Title

Interspecific Variation In Gill Size Is Correlated To Ambient Dissolved Oxygen In The Amazonian Electric Fish Brachyhypopomus (Gymnotiformes: Hypopomidae)

Keywords

Anoxia; Floodplain; Gill morphology; Hypoxia; Knifefishes

Abstract

Gymnotiform electric fish assemblage structure is strongly correlated to dissolved oxygen (DO) availability, which exhibits considerable heterogeneity among Amazonian aquatic systems. DO is known to influence the respiratory morphology of gymnotiform fishes, and yet species-level variation among congeners endemic to alternative DO regimes has not been examined. We describe the DO environment experienced by four congeneric species of gymnotiforms (Brachyhypopomus) and correlate this to quantitative variation in a suite of gill metrics. Whitewater floodplain lakes flanking nutrient-rich whitewater rivers are seasonally hypoxic, exhibiting oxygen concentrations close to 0 mg/l from late April until September. In contrast, DO levels in blackwater floodplain lakes and in terra firme forest stream habitats remain high throughout the year. Two common species of Brachyhypopomus restricted to periodically anoxic whitewater floodplain exhibited a substantially greater gill size than two common species restricted to the perpetually well-oxygenated waters of blackwater floodplain lakes and terra firme stream systems. Discriminant Function Analysis (DFA) based on gill metrics separated the species that live in seasonally anoxic whitewater floodplain species from those that live in perpetually-well oxygenated habitats. Our observations suggest a history of adaptive divergence in the gill morphology of Brachyhypopomus associated with oxygen availability. © 2007 Springer Science+Business Media B.V.

Publication Date

10-1-2008

Publication Title

Environmental Biology of Fishes

Volume

83

Issue

2

Number of Pages

223-235

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1007/s10641-007-9325-3

Socpus ID

56749156831 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/56749156831

This document is currently not available here.

Share

COinS