Growth and Reproduction of Earthworms in Ultramafic Soils

Abstract

Ultramafic soils are characterized by high concentrations of heavy metals of natural origin-such as chromium, cobalt, manganese, and nickel-as well as a shortage of primary nutrients. This can result in extremely disadvantageous living conditions for all soil-dwelling organisms. Responses to these conditions were addressed by studying growth, cocoon production, and fecundity of earthworms as endpoints of sublethal effects and how this influences the reproductive system and, consequently, population development. Mature specimens of two ecophysiologically different species of earthworms, Eisenia fetida (Savigny) and Aporrectodea caliginosa (Savigny), were exposed for 56 days to an uncontaminated soil and ultramafic soils collected from six ultramafic sites in the Barberton greenstone belt. In all ultramafic soil samples, the specimens of both species grew slower than those in the control soil. In A. caliginosa, an autotomization of the tail section was observed at higher concentrations of heavy metals. At high levels of heavy metals such as manganese, chromium, nickel, and cobalt, a significantly lower cocoon production was recorded for E. fetida, and at medium levels, a time delay in cocoon production was found. A. caliginosa showed an increase in production at medium levels and a decrease at high levels of heavy metals. In both species, no correlation between growth and cocoon viability was found, indicating different target levels for toxicants present in ultramafic soils. To determine effects of these soils on population dynamics, hatching success may be a more useful endpoint of reproduction.

Effects of metal contaminated soils on Eisenia fetida (Savigny) at Ludhiana (Punjab), India

“…Percentage of worms having morphological abnormalities is given in Table 2. Similar abnormalities have been reported in other studies also where soils were contaminated with heavy metals such as Cr, Co, Mn and Pb (Rao et al, 2003;Maleri et al, 2007). Changes in body weight: In control sample of soil taken from PAU campus, non-significant decrease in body weight was observed, while a discontinuous pattern of body weight was observed in worms reared in all the contaminated samples of soil as shown in Fig.…”

“…Reproduction is likely to be of particular importance in eco-toxicological assessment because of its influence on population dynamics. At high levels of heavy metals such as manganese (Mn), chromium (Cr), nickel (Ni) and cobalt (Co), significantly lower cocoon production and at medium levels, a time delay in cocoon production has been observed (Maleri et al, 2007). Reduction in cocoon production due to Pb and Cd exposure has also been reported in several studies in E. fetida (Zaltauskaite and Sodiene, 2010).…”

Reproductive parameters as assessment tools for arsenic and chromium induced toxicity in Eudrilus eugeniae

“…Cocoon production was observed to be the most sensitive and effected parameter of heavy metal toxicity which may also be due to delayed maturation of worms and contaminated substrate as stated by Garg et al (2009). Reduction in cocoon production due to heavy metal exposure has been previously reported by Maleri et al (2007) and Kaur and Sangha (2014).…”

Time Efficient Co-composting of Water Hyacinth and Industrial Wastes by Microbial Degradation and Subsequent Vermicomposting

“…Solid textile mill sludge mixed with cow dung (CD) can be used as a substrate for vermicomposting [28]. Several earthworm species have been tested for vermicomposting process; however, a large number of reports are based on the utilization of E. fetida for vermicomposting [29][30][31].…”