Pomacea paludosa (Florida Apple Snail) Reproduction in Restored and Natural Seasonal Wetlands in the Everglades

Abstract

Seasonal wetlands have high variability in the timing, depth, and duration of flooding. The timing of hydroperiod relative to reproduction may be especially critical since reproductive timing may be constrained by other factors. Pomacea paludosa (Florida apple snail) is a large, aquatic snail that tolerates a range of hydroperiods. This study compared P. paludosa reproduction in depressions in natural (N=20) and restored (N=60) seasonal wetlands (wet 6 to 8 months) in the southern Everglades for five years. The total number of egg clusters in a year ranged from 260 to 621. Restored sites always had fewer egg clusters per year (mean±standard error of 54.6±4.8 to 64.2±23.1) compared to a natural site (207.0±38.4). Peak oviposition occurred after the onset of the wet season, typically in July, and then decreased approximately two months later even though similar surface water levels occurred. Compared to long hydroperiod wetlands, the average number of eggs per cluster was lower and reproductive timing shifted from the non-rainy/dry season to early wet season. A combination of hydrological characteristics appeared to influence the timing and amount of oviposition. Moreover, functionality of seasonal wetlands in the southern Everglades may change depending upon cumulative hydrological conditions over several years.

Insights from an Integrated View of the Biology of Apple Snails (Caenogastropoda: Ampullariidae)

“…Snails become inactive when temperatures drop below 13°C (Stevens et al, 2002), and relatively cool temperatures may delay oviposition in the spring (Hanning, 1979). The spring oviposition peak is associated with the dry season, which often culminates in a dry down (i.e., the water table falls below ground level) during which the snails become inactive (Darby et al, , 2008, but, following summer rains, they reinitiate reproduction (O'Hare, 2010).…”

Direct chemical inhibition responsible for displacement of a native herbivore by an invasive congener

“…Apple snails have low densities, typically < 0.5 m -2 , so to better monitor the assemblages we quantified apple snail relative abundances at the scale of each wetland for three years during the invasion by counting egg masses laid above the water surfaces on emergent vegetation (Turner 1996). Pomacea paludosa lay pale pink to white masses of typically 15-35 eggs (Hanning 1979, O'Hare 2010 while P. maculata lay vibrant pink egg masses of small eggs that can often number up to 2000 per mass (Barnes et al 2008). In LILA the typical egg masses appear to be smaller (~200-900 eggs • mass -1 , Dorn, unpublished estimates using regressions in Kyle et al 2014).…”