Morphometry of the epidermis of an invasive megascoelecid earthworm (Amynthas gracilis, Kinberg 1867) inhabiting actively volcanic soils in the Azores archipelago

Abstract

a b s t r a c tFor the first time, the structure, dimensions, and composition of the epidermis of an invasive earthworm species that has successfully colonized hostile conditions in actively volcanic soil on São Miguel (Azores) have been measured. Metal concentrations in actively volcanic (Furnas) and volcanically inactive (Fajã) soils were similar; however, Furnas soil was characterised by elevated temperature (10 1C differential), relative hypoxia, extremely high CO 2 tension, and accompanying acidity. The epidermis of earthworm's resident at Fajã was approximately twice the thickness of the epidermis of conspecifics resident in Furnas soil. Reference worms transferred to Furnas soil for 14 days experienced an epidermal thinning of approximately 51%. In comparison, when Furnas earthworms were transferred to mesocosms at the relatively benign Fajã site, their epidermal thickness increased by approximately 21% over 14 days. Earthworms resident in Furnas soil had higher goblet cell counts than the residents of volcanically inactive soil on a neighbouring island (S. Maria). Transferring worms from S. Maria to mesocosms at Furnas induced a significant increase in goblet cell counts. Clearly, the active volcanic environment at Furnas poses a multifactorial stress challenge to the epigeic A. gracilis colonizer.

The Impact of Silver Nanoparticles Produced by Bacillus pumilus As Antimicrobial and Nematicide

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Living on a volcano’s edge: genetic isolation of an extremophile terrestrial metazoan

“…The presence and high abundance of this species in the Azorean geothermal field may indicate its relative tolerance to the multifactorial stress challenges inevitably posed by active volcanism. Morphometric analyses of the epidermis of Amynthas gracilis (another invasive earthworm species, albeit a megascolecid, also inhabiting Furnas soil) show that its respiratory exchange surface is B50% thinner than the one in conspecifics resident on inactive volcanic soils (Cunha et al, 2011). The complete absence of any lumbricid earthworm species from the 'undisturbed' active volcanic soils, in contrast to their ubiquity in a range of different soil types outside the caldera (Cunha, unpublished), gives credence to the notion that tropical invaders are particularly adept at evolving adaptive adjustments.…”

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