Abstract
Ecological and life history traits have been used to understand the basic ecology of fishes. This study aimed to examine the existence of plasticity in life history traits of populations of Hollandichthys multifasciatus in ten blackwater streams. This is an inseminating Characidae, endemic to the Atlantic coastal drainages of Brazil. Different aspects of the life-history of the species, such as mean length, sex ratio, absolute and relative fecundity, gonadosomatic index, condition factor, length-weight relationship and the growth parameter (b) of 185 specimens were studied during the period of low precipitation (June-September). Fish samples were obtained along a 100 m stretch of each stream, and some habitat variables recorded. ANOVA and Kruskal-Wallis tests indicated a similarity in most of the analyzed traits, with exception of the mean length of immatures, Gonadosomatic Index of mature males and condition factor of immatures and mature adults. Also, slope tests of the length-weight relationship were significantly different for immatures. The observed differences were attributed to heterogeneity in food availability and/or other site-specific factors, which may influence growth and/or breeding aspects among the studied localities. The approach used herein may improve understanding of trait plasticity under natural conditions, helping to understand fish-community responses to anthropogenic changes.
Highlights
Variations in life-history traits between and within fish populations have been described for several native populations from tropical (Winemiller, 1989; Grether et al, 2001; Gomes & Monteiro, 2007) and temperate habitats (García & Braña, 1988; Lobón-Cerviá & Rincón, 1998; Craig et al, 2017), with spatial and temporal patchiness of resources resulting in variation in reproductive traits
For Dissolved Organic Carbon (DOC) values, no information was found for Atlantic Forest backwater streams, but when they are compared to those observed in blackwaters of the Rio Negro, the major tributary to the Amazon, we obtained higher values than Duarte et al (2016), who recorded concentrations between 8‐12 mg C L−1, but up to 35 mg C L−1
Most of the analyzed life-history traits of H. multifasciatus were similar among streams, suggesting that site-specific factors did not influence size of adults, maturation, sex ratio or fecundity
Summary
Variations in life-history traits between and within fish populations have been described for several native populations from tropical (Winemiller, 1989; Grether et al, 2001; Gomes & Monteiro, 2007) and temperate habitats (García & Braña, 1988; Lobón-Cerviá & Rincón, 1998; Craig et al, 2017), with spatial and temporal patchiness of resources resulting in variation in reproductive traits. Resource availability is considered a major driver for selection of various life-history strategies in organisms and can affect population growth and productivity (Begon et al, 2006). Other factors, such as environmental stability (e.g., hydrology; Lytle & Poff, 2004), light radiance, temperature, and oxygen levels may be. Organisms are likely to mature later than those in more productive environments where they can grow faster and get larger quicker (Stearns & Koella, 1986) In this respect, important drivers of freshwater productivity as Dissolved Organic Carbon (DOC) have been shown to affect life-history characteristics of Lepomis macrochirus Rafinesque, 1819 in North American lakes such
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