Abstract
Abstract: Aim In the present study has analyzed several aspects of the life history traits of Melanoides tuberculata, an exotic species, under laboratory conditions, and its response to some stressors has also been applied. Methods Sensitivity to two toxic substances was tested. The mollusks were collected and cultured in the laboratory under controlled conditions of temperature of 25 ± 1 °C and ad libitum food regime. Growth rates and biomass were experimentally obtained and the individual growth curve obtained. Results The experiment lasted 287 days and the maximum shell lengths registered was 11.67 mm. The growth curve indicated a rate of 3.98 year-1 and a maximum theoretical length of 10.61 mm. The mean post-embrionary development time until first reproduction was 275 days and the size of the primipara was 10.13 mm. An accelerated growth of juveniles was observed with fast increase in the shell length until sexual maturity, but growth rate decreased afterwards as more energy was devoted to reproduction. Under the combination of 25 °C and fed on alternate days, M. tuberculata had a slow growth and a long-life expectancy under laboratory conditions. The tolerance of this mollusk to temperature as a stressor ranged between 16 °C and 37 °C, being the optimum temperature situated between 29 °C and 34 °C. The LC(I)50-24h for reference substances were: 0.70 g L-1 for KCl and 9.05 g L-1 for NaCl. Conclusion Based on these results, we can conclude that M. tuberculata is a species tolerant to temperature and salinity, what partially explains to accordance to its wide and rapid dispersion throughout tropical waters.
Highlights
Studies on the life history traits of invasive mollusks are relevant to subsidize management and control actions since it has been shown they can cause great economical losses (Mead, 1979), extinguish endemic elements of faunas (Civeyrel & Simberloff, 1996) and be vectors of human parasites (Malek, 1980)
The individual growth of M. tuberculata was measured by the changes in the size of the shell over time
The duration of the experiment did not evaluate the longevity of the organisms, and growth measurements were performed for 287 days
Summary
Studies on the life history traits of invasive mollusks are relevant to subsidize management and control actions since it has been shown they can cause great economical losses (Mead, 1979), extinguish endemic elements of faunas (Civeyrel & Simberloff, 1996) and be vectors of human parasites (Malek, 1980). According to Fernandez et al (2003), especially the native species in South America freshwaters have suffered with numerous invasions by exotic species of mollusks in recent years as happened with Corbicula fluminea Müller, 1774 (Corbiculidae, Bivalvia), Limnoperna fortunei Dunker, 1857 (Mytilidae, Bivalvia) and Melanoides tuberculata Müller, 1774 (Thiaridae, Gastropoda). There are evidences suggesting that the introduction was accidental, probably attached to aquatic plants and ornamental fishes brought by aquarists or fish‐farmers (Fernandez et al, 2003). Later this species was intentionally transferred to other regions in the country for biological control as competitors of mollusks vectors of human diseases, species of the Planorbidae family (Guimarães et al, 2001; Giovanelli et al, 2002). Little is known on the effects of M. tuberculata upon the native malacofauna in places where this species was introduced
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