buleji and Sunehri sites of the Karachi coasts is "very bio-accumulative" (BCF > 5000) during both sampling seasons.

A Review on Heavy Metal Levels in Sea Cucumbers

“…Ahmed et al (2017) suggested that these sea cucumber species might be served as good bioindicators. Ahmed and Bat (2020) showed similar result that Hg levels in Holothuria leucospilota from Karachi coast in Pakistan was very bioaccumulative (BCF > 5000). Since, BSAF values of Hg for the muscles of Holothuria leucospilota ranged from 1.44 to 1.63, considered as micro-concentrator, but this value is higher than 2 on the skin of Holothuria leucospilota, it was evaluated as macro-concentrator (Ahmed and Bat, 2020).…”

“…Ahmed and Bat (2020) showed similar result that Hg levels in Holothuria leucospilota from Karachi coast in Pakistan was very bioaccumulative (BCF > 5000). Since, BSAF values of Hg for the muscles of Holothuria leucospilota ranged from 1.44 to 1.63, considered as micro-concentrator, but this value is higher than 2 on the skin of Holothuria leucospilota, it was evaluated as macro-concentrator (Ahmed and Bat, 2020). Moreover, Mohsen et al (2019) reported that BSAF showed that Apostichopus japonicus was a macro-concentrator for Cd in China.…”

“…The body wall of Acaudina leucoproctais apt to absorption and accumulation of heavy metals, which may be considered as a precious bioindicator for assessing and monitoring metals contamination in surrounding seawater (Lin et al, 2018). The amount of Hg in the muscles of Holothuria leucospilota from Karachi coasts in Pakistan was found to be less than its skin (Ahmed and Bat, 2020). Al-Najjar et al (2018) determined that Zn, Pb, Fe and Mn levels were lower in Actinophyga bannwarth and Holothuria impatiens than in the sediments.…”

“…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.…”

“…There are many studies on heavy metals in sea cucumbers from across the world and these studies are increasing International Journal of Environment and Geoinformatics 7(3): 252-264 (2020) Reaserch Article How to cite: Bat et al, (2020). A review on heavy metal levels in sea cucumbers, International Journal of Environment and Geoinformatics (IJEGEO), 7(3): 252-264.…”