The Strength of Nocomis Nest Association Contributes to Patterns of Rarity and Commonness among New River, Virginia Cyprinids

2015

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Chubs of the genus Nocomis build large pebble nests that may serve as an important microhabitat for macroinvertebrates and small vertebrates in streams of eastern North America. Macroinvertebrates that use chub nests have not been systematically documented. In this study, we examined the macroinvertebrate communities present inside bluehead chub Nocomis leptocephalus nests in a small tributary creek of the New River in Virginia, USA. Individuals from 38 families of macroinvertebrates were recovered from nests. Snails from the family Pleuroceridae were the most numerous invertebrates in four nests examined, making up an average of 13.6 § 7.53% of the macroinvertebrate community. This study revealed that communities in chub nests are diverse but not necessarily unique from the surrounding stream substrate. More longterm studies on macroinvertebrate communities of chub nests are needed to elucidate the function of nests as a stream microhabitat.

Section: Resultsmentioning

confidence: 99%

A survey of macroinvertebrates colonizing bluehead chub nests in a Virginia stream

Swartwout

Keating

2015

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“…Nest associate reproduction often is closely tied to that of Nocomis (Wallin 1992). This spawning mode greatly influences associate reproductive success (Peoples & Frimpong 2013), geographic distribution (Pendleton et al 2012), and dispersal processes (Walser et al 2000;Hitt & Roberts 2011). Thus, protection of Nocomis spawning habitat benefits numerous species.…”

Section: Discussionmentioning

confidence: 99%

Recognizing gape limitation and interannual variability in bluehead chub nesting microhabitat use in a small Virginia stream

Bolton

Peoples

2015

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Understanding the reproductive microhabitat requirements of keystone species such as the gravel mound nesting bluehead chub Nocomis leptocephalus can be useful for whole-community management. Nocomis have been shown to be microhabitat specialists, but no study has accounted for interannual variability in microhabitat use or for the possibility that substrate choices are constrained by mouth size. Our goals were to quantify the spawning microhabitat requirements of bluehead chub in the North Fork Roanoke River, Virginia, USA. Specifically, we sought to (1) account for gape limitation of nesting chubs when quantifying substrate size preference and (2) to examine interannual variability in their nesting microhabitat preferences. In June 2012 and 2013, we measured pebbles on chub nests and determined the gape limit as the largest measured pebble. With the gape limit as a ceiling for measurable particles, we compared substrate used by chubs to randomly selected particles adjacent to each nest. Depth and velocity were also measured at nests during both years and compared to random points near nests. Patterns in microhabitat selection differed between years. Chubs exhibited substrate size preference in 2012, but not 2013. The mean size difference in 2012 was approximately 3 mm but we do not consider this biologically meaningful. This stands in contrast with other studies showing large mean differences in preferred and available substrate. We suggest that the gape limitation of adult male Nocomis imposes a restriction on usable nesting substrate, causing observed significant differences between preferred and available substrate sizes. Current velocities used by chubs were significantly slower than paired measurements in 2013, but did not differ in 2012; depth preference did not differ between years. Differences in velocity preference likely represent adjustment to the above-average instream flow conditions of 2013. This study demonstrates the importance of examining interannual variability in fish spawning habitat requirements.

“…Nest association is a widespread and complex reproductive behavior among fishes and can be an important mechanism structuring stream fish communities (Walser et al 2000;Hitt & Roberts 2011;Pendleton et al 2012;Peoples & Frimpong 2013). However, we still know relatively little about the basic mechanisms that determine host and associate behavior (Wallin 1992;Johnston 1994a;Shao 1997b) or interaction outcomes (Fletcher 1993;Johnston 1994b;Shao 1997a).…”

Section: Discussionmentioning

confidence: 99%

“…Further, most nest associates do not exhibit fidelity to a single host. Many associates are capable of opportunistically switching hosts (Pendleton et al 2012), even when multiple host species are spawning in relative spatiotemporal proximity (Grady & Cashner 1988).…”

Section: Introductionmentioning

confidence: 99%

Nesting microhabitat comparison of Central stoneroller and Bluehead chub: potential inference for host-switching by nest associates

Peoples

Floyd

2015

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Several nest-building North American minnows (Cyprinidae) function as reproductive hosts to nest associatesÀspecies that require nests of other species for spawning. Understanding the microhabitat preferences of hosts can yield insight into the reproductive ecology of many species, especially of nest associates that can utilize nests of two or more hosts. We observed nests of Central stoneroller Campostoma anomalum in which several associate species were actively spawning. Bluehead chubs Nocomis leptocephalus began constructing nests two days later in the same stream, at which time associates abandoned stoneroller nests and continued on to spawn on chub nests. This presented a unique opportunity for accomplishing two objectives: (1) quantifying stoneroller nesting microhabitat preference and (2) comparing stoneroller and chub habitat preference to gain insight into the mechanisms that may drive host switching by nest associates. We measured substrate size, current velocity, water depth, and egg depth on seven paired stoneroller and chub nests, and compared these measurements to paired microhabitat measurements at a randomly selected point near each nest. Repeated measures analysis of variance with post hoc Tukey tests revealed that stonerollers exhibited distinct nesting microhabitat preferences from chubs. Gravel on stoneroller nests was considerably smaller than on chub nests and stonerollers nested in shallower depths than chubs. However, both species nested at similar current velocities. If nest associates switch partners based on the physical characteristics of nests, then substrate size is likely the most important factor. The larger gravel sizes on chub nests likely provide better egg aeration than stoneroller nests. Chub nests may also be safer for associate broods because male Bluehead chubs cover eggs with gravel after spawning; stonerollers do not. Future work should take an experimental approach to elucidate these mechanisms.