Chemical Cues Released by an Alien Invasive Aquatic Gastropod Drive Its Invasion Success

Abstract

BackgroundChemical cues provide aquatic organisms with sensory information that guides behavioural responses and thus interactions among themselves, each other and the environment. Chemical cues are considered important for predator avoidance, foraging, larval settlement and broadcast spawning in aquatic environments. However, the significance of their role as drivers of direct interactions between heterospecifics has been largely overlooked.Methodology/Principal FindingsA video camera and a demarcated arena were used in situ to record behavioural responses of three native gastropod species, Assiminea cf. capensis, Melanoides tuberculata and Coriandria durbanensis, exposed to treatments representing chemical cues released by a non-native invasive gastropod, Tarebia granifera. The responses were measured quantitatively as displacement and orientation of movement at locations in St Lucia Estuary, within the iSimangaliso Wetland Park, a UNESCO World Heritage Site on the east coast of South Africa. All native gastropods exhibited a negative taxis response to chemical cues released by T. granifera, while T. granifera individuals responded randomly to conspecifics. Displacement was measured relative to the source of the extract, the number of steps taken were determined with path analysis and orientation was determined from the mean (±95% CIs) turning angles, with significant negative turning angles representing negative taxis. Responses to treatments corresponding to the environment and conspecifics were random and undirected, indicating kinesis.Conclusion/SignificanceThis study presents evidence for interactions driven by chemical cues between a non-native invasive gastropod and several gastropods native to South Africa. The results indicate that chemical cues can facilitate invasion success as the behavioural response of native gastropods is to move away allowing additional food and space resources to become available to T. granifera.

Biodiversity census of Lake St Lucia, iSimangaliso Wetland Park (South Africa): Gastropod molluscs

“…was in fact Assimineidae sp.. This false sentinel snail seems to prefer the more saline conditions in the northern parts of St Lucia and has been previously referred to as Coriandria durbanensis or Assiminea durbanensis ( Raw et al 2013 ; Weerts 1993 ). It is clear that Assiminea cf.…”

“…Typically the system experiences sub-decadal alternations of droughts and anomalous wet conditions, at times resulting in severe floods. Recently, the system has undergone a major shift, from a prolonged dry phase during 2002–2011 to flood conditions during 2012–2013, which has resulted in the current predominance of oligohaline conditions through most of its basins ( Raw et al 2013 ; Peer et al 2014 ).…”

Two Asian Freshwater Snails Newly Introduced into South Africa and an Analysis of Alien Species Reported to Date

“…Recent research has shown how one such species, Tarebia granifera (Lamarck, 1822), can become extremely abundant, dominate benthic communities (Miranda et al 2011b;Miranda et al 2014a,b) and alter the functioning of environments it has invaded (Miranda et al 2011a;Moslemi et al 2012). Indigenous snail species in particular are being affected and displaced by T. granifera in South Africa (Miranda & Perissinotto 2012;Raw et al 2013). There is evidence that another invasive, Physa acuta Draparnaud, 1805, can displace the snail host of urogenital schistosomiasis and interrupt transmission of the disease (Dobson 2004).…”

Strangers in the dark: behavioral and biochemical evidence for trail pheromones in Hawaiian tree snails

“…; Raw et al. ). However, fewer recent studies have focused on the function of mucus in land snails other than for use in locomotion or prey tracking (Cook , ; Davis ; Ng et al.…”