Water Quality Influences Reproduction in Female Mosquitofish ( Gambusia holbrooki ) from Eight Florida Springs

Abstract

Contamination of freshwater ecosystems with nitrate is a growing global concern. Although nitrate pollution is recognized as a cause of aquatic eutrophication, few studies have examined the possible physiological impacts of nitrate exposure. In this study, we surveyed several reproductive variables of viviparous female Gambusia holbrooki (Poeciliidae) captured from eight springs in Florida. The eight springs represent a gradient of nitrate contamination (1–5 mg/L nitrate–nitrogen). We had two objectives in this study: to describe reproductive biology of female mosquitofish in the springs and to understand reproductive variation in the context of water quality, particularly the nitrate concentration. Our data show a significant negative association between nitrate and both dry weight of developing embryos and rate of reproductive activity among mature females. In addition, variation in Gambusia condition index and embryo number and dry weight was related to temperature variation, and hepatic weight was negatively related to dissolved oxygen concentration. Finally, we observed that many of the measured reproductive variables were interrelated and changeable, depending on gestational stage. Specifically, we provide evidence that maternal support of the embryo occurs at least during the first two thirds of gestation and that female fecundity is affected by an apparent tradeoff between embryo size and embryo number.

Reproductive life history of Heterandria bimaculata (Heckel, 1848) (Poeciliinae: Poeciliidae) in the Honduran interior highlands: trait variation along an elevational gradient

“…While all water quality variables measured in this study have been shown to affect reproductive characteristics of poeciliids (Rubin, 1985;Edwards et al, 2006), one of the most important is temperature. Indirectly, the temperature patterns observed in CNP can work in conjunction with longitudinally increasing nutrient input and insolation to influence productivity.…”

Birth Defects in Wildlife: The Role of Environmental Contaminants as Inducers of Reproductive and Developmental Dysfunction

“…Similar to the mammalian penis, the gonopodium in mosquitofish develops under the control of androgens [Edwards and Guillette 2007]. In female mosquitofish, nitrate was negatively associated with embryo weight and rate of productivity [Edwards et al 2006]. Although mechanisms were not established, investigators theorized that reduced embryo weights and productivity rates were due to nitrate altered thyroid function, which has been demonstrated in other fish and mammals [Jahreis et al 1991;Allen et al 1996;Crow et al 1998;Zaki et al 2004].…”

The role of ovarian steroids in reproductive plasticity in Hoplias malabaricus (Teleostei: Characiformes: Erythrinidae) in tropical reservoirs with different degrees of pollution

“…As mentioned, the presence of xenobiotics in the water and the great variability of chemicals resulting from anthropogenic activities modify the reproduction of fish and other aquatic organisms in various ways (Edwards et al, 2006;Edwards and Guillette, 2007;Wu, 2009;Prado et al, 2011;Hued et al, 2013). Many effects of pollutants, such as the reduction in GSI and the inhibition of ovarian growth, can be attributed to changes in steroidogenesis (Kime, .…”