Niche segregation in two closely related species of stickleback along a physiological axis: explaining multidecadal changes in fish distribution from iron-induced respiratory impairment.

Wilco C E P Verberk,Piet J J Van Den Munckhof,Bart J A Pollux

doi:10.1007/s10452-012-9395-y

Abstract

Acute exposure to iron can be lethal to fish, but long-term sublethal impacts of iron require further study. Here we investigated whether the spatial and temporal distribution (1967–2004) of two closely related species of stickleback matched the spatial distribution of iron concentrations in the groundwater. We used the ‘Northern Peel region’, a historically iron-rich peat landscape in The Netherlands as a case study. This allowed us to test the hypothesis that niche segregation in two closely related species of stickleback occurred along a physiological axis. Patterns in stickleback occurrence were strongly associated with spatial patterns in iron concentrations before 1979: iron-rich grid cells were avoided by three-spined stickleback (Gasterosteus aculeatus, Linnaeus 1758) and preferred by nine-spined stickleback (Pungitius pungitius, [Linnaeus, 1758]). After 1979, the separation between both sticklebacks became weaker, corresponding to a decreased influence of local groundwater on stream water quality. The way both species changed their distribution in the field provides a strong indication that they differ in their susceptibility to iron-rich conditions. These observed differences correspond with differences in their respiration physiology, tolerance of poor oxygen conditions and overall life-history strategy documented in the literature. Our results exemplify how species can partition niche along a non-structural niche axis, such as sublethal iron-rich conditions. Other fish species may similarly segregate along concentration gradients in iron, while sublethal concentrations of other metals such as copper may similarly impact fish via respiratory impairment and reduced aerobic scope.Electronic supplementary materialThe online version of this article (doi:10.1007/s10452-012-9395-y) contains supplementary material, which is available to authorized users.

Highlights

Metal toxicity can cause a decline or loss of fishery resources (Carpenter 1927; Spry and Wiener 1991)
We assess this in two ways: first, we examine whether the spatial distribution of three- and nine-spined stickleback corresponds to iron-poor and iron-rich habitats, respectively
The distribution of the three-spined stickleback was balanced towards the iron-poor region, while the nine-spined stickleback was distributed across both regions (Fig. 2a)

Summary

Introduction

Metal toxicity can cause a decline or loss of fishery resources (Carpenter 1927; Spry and Wiener 1991). Iron and copper and zinc are believed to act primarily on the gills, impairing respiration and causing death through asphyxiation (Jones 1939; Dalzell and Macfarlane 1999; Waser et al 2010). Iron has been shown to precipitate on the gills, physically impairing oxygen uptake; the absorption and subsequent bioaccumulation of iron in a fish’s organs is less likely to be an important toxic pathway (Dalzell and Macfarlane 1999). Iron can be beneficial for freshwater wetlands as free Fe can bind phosphate and inhibit eutrophication (Smolders et al 2001; Lucassen et al 2006), which makes it important to study potential toxic effects on wildlife. We use an extensive database containing distribution records for both

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Conclusion