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

Abstract

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.

Mutualism or parasitism: Partner abundance affects host fitness in a fish reproductive interaction

“…To the best of our knowledge, Nocomis occurs nowhere without at least one associate species (Pendleton, Pritt, Peoples, & Frimpong, ), and spawns with up to six associates simultaneously in parts of its range (Peoples et al., ). Moreover, associates usually have the opportunity to spawn among several nest‐building host species, each with slightly different nesting habits (Peoples et al., ). Quantifying interactions between partner diversity and abundance is necessary for understanding context dependency in this system.…”

Spawning periodicity and synchrony of bluehead chub (Nocomis leptocephalus) and a nest associate, yellowfin shiner (Notropis lutipinnis), across local streams

“…Bluehead chub prefer to spawn in distinct mesohabitats (e.g. pool tails and shallower runs covered by gravel and pebble; Jenkins & Burkhead, ; Peoples, Tainer, & Frimpong, ) and microhabtiats based on depth and velocity (Bolton et al, ; Peoples et al, ). Specifically, the range of water velocity is important for depositing eggs (Maurakis, Woolcott, & Sabaj, ) and shallower depths enable bluehead chub to avoid large‐bodied predators (Bolton et al, ).…”

“…Understanding spawning periodicity of a keystone species (i.e. bluehead chub) would provide valuable insights into community structure and dynamics because nest associates rely on keystone species for reproduction (Peoples et al, ; Peoples & Frimpong, ; Wallin, ).…”

“…This interaction (i.e. nest association) is mutually beneficial because bluehead chub extend parental care to nest associates, which in turn provide a dilution effect when predators invade bluehead chub nests (Johnston, 1994b;Peoples, Floyd, & Frimpong, 2016;Vives, 1990). In the upper Piedmont region of the southeastern USA, bluehead chub interact reproductively with yellowfin shiner (Notropis lutipinnis) via nest association (Marcy, Fletcher, Martin, Paller, & Reichert, 2005;Wallin, 1989Wallin, , 1992.…”

Partner swapping and cheating: why do different minnow species spawn together?

“…This is probably because chubs have larger, forward-pointing mouths, whereas stonerollers have smaller, downward-facing mouths. However, both species selected similar flow velocities (Peoples et al 2015). Nest association can be advantageous to associates for several reasons.…”