Responses of survival, growth, and feeding of the invasive Golden Apple Snail (Pomacea canaliculata) to salinity stress

Abstract

The Golden Apple Snail Pomacea canaliculata (Lamark, 1822) is one of the most aggressive invasive freshwater snails and has been found in tropical and subtropical regions around the world. Their presence threatens trophic structure in invaded ecosystems (e.g., wetlands) and harms human health both directly (e.g., as a vector of parasites) and indirectly (e.g., through altering the provision of ecosystem services from uninvaded ecosystems). The tolerance of Golden Apple Snails to saltwater is of concern because they may pose an invasion risk into estuary habitats. We studied the salinity tolerance of Golden Apple Snails by determining differences in their survival, growth, and feeding at 5 salinity levels (0, 2.5, 5.0, 7.5, and 10.0 practical salinity units [PSU]) over 30 d. Artificial seawater was prepared with aerated tap water and synthetic sea salt, consisting of NaCl (68.88%), KCl (1.79%), CaCl2 (2.55%), MgCl2 (8.67%), MgSO4 (5.36%), and NaHCO3 (12.75%). Snails were classified into 3 life stages based on shell length: juvenile (10–19.99 mm), mature (20–29.99 mm), and old snails (30–39.99 mm). Snails at all 3 life stages survived in salinities of 0 to 5.0 PSU but died within 9 d in salinities of 7.5 and 10.0 PSU. The survival percentage of snails decreased in the order: mature > old > juvenile. Snails across all life stages had reduced shell and mass growth with salinity exposure, but their feeding rate in salinity 2.5 and 5.0 PSU became similar to the control group after 23 d. Generally, Golden Apple Snails may live in waters of ≤5.0 PSU. Therefore, special attention should be paid to the activity of Golden Apple Snails in tropical and subtropical areas with salinities ≤5.0 PSU, which would be important for protecting against the snails’ destructive effects on productive resources.