Polyphasic growth in fish: a case study with Corydoras paleatus (Siluriformes, Callichthyidae)

Abstract

]; where W is the expected weight for a specifi c length L, a 1 and a 2 are the proportionality coeffi cients for stanzas 1 and 2, b 1 and b 2 are the allometric coeffi cients for stanzas 1 and 2, R sc is the stanza changing rate for the switch function and SCP is the stanza changing point for the switch function. The stanza changing point was estimated as 5.28 cm, corresponding with the length at fi rst maturity for this species L mat (5.29 cm). Our data suggest that a complex growth pattern can be in nature, and perhaps not often identifi ed because trends are obscured by natural variability.KEYWORDS. Allometric growth, length at fi rst maturity, reproduction, sexual maturity, length-weight relationship.RESUMO. Crescimento polifásico em peixes: estudo de caso com Corydoras paleatus (Siluriformes, Callichthyidae). Foi estabelecida uma relação peso-comprimento para Corydoras paleatus (Jenyns, 1842) (Siluriformes, Callichthyidae) (n = 596) a partir de amostras obtidas em novembro-dezembro de 2009 e março-abril de 2010, na lagoa da Pinguela (29°46'57"S; 50°11'16"W), Rio Grande do Sul, Brasil. A espécie apresentou um padrão de crescimento alométrico polifásico, cada estágio descrito por uma equação de potência independente e controladas por uma função de interruptora:; onde W é o peso esperado para um comprimento L, a 1 e a 2 são os coefi cientes de proporcionalidade para as fases 1 e 2, b 1 e b 2 são os coefi cientes alométricos para as fases 1 e 2, R sc é a taxa de mudança de fase e SCP é o ponto de mudança de fase. O ponto de mudança fase foi estimado em 5,28 cm, correspondendo com o comprimento de primeira maturação desta espécie (L mat ) (5,29 cm). Nossos dados sugerem que um padrão de crescimento complexo pode ser frequente na natureza, e que talvez muitas vezes não seja identifi cado porque as tendências são obscurecidas pela variabilidade natural. PALAVRAS-CHAVE.Crescimento alométrico, tamanho de primeira maturação, reprodução, maturação sexual, relação peso-comprimento.The weight-length relationship (WLR) is considered frequently as "second class" science (Froese, 2006), and just regular task for any fi shery biologist. Research about WLR are frequently published only as short-communication for species that this information is not yet known (Froese, 2006). As a result, specifi c work on weight and length do not stand out, restricting knowledge of the WLR to a very small number of species (Kulbicki et al., 2005).Of course, it's easy to understand the need of WLR for commercial fi shery, when we need to convert both measurements as an ordinary task. However, the parameters of the WLR, as the proportionality coeffi cient (a) and the allometric coeffi cient (b) could inform several aspects of the fi sh biology, as the general growth pattern or seasonal changes in the fi sh condition (Froese, 2006). The amount of information that could be inferred using this general approach makes it very useful the understand ecological patterns, even for small and not commercial fi sh species. Froese et al. (2014) made a rece...

Sexual dimorphism in the catfish Genidens genidens (Siluriformes: Ariidae) based on otolith morphometry and relative growth

“…To support interpretations regarding changes in morphometric otolith patterns, the otoliths were photographed, and an illustrative schematic of male and female lapilli otoliths during different development stages was elaborated. The relationships between somatic and otolith growth for G. genidens males and females were estimated based on two methodologies, by adjusting the traditional power model (Huxley, 1924) and the polyphasic model (Bervian et al, 2006, modified by Barradas et al, 2016). The latter approach considers a growth pattern comprising two distinct phases, separated by a stanza changing point (SCP), which indicates the Lt at the time individual growth pattern changed.…”

“…The nonlinear least squares method was applied to the proportional residuals to y through the Levenberg-Marquardt algorithm using the nlsLM function present in the minpack.lm (Elzhov et al, 2016) package of the statistical platform R (R Core Team, 2017). Due to the naturally occurring heteroscedasticity of this data set, homocedastic residues were used for model fit, instead of gross residues (Barradas et al, 2016). For the polyphasic model analysis, the moving average of the residuals was used to verify the somatic length range in which changes in male and female growth patterns occur, by observing the trends for each point.…”

New approaches to basic population ecology studies: Revealing more complex patterns of a small Characidae that inhabit streams

“…It was biphasic for both males and females, trending to allometric negative and positive for males and females in first stanza, respectively. Polyphasic growth pattern has already been reported for other fish species, including the Characidae A. jacuhiensis and Cheirodon ibicuhiensis (Fontoura, Jesus, Larre, & Porto, 2010), as well as for the Siluriformes Auchenipterichthys longimanus (Freitas, Almeida, Montag, & Fontoura, 2016) and Corydoras paleatus (Barradas, Lermen, Larré, Martins, & Fontoura, 2016). These studies associated polyphasic growth with reproductive investment, that is, stanza change coinciding with first maturation size.…”

Ensambles parasitarios de Corydoras paleatus en un arroyo pampeano con condiciones contrastantes de calidad de agua y hábitat

“…Se calculó la prevalencia, la intensidad media y la abundancia parasitaria según Bush et al (1997) para cada especie de parásito en cada sitio de estudio. Estos parámetros a su vez se discriminaron según talla de primera maduración (Barradas et al, 2016) entre ejemplares mayores y menores a 60 mm de longitud total. A nivel de comunidad componente se calculó la riqueza específica, el índice de diversidad de Shannon-Wiener y el índice de equitatividad de Pielou (Magurran, 1988).…”