Physical Habitat Used by Spikedace, Meda Fulgida, in Aravaipa Creek, Arizona

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PHYSICAL HABITAT USED BY SPIKEDACE, MEDA FULGIDA, IN ARAVAIPA CREEK, ARIZONA

John N. Rinne Research Fisheries Biologist USDA Forest Service Rocky Mountain Forest and Range Experiment Station

and

Erich Kroeger Graduate Student Arizona State University

Abstract

In Aravaipa Creek, spikedace, Meda fulgida, occupied shallow (mean, 20 cm) moderate velocity (mean, 35 cm/sec) waters over gravel-pebble (3-64 mm) substrate. Habitat use varied in space and time but generally paralleled habitat availability. Larger schools of spikedace (10 or more fish) were captured in deeper (mean, 27 cm) and slower (mean, 25 cm/sec) waters than those inhabited by single fish (16 cm and 37 cm/sec, respectively). These deeper, slower stream areas were characterized by eddying currents, and were associated with shear zones, instream boulders, and canyon walls. Introduction

The spikedace, ?Oda fulgida, is a small (< 100 mm) cyprinid endemic to the Gila River basin, Arizona and New Mexico (Miller and Hubbs, 1960; Minckley, 1973). It is currently listed as a threatened species by both State (Arizona Game and Fish Commission, 1985) and Federal (USDI, 1986) agencies; New Mexico lists the species as endangered (New Mexico Wildlife Conservation Act 1975).

The literature on the species primarily addresses its distribution and taxonomy (Miller and Hubbs, 1960; Minckley, 1969; LaBounty and Minckley, 1972; Mincldey, 1973; Anderson, 1978). Aside from recent agency reports (Turner and Tafanelli, 1983; Propst et al., 1986) information in the open literature on the life history and habitat of spikedace has come exclusively from studies in Aravaipa Creek (Barber et al., 1970; Schreiber and Mincldey, 1981) In southeast Arizona. Because of the status of and limited information on the spikedace, a study was initiated to quantify its physical habitat requirements. This paper reports on habitat use of spikedace in Aravaipa Creek; a more comprehensive report on comparative habitat use in several desert streams in Arizona and New Mexico and its management implications will appear later. Study Area

Aravaipa Creek is a low-gradient (%), small (3-5 m wide) often- braided, hydrologically-stable stream with primarily gravel-pebble (3-64 mm) substrate (Barber and Minckley, 1966; Minckley, 1981; Rinne, in press). Modal discharge ranges between 0.5 and 1.0 m3/sec with greatest flow in winter months. Late summer storms are capable of producing sudden, sometimes violent floods. Methods

Aravaipa Creek was sampled six times to include winter (Dec-Feb), spring (April-May), and summer (Aug-Sep) seasons. Initial sample sites were selected based upon previous personal experiences with collection of spikedace and upon qualitative description of its habitat (Barber and Minckley, 1966; Minckley, 1973). Habitat transects in stream reaches sampled were determined by location of initial capture of this species. Once a capture was made, at least two more transects were sampled; one 5 m upstream and one 5 m downstream. If spikedace were taken at either of these transects, then additional transects were established in an up- and/or downstream direction (Rinne, 1985). Normally, a maximum of 9 additional transects were sampled in addition to the initial transect where spikedace were found. If spikedace were absent, sampling effort was moved to another reach of stream.

Spikedace were immobilized by electrofishing and captured by a one-meter block net positioned about 1 to 2 m downstream. Physical habitat characteristics of these approximately 1 to 2 m2 sample areas (not all with spikedace present) were measured using the meter transect method and a habitat sampler (Rinne, 1985; Rinne, in press). With this apparatus, one set (velocity, depth, substrate) of 21 measurements each (at 5 cm intervals along a guide rod) was made at each transect. These 21 data points for depth and velocity were averaged prior to.statistical analyses. For substrate, modal class values were used as substrate "indices" (Table 1).

Because this same approach was also used for the other six native fish species inhabiting Aravaipa Creek (Barber and Minckley, 1966), an estimate of total habitat availability (all transect data combined) in Aravaipa creek was provided.

Depth was measured with a modified meter rule, and velocity was measured 5 cm off substrate. Ini- tially, substrate was visually classified into one of five categories (sand, mm; gravel, 3-16 mm; pebble 17- 64 mm; cobble, 65-256 mm; and boulder, 256 mm). Because of often near equal frequency of occurrence of two substrate modes (gravel and pebble), two additional classes, sand-gravel and gravel-pebble, were added for a total of seven substrate classes.

Depth and velocity data from transects with and without spikedace were compared using unpaired t- tests; chi square analysis was used on substrate data. Habitat use among sampling dates in Aravaipa was compared by analyses of variance (ANOVA) If homogeneity of variances (Bartlett's test) was established. If variances were heterogenous, Welch's test (Milliken and Johnson, 1984) was applied. If significant varia- tion among samples was detected, Tukey's or Dunnett's T3 tests (Dunnett, 1980) were used to determine and illustrate (Fig 1.) specific differences in habitat use among samples. Results

In Aravaipa Creek, spikedace were collected In significantly (P < .05) deeper water than where it was absent only in December 1982 and April 1983 (Table 1). By comparison, spikedace inhabited significantly (P < 0.05) slower water only in August 1983. Spikedace occupied waters over gravel-pebble substrate that was significantly (P <0.05) smaller in size than where the species was absent only in December 1982. Overall, spikedace appeared to use physical habitat in Aravaipa Creek based on availability (Figs. 1, 2).

The variances in depth among sample dates were heterogenous (P < 0.001); those for velocities were not (P = 0.82). Welch's test of depths occupied by spikedace indicated significant differences (P < 0.001) among sample dates. They were present in shallower (14-16 cm) waters in December, February, and August than in April, May, and September (23-27 cm). Similarly, ANOVA indicated significant differences (P < 0.001) in velocities occupied by spikedace among dates. Tukey's multiple range test grouped velocities used by spikedace among sample periods into three groups that, similar to depths, suggested no definite seasonal patterns.

Based on relative numbers at transects, rather than mere presence or absence of the species, spikedace preferred deeper, slower waters (Fig. 3). Transects with 10 or more fish averaged 22.8 cm in depth, and those with 12 or more fish averaged 27.3 cm in depth. By comparison, transects with a single fish averaged only 15.7 cm in depth. Velocity at these same transects averaged 25.7 cm/sec and 22.7 cm/sec compared to a mean of 36.6 cm/sec at transects with a single fish. At 5 of the 10 transects with more than 10 individuals, 60% were juveniles (28 to 37 mm total length), which suggest ontogenetic differences in habitat preferences. Discussion

Miller and Hubbs (1960) described spikedace as Inhabiting moving, deep (61 to 122 cm) waters, and typically found in "swift deep pools, or the deeper parts of long pools, near riffle mouths over sandy or gravelly bottoms." In the Gila River, these same researchers also observed adults on shallow, algae- dominated riffles. In the Verde River, they noted adult spikedace on a very swift riffle over a bedrock bottom; young occupied backwater areas over silt-sand bottom adjacent to pools. Barber et al. (1970) noted that, during the day, spawning females inhabited deeper pools and eddies, while males occupied riffles (8-15 cm) over sand gravel beds.

More recently, Anderson (1978) reported spikedace common only in moderate to swift riffles less than 30 cm deep and comprised of "gravel-rubble" (15-120 mm) substrate. Similar to Miller and Hubbs (1960), he recorded larval fish in "slow" currents if in the immediate vicinity of riffles containing adults. Adult spikedace generally did not occupy areas with "slow" current or pools with no current. Turner and Tafanel- li (1983) reported spikedace in Aravaipa Creek to be most commonly collected in waters 18 to 37 cm deep and in velocities ranging between 39 and 82 cm/sec. Spikedace were rarely captured in velocities less than 18 cm/sec or greater than 90 cm/sec. Propst et al. (1986) reported spikedace in the upper Gila River inhabiting waters averaging less than 32 cm deep with velocities of less than 15 cm/sec.

Our quantification of physical habitat of spikedace, combined with the earlier and more recent reports, suggest a wide range of physical habitat use by this species. In part, this variability may reflect ontogenetic differences and habitat availability (Propst et al., 1986). We recorded spikedace in much shallower waters than those suggested by Miller and Hubbs (1960) in the upper Gila River. However, our values were corn- parabe to depths listed by Anderson (1978) and Propst et al. (1986). The ranges of depth (15-18 cm) recorded for in Aravaipa Creek by Turner and Tafanelli (1983) were similar to our values; those for velocities (39-82 cm/sec) were greater. This discrepancy is undoubtedly attributable to point of velocity measure- ment in the water column, as Rinne (in press) discussed for loach minnow, Tiaroga cobitis. Turner and Tafanelli (1983) also reported that spikedace very rarely occupy waters with a velocity of less than 18 cm/sec. In contrast, we recorded spikedace in Aravaipa in waters with velocities less than 18 cm/sec at about 20% (19 of 91) of the transects where the species was present; mean values ( cm/sec) reported by Propst et al. (1986) also suggest spikedace do occupy low-velocity waters.

If the number of individuals at respective transects is an indicator of optimum or preferred habitat, our data suggest spikedace prefer deeper (25 cm) water and/or pools with slow ( cm/sec) current (Fig. 3). In Aravaipa Creek, such habitats were frequently associated with "shear zones" where two (or more) braids of stream converged. These areas, those along canyon walls, and those downstream of large boulders provided physical structure that produced eddying and, in some cases, pool formation. Based on personal observations, qualitative descriptions in the literature, and our data, such habitats are frequented by spikedace. The lifestyle of these fish may be facilitated by these areas of greater water depth and reduced, eddying currents. For example, spikedace conceivably could feed on drift items (Schreiber and Minckley, 1981) in these areas with reduced energy expenditure.

The results of this study on spikedace habitat in Aravaipa Creek should not be extrapolated to other streams. Comparison of physical habitat use in larger streams and rivers based on data collected by the same methodology is desirable to refine and substantiate estimates given here. Further, habitat use by the various life states, spawning habitat, and comparative habitat use by introduced, apparently competitive fishes such as the red shiner, Notropis lutrensis, should also be delineated. Synthesis of this information will aid in making viable recommendations for the management and recovery of this rare southwestern cyprinid.

Literature Cited

Anderson, R. M. 1978. The distribution and aspects of the life history of Matta fulgida In New Mexico. Unpubl. M.S. Thesis. New Mexico State University, Las Cruces, New Mexico.

Arizona Game and Fish Commission. 1985. Threatened wildlife of Arizona. Arizona Game and Fish Department Publication. 12 pp.

Barber, W. E., and W. L Minckley. 1966. Fishes of Aravaipa Creek, Graham and Pinal Counties, Arizona. Southwest. Nat. 11(3): 313-324.

Barber, W. E., D. C. Williams, and W. L Minckley. 1970. Biology of the Gila spikedace, Mgla fulgida , In Arizona. Copeia 1970(1): 9-18.

Dunnett, G. W. 1980. Pairwise multiple comparisons in the unequal variance case. J. Amer. Stat. Assoc. 75(372):796-800.

LaBounty, J. F. and W. L Minckley. 1972. Native fishes of the upper Gila River system, New Mexico. Pp 134-146 in Symposium on rare and endangered wildlife of the southwestern United States. New Mexico Game and Fish Department, Santa Fe, New Mexico.

Miller, R. R., and C. L Hubbs. 1960. The spiny-rayed fishes (Plagopterini) of the Colorado River system in western North America. Misc. Publ. Mus. Zool. Univ. Michigan, 115:1-39.

Milliken, G. A., and D. E. Johnson. 1984. Analyses of messy data. Volume 1: Designed experiments. Lifetime Learning Publ., Belmont, Calif. Minckley, W. L 1969. Native Arizona fishes, Part II. Spiny-rayed minnows. Arizona VVildi. Views 16: 6-8.

. 1973. Fishes of Arizona. Arizona Game and Fish Department, Phoenbc. 293 pp.

. 1981. Ecological studies of Aravaipa Creek, central Arizona, relative to past, present, and future uses. Final Report. U. S. Bureau of Land Management, Safford, Arizona.

Propst, D. L, K R. Bestgen, and C. W. Painter. 1986. Distribution, status, biology and conservation of the spikedace (Meda fuigida) In New Mexico. USDI. Fish and Wddl. Serv., Albuquerque, New Mexico. Endangered Species Rep. 15:1-93.

Rinne, J. N. 1985. Physical habitat evaluation of small stream fishes: point vs. transect, observation vs. capture methodologies. J. Freshwater Ecol. 3(1): 121-131.

. In press. Physical habitat use by ioach minnow, Tiaroga cobitis (Pices: Cyprinidae), in southwestern (USA) desert streams. Southwest. Nat.

Schreiber, D. C., and W. L Minckley. 1981. Feeding interrelationships of native fishes in a Sonoran Desert stream. Great Basin Nat. 41(4): 409-426.

Turner, P. R., and R. J. Tafanelli. 1983. Evaluation of the instream flow requirements of the native fishes of Aravaipa Creek, Arizona by the incremental methodology. Final Report. U. S. Fish and Wildlife Service, Albuquerque, New Mexico.

USDI. 1986. Endangered and threatened wildlife and plants; determination of threatened status for the spikedace. Fed. Reg. July, 1986. Table 1. COmparison of mean depth and velocity (t-tests) and substrate composition (Chi Square Analysis) and indices (class =des) where spikedace, Emdb =alga, were present (F) or absent (AL) in Aravaipa Creek, 1982-85. Significance at the 0.05 (*) and 0.01 (**) levels and sample size (transacts; in parentheses) for the 3 habitat variables are indicated.

Substrate Sample Depth (an) Velocity(cm/sec) index date A P A

Dec. 82 (13) 14.5** (45) 11.8** 58.7 55.1 2.7** 3.6** April 83 (14) 23.2** (60) 15.0** 32.4 40.9 3.2 3.4 August 83 (34) 15.7 (19) 18.8 33.1** 49.6** 2.8 3.6 Feb. 84 ( 9) 15.9 (22) 14.0 25.2 37.0 3.1 3.3 , Sept. 84 (14) 25.0 (30) 26.3 23.3 35.6 2.4 2.9 z ; May 85 (11) 27.9 (31) 23.2 35.2 29.9 3.1 3.3 , : 1 9 .1 Figure Captions

Figure 1. Means and 95% confidence intervals of depths and velocities available (dashed) and that used (solid) by Meda fulgida in Aravaipa Creek, 1982-85.

Figure 2. Substrate used by spikedace, mda fulgida, in Aravaipa Creek relative to that available and to where spikedace were absent. Substrate class sizes (HB) are given in text. Figure 3. clomparison of physical habitats used by spikedace, EWA fulgida, in Aravaipa Creek based on abundance of indivi di n1 s at a transect.