A comparison of survivourship and function (grazing and behaviour) of three gastropod species used as clean-up crew for the marine aquarium trade.

Abstract

Several million gastropods are collected each year for the marine ornamental trade to graze on algae detrimental to aquarium species, however, little is known about popular species' suitability to perform this clean-up crew role. Three commonly traded gastropods, Turbo bruneus, Tectus fenestratus, and Tegula eiseni were assessed on their performance. Their survival was quantified as was their movement, and positioning with respect to water level and growth rates were calculated from the start and end weights. Nitrocellulose-coated slides were impregnated with an algal extract and the amount of grazing by each species was also compared. After 53 days final mortality levels of species were significantly different with all T. bruneus individuals surviving, whilst all T. fenestratus individuals apart from two and 35% of the T. eiseni had died by the end of the experiment. T. bruneus grazed significantly more than individuals of T. eiseni, and T. fenestratus. Both T. bruneus and T. eiseni were heavier after one month with T. bruneus gaining significantly more weight than T. eiseni. Greater percentages of algae were grazed by T. bruneus of increasing weight, although this relationship was not found for T. eiseni and T. fenestratus. All three species were generally active and remained within the water for the vast majority of time, although a small, but significant amount of time was spent out of the water for T. eiseni. T. fenestratus were significantly less active than T. bruneus, although the mean activity of T. eiseni was not significantly different from either species. T. bruneus out performs the other two species as a cleaning organism especially in the context of fluctuating water quality, thus highlighting the varying suitability of organisms for this task. Preference in the ornamental trade should be given to T. bruneus over the other topshells, but accurate species identification is critical.