Neuston: A relevant trophic resource for apple snails?

Abstract

a b s t r a c tApple snails are known for the strong impacts they provoke in wetlands and aquatic crops by their macrophytophagous habits. Interestingly, they are able to persist after they have eradicated most palatable aquatic macrophytes in the invaded wetlands. Pedal surface collecting is a distinctive mechanism that apple snails use to capture materials in the water surface. We were interested in knowing the relevance of neuston, the organisms associated with the air-water interface, as an alternative trophic resource. Using the invasive Pomacea canaliculata as a model, our experiments with simulated trophic resources in the laboratory showed that neuston is highly consumed even in the presence of abundant palatable macrophytes. P. canaliculata was able to grow efficiently using neuston as an alternative trophic resource both under laboratory and natural conditions. Neuston probably plays a relevant role specially when other trophic resources are inedible or absent or have been depleted by apple snails. Pedal surface collecting probably evolved in apple snails as an adaptation to cope with fluctuating trophic resources.

Environmental risk assessment for invasive alien species: A case study of apple snails affecting ecosystem services in Europe

“…abundance the risk of an ecosystem shift from clear water and macrophyte dominance towards turbid waters and phytoplankton dominance is of major concern since such ecosystem shifts are not easily reversible (Scheffer et al, 1993). The recolonization potential of macrophytes in turbid, phytoplankton dominated waters is very low and remaining apple snails, which are able to persist using quite diverse trophic resources other that macrophytes (Saveanu and Martín, 2015), will make this undesirable shift even less reversible by consuming the few macrophytes that do recolonize.…”

Collecting differently sized particles on water surface by maneuvering pedal waves on the foot of the water snail Pomacea canaliculata

“…[7][8][9] When the food is floating on the water surface, the water snail crawls or floats on the waterair interface and collects the floating food through the anterior part of the foot. [9][10][11][12] While feeding in this mode, the snail attaches on the surface to a substrate (e.g., a stem of aquatic plant) with the posterior part of its foot, while it forms a coneshaped funnel with the anterior part of the foot. If attached to a larger solid surface (e.g., a piece of stone), the water snail may use the substrate itself as an integral part of the funnel.…”

Freshwater snail feeding: lubrication-based particle collection on the water surface

“…In the presence of floating food particles, apple snails move to the water surface and use their foot to collect the particles at the air-water interface [9][10][11][12][13]. In general, when feeding in this mode, the snail attaches at the surface to a substrate (e.g.…”

“…Subsequently, ciliary movements were reported on the anterior part of the foot [9]. Recent studies [10,13] termed this feeding mode 'pedal surface collecting', a term we prefer over 'ciliary feeding' because (1) it is not clear that ciliary beating alone generates the current, rather than in conjunction with muscular wave-like contractions of the foot, and (2) 'ciliary feeding' has been generalized [14] to include all instances of gastropods using ciliary beating and mucus to collect food throughout the water column, whereas the mode of feeding considered here is specifically adopted at the air-water interface.…”