Trophic polymorphism in introduced pumpkinseed (Lepomis gibbosus) inhabiting Iberian reservoirs

Abstract

Introduced pumpkinseed in Iberian reservoirs display marked external morphological differentiation along two simultaneous dimensions of flow and trophic structure. We assessed the degree of internal morphological differentiation using gill rakers, pharyngeal jaws and the levator posterior muscle among pumpkinseeds occupying four different habitats and determined whether prey consumption accounted for any discernible differences in feeding structures among ecomorphs. Results showed significant differentiation by habitat based on pharyngeal muscle and jaw dimensions in all study reservoirs, with pelagic pumpkinseeds having smaller jaws than littoral pumpkinseeds in four of the five reservoirs. Gill rakers, however, differentiated morphs in only three of the five reservoirs, corresponding to differences in zooplankton consumption among pelagic and littoral individuals in those reservoirs. Based on all internal morphological traits, greater divergence was seen along the littoral-pelagic trophic axis in the lacustrine zones of reservoirs compared to the fluvial zone. Overall differences noted in internal morphology are likely the result of phenotypic plasticity; the ability of this species to readily adapt to changing physical environments may explain the success of the pumpkinseed in its introduced range.

Long term patterns in the late summer trophic niche of the invasive pumpkinseed sunfishLepomis gibbosus

“…Recognized as one of the most invasive fish in Europe (Fox and Copp, 2014), pumpkinseed were introduced about 40 years ago to the Western Iberian Peninsula, becoming a major, ecologically damaging invader (García-Berthou and Moreno-Amich, 2000). Trophic plasticity is common among introduced pumpkinseed populations (Bhagat et al, 2011) and has been associated with its local success and the decline of native fish and prey diversity (Almeida et al, 2009). However, there is scarce evidence of diet variation over the invasion process making it difficult to evaluate whether ecological effects of pumpkinseed may change over time.…”

Does latitude drive the phenotypic plasticity of morphological traits in non-native pumpkinseed populations from Europe?

“…It has a circular morphometry with gentle slope banks and a bottom dominated by fine sediments, resulting in well developed littoral areas, colonized mostly by emergent macrophytes and floating vegetation; and (v) Fratel Reservoir (PF), located in the main course of the River Tejo and has a narrow and elongated morphometry, with steep banks containing an incipient littoral zone. PF runs through constrained, V-shaped valleys and is delimited by another Bhagat et al (2011b). Specimens were collected during the respective spawning periods of the populations (mainly from mid-May to early July) by various means (electrofishing, netting, funnel trapping, and angling): in Belgium, England, France and the Netherlands in 2006 (Cucherousset et al, 2009);in Portugal during 2004(Bhagat et al, 2011b.…”

“…PF runs through constrained, V-shaped valleys and is delimited by another Bhagat et al (2011b). Specimens were collected during the respective spawning periods of the populations (mainly from mid-May to early July) by various means (electrofishing, netting, funnel trapping, and angling): in Belgium, England, France and the Netherlands in 2006 (Cucherousset et al, 2009);in Portugal during 2004(Bhagat et al, 2011b. Captured fish were immediately killed by an overdose of anaesthetic and placed in a slurry of ice water and chilled to freezing for storage.…”

Morphological variation of pumpkinseed (Lepomis gibbosus) with emphasis on allometry

“…Morphological variation of L. gibbosus has been intensively studied, especially trophic (Wainwright et al, 1991;Robinson and Wilson, 1996;Bhagat et al, 2011a) and sexual (Naspleda et al, 2012) variations. L. gibbosus has been shown to demonstrate inter/intrahabitatbased differences (Bhagat et al, 2006(Bhagat et al, , 2011b, as well as ontogenetic variations Tomeček et al, 2005).…”