Monette, Dean

Pomacea maculata is invading Florida’s freshwater ecosystems. P. maculata is potentially competing with native Pomacea paludosa. However very little work has looked at the consumption behavior to Vallisneria americana. V. Americana, a restoration plant used by resource managers provides important habitat to nursery species. This study examines P. maculata and P. paludosa’s rate of physical, herbivory, and total damage on V. americana. Our results show P. maculata and P. paludosa demonstrate an average rate of physical damage of 2.5 cm/hr and 1.2 cm/hr, herbivory rates of 1.8 cm/hr and 0.2 cm/hr and total physical damage rates of 4.2 cm/hr and 1.4 cm/hr respectively; and with t-values of 0.180, 0.006, and 0.024 respectively. This study illustrates P. maculata herbivory is significantly greater compared to P. paludosa herbivory, and total damage rates but not physical damage. Resource managers need to consider these higher rates when planning to use V. Americana.

The exotic apple snail Pomacea maculata appears to be gradually extending its range and increasing its density through much of south Florida. As a consequence, there is increasing interest in understanding its life history. One difficulty encountered in studying P. maculata is that it lays large, multilayered clutches of very small eggs that are impossible to count without disaggregating the egg mass; which results in the loss of viability. Using a previously described dis-aggregation technique, we weighed, dis-aggregated, photographed, and counted 70 egg masses of P. maculata collected from various locations in Lake Okeechobee. Using the resulting mass and egg numbers we developed an algorithm that reliably relates clutch mass to the number of eggs in a clutch, allowing the estimation of the number of eggs in a clutch without impacting the eggs’ viability and paving the way for investigations into studies on fecundity, hatching rate, etc.