Effects of water-soluble fraction of petroleum on growth and prey consumption of juvenile Hoplias aff. malabaricus (Osteichthyes: Erythrinidae)

Abstract

The influence of the water-soluble fraction of petroleum (WSF) on prey consumption and growth of juvenile trahira Hoplias aff. malabaricus was investigated. Juveniles were submitted to either WSF or Control treatment over 28 days, and jewel tetra Hyphessobrycon eques adults were offered daily as prey for each predator. Total prey consumption ranged from 16 to 86 individuals. Despite the initially lower prey consumption under WSF exposure, there were no significant differences in overall feeding rates between the two treatments. Water-soluble fraction of petroleum had a negative effect on the growth in length of H. aff. malabaricus juveniles. Although unaffected, prey consumption suggested a relative resistance in H. aff. malabaricus to WSF exposition and the lower growth of individuals exposed to WSF than the Control possibly reflects metabolic costs. The implications of the main findings for the individual and the food chain are discussed, including behavioral aspects and the role played by this predator in shallow aquatic systems.Keywords: body size, ecotoxicology, growth performance, juvenile trahira, predation, survival. Efeitos da fração solúvel de petróleo no crescimento e consumo em juvenis deHoplias aff. malabaricus (Osteichthyes: Erythrinidae) ResumoA influência da fração solúvel de petróleo (FSP) no consumo de presas e crescimento de juvenis da traíra Hoplias aff. malabaricus foi investigada. Os juvenis foram submetidos aos tratamentos FSP e Controle durante 28 dias, e adultos de matogrosso Hyphessobrycon eques foram oferecidos diariamente como presa para cada predador. O total de presas consumidas variou de 16 a 86 indivíduos. Apesar do menor consumo inicial de presas sob exposição de FSP, não houve diferenças significativas nas taxas de consumo entre os dois tratamentos. A FSP teve um efeito negativo no crescimento em tamanho de juvenis de H. aff. malabaricus. Embora a ausência de efeito no consumo de presas sugira uma relativa resistência de H. aff. malabaricus à exposição à FSP, o menor crescimento em tamanho dos indivíduos expostos ao poluente reflete possivelmente custos metabólicos. As implicações dos principais resultados nos níveis do organismo e da cadeia alimentar são discutidos, incluindo aspectos comportamentais e o papel desempenhado por este predador em ecossistemas aquáticos rasos.Palavras-chave: tamanho do corpo, ecotoxicologia, performance de crescimento, juvenis de traíra, predação, sobrevivência.

Acute and subchronic effects of petroleum on the freshwater fish Hoplias aff. malabaricus

“…By using the same WSF as those adopted in the present work, we previously detected only mild effects on growth and prey consumption of juvenile H. aff. malabaricus and attributed the resistance and/or the capacity of excretion of components metabolized by the liver of the top-predator as reasonable mechanisms to explain those findings (Santos et al, 2016). But the high metabolic and hydrocarbon metabolites excretion rates of fish (Mason, 1945) may explain the low cellular and molecular damage found in H. aff.…”

“…The heavy crude oil (API 17º; Trevisan et al, 2009) was obtained from the Jubarte oil field situated at 77 km off the southeast of Brazil, which composition of benzene, ethylbenzene, toluene and xylene (BTEX analysis) are shown in Table 1. WSF preparation followed Anderson et al (1974) with modifications (for details, see Santos et al, 2016). Modifications were based on a previous work (Weber et al, 2013), which used the relation of Jubarte crude oil:water (1:4 w.v -1 ) and proved to be not lethal for a much more sensible organism (amphipod, Crustacea; LC 50(72 h) = 51% WSF) at the level of 17.6% WSF.…”

“…This species is widespread through almost all hydrographic basins of South America and exerts a keystone effect (Oyakawa, 2003;Petry et al, 2010;Silva et al, 2011). This sedentary and ambush fish since the juvenile stage has been used as a model in several experimental studies, which investigated the effects of temperature over growth and prey consumption (Petry et al, 2007); of pesticides over liver tissue (Miranda et al, 2008); of metals and pesticides over DNA (Cestari et al, 2004;Ferraro et al, 2004;Ramsdorf et al, 2009); and of petroleum over feeding and growth rates (Santos et al, 2016).…”