Carol E. Johnston

Movement Patterns of Stream Fishes in a Ouachita Highlands Stream: An Examination of the Restricted Movement Paradigm

Abstract The restricted movement paradigm (RMP), which states adult fish do not move out of a pool or restricted stream reach, does not fully define the movements of stream fishes. Although stream fishes may spend the majority of their time in a home pool, they also make regular exploratory trips away from the home pool. Recapture of Ouachita Highlands stream fish marked with passive integrated transponder (PIT) tags showed that the majority of the uniquely marked fish in this study were in the pools of initial collection. The following percentages of marked fish were recaptured outside the pool of initial collection: 12% of creek chub Semotilus atromaculatus; 33% of blackspotted topminnow Fundulus olivaceus; 12% of green sunfish Lepomis cyanellus; and 14% of longear sunfish Lepomis megalotis. Standard lengths and weights did not differ significantly between nonmobile and mobile recaptured fish, and patterns of multiple recaptures indicated exploratory, round-trip movements. Such regular exploratory trips...

The relationship of spawning mode to conservation of North American minnows (Cyprinidae)

Approximately 20% of North American minnows are considered imperiled. The factors responsible for imperilment in this group are complex, but the relationship of spawning mode to conservation of North American minnows has not been explored. I provide a summary of the spawning modes of imperiled North American minnows, discuss patterns between these modes and conservation status, and predict the spawning modes for several poorly-known imperiled species. Of the 46 species of North American minnows that are imperiled, spawning modes are known for only 13 species. All spawning modes are represented in the imperiled group of minnows except mound-building and egg-clustering, and with the exception of crevice-spawners and pit-ridge-builders, the percentage of imperiled minnows in each category of spawning mode is roughly proportional to the percentage of minnows in that category overall. Species with complex spawning modes, such as mound-building, pit-building and egg-clustering, are among the most common fishes in North American streams. This pattern suggests that there is a relationship between parental care and success (lack of imperilment) in minnows. Spawning mode is an important consideration in the formulation of recovery plans and proactive conservation efforts.

The benefit to some minnows of spawning in the nests of other species

SynopsisFishes that act as nest associates spawn simultaneously with nest-building hosts and then abandon their eggs. The proposed benefit for this behavior is increased brood survivorship, arising from the physical environment provided by the nest or the parental care provided by the host. Field and enclosure experiments indicated that associates benefit from the parental care provided by the host, and not from the physical environment provided by the nests of hosts. This information, along with the effect of nest association on host reproductive success, is necessary before the nature of this nesting symbiosis can be characterized.

Nest association in fishes: evidence for mutualism

Nest association, or the habit of spawning in the nest of another species, is a widespread reproductive strategy among North American fishes, especially minnows. The hosts of nest associates include sunfishes and nest-building minnows. Previous experiments demonstrated that nest associates benefited from the parental care of hosts. The purpose of this study was to determine the effect of nest associates on hosts, and thereby characterize the relationship as parasitic, mutualistic or commensal. Since hosts with associates had higher reproductive success than those without associates in this experiment, I characterize nest association as a mutualistic relationship, at least in some systems. The dilution effect is the proposed mechanism responsible for the higher reproductive success of hosts with associates.

Spawning in the creek chubsucker,Erimyzon oblongus, with a review of spawning behavior in suckers (Catostomidae)

SynopsisErimyzon oblongus was observed spawning in small ditches in central Illinois in 1986, 1987, and 1988. Males defended territories over beds of gravel or near pits that had been constructed byCampostoma anomalum orSemotilus atromaculatus. Females were located upstream in quiet water and drifted downstream tail first into the territory of a male. After a female entered a males territory, she dug in the gravel with her snout, an action which appeared to signal the male that she was ready to spawn. Of the 22 spawns observed in 1986–1988, 18 involved one male and one female, and four involved two males and one female; 19 were over pits constructed by other fishes, and three were over gravel runs; eight were interrupted by other males. Published descriptions suggest relatively little variation in behavior associated with reproduction in suckers. Spawning characteristics ofE. oblongus that appear to be derived within Catostomidae are small size, males as large as females, strongly territorial males, large head tubercles, and pair spawning.

Sound Production in Pimephales notatus (Rafinesque) (Cyprinidae)

Abstract Male Pimephales notatus produce sounds during aggression associated with the breeding season. Females were not found to produce sounds during this study. Males produced sounds while in the nest cavity, chasing other fish, and during escalated aggressive displays. We identified four sound types characterized by differences in pulse duration and interval, which may be part of a continuum of sound parameters. The sound types were produced singly, in series, or as complex sounds composed of various combinations of three of the sound types. Complex sounds were made under all behavioral contexts and by all males studied. The mechanism of sound production in this species is unknown.

Sound Production during the Spawning Season in Cavity-Nesting Darters of the Subgenus Catonotus (Percidae: Etheostoma)

Abstract The cavity-nesting darters Etheostoma nigripinne, Etheostoma crossopterum, and their hybrid (E. nigripinne × E. crossopterum) were found to produce sounds associated with reproduction. Males produced sounds during aggressive encounters and courtship activities. All three taxa produced nonpulsed sounds categorized as drums and shorter, usually pulsed, sounds categorized as knocks. In addition, E. nigripinne produced pulsed sounds referred to as purrs that differ from knocks in having a higher pulse number and rate. All sound types were made under both aggressive and courtship contexts by males of all three taxa. The dominant frequency and duration of sounds differed by sound type (drums, knocks, purrs) for all taxa. In addition, within the drum sound type, the dominant frequency differed between contexts (aggression vs courtship) and among taxa. Although sound production has been documented for numerous fish species, this is the first time sounds have been described for percids. The mechanism and role of sound production in darters has yet to be determined.

Environmental DNA as an effective tool for detection of imperiled fishes

Detection of aquatic species is imperfect, especially if the species is rare and exhibits spatial and temporal variability. Many fish species require a number of sampling trips before detection is positive. And yet, information on species persistence is critical for effective conservation efforts. New forensic genetic techniques, such as environmental DNA (eDNA), have been developed and successfully used to validate the presence of exotic aquatic species in new areas. We compared detection of a federally listed, threatened, migratory fish species the Slackwater darter (Etheostoma boschungi); using eDNA to concomitantly collected field collections. Detection probabilities for this species are variable, but consistently low in recent collections. Our results indicated that detection using eDNA was vastly more effective than traditional sampling at confirming the presence of the Slackwater darter. Positive detection at non-breeding sites was half of the detection rate at breeding sites, most likely to the greater area available in non-breeding streams. These data suggest that eDNA is an effective tool for quickly evaluating a relatively large number of sites for the presence of rare aquatic species.

Sound Production in Codoma ornata (Girard) (Cyprinidae)

Male Codoma ornata produce sounds associated with aggression and spawning activities during the breeding season. Females do not produce sounds. Males most often produced sounds associated with escalated displays of aggression, courtship and the spawning act. C. ornata spawn in crevices, but previously were reported to spawn as egg-clusterers in cavities. Structurally, sounds are low frequency, vary in duration according to context and are not harmonic. The mechanism of sound production is unknown.

Geographical divergence of acoustic signals in Cyprinella galactura, the whitetail shiner (Cyprinidae)

Geographical acoustic signal divergence in fish has been virtually unexplored. Minnows in the genus Cyprinella produce agonistic and courtship sounds during the spawning season, and Cyprinella galactura, with a disjunct distribution in the Ozark and Appalachian mountains, provided a good model for examining signal divergence. We found significant amounts of geographical variation between the four populations of C. galactura examined, and pulse signal parameters (pulse rate, pulse duration, pulse interval) were most important in distinguishing between the populations. Courtship signals differed from agonistic signals, with courtship signals less variable and more stereotyped. Adjacent populations from the Ozark Mountains were more similar than nonadjacent populations. Signal divergence in agonistic signals appears more random, with adjacent populations clustering with nonadjacent populations. Genetic drift may play a role in agonistic signal divergence, while geographical isolation may be responsible for courtship signal divergence.