Clinostomus Funduloides Research Articles

The relationship between water velocity, energetic costs, and microhabitat use in four North American stream fishes

We employed field and laboratory data to test the hypothesis that microhabitat use by rainbow trout (Oncorhynchus mykiss), rosyside dace (Clinostomus funduloides), longnose dace (Rhinichthys cataractae) and mottled sculpin (Cottus bairdi) was affected by energetic constraints. Both rainbow trout and rosyside dace occupied water-column microhabitats in Coweeta Creek, North Carolina, U.S.A. These species were over-represented at velocities requiring lower rates of oxygen consumption, as predicted by an energetic cost hypothesis. Morphological and behavioral adaptations of the two benthic species (mottled sculpin and longnose dace) enabled them to hold position over a wide range of velocities without significant changes in oxygen consumption. Focal point velocities of longnose dace were not significantly different from those available, suggesting a lack of velocity preference. Mottled sculpin, however, consistently were over-represented at low velocities, even though oxygen consumption data showed that energetic costs were not decreased by occupying these microhabitats. Our results indicate that microhabitat use by rainbow trout and rosyside dace is consistent with predictions of an energetic cost hypothesis, whereas the morphological adaptations of longnose dace and mottled sculpin minimize the constraints of energetic costs in microhabitat selection.

Group foraging by a stream minnow: shoals or aggregations?

The importance of social attraction in the formation of foraging groups was examined for a stream-dwelling cyprinid, the rosyside dace, Clinostomus funduloides. Dace arrivals and departures at natural foraging sites were monitored and tested for (1) tendency of dace to travel in groups, and (2) dependency of arrival and departure rates on group size. Dace usually entered and departed foraging sites independently of each other. Group size usually affected neither arrival rate nor departure probability. Thus, attraction among dace appeared weak; foraging groups most often resulted from dace aggregating in preferred foraging sites. The strongest evidence of social attraction was during autumn, when dace departure probability often decreased with increasing group size, possibly in response to increased threat of predation by a seasonally occurring predator. Dace also rarely avoided conspecifics, except when an aggressive individual defended a foraging site. Otherwise, there was little evidence of exploitative competition among dace for drifting prey or of foraging benefits in groups, because group size usually did not affect individual feeding rates. These results suggest that the benefits of group foraging demonstrated under laboratory conditions in other studies may not always apply to field conditions.

Habitat Suitability and Reproductive Traits of the Orangefin Madtom Noturus gilberti (Pisces: Ictaluridae)

-The orangefin madtom (Noturus gilberti), a candidate species for federal protection in Virginia and North Carolina, was sampled at 256 sites to characterize its habitat, species associations and reproductive traits. Only the Roanoke darter (Percina roanoka) consistently co-occurred with the orangefin madtom. Several fish species: Nocomis spp., Phoxinus oreas, Clinostomus funduloides and Notropis cerasinus, and crayfish were negatively associated with its presence at sites. Sand and silt levels were significantly lower at sites with orangefin madtoms, whereas small cobble, local gradient and water depth were significantly higher. Discriminant function analysis provided a predictive model that correctly classified 85% of the sites which contained this species. Spawning of the orangefin madtom occurred from late April through June at water temperatures from 18-22 C. Age 2 adults were the primary spawners of the three age groups in the population. Estimated longevity for this species is 24-28 mo.

Effects of Rosyside Dace (Clinostomus funduloides) on Microhabitat Use of Rainbow Trout (Oncorhynchus mykiss)

We experimentally examined the effects of competition for space between rainbow trout (Oncorhynchus mykiss) and rosyside dace (Clinostomus funduloides) in an artificial stream. These species generally do not exhibit statistically significant differences in microhabitat use in Coweeta Creek, North Carolina, USA. Two competition (trout and dace) and two control (trout only) trials were conducted during spring and summer. Microhabitat use data indicated that the presence of dace did not produce microhabitat shifts in trout. Most behavioral changes could be attributed to acclimation effects or intraspecific competition. Based on field and laboratory results, it does not appear that interspecific competition with dace strongly affects the use of spatial resources in rainbow trout.

The Metabolic Cost of Maintaining Position for Four North American Stream Fishes: Effects of Season and Velocity

We used a swimming respirometer to measure oxygen consumption (i. e., metabolic cost) of four species of stream fishes while they held position at diferent velocities. We tested naturally acclimatized individuals during spring, summer, fall, and winter at seasonal temperatures and photoperiods. Rosyside dace (Clinostomus funduloides), longnose dace (Rhinichthys cataractae), mottled sculpin (Cottus bairdi), and juvenile rainbow trout (Oncorhynchus mykiss) all showed seasonal changes in oxygen consumption. Seasonal changes in standard metabolic rates seemed to be influenced by changes in reproductive condition as well as ambient temperature. The metabolic cost of maintaining position for rainbow trout and rosyside dace generally increased with velocity. At velocities below eight body lengths per second, longnose dace did not exhibit a significant change in oxygen consumption, because they held position without swimming. At higher velocities, however, long-nose dace swam to maintain their position and oxygen consumption increased rapidly. Mottled sculpin held position without swimming and therefore showed little or no change in energy use with changing current velocity.

Fish Assemblage Stability in a Southern Appalachian Stream

We monitored fish populations at three sites in a southern Appalachian stream system during a 40-mo study. Assemblages at two sites, consisting of four and five resident species, were persistent in terms of relative species abundances and production. This persistence was related to low variation in abundance of the two numerically dominant fishes, mottled sculpins (Cottus bairdi) and longnose dace (Rhinichthys cataractae). Less abundant residents, rosyside dace (Clinostomus funduloides), rainbow trout (Salmo gairdneri), and greenside darters (Etheostoma blennioides), displayed lower levels of persistence. We also observed pronounced annual variation in either young-of-the-year recruitment and/or subsequent year-class strength of four resident species, possibly resulting from a severe drought during the third year of study. Abundance and production of rosyside dace and trout were greatly affected by fluctuations in recruitment and year-class strength, suggesting that environmental variability strongly influenced these populations. Density-dependent mechanisms may have regulated sculpin and longnose dace populations. The three-species asssemblage at a third site also was persistent as a result of relatively stable sculpin and longnose dace populations, whereas the rainbow trout population fluctuated among years. We observed significant intersite differences in relative year-class strength in a given year and in population structures of sculpins and longnose dace, suggesting that spatial variation in habitat characteristics affected assemblage dynamics and responses to environmental fluctuations.

Microhabitat use in a stream fish assemblage

We examined microhabitat use among fishes in a 37‐m section of Coweeta Creek, North Carolina. Numerical abundances of species changed substantially during the 17‐month study period. Microhabitat availability, however, did not change markedly during our investigation. Seasonal principal component analyses of microhabitat availability and fish microhabitat use data extracted two main patterns of non‐random microhabitat use. Clinostomus funduloides, Notropis eoccogenis and Semotilus atromaculatm were significantly over‐represented in deep areas with low to intermediate velocities and depositional substrata. Campostoma oligolepis, Coitus bairdi, Etheostoma blennioides, Rhinichthys cataractae and Salmo gairdneri all occurred in intermediate to deep microhabitats with moderate to high velocities and erosional substrata. Five of seven species exhibited seasonal variation in microhabitat utilization, whereas six species displayed size‐related variation in use. Size‐related variation was probably ontogenetic. We attributed most seasonal changes in microhabitat use to variations in microhabitat availability.We used canonical analysis of discriminants to identify factors maximizing interspecific differences in microhabitat use. This analysis indicated that species could be assigned to either a benthic or a water column guild. Species within a guild generally could not be differentiated statistically, whereas members of different guilds were readily separable. These patterns persisted throughout the study, despite changes in numerical abundances of assemblage members. There was no evidence of either exploitation or interference competition for microhabitat, consequently it is unlikely that spatial resources were limiting during our study.

Mercury concentrations in fish from the great smoky mountains national park

Excessive mercury concentrations ostensibly due to pollution have been widely reported in fish tissue. The concentrations of mercury occurring naturally in fish tissue have not been well defined. A collection for mercury analysis of 198 fish of five species was made in 1972 in three high altitude streams in the Great Smoky Mountains, 20–25 km from the nearest pollution source. Mercury concentrations were (means, p.p.m.): rainbow trout Salmo gairdneri, 0.036; brook trout Salvelinus fontinalis, 0.018 ; banded sculpin Cottus carolinae, 0.025; rosyside ace Clinostomus funduloides, 0.044; stoneroller Campostoma anomalum, 0.039. There was no significant difference in mercury concentration among fish analyzed whole, with gastrointestinal tract removed, or a strip of axial musculature. There was a significant (P0.05) difference in mercury concentration among species in one stream and in three species from different streams. A second collection of fish of the same species in 1973 verified the 1972 results. Methylmercury constituted 93 ±2.6% of total mercury. These results indicate that all fish acquire about the same tissue concentrations of mercury at chronic exposure to very low levels.

Age, Growth, and Fecundity of the Rosyside Dace, Clinostomus funduloides Girard

Information on growth rate, age composition, and fecundity of rosyside dace was obtained from a sample of 212 fish collected from April to August 1970 from the North Branch of Jennings Run, Potomac River drainage. Total lengths ranged from 46 to 94 mm and average weights ranged from 1.4 g (40–49 mm length class) to 10.4 g (90–99 mm length class). Ages of rosyside dace included age groups I to IV. Sexual maturity was attained at about 53 mm and age I for both sexes. The spawning season lasted from early May until late June. The mean diameter of eggs during the spawning season ranged from 1.05 mm in May to 1.20 mm in June. Fecundity ranged from 139 (56–59 mm length class) to 802 (90–95 mm length class). There was a high correlation between fecundity and length and weight of dace, but a low correlation between fecundity and age and weight of ovaries.