Environmental Parasitology: intestinal helminth parasites of the siganid fishSiganus rivulatusas bioindicators for trace metal pollution in the Red Sea

Abstract

Studies on host-parasite systems as bioindicators for monitoring trace metal pollution in marine environments are still scarce. Here, 11, 14 and 17 infrapopulations of Gyliauchen volubilis (Trematoda: Digenea), Procamallanus elatensis (Nematoda) and Sclerocollum rubrimaris (Acanthocephala), respectively, were collected from the fish Siganus rivulatus (Siganidae) in the Red Sea, from a chronically polluted small bay at Sharm El-Sheikh, South Sinai, Egypt. Water and sediment samples from the bay, tissue samples (intestines, liver, and muscle) from each fish, and samples from each parasite were taken for heavy metal analyses of cadmium and lead. Cadmium concentrations in intestines, liver and muscle of non-infected and infected fishes were much lower than those of lead, and both metal concentrations decreased in the order: liver > intestines > muscle. Cadmium and lead concentrations in the tissues of fishes infected with G. volubilis or P. elatensis were slightly lower than those in non-infected ones, while in the tissues of fishes infected with Sc. rubrimaris, they were much lower. Low concentrations of cadmium and lead in G. volubilis and P. elatensis are associated with their limited ability or capacity to accumulate trace metals. Therefore, bioconcentration factors corresponding to these species were relatively low, and both are herein considered as weak bioindicators. By contrast, high concentrations of cadmium and lead in S. rubrimaris are associated with its high ability to accumulate trace metals. Of the present three host–parasite systems, only the Siganus rivulatus–Sclerocollum rubrimaris system seems to be promising for biomonitoring of metal pollution in the Red Sea.

Biomonitoring of Effects and Accumulations of Heavy Metals Insults Using Some Helminth Parasites of Fish as Bio-Indicators in an Afrotropical Stream

“…Heavy metals ingested by the fish (through intestines or their gills) are transported through the blood to the fish liver, where majority of the metals are extracted to manufacture organometallic complexes which are conveyed with bile to either the intestine, to continue the liver-intestinal cycles, or taken out of the fish body by egestion (Sures, 2001 and2003;Al-Hasawi, 2019;Mehana et al, 2020). Intestinal parasites do not have the capacity to manufacture their own cholesterols and fatty acids and, due to lipophilicity, they meddle in the cycle by easily ingesting the organo-metallic-bile complexes from their host, and this results to a reduction in the capacity of the fish host to accumulate metals (Al-Hasawi, 2019;Mehana et al, 2020). This could possibly suffice to define the higher concentrations of heavy metals in parasites in comparisons to the fish muscles in our study; and could also explain the reason Pb was not recorded from the muscle of Raimas nigeriensis but was found in the parasites.…”

“…The absence of digestive tract in cestodes necessitates their ability to accumulate more heavy metals relative to their hosts; and utilize the bile salts in reproduction (Hassan et al, 2018). Similarly, Acanthocephalans and nematodes have wide range of capacity to extract bile than the intestine of their host fish (Sures et al, 2017;Al-Hasawi, 2019). Bamidele and Kuton (2016) reported that intestinal nematodes accumulated more metals (Cu, Cr, Ni, Pb and Fe) than their fish host muscle (Clarias gariepinus and Parachanna obscura) in Lekki lagoon.…”

“…Currently, emphasis is shifting to the use of parasites as both effect indicators and accumulation indicators, given that they respond differently to a variety of pollutants in the environment (Vidal-Martínez et al, 2014;Vidal-Martínez and Wunderlich, 2017;Hassan et al, 2018;Al-Hasawi, 2019;Mehana et al, 2020). Helminth parasites of fish (e.g., trematodes, nematodes, cestodes, and acanthocephalans) have been employed as ideal tools for biomonitoring of heavy metal insults in aquatic ecosystem studies (Bush et al, 2001;Sures, 2003;Hassan et al, 2018;Al-Hasawi, 2019).…”

“…Currently, emphasis is shifting to the use of parasites as both effect indicators and accumulation indicators, given that they respond differently to a variety of pollutants in the environment (Vidal-Martínez et al, 2014;Vidal-Martínez and Wunderlich, 2017;Hassan et al, 2018;Al-Hasawi, 2019;Mehana et al, 2020). Helminth parasites of fish (e.g., trematodes, nematodes, cestodes, and acanthocephalans) have been employed as ideal tools for biomonitoring of heavy metal insults in aquatic ecosystem studies (Bush et al, 2001;Sures, 2003;Hassan et al, 2018;Al-Hasawi, 2019). Some of the advantages of using parasites as bioindicators of effects and accumulation include, but not limited to, the following: (1) they do not have complex species richness, particularly in benthic freshwater ecosystem; (2) their taxonomic attributes and life-history are very familiar; (3) each individual host forms a sampling domain with its own group of parasite taxa (Kuris, 1980); (4) given that parasites of high-level predators are regarded as high-level consumers, they inevitably represent ideal indicators of trophic level accumulation (Tellez and Merchant, 2015;Vidal-Martínez and Wunderlich, 2017).…”

Heavy metals, parasitologic and oxidative stress biomarker investigations in Heterotis niloticus from Lekki Lagoon, Lagos, Nigeria

“…In all these studies, heavy metal concentrations were reported to be several thousand times higher in the parasites than in the fish hosts. Al-Hasawi [ 27 ] reported accumulation of lead and cadmium in Procamallanus elatensis (Nematoda) and Sclerocollum rubrimaris (Acanthocephala) from the fish Siganus rivulatus (Siganidae) collected in the Red Sea, Egypt, in concentrations higher than those of their fish hosts. Similarly, Elsayed et al [ 28 ] also reported significantly higher concentrations of heavy metals in trematodes infecting fish species in the Arabian Gulf in comparison with their fish hosts.…”