Spawning observations of clinch dace: comparison of chrosomus spawning behavior.
Species that exhibit nonguarding spawning behavior fall under the classification of broadcast spawners, the least studied of all spawning behaviors in minnows (Johnston, 1999). Fish that use the nests of other species for spawning are known as nest associates and can experience increased fitness as a result of parental care and protection by the nest host (Johnston and Page, 1992). Due to small population sizes, little is known about Clinch Dace (Chrosomus up. cf. saylori), and few studies have been conducted on this species of cyprinid, specifically their reproductive behavior. One study yielded spawning observations in two creeks over 2 d (White and Orth, 2014b).
White and Orth (2014) classified Clinch Dace as a nest associate of Central Stoneroller (Campostoma anomalum) and Creek Chub (Semotilus atromaculatus) and observed spawning from mid-May to July at a water temperature of approximately 15 C. The present study differed in that it focused on a single site, which consisted of approximately 50 m of stream around an area of high spawning activity, over 3 d. Clinch Dace are rare and occur only in small tributaries of upper Clinch River in two counties in Virginia. Clinch Dace occupy headwater streams with forested watersheds ranging from 2-4 m wide with a preference for pool and run habitat. Currently, the Clinch Dace is classified as a species of greatest conservation need (Tier-1, high risk of extinction or extirpation) by the Virginia Department of Game and Inland Fisheries (VDGIF, 2005).
Understanding reproductive strategies of a species allows for more effective management of fishes (Johnston, 1999). Nest associates depend on host species that may be integral to the proliferation and survival of associates (Johnston, 1999). Characterizing the reproductive strategies of Clinch Dace, principally the habitat and time of year, could direct conservation measures and allow more effective protection of this undescribed species. Furthermore, understanding the reproductive strategies of fish in a natural setting facilitates captive propagation, which can be important to the survival of rare species (Rakes et al., 2013). The aim of this study was to describe the reproductive behavior of Clinch Dace and make behavioral comparison with congeners.
We observed Clinch Dace congregating over what appeared to be a C. anomalum nest on 4 June and 6 June, 2014, at Pine Creek in Russell County, Virginia (37.110737, -81.917813) (Fig. 1). The nest was located near the head of a riffle and downstream of a pool. The nest consisted of a circular pit in the substrate approximately 20 cm in diameter and having a maximum depth of 18 cm from the water surface. No mound structures could be observed in the area around the nest. Nest substrate consisted mainly on gravel in an area of the stream otherwise comprised of finer substrate.
Five underwater video clips totaling approximately 1 h and 5 min were recorded over the 2 d using a Panasonic Lumix digital camera (Fig. 2). Video duration was determined by time limitations, memory card space available, and camera battery life. The camera was positioned downstream and to the side of the nest. We attempted placing the camera upstream but the visual presence or the disruption of streamflow dissuaded fish from returning to the nest. Additionally, three videos were recorded from the stream bank.
Videos were analyzed for spawning behaviors including: long duration chase, short duration chase, benthic feeding, nest construction, and number of Clinch Dace on screen (Table 1). To reduce observer bias, two observers analyzed videos independently and an average of the two counts was taken. We recorded the presence of behaviors in each 10 s interval and compared data between 4 and 6 June both visually and based on percent change to identify changes in behavior. We did not attempt to identify the sex of individual Clinch Dace in the video as sex determination of the species is difficult and often requires examination of internal anatomy (White and Orth, 2013).
To locate all accounts of Chrosomus spawning behavior, we conducted a Google Scholar search using the search parameters, "Chrosomus" or "Phoxinus" or "spawning" and "reproduction" or "observations," as well as a Web of Science search for "TOPIC: (chrosomus) OR TOPIC: (phoxinus) AND TOPIC: (spawning) AND TOPIC: (reproduction)." Finally, we searched through the state fish taxonomy books for all states where Chrosomus are native. This analysis yielded 12 relevant studies, including these observations. We excluded all studies of breeding behavior in Northern Redbelly Dace (Chrosomus eos) and Finescale Dace (Chrosomus neogeus) because they can occupy more lentic habitats. We compiled data from all 10 studies, including our own, for comparison of spawning behavior among Chrosomus species. We recorded geographic region, time of the year, water temperature, nest type, behaviors observed, and host species for each study.
Although the identity of the nest host cannot be determined with complete certainty, the pit structures of the nest in combination with observed nest construction activity indicate that the nest had likely been constructed by a male C. anomalum (Miller, 1962).
On 4 June Clinch Dace in breeding coloration were observed holding in the current over and around the nest site. A single individual occupied a central location over the nest and chased away other individuals that attempted to enter the nest area on multiple occasions. On 5 June, after heavy rains late in the night of 4 June, Clinch Dace were not observed over the nest but instead had relocated to a pool approximately 15 m upstream from the nest site to feed. On 6 June the Clinch Dace returned to stage over the nest site. High numbers of brightly colored Clinch Dace hovered over the nest site as well as numerous Blacknose Dace (Rhinichthys atratulus) and Creek Chubs. Intense activity was seen with individual interactions difficult to distinguish in the large mass of fish. Occasionally a less brightly colored Clinch Dace would drift down from the upstream pool and incite a disturbance, with numerous other Clinch Dace pursuing this individual. Heavy benthic feeding could also be seen in the nest by all species present continuously throughout observation on 6 June.
Average water temperature for 4-6 June was 21.8 C, 20.7 C, and 20.5 C, respectively. Between 4 June and 6 June an increase in all behaviors and counts was observed (Fig. 2). Furthermore, we observed a greater than 50% increase in the following behaviors: intraspecific long duration chases, other species chasing Clinch Dace, Clinch Dace chasing other species, Clinch Dace benthic feeding, benthic feeding by other species, nest construction, and the number of Clinch Dace on screen at intervals (Fig. 2).
On 4 June we observed Clinch Dace staging, or spending significant amounts of time, over a nest. Activity on 4 June consisted primarily of Clinch Dace over the nest chasing and bumping one another for position. A single Clinch Dace swimming over the center of the nest would chase numerous other Clinch Dace in an effort to maintain control of the optimal spawning location. Sudden movements outside of the stream or by the observers would cause the fish to vacate the nest, swimming upstream to a large pool. Although Clinch Dace seemed focused on the nest, a majority of activity near the nest consisted of brightly colored nuptial individuals only, and very little benthic feeding occurred in the nest on the 4 June.
On 5 June Clinch Dace switched to feeding related behavior. Heavy rain on the night of 4 June increased flow likely disrupting spawning behavior. On this day we observed Clinch Dace in a large pool, 15 m upstream of the nest site. Blacknose Dace, White Suckers (Catostomus commersonii), Fantail Darters (Etheostoma Jlabellare), and Creek Chubs were also present in the pool but only Creek Chubs exhibited similar feeding behavior, with the Blacknose Dace, White Suckers, and Fantail Darters engaging in benthic feeding.
On 6 June Clinch Dace returned to the C. anomalum nest. We observed behaviors indicative of spawning activity such as chasing and benthic feeding in the nest. Frequency and intensity of many behaviors had increased. We also observed a two fold increase in the number of Clinch Dace and other species near the nest between 4 June and 6 June. Numerous Clinch Dace as well as Blacknose Dace swam over the nest feeding in the substrate. A male C. anomalum also visited the nest and began moving rocks out of the nest pit. The C. anomalum chased away a large male Creek Chub, which appeared to be investigating the nest site. Increases in benthic feeding and long duration chase activity between Clinch Dace were apparent. We also observed possible gamete release when a single male Clinch Dace guided a female downstream toward the nest site where four males worked together to push the female from above and pin her against the substrate. Low visibility prevented a definite confirmation of gamete release. It should also be noted that sex identification was based largely upon intensity of coloration and behaviors exhibited, though these methods have little data to support their use.
Four Chrosomus species are included in the compiled reproductive studies in Table 2: Clinch Dace, Southern Redbelly Dace, (Chrosomus erythrogaster), Tennessee Dace (Chrosomus tennesseensis), and Blackside Dace (Chrosomus cumberlandensis). We summarized timing of spawning behavior, species observed, location, sexual dimorphism, water temperature, substrate, nest type, behaviors, and host species. Twelve spawning observation studies were used for a comparison of different Chrosomus species to identify basic similarities and differences in spawning behavior. Of these 12, six included a recorded water temperature. Our observations occurred at a water temperature of 21.8 C which exceeds the temperature range of 11.9-21 C for the other studies (White and Orth, 2014b; Settles and Hoyt, 1978; Hamed et al., 2008; Rakes et al., 2013; Mattinglyand Black, 2013; Starnes and Starnes, 1981). Clinch Dace were observed spawning over pits in both White and Orth's (2014b) study as well as our own, these pits could have been constructed by C. anomalum or Semotilus. Southern Redbelly Dace were observed spawning over pits, mounds, and clean gravel beds which could have been constructed by Campostoma or Nocomis (Smith, 1908; Settles and Hoyt, 1978; Etnier and Starnes, 1993; Pflieger, 1997). Tennessee Dace were observed spawning over a pit and mound style nest characterized as either Semotilus or Campostoma (Hamed et al., 2008). Blackside Dace were observed spawning over pit and pit mound style nests indicative of both Semotilus and Campostoma (Cicerello and Laudermilk, 1996; Mattingly and Black, 2013; Starnes and Starnes, 1981; Scheer and Santangelo, 2013), with an aquaria observation occurring over a mound structure (Rakes et al., 2013). Behaviors observed remained relatively consistent for all five species with each describing fish over the nest, territorial chases, and erratic swimming. Observable spawning events were reported in just four studies: one for Clinch Dace (White and Orth, 2014b), one for Southern Redbelly Dace (Smith, 1908), and two for Blackside Dace (Rakes et al, 2013; Starnes and Starnes, 1981).
The progressive behavioral shifts during our observations allow us to outline a multiday timeline of spawning behaviors by Clinch Dace. Spawning activity begins with a host fish building a nest in the gravel. As we observed this may occur well in advance of spawning by some associates. Next, Clinch Dace exhibit prespawning activity engaging in short distance chases and bumping one another in competition for position over the nest. Activity then increases and paired long distance chases of female fish ensue. At this time it is likely gamete release occurs. Finally, other species and occasionally Clinch Dace gather around the nest to feed on the eggs deposited in the benthos.
Observations and video analysis indicate changes in the behavior of the fishes in the area around the C. anomalum nest. Increases in occurrence of all behaviors indicate an increase in intensity of spawning and a potential progression in the spawning process. The number of Clinch Dace over the nest also increased, suggesting a greater interest in the nest among Clinch Dace in the stream. A majority of behaviors increase by a margin of 50% or greater whereas Clinch Dace chasing other species by just 29%.
Clinch Dace infrequently chased other species off the nest even when egg predation appeared to be high. This suggests Clinch Dace do not participate in parental care or guarding of the nest and focus energy on intraspecific interaction. Furthermore, short duration chases increased less (5.7%) than long duration chases (93%). Color intensity among individuals observed over the nest site remained constant throughout observations.
Nest construction activity by a C. anomalum indicated the observations took place on a C. anomalum nest. Had the nest been constructed by a Creek Chub (Semotilus atromarulatus), the structure would have likely included a ridge structure upstream of the pit (Jenkins and Burkhead, 1993). We observed the same nest in mid-May before these spawning observations and it exhibited the same structure. The unchanged pit structure of the nest throughout the duration of the spawning season discounts the possibility of Creek Chub construction. However, we also observed Clinch Dace spawning activity over a nest being maintained by Creek Chubs in Greasy Creek in June 2015 (Michael Moore, unpubl.). This nest also was a simple depression in the gravel. Perhaps in streams with mostly small substrate the ridges upstream of Creek Chub nests do not persist. It is also possible that nests are shared by both Central Stonerollers and Creek Chubs throughout a spawning season in space limited headwater streams, although this notion is speculative and has not been observed previously.
Behaviors on 5 June appeared more geared toward feeding, following a heavy rain event the night of 4 June. Increased flow could have altered the hydrologic properties of the nest creating unsuitable spawning conditions or excessive turbidity. Alternatively, fish may have been taking advantage of improved feeding conditions associated with higher flow and temperature changes. This suggests human activities that would disrupt stream flow or turbidity should be avoided during this critical time of year. This includes road crossing maintenance or construction, irrigation, and riparian vegetation disturbance.
Spawning observations occurred later in the season and at a much higher water temperature than the observations of White and Orth (2014). However, Blackside Dace (Chrosomus cumberlandensis) spawning has been recorded at temperatures up to 21 C, higher than normal for Chrosomus, as well (Rakes et al., 2013). The pool where observation occurred was not shaded and thus may have been warmer than nearby habitats.
Comparisons between 12 studies documenting spawning behavior, including our own, characterizing four Chrosomus species identified similarities and differences among species. First, most observations of spawning activity occurred at water temperatures in a range of 11-21 C. Here, we document spawning behavior at 21.8 C. These observations suggest temperature may not be as significant an indicator for spawning in Clinch Dace as it is in other species, or perhaps Clinch Dace simply spawn within a wider temperature window. Chrosomus spp. most commonly use pit type nests for spawning, constructed by Campostoma spp. or Semotilus spp. with eight of the 12 studies characterizing some spawning in pit type nests. Southern Redbelly Dace spawned over a mound nest most likely constructed by a Nocomis sp. (Smith, 1908). Blackside Dace have also been observed spawning over mound structures in aquaria as documented by Rakes et al (2013). Clinch Dace have not been observed to co-occur with Nocomis in the upper Clinch, species such as River Chub (Nocomis micropogon) only occur in larger streams, therefore association with Nocomis is unlikely. Overall, these data suggest Chrosomus dace may exhibit flexibility in nest host species.
Though nest construction by a C. anomalum was observed at the study site, the identity of the host cannot be concluded with certainty. The possibility of sequential nest use by both C. anomalum and Semotilus also exists, with one of the two utilizing a nest early in the year with the other utilizing the same nest soon after, with nest associates eventually using the same nests even later in the year. Chrosomus spp. may spawn multiple times during the spring and summer months and simply use whatever suitable host nests are available during this time period.
During the course of this study Clinch Dace were observed over the nest for prolonged periods of time, which differs significantly from observations from White and Orth (2014). Such behavior may expose Clinch Dace to more terrestrial predators. White and Orth (2014) observed Clinch Dace seeking cover near an undercut bank, venturing out only for a few seconds before returning to the shelter of the undercut bank. Tennessee Dace have also been observed to display similar behavior, gathering over the nest in large numbers only briefly before dispersing, leaving only a few individuals to defend the nest (Hamed et al., 2008). These disparities in behavior were a result of variations in habitat conditions or possibly observer activity.
Distinguishing males and females was difficult. However, we did notice grades of intensity in nuptial coloration among individuals. Initially we believed females were the less brightly colored fish with expanded abdomens suggested they were gravid. Pectoral fin shape is the most reliable external feature used to distinguish sexes in Chrosomus Dace, however the video quality in this study precluded us from using this trait (White and Orth, 2014a). Other studies classify spawning events as behaviors that include females being corralled and clasped by males, and both of these behaviors were observed during the course of this study, though gamete releases were not confirmed (Mattingly and Black, 2013). Spawning activity typically intensifies in the morning for Chrosomus dace (Rakes et al., 1999). All observations in this study occurred in the evening, due to other time obligations in the morning, which may not have been peak activity levels.
Further research is needed to clarify the importance of these behaviors, their variability, and ascertain measures to protect spawning habitat during this sensitive time period. Future studies should seek to more accurately describe spawning behavior over a longer period of observation. Efforts should also be made to understand important factors in determining host nest placement and Clinch Dace spawning habitat selection.
Acknowledgments.--This project was funded by State Wildlife Grants from the United States Fish and Wildlife Service managed through the Virginia Department of Game and Inland Fisheries. Permits for research were obtained through IACUC Protocol Number: 13-184-FIW and the Virginia Department of Game and Inland Fisheries: Scientific Collectors Permit 044781, and Threatened/Endangered Species Permit 048447. Huge thanks to Kevin Hamed, Dr. Carol Johnston, Dr. Brandon Peoples, and Shannon White for reviews of drafts.
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HUNTER R. HATCHER, MICHAEL J. MOORE, and DONALD J. ORTH, Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, Virginia 24060. Submitted 9 July 2016; accepted 4 November 2016.
Caption: Fig. 1.--Map of the field site on Pine Creek in Russell County, Virginia
Table 1.--Description of behaviors quantified in video review Behavior Description Off-nest (long duration) chase One Clinch Dace chasing another for longer than 2 s. On-nest (short duration) chase One Clinch Dace chasing another for shorter than 2 s. Benthic feeding Rooting the gravel or pecking at substrate by both Clinch Dace and other species. Nest construction Central Stoneroller in the nest rooting in the substrate and moving stones. Clinch dace on screen Number of Clinch Dace visible at an interval on screen at every 10s interval. Table 2.--Comparison of characteristics of 12 Chrosomus spawning observation studies, including this one Hatcher et al, White and Setdes and 2014 Orth, 2014b Hoyt, 1978 Time Frame May-June April-June April-June Species Clinch Dace, Clinch Dace, Southern Chrosomus sp. Chrosomus sp. Redbelly cf. saylori. cf. saylori Dace, Chrosomus erythrogaster Location Virginia Virginia Kentucky Water 21.8 C 15.4-15.7 C 21 C Temperature Nest Type Pit Pit Pit Behaviors Territorial Territorial No observations chases, chases, reported benthic spawning feeding, events, stoneroller stoneroller nest nest construction, construction, erratic sheltering swimming under bank, erratic swimming Host Campostoma Campostoma Campostoma anomalum. anomalum anomalum Smith, G.S., Fishes of Fishes of 1908 Tennessee Missouri Time Frame May-June April-July May Species Southern Southern Southern Redbelly Redbelly Redbelly Dace, Dace, Dace, Chrosomus Chrosomus Chrosomus erythrogaster erthyrogaster erthyrogaster Location Illinois Tennessee Missouri Water None Given None given Temperature None given Nest Type Mound Pit or clean Clean gravel, gravel pit, or mound Behaviors Spawning Males stage over Males over events, erratic nest, females the nest, swimming venture over females nest and two clasped by males drive two males her into in spawning substrate events over nest Host None identified Campostoma Campostoma (Likely Nocomis) or Nocomis Hamed, Alsop, and Laughlin, Rakes et al., Cicerello and 2008 2013 Laudermilk, 1996 Time Frame May-July April-May May Species Tennessee Blackside Dace, Blackside Dace, Dace Chrosomus Chrosomus Chrosomus cumberlandensis cumberlandensis tennesseensis Location Tennessee Aquaira/Lab Kentucky and Water Tennessee Temperature 21 C 16-21 C None given Nest Type Pit and mound Mound Pit Behaviors Males chasing 2-3 males Males chasing females, follow females, females, territorial presumed Semotilus chases spawning over the nest. events over nest Host Semotilus Artificial Semotilus atromaculatus atromaculatus and Campostoma anomalum Scherer Starnes and Mattingly and Starnes, Santangelo, and Black, 2013 1981 2013 Time Frame May-July April-June Species Blackside Dace, Blackside Dace, Blackside Chrosomus Chrosomus Dace, cu mberlandensis cu mberlanden sis Chrosomus cumberland- fj;ensis Location Kentucky and Kentucky Kentucky Water Tennessee Temperature 11.9-18.2 C 17.5 C None given Nest Type Pit and Pit Pit mound Behaviors 2-4 males pursuing, Males chasing Males over corralling, and females, the nest. clasping a single spawning female. Benthic events, nest feeding construction Host Semotilus Campostoma Campostoma atromaculatus Fig. 2.--The proportion of 10 s intervals with each behavior present between the 2 d of observations averaged between two observers plotted against the left y-axis, and the average number of Clinch Dace on screen at 10 s intervals averaged between two observers plotted against the right y-axis 6/4/14 Average 6/6/14 Average Long duration chase 0.15 0.44 Short duration chase 0.35 0.37 Clinch Dace chase other species 0.07 0.09 Other species chase Clinch Dace 0.01 0.07 Clinch Dace benthic feeding 0.13 0.68 Other species benthic feeding 0.05 0.81 Nest construction 0.00 0.28 Number of Clinch Dace on 2.30 5.18 screen at intervals Note: Table made from bar graph.
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|Title Annotation:||Notes and Discussion Piece|
|Author:||Hatcher, Hunter R.; Moore, Michael J.; Orth, Donald J.|
|Publication:||The American Midland Naturalist|
|Date:||Apr 1, 2017|
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