Carnivory during Ontogeny of the Plagioscion squamosissimus: A Successful Non-Native Fish in a Lentic Environment of the Upper Paraná River Basin

Abstract

This study evaluated feeding patterns and ontogenetic variations in a non-native fish species (Plagioscion squamosissimus) in an isolated lake in the Upper Paraná River floodplain. Quarterly samplings were performed from April 2005 to February 2006 using plankton nets to capture larvae, seining nets for juveniles, and gill nets and trammel for adults. Stomach contents (n = 378) were examined according to the volumetric method in which the volume of each food item was estimated using graduated test tubes or a glass counting plate. During early development (larval stage), P. squamosissimus consumed mainly Cladocera and Copepoda. Juveniles showed a more diverse diet, including shrimp (Macrobrachium amazonicum), fish, aquatic insects (Trichoptera, Ephemeroptera, Chironomidae and pupae of Diptera) and plants. It was notable the high proportion of cannibalism (23.3%) in this stage. Adults consumed predominantly shrimp and fish. The use of food resources varied significantly between development stages (ANOSIM; r = 0.458; p<0.005), showing changes in food preferences during ontogeny. The Similarity Percentage Analysis (SIMPER) indicated that Cladocera and Copepoda were responsible for the differences observed between the larval stages of pre-flexion, flexion and post-flexion. M. amazonicum and Chironomidae were responsible for the differences between juvenile and larval stages, while M. amazonicum and other fishes caused the differences between adults and other ontogenetic stages. These results are confirmed by the relationship between standard length and developmental periods (ANCOVA; r2 = 0.94; p<0.0001). In general, there were low values of trophic niche breadth. The essentially carnivorous habit from the early stages of P. squamosissimus and the predominant use of M. amazonicum by adults have important roles in feeding patterns of the species, suggesting a major contribution to its success and establishment, especially in lentic environments.

Spatial distribution and habitat use by early fish stages in a dammed river basin, Southern Brazil

“…The fish species with the highest density was P. squamosissimus and was exclusive to the lagoon habitat. In the larval stage, their diet consists of cladocerans, copepods, rotifers, algae, larvae of other fish species and perform cannibalism (Makrakis et al, 2005;Neves, Delariva, Guimarães, & Sanches, 2015). Maturation in the first year of life, partial spawning, high fecundity (Vazzoler, 1996), and prolonged reproductive periods (Reynalte-Tataje et al, 2011) are responsible for their great reproductive success.…”

Evidence of morphological and functional variation among BluegillLepomis macrochiruspopulations across Grand Lake St Mary's watershed area

“…Across a given species complete ontogeny the morphological variation exhibited is often the greatest contributor to shape change (Wainwright 1996). Ontogenic variation in growth-morphology trajectories are shaped by selective pressures relating to a variety of functional factors, including diet, maturity, predation pressures, and habitat type (Hjelm et al 2001;Neves et al 2015) that coincide with change during a lifetime of development. Morphological changes during ontogeny strongly influence performance and can provide implications for success of particular size classes dependent on diet, sex, and/or habitat.…”

Effects of light-dark cycle on the spatial distribution and feeding activity of fish larvae of two co-occurring species (Pisces: Hypophthalmidae and Sciaenidae) in a Neotropical floodplain lake

“…Larvae were classified according to the degree of notochord flexion and development of the caudal fin supporting elements, as proposed by Nakatani et al (2001), into the stages: (i) pre-flexion: from the beginning of the exogenous feeding to the beginning of the notochord flexion with the emergence of the caudal fin supporting elements; (ii) flexion: from the notochord flexion through the formation of the caudal fin supporting elements to the beginning of pelvic fin formation; and (iii) post-flexion: from the beginning of pelvic fin formation to the segmentation of ray fins, embryonic fin absorption and the emergence of scales. Then, the data on larval abundance were standardized to a volume of 10 m -3 of water filtered, according to Nakatani et al (2001).…”

“…P. squamosissimus larvae basically consumed cladocerans and calanoid copepods (mainly A. furcatus), and more predominantly copepods at the flexion and post-flexion stages. Makrakis et al (2005) and Neves et al (2015) associated the preference for calanoid copepods in P. squamosissimus diet during the larval period with increased visual acuity, swimming ability and protraction of the jawbone. These characteristics facilitate the capture of copepods by these fish larvae despite the larger size and greater agility of copepods in relation to rotifers and cladocerans.…”

“…The combined investigation of feeding behavior and spatial distribution of food resources allows the elucidation of ecological relationships between fish species (Temming et al, 2002;Neves et al, 2015). Feeding strategies of fish larvae are complex.…”