Humic acid of commercial origin causes changes in gill morphology of silver catfish <i>Rhamdia quelen</i> exposed to acidic water

Costa, Silvio Teixeira da; Gressler, Luciane Tourem; Sutili, Fernando Jonas; Loebens, Luíza; Fernandes, Marisa N.; Lazzari, Rafael; Baldisserotto, Bernardo

doi:10.1002/jez.2136

Cited by 3 publications

(1 citation statement)

References 59 publications

(98 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Aldrich humic acid was also much less protective against Ag toxicity to daphnia (Glover, Pane, 2005) and less effective on reducing urea excretion at low pH in daphnia (Al‐Reasi, Yusuf et al, 2013) than would have been predicted by its optical properties. Likewise, exposure to environmentally relevant concentrations of Aldrich humic acid at low pH decreased the survival of the silver catfish ( Rhamdia quelen ) and altered gill morphology, suggesting ionic and respiratory disturbances (da Costa et al, 2017, 2015).…”

Section: Physicochemical Properties Of Docmentioning

confidence: 99%

The physiology of fish in acidic waters rich in dissolved organic carbon, with specific reference to the Amazon basin: Ionoregulation, acid–base regulation, ammonia excretion, and metal toxicity

et al. 2021

View full text Add to dashboard Cite

Although blackwaters, named for their rich content of dissolved organic carbon (DOC), are often very poor in ions and very acidic, they support great fish biodiversity. Indeed, about 8% of all freshwater fish species live in the blackwaters of the Rio Negro watershed in the Amazon basin. We review how native fish survive these harsh conditions that would kill most freshwater fish, with a particular focus on the role of DOC, a water quality parameter that has been relatively understudied. DOC, which is functionally defined by its ability to pass through a 0.45‐µm filter, comprises a diverse range of compounds formed by the breakdown of organic matter and is quantified by its carbon component that is approximately 50% by mass. Adaptations of fish to acidic blackwaters include minimal acid–base disturbances associated with a unique, largely unknown, high‐affinity Na+ uptake system that is resistant to inhibition by low pH in members of the Characiformes, and very tight regulation of Na+ efflux at low pH in the Cichliformes. Allochthonous (terrigenous) DOC, which predominates in blackwaters, consists of larger, more highly colored, reactive molecules than autochthonous DOC. The dissociation of protons from allochthonous components such as humic and fulvic acids is largely responsible for the acidity of these blackwaters, yet at the same time, these components may help protect organisms against the damaging effects of low water pH. DOC lowers the transepithelial potential (TEP), mitigates the inhibition of Na+ uptake and ammonia excretion, and protects against the elevation of diffusive Na+ loss in fish exposed to acidic waters. It also reduces the gill binding and toxicity of metals. At least in part, these actions reflect direct biological effects of DOC on the gills that are beneficial to ionoregulation. After chronic exposure to DOC, some of these protective effects persist even in the absence of DOC. Two characteristics of allochthonous DOC, the specific absorbance coefficient at 340 nm (determined optically) and the PBI (determined by titration), are indicative of both the biological effectiveness of DOC and the ability to protect against metal toxicity. Future research needs are highlighted, including a greater mechanistic understanding of the actions of DOCs on gill ionoregulatory function, morphology, TEP, and metal toxicity. These should be investigated in a wider range of native fish Orders that inhabit one of the world's greatest biodiversity hotspots for freshwater fishes.

show abstract