Concentration And Distribution Characteristics Of Typical Heavy Metals In Ligia Cinerascens And Its Assessment Serving As Biomonitoring Species For Coastal Rocky Environment

Coastal zones are not only a region of high productivity and ecosystem diversity,but also the main receiving area of terrigenous pollutants.Biological monitoring has attracted wide attention from scholars all over the world due to its high sensitivity,obvious indication effect and timely response to new pollutants.The animals of the genus Ligia(wharf roach)are the largest and most primitive group in the suborder Oniscoidea of terrestrial isopods,and are the dominant species in the supralittoral zone and the high tide zone.In recent years,studies have indicated that wharf roach is suitable for monitoring coastal pollution.L.cinerascens is distributed in the coastal rocky area from Dandong,Liaoning to Qingdao,Shandong.It is an endemic species in East Asia.In this project,we sampled three regions of Changshan Island,Dalian Bay and Heishijiao Gulf in the coastal area of Dalian,and tested the contents of lead,cadmium,arsenic,copper and chromium in the whole animal samples and their exoskeleton,paraeiopod,second antennae,uropoda and hepatopancreas.Furthermore,the accumulation and distribution of heavy metal cadmium in the L.cinerascenses were detected,and its feasibility as a biological monitoring species in the coastal rocky zone was evaluated.The results showed that:1)in three different sea areas,the content of Cu in the L.cinerascens was the highest,the content of Pb was the lowest,and the contents of Cr,Cd and As were in the middle.The contents of Cu,Pb and As in the L.cinerascens of Changshan Island were lower than those of the other two places,and the contents of Cr and Cd were moderate.It is worth noting that the total amount of heavy metals in wharf roaches is high.The total amount of heavy metals in the L.cinerascens can be roughly judged.The Changshan island has the best near shore water quality,the Dalian Bay is in the middle,and the Heishijiao Gulf is the most polluted.2)the total heavy metal content of L.cinerascens in the same area varies with body weight,but the change of different heavy metals is different.The heavy metal content of the same body weight in the L.cinerascens is also different in the area,but basically any sample of the L.cinerascens can reflect the difference in the same weight.The degree of heavy metal pollution is different between regions.Only the male and female samples of L.cinerascens on Changshan Island showed differences in Cd and As contents.Comparison of sex data showed that the variation trend of heavy metal contents in marine wharf roaches was almost the same in different regions.3)according to the distribution characteristics of heavy metals in different tissues,the distribution of Cu and Cd was the same,with the highest content of hepatopancreas,second antennae,uropoda and exoskeleton,and the lowest level of paraeiopod.The distribution of As and Cr was the same.The accumulation of second antennae and uropoda was the most obvious.With the difference in the degree of pollution in different regions,the distribution of As and Cr was gradually transferred from the external structure of the second antennae,uropoda and paraeiopod to the internal hepatopancreas.The distribution of Pb is similar to that of As and Cr,with the accumulation of second antennae and uropoda,but it does not appear to be distributed to hepatopancreas with the increase of the degree of pollution in the region.The distribution of various heavymetals in the same part of the L.cinerascenses is not very distinct.It is believed that the distribution of heavy metals in the L.cinerascenses is not affected by sex factors.4)after 4 weeks of Cd exposure test,the content of Cd in the exposure treatment group was 36.85 times more than that of the control group.The content of the male body increased by 47.05 times,the content of the female in the female increased by 27.49 times,the Cd accumulation in the male was greater,but the Cd content of the sexes did not show significant difference.The accumulation of Cd in the hepatopancreas of the treatment group was 70 times more than that of control group,while the accumulation effect of exoskeleton and paraeiopod was very obvious,but far less than the hepatopancreas.Compared with the control group,the Cd accumulation in the hepatopancreas of male was higher than that of female,but there was no significant difference in Cd content between male and female.