Shorter Gills in Mouth-brooding Females of the Cichlid Pseudocrenilabrus multicolor

Abstract

In mouth-brooding fishes, there may be a trade-off between respiratory function (gill size and shape) and reproduction (space in the buccal cavity for offspring) during periods of parental care. This trade-off may become particularly apparent under low-oxygen conditions if a mouthful of eggs compromises respiratory pumping. In this study, we compare gill size and position among five males, ten brooding females, and eight non-brooding females of the African cichlid, Pseudocrenilabrus multicolor victoriae collected from a hypoxic swamp in Uganda. Brooding females exhibited a smaller total and average gill filament length than non-brooding females and males and a more elongated arch that may relate to spatial constraints imposed by the young. Importantly, brooding females also exhibited smaller overall hemibranch surface area than non-brooding females and males. In conjunction with earlier studies on this species that have reported a higher metabolic rate, higher aquatic surface respiration thresholds, and d...