•

AQUATIC BIOTA OF THE BASIN, SANTA CRUZ COUNTY, ARIZONAV

W. L. Minckley JIDelEtiast of Zooloa, State University, kmpe 85281

Contents Introduction ...... 2 Historical Description of the Area ...... 2 Studies of the Aquatic Biota ...... 5 Fishes of the Sonoita Creek basin ...... 5 Other Aquatic Organisms ...... 19 Aquatic and Semi-aquatic plants ...... 19 Invertebrate animals ...... 20 Quality and Permanence of Aquatic Habitats ...... 22 Conclusion ...... 26 Literature Cited ...... 27

1/ — Studies of the aquatic biota of southern Arizona have been supported since 1963 by the University Grants Committee, Arizona State University, by the Sport Fishing Institute, and by the National Science Foundation (NSF Grant GB-154, to G. A. Cole). The specific survey of the Sonoita Creek basin was supported by he Nature Conservancy. I thank members of the Sonoita Creek Sanctuary Committee of the Cons- ervancy, especially Mr. Edward Steele, for their encouragement and assistance. Landowners in the area cooperated fully in allowing access to the waters. The help of numerous students and colleagues in the field and the laboratory is also gratefully acknowledged.

15 March, 1968 Since Autumn 1963, the aquatic biota of the drainage of Sonoita Creek, Santa Cruz County, Arizona, has been studied periodically; in

1967, an intensive survey was made. This report is a result of those investigations. It describes the historical and current status of aquatic habitats of the area. By most standards Sonoita Creek is a small, insignificant system that consists presently of dry washes throughout much of the year.

It was not always so, however, and persistence of surface waters make the drainage one of the few such places in southern Arizona to preserve remnants of its generally-depleted, indigenous aquatic biota.

About 10 linear miles of perennial flow now remains, if one includes the disjunct segments of z.maller tributaries (Fig. 1). Such habitat is supplemented by two major springs, and by a number of earthen tanks. Past conditions in the area are inferred from old records and photographs that were recently made available in the excellent review by Hastings and Turner (1965). The influence of changes on the aquatic biota are proposed in light of information from Sonoita

Creek, and from adjacent streams in southern Arizona, obtained by myself in recent years, and by various investigators in the region since the 1850s.

Historical Description of the Area

Prior to 1890, Sonoita Creek probably flowed through a broad, marshy floodplain in multiple channels or by seepage. Dark, rich, organic deposits form parts of the walls of now-incised stream channels of the Sonoita basin, especially in the grasslands upstream

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SANTA SANTA CRUZ COUNTY, AR I ZONA%. CRUZ Jr RIVEN 4 MILES j • ^-0.■ • r 1/4-- • 0400 -4-

from the town of Patagonia. Riparian galleries of cottonwoods, now

so prominant near the creak, were absent or localized in places of relatively well-drained soils. Areas of entrenched channel also were

undoubtedly present, however, along which mesquite "bosques" would

have occurred. Under such conditions, stream bottoms are of mud and organic debris, except in places of channel cutting or the

occurrence of stony dikes. Currents are mostly slow, impeded by debris and by the tortuous nature of channels, and effects of floods are minimized by dense streamside stands of sedge and perennial grass.

The present aspect of Sonoita Creek, with eroding banks, moving

sand bottoms, and invasion of its floodplains by extensive, woody vegetation, originated in the 1890s with onset of "arroyo cutting."

Similar erosional phenomena are recorded in a 20-year period, 1875-95, in streams of Arizona, New Mexico, Sonora, and Utah. The uniformity

over such a wide area "makes it difficult to link settlement..., with arroyo cutting; the uniform onset of erosion, on the other hand,

points to the operation of a broad, regional factor like climate

(Hastings and Turner, 1965)." Yet, in southern Arizona, severe over-grazing by cattle in the period from 1870-90 resulted in death of an estimated 75 per cent of the herd when protracted drought grasped the region in 1891-3, Effects of this catastrophe on land and vegetation in southern Arizona are vividly documented by the

paired photographs published by Hastings and Turner (op.

There can be no doubt that severe changes must also have occurred at that time in the aquatic habitats. It is redundant to discuss the controversy on "causation" of such a marked erosional increase. 4 -5-

obviously occurred, and a combination of factors is the most-often- cited explanation. "The factor" of initiation undoubtedly differed from place to place.

Studies of the Aquatic Biota

The aquatic fauna of the American Southwest is, as yet, largely

unstudied. Fishes are a major exception, however, and most inter- pretation that follows is based on that group of animals. Early

collections in Arizona were made in conjunction with the U. S. and

Mexican Boundary Surveys of 1851-4 (Baird, 1859, and papers cited therein). None of these was in the Sonoita Creek basin, but many of

them, and others made by Edgar A. Mearns in 1892-4 (Snyder, 1915), were from the upper Santa Cruz and San Pedro rivers, thus providing

valuable data on early conditions. In 1904, F. W. Chatberlain sampled in the Sonoita drainage, among other places, and his data

were reported on by Miller (1961). Other workers, principally C. E

Burt, C. L. Hubbs, and R. R. Miller, sampled the stream in the period 1928-59 (Miller, 22. cit.), thereby providing a chronology of faunal

change up to the time of the present studies.

Fishes of the Sonoita Creek Basin

Fourteen species of fishes, seven of which are native, have been taken in the Sonoita Creek basin. Material preserved from the area,

upon which this report is based, is housed at the U. S. National Museum, the University of Michigan Museum of Zoology, and Arizona State University. Literature records for the basin prior to 1964 all are cited by Miller and Lowe (1964), and are not repeated as such. All more recent citations are given in the text.

Family Cyprinidae, minnows

Carassius auratgs (Linnaeus), goldfish.--Introduced. Goldfish are not yet established in the Sonoita Creok drainage, but one was

caught at Patagonia in 1966. The species does not commonly establish in eroding creeks, but .dadazds ponds, or stabilized pools of

streams, when such are available. It is abundant in Babacomari

Cienega at the Babacomari Ranch, Cochise County, Arizona, where tMŠ

feeding activities visibly roiled the water and uprooted aquatic vegetation in Autumn 1967. This fish (and another foreign introduc-

tion, the carp, gmatras carpio Linnaeus, which has not yet been recorded in Santa Cruz County) should be vigorously excluded from the

drainage, especially if proposed impoundment of lower Sonoita Creek is realized.

Gila robusta intermedia (Girard), Gila chub.--Native. This fish was formerly widespread in the upper Santa Cruz basin, as indicated by its common occurrence in early collections. It was never taken in Sonoita Creek, but thrives in Monkey Spring and in ponds fed by that spring on the Rail-X Ranch, 7 miles northeast of Patagonia. It almost certainly occupied deeper cienega habitats of Sonoita Creek in early days. In the presently-undissected Babacomari Cienega,

this species is abundant, though highly secretive, in an artificial pool and in deeper channels of the aggraded, eutrophic cienega itself.

In Monkey Spring, young G. r. intermedia congregate in swift areas -7-

while the adults use under-cut banks and heavily-vegetated margins of the spring run. In the pond directly fed by a canal from Monkey

Spring, the tiny young are in shallowest water, in vegetation along with young of other species of fish. Juveniles between 25 and 75 millimeters (mm) in length move to the current of the inflow canal.

Larger fish are usually in more than three feet of water, either in the open, 12-feet-deep center of the pond or adjacent to the extensive stands of sedges that rim the banks. Young Q. r. irltamtdja mailer than 20 mm in length have been taken thro9ghout the spring and summer months (late February--September), and once in late

November. In the constant-temperature spring, at least, reproduction may occur throughout the year. Males of the Monkey Spring population of G. r. intermedia are much smaller than females (maxima are less than 100 mm and more than 200 mm, respectively). Whether such . disparity in tize is a characteristic of the form is unknown at present. Breeding coloration in this fish may be far more intense than in other forms of the genus in Arizona. The axial and inguinal regions become a deep orange-red, which may develop further into a broken, orange-red band along the lower sides and caudal peduncle, and extend foreward to include the brancheostegal rays and cheeks.

The eyes of males become yellow to yellow-orange and the body is blue-black dorsally. Fins of some individuals, especially the larger ones, may be washed with lemon-yellow.

Although only algae has been found in 20 stomachs of G. r. intermedia from Monkey Spring Pond, I have seen what appeared to be predatory behavior at that locality. A band of smaller fish, mostly -8-

Gila topminnows (see below) was first observed along the shoreline, milling close to the sedge-choked margins, or moving back and forth in waves in a most unusual manner. Closer inspection on two separate occasions revealed a number of large Gila abut four feet from the band of smaller fish, moving slowly parallel to the sh:re. Violent wave-like movement of the topminnows resulted from "passes" by individual Gila toward the group. Harassment of this type has been similarly observed, using G. r. robusta and the Gila topminnow, in an artificial pool at Arizona State University. In no case was

predation actually seen.

The population of G. r. intermedia at Monkey Spring is somewhat differentiated, morphologically, from other populations in southern

Arizona (especially in size of scales; the minimum numbers:recorded by Barber and Minckley, 1966, were from Monkey Spring Pond). Its status is under investigation by John N. Rinne of this Department.

G. r. intermedia may soon be an "endangered species," if the current trend continues. It once was widespread in the Santa Cruz system, in smaller tributaries of the San Pedro River, denegas of the upper San Simon River, and in certain local habitats of the Salt and

Gila rivers of central Arizona. It now is abundant at fewer than 10 places within this formerly-large range.

Rhinichthys osculus osculus (Girard), speckled dace.--Native.

This highly-speckled form of the widespread R. osculus was described from Babacomari River (Girard, 1856) that has its headwaters just east of the Sonoita basin. This species was considered extinct in Sonoita

Creek in 1959 (Miller, 1961), and in 1963 it took about four bours -9-

and a detailed selection of habitat in thr canyon about 5 miles down- stream from Patagonia to catch two individuals. In 1966, following favorable precipitation in the preceding winter, pronounced reprod- uction occurred, and the species was frequent in suitable habitat in 1967. A similar situation occurred in , a tributary of the San Pedro River (Final and Graham counties, Arizona). One specimen was taken in the survey of that stream in 1964 and 1965

(Barber and Minckley, 1966); our collections in 1966-7 found the species uncommon,bUt,witlespread, in the upper part of that stream

(unpublished data).

R. osculus is a riffle fish, living actively in swift, turbulent waters over gravel-rubble bottoms throughout its range in Arizona.

Males in brilliant nuptial coloration were caught at Patagonia in

April 1967; in November 1967 (and undoubtedly earlier), the same riffle was dry; aa was the stream for half a mile downstream. This species is capable of persisting under remarkably adverse conditions, ranging from extreme flooding in narrow montane canyons, to periods of ponded, intermittent flow (John, 1963, 1964). Its resistence to extirpation does not approach that of the following minnow, however,'

R. osculus, like G. r. intermedia discussed above, has suffered marked reduction in its southern range since 1890.

Agosia chrysogaster Girard, longfin dace.--Native. In most of the desert watercourses in southern Arizona this species comprises the major component of the fish fauna. It is almost ubiquitous in habitat selection, especially when it occurs alone. In streams where other minnows are present, Mosia is most common in shallow, sand-bottomed -10-

pools, in places where a slight current persists. In Sonoita Creek, this species dominates the fauna, and is relatively unselective.

Agosia was absent or rare only on the swiftest, rubble-bottomed riffles in 1967.

A. chrysogaster disperses rapidly when conditions become favor- able. The fish lives in remarkably small and ephemeral places in the Sonoita drainage (and elsewhere; Miller, 1961), and when the opportunity presents itself, moves into, and matures, in small pools far above and below zones of permanent water. A pool, shaded by a cliff or a fallen tree in the stream channel, may be expected to harbor a few individuals of this fish anywhere in the basin. This is how the species maintains the largest distribution of any fish in the system. It is interesting, however, that in the canal draining Cottonwood Spring (Fig. 1), this fish occurs to 50 yards from the source, and no farther (1964-67 data); Oeasons for avoidance of springs, and headwaters in general, by Agosia, even in lower desert areas, are unknown.

Spawning by A. chrysogaster was observed above a small, low-water bridge at Patagonia in April 1967. A sandy area, 3 to 5 inches under water and measuring about 10 by 20 feet, was almost totally disturbed by fish activities. Nest areas were obvious since the sandy bottom supported a film of diatoms in undisturbed places and the fish digging through this layer exposed clean, yellowish sand. Nesting depressions in isolated places at the margin of the bar resembled tracks of cattle! it is possible that some breeding activity occurred in depressions formed in that way. A number of fish (20 to 30), some of which were -11-

definitely males as based on subsequent observation of selected ind- ividuals, moved casually over the sand bar. Large schools of other

individuals, perhaps mostly females, moved around the periphery,

mostly on the side toward the current. Intermittently, a few fish

moved from the schools onto the bar, where they were immediately accosted by 3 to 5 males. The males moved back and forth, and around, a given female. Males often "posed" jerkily, with their fins erect and body stiffened, either toward the female, or lateral to the

milling group; the latter may have been a display toward competing males. It is notable that Mosia has little development of nuptial coloration, other than an intensification of dark parts of the body and development of milky-white underparts; the fins are washed with

weak lemon-yellow in some males, but not in others. Chase, display, and milling about lasted for perhaps a minute after a female entered

the area and was given attention. Then, the female would enter a depression in the sand, followed by a male (or two males as seen in

2 of 33 apparent spawnings), and a violent flurry of sand totally

obscured further observation. This flurry appeared initiated by the female. The individuals were quiescent before leaving the depression for 1 or 2 seconds, and sand settled over them. They then moved rapidly out of the depression, the female left the area, and the male

usually began random movements over the sand bar. No aggression was observed between males over the spawning area when females were absent, though they tended to maintain a few inches of space between individuals. Seiving of sand in the depressions obtained numerous fish ova (though not as many as anticipated), and some of these were -12-

in fairly advanced stages of development. Some depressions near

the edge of the sand bar had 10 to 50 (estimated) young of A. chnimogaster moving about in them (identified by use of Winn and Miller, 1954). No young fish were on the sand bar with the active group of adults. A number of older•depresaions4 as judged by the re-establishment of diatoms, were likewise devoid of young fishes,

but they were swarming with corixid hemipterans.

Similar observations of breeding activities of A. chrimoW4!m were made by Miller (1952), but were not detailed, and by Willard

E. Barber and David C. Williams in Aravaipa Creek in 1966-67 (pers-

onal communication).

Family Catostomidae, suckers

Catostomus insignis Baird and Girard, Gila coarse-scaled sucker.— Native. This large sucker was first (and last) taken from Sonoita

Creek by Chamberlain in 1904 (Miller, 1961). The fish lives in large

pools of smaller creeks, and in larger rivers, of the Gila and Bill Williams drainages of Arizona. C. insignis. is now found in southern

Arizona only in the Babacomari River, and, very rarely, in the upper Santa Cruz River (one collection from an isolated, flood-scoured pool

north of Locheil in 1967).

Pantosteus clarki (Baird and Girard), Gila mountain-sucker. -- Native. Remarks given above for Rhinichthys osculus apply equally

well for P. clarki. It was not caught in 1959 by Miller and his party, after being consistently present in earlier collections from Sonoita Creek (and from the upper Santa Cruz River basin in -13-

general). In 1963-4, we felt fortunate to catch 2 and 3 specimens of this species, respectively, in Sonoita Creek. In 1966-7, however the sucker was second in abundance to Agosia. P. clarki is most often associated with Rhinichthys in the Sonoita Creek basin, sharing the swift-water by remaining mostly on the bottom in areas of rubble.

Mountain-suckers were in reproductive condition at the same time as R. osculus in Sonoita Creek (April 1967), and gametes were extruded by both sexes as they struggled in the seine. In the south of Arizona the breeding colors of this fish are of intense black dorsolaterally, or brownish dorsally with a jet-black lateral band, and milky-white ventrally. There is little indication of a reddish or rusty lateral stripe which appears in the species in the northern part of the Gila basin. Populations of P. clarki in small streams of southern Arizona rarely exceed 125 mm in length. To the north, individuals of twice that size are not uncommon.

Family Ictaluridae, North American catfishes

Ictalurus pricei (Rutter), Pacific channel catfish.--Introduced.

This catfish was stocked into the Sonoita Creek drainage, into a now-dry impoundment called Monkey Lake, in 1899 (Chamberlain, in

Miller, 1961). The species was last taken in the 1950s, and it appears to have failed since then; we have been unable to catch the fish since 1963, despite extensive netting. Numerous pectoral spines, and other skeletal remains, litter the floor of the desiccated lake just below Monkey Spring. This catfish was not otherwise known from the United States, though it was described from San Bernardino Creek, -14-

Sonora, Mexico, just south of the International Boundary in southeast

Arizona. That stream now is dry, except for isolated springs and tanks in its drainage, in the United States.

Ictalurus melas (Rafinesque), black bullhead.--Introduced. This small catfish occurs in at least one tank in the Sonoita Creek basin, and probably is more widespread than our data indicate. Black bullheads rarely support a useful fishery, and tend to become overcrowded in ponds and to stunt; there seems no reason for introduction of this generally-undesirable species.

Family Cyprinodontidae, killifishes

Cutrinado macularius Baird and Girard, desert pupfish.--Native.

Desert pupfish once inhabited quiet, cienega habitats throughout the entire lower Gila basin, and were repeatedly taken in the upper Santa

Cruz and San Pedro rivers in early years. Today, the species is restricted in Arizona to two localities. One is Quitovaquito Spring in Organ Pipe National Monument, and the second is the pond fed by water from Monkey Spring. Neither of these remnant populations is representative of the formerly-widespread form, however. Each is an isolated population that has diverged from the typical form, and each may be recognized taxonomically in the near future.

Pupfishes have been under study at Arizona State University for a number of years, and a summary of their general habits will suffice to describe the population at Monkey Spring Pond. The group is characteristic of desert springs, marshes, and slowly-flowing streams in the southwest. They tolerate great extremes in environment. -15-

ranging from high temperatures and salinities in cut-off pools near the Salton Sea (Barlow, 1958, 1961). Aggregations of C. macularius in severe habitats move from place to place in response to changes in temperature and salinity, and in this way remain in the most hospitable places throughout a day or a season. In the Salton Sea area, pupfishes sometimes lived in temperatures exceeding 100° F., and at salinities almost three times that of sea water. Monkey

Spring fish do not encounter such extremes. In fact, their habitat in a constantly.replenished pool is one of the "better" abodes when compared to most.

Breeding of C. macularius at Monkey Spring Pond has been seen from March through September. The males are dark, sky-blue, with blackened dorsal and anal fins, and show little of the caudal pig- mentation (orange or lemon yellow) described by Miller (1943) for fish from other areas. Male pupfishes are violently active when breeding, and highly pugnacious and territorial. Females are drab and inconspicuous. They move into a male's territory when prepared to spawn, make specific movements to trigger the spawning act, then leave as inconspicuously as they came. Eggs are deposited in the spft, silty bottoms at random. There is no parental care for the young. After hatching, maturity may occur in six weeks in warmer waters, and the cycle repeats.

Cazinodon was taken in the mainstream of Sonoita Creek near

Patagonia in 1927, but since has been restricted to the Rail-X Ranch locality. This form is difficult to maintain in captivity, unlike many other species of the genus, and should be established in other -16-

ponds in the area to insure its survival.

Family Poeciliidae, livebearers

Gambusia affinis (Baird and Girard), mosquitofish.--Iktroduced.

This species probably was introduced into Arizona about 1922 (Miller and Lowe, 1964), and has now spread to occur in almost all the major and minor streams in the state. The mosquitofish, as its name implies, is an efficient predator on aquatic larvae of insects, including mosquitos, and for this reason it now enjoys an almost-worldwide distribution. This small species also is an efficient predator on other small fishes, however, and has been found capable of limiting population growth of sane larger fishes, such as largemouth bass an,i goldfish (Myers, 1965). Throughout the world where this species has been introduced outside its native range, other small, mosquito-eating species have disappeared. The same situation prevails in Arizona, where the deolines of Cvorinodon macularius and the native poeciliid discussed next do not immediately follow arroyo cutting and drainage of their preferred marsh habitats, but rather follow discovery and progressive extablishment of G. affinis in the State.

Mosquitofish live in a tank fed by water from Cottonwood Spring about 8 miles northeast of Patagonia. For some reason they have not invaded upstream in the canal. It is recommended that the pond be dried and the population destroyed before they spread throughout the

Sonoita system. Their provenance is unknown; some public health agencies stock the species indiscriminately, for mosquito control, but this is unnecessary in the Sonoita basin where the Gila topminnow lives. -17-

Poeciliopsis occidentalis (Baird and Girard). Gila topminnow. —

Native. This fish, endemic to the Gila River basin, was recently discussed in detail by Minckley and Deacon (1968). In short, it ranged until the 1920s from Frisco Hot Spring in New Mexico, south to the north-flowing tributaries of the Gila in Sonora and Arizona, north to the junction of the and , and west to the mouth of the Gila River near Yuma. The species now is totally restricted to the Sonoita Creek drainage, with healthy populations at Monkey and Cottonwood springs and sporadic occurrences in Sonoita

Creek in periods of relatively stable flow. Attempts are being made to establish the species in other isolated drainages in Arizona, but they have met with varying success (Minckley, 1968). Stocks are also being held at Arizona State University as insurance against extirpation of the last remnants of the species.

P. occidentalis occurs in great abundance in Monkey Spring and the pond fed by that spring, and in the upper 50 yards of so of

Cottonwood Spring Run. In current, males are most obvious in their movements away from the banks; females remain along the margins in quieter water and young are largely restricted to dense beds of vegetation or shallow margins. In Sonoita Creek the fish usually is taken in beds of aquatic vegetation or in the quiet backwaters at the mouth of inflowing washes or behind sand bars. The largest pop- ulation is in the pond fed by Monkey Spring. Here the fish is distributed all around the margin, with concentrations of the largest females often "maintaining position" near the surface at the inflow.

Males of P. occidentalis become intensely black when in breeding -18-

array; fighting between males is frequent and violent in summer, and they sometimes appear to maintain territories, for a time at least.

Other times, two or more males will follow a given female, both attempting to copulate, and with no hostility toward each other.

Young are born, and sexual activity isobvions.s in almost all months of the year. The small size of such fishes allows them to utilize very shallow waters that warm rapidly, especially in winter. The suppressing effects of cold water temperatures on reproduction may thus be minimized. Reproductive activity of P. occidentalis is most intense, however, in spring and early summer.

Family Centrarchidae, sunfishes

Micropterus salmoides (Lac;p;de), largemouth bass. --Introduced. Largemouth bass were found in two tanks, but are reportedly widely distributed in larger ponds of the area. All the centrarchids taken in the Sonoita basin were in artificial tanks rather than the stream. All are considered game fish, of greater or lesser value, hence their presence and dispersal in the southwest. Little can be written that will add to the already-voluminous literature on such a species.

Lepomis macrochirus Rafinesque, bluegill sunfish.—Introduced.

This sunfish was taken along with M. salmoides in two tanks.

Lepomis cyanellus Rafinesque, green sunfish,—Introduced. This species falls into about the same category as the black bullhead dis- cussed before. Its spread in the State should be avoided if possible..

One individual was caught in April 1967 in an artificial tank fed by Cottonwood Spring. -19-

Other Aquatic Organisms

Aquatic and semi-aquatic plants.--A list of the kinds of aquatic

and semi-aquatic plants identified from the Sonoita Creek basin is in

Table 1. Stream channels, in general, are devoid of higher plants

because of their unstable, sandy bottoms. After extended periods of

low discharge, however, watercress (1111r12111 nasturtium-aquaticum),

sedges (mostly Eleocharis spp.) and dense beds of filamentous algae

(Cladaphora, Pitophora, Hydrodictvon, and others) sometimes develop.

Rich aquatic vegetation persists at the headsprings (Monkey and

Cottonwood springs), and in the clearer, permanent ponds. Of special

note is Lilaeopsis recurva, which was described from near Tucson

(Santa Cruz River), and now may be restricted in the United States

to Monkey Spring. Also, Ludwigia natans, from Monkey and Cottonwood

springs, has not before been recorded in Arizona. Plants along the

stabilized margins of springs and ponds that are protected from live-

stock include watercress, sedges (Scripus californica, Scirpus sp.,

Cvperus strigosus, and others), mesic grasses (gozamma sp.), and cattail (TVpha sp.), plus a number of trees and shrubs (cottonwood,

willow, Baccharis spp., and others). Submergent plants in such

habitats, in addition to those mentioned above, are mosses (unident-

ified) Potamogetop foliosus, Hvdrocotvl verticilliata (often emer- gent), and Chara spp. Ponds and stream margins where cattle have access seldom support more than a few small sedges, and Chara may live in deeper waters. In artificially enriched ponds that receive

sewage effluent from Patagonia, water fern (Azolla filiculoides) and small duckweed (Lemna spp.) were present in autumn 1967. -20.-

Table 1. Aquatic and semi-aquatic plants identified from the Sonoita Creek basin, Santa Cruz County, Arizona.

Characeae Cyperaceae Chara sp. (vIllgaris group) Eleocharis radicans (Poir.) Chara sp. (zelanica group) Kunth. D.eocharis sp. Salviniaceae Scirpus californica (C. Meyer) --Stend. Azolla filiculoides Lam. 221.1".R11 sp. Compositae strigosus L. Baccharis glutinosa Pers. UMbelliferae B. pteroniodes Lilltorsis recual A. W. Hill B. sarothroides Gray Hydrocotyl. verticilliata Thunb.

Cruciferae Onagraceae Rorippa nasturtium- Ludwigia natans Ell. var. awaticum (L.) Schinz & stioita.ta Fern. & Griscom Thell Potamogetonaceae Lemnaceae Potamogeton diversifolius Raf. Lemna minor L P. foliosus Raf. L. gibba L. Potamogeton SD.

Invertebrate animals.--Only certain groups of invertebrates have been studied, and, unfortunately, even those that are available in our collections have in large part yet to be identified. The general statements given above for aquatic plants apply also to invertebrates.

Headsprings and permenant ponds have a rich fauna, ponds that are disturbed by cattle or that dry in summer are less rich, and the large streams with shifting sand bottoms are poor in invertebrates except after extended periods of low flow.

The headspring fauna is quite distinctive, and differs from that of other habitats in the area. Planariid flatworms, talitrid amphipods,

Hyalella azteca (Saussure), and an undescribed, minute species of -21-

hydrobiid snail, dominate in such areas. Larval aquatic insects,

mayflies (Baetis sp. and one other genus), a tiny caddisfly (Agraylea?),

and a few beetles, dytiscids and waterpennies (Psephenidae), are pres-.

ent. The largest predatory invertebrates in springs are true bugs

(families Belostomatidae and Naucoridae), that often catch smaller

fishes, and a few larval dragonflies (Odonata).

Permanent ponds in the Sonoita Creek basin have a bottom fauna

consisting primarily of insect larvae. Animals living in the sediments

include many genera of dragonflies, baetid mayflies, and chironomid

dipterans. Segmented worms, oligochaetes and leeches (Hirudinea), also

are abundant in local areas. On the surface of softer sediments,

large populations of ostracods (Crustacea) have been found, especially

where fishes are absent, and a few red water mites (Acri) are seasonally

present. Vegetated ponds have the most diversified assemblage of

invertebrates. Snails (Phvsa sp.) often are common, along with many

kinds of damselfly larvae (Odonata), case-building caddisflies, and

belostomatid hugs. Surface-dwelling bugs, gerrids, veliids, and

microveliids, springtails (Collembola), and gyrinid beetles form a

substantial fauna in some areas. Planktonic forms, especially crustac-

eans, have been scarce in the ponds we have sampled.

Stream invertebrate faunas include most of the groups mentioned

above for permanent ponds, especially after periods of relative stabil-

ity. Two families of true bugs, the notonectids and the corixids

(backswimmers and water boatmen, respectively), become remarkably

abundant at times of low flow--almost a pint of corixids was caught

in a single scoop of a quart jar from a backwater of Sonoita Creek -22-

in April 1967. Even when conditions are optimal, as in late summer when discharge of Sonoita Creek is low (prior to the summer rains), most invertebrates are located along the margins or in clumps of vegetation; the shifting sands of the mid-channel areas support only a very small, actively-burrowing component of the fauna.

The artificially-enriched marshes downstream from Patagonia had a number of kinds of animals that were not found elsewhere. Included were tubificid oligochaetes, dipterans of the families Tabanidae,

Syrphidae, and Chironomidae, numerous daphnid crustaceans, and snails,

Physa, virgata Gould and Planorbella tonuis.(Dunker). Some of the oligochaetes and dipterans, are characteristic of organically polluted waters, and their populations reach remarkable sizes in such habitats.

Quality and Permanence of Aquatic Habitats

Stream and spring waters in the Sonoita Creek basin generally have more than 200 milligrams per liter (mg/l) total hardness, and range as high as 750 mg/i. Most waters are chemically unique for

Arizona in having a relatively high proportion of sulfate ions and a low proportion of chlorides.

Monkey Spring and its immediate environs has been studied most intensively. When it emerges from the ground, water in all the small flows of the Monkey Spring system averages 81.5° F. The hydrogen-ion concentration (pH) at the sources ranges from 6.8 to 7.0. there is no detectable turbidity, and dissolved oxygen concentrations are low

(2.3 to 2.6 mg/1), but adequate for maintenance of fish and invert- ebrate populations. The following are average concentrations of the -23-

principal ions present in the spring inflow: Ca++ 210 mg/1; Mg++

+ -- -- - 50 mg/1; Na 3 mg/1; CO3 130 mg/1; SO4 350 mg/1; and Cl 4 mg/l. As the water moves downflow from Monkey Spring, carbonates are

precipitated as extensive ridges along canals and as a substantial bar

at the entrance of water into "Hill Pond" that lies just above the

headquarters of the Rail-X Ranch (Cole, 1968). This is detectable +4. in the water chemistry The average Ca in water from Hill Pond is

-- about 198 m311, and CO3 averages 117 mg/l. Other limnological

features of Hill Pond include a range in pH from 7.2 to 8.1, consid-

erable variation in temperature and development of a thermocline in

summer (though weakly defined and transitory), some development of

turbidity as a result of fish activity and wind, and dissolved oxygen

concentrations that fluctuate with diurnal changes, seasonal changes in vegetation, and temperature.

Other ponds in the drainage, unless fed by springs, have less

total hardness, higher turbidities, and a generally less stable

array of physico-chemical conditions.

Flowing streams of the drainage also are variable in physics and

chemistry of their waters. In periods of low discharge, when ground

waters provide the major sources of flow, dissolved solids approach

Monkey Spring in their concentrations--along Sonoita Creek, a rim

of salts often develops lateral to the channel as a result of move-

ment of water upward through the sand and gravel by capillary action.

Dissolved oxygen content has been near 100 per cent of saturation in

all samples from flowing streams, including those from below the

inflow of domestic wastewaters from Patagonia into the Sonoita Creek -24-

mainstream. Turbulence effectively aerates the water in such systems. Hydrogen ion concentration has varied from 7.5 to 8.4 in 11 samples from the mainstream of Sonoita Creek. In periods of flooding, cond- itions are quite different from those indicated above. Turbidities are sometimes phenomenal; runoff from the local terrain is relatively low in dissolved solids, however. Radical thermal change can occur in a period of a few minutes as cool rainwaters flow into the relatively warm stream in summer. Some mortality of fish after such a spate in

August 1966 may have resulted from thermal stress. Thermal relations in Sonoita Creek are complex, and do not follow a generalized trend of increasing temperatures at downstream localities. This results from differential shading along the stream, and from the differences in bottom materials from place to place that dictates the amount of water moving beneath the sediments. In areas of relatively deep, coarse sed- iments, exchange of water from the flowing stream to the subSurface interstices of the bottom is facilitated. The subsurface water is cooler (and cooled), and temperatures may decrease even in areas that are exposed to full sunlight.

One stream in the drainage, Temporal Creek, apparently receives outflow or seepage from now-abandoned mines. Fishes and other animals live there, but only in local areas, and considerable variation in chemistry can be attributed to inorganic pollutants (L. H. Carufel, personal communication). Organic materials from Patagonia wastewaters are not presently of a sufficient volume to influence the biota or over-all quality of water in Sonoita Creek, except in the immediate area of inflow. -25-

Permanence of the aquatic habitats in the basin, and maintenance of their relatively undisturbed physico-chemical condition, are diff- icult to estimate. Flow of Sonoita Creek undoubtedly depends on springs and underflow in its channel and on such sources as Monkey and

Cottonwood springs that rise on hillsides above the channels. The thermal nature of the last two sources indicates a deep aquifer, and they will probably maintain flow despite man's modification of the surrounding area. Diversion and use of their waters may, however, influence the discharge of the creek substantially. Pumpage from the alluvial fill of the valley will almost certainly curtail flow in the

Sonoita Creek channel, when it becomes extensive. Increasing impound- ment of the tributary canyons will also reduce the amount of water available, unless seepage or controlled release of water from such lakes can be utilized to maintain flow. Increasing fluctuations in water levels seems inevitable, especially since water-holding soils of cienegas are no longer present along the creek and its tributaries.

Biological changes that will accrue with increased human pop- ulation in the area and an increasingly fluctuant environment will most likely include introductions of additional exotic species (especially in reservoirs and smaller impoundments), a decline in most native fishes accompanied by an increase in populations of Agosia (as is evident in drought years, see above), and an ever-increasing enrich- ment of surface waters by organic materials produced by man. The construction of a major lake on lower Sonoita Creek, as is now contemplated, will accelerate man's influence in the area. If natural areas are to be maintained in the Sonoita Creek drainage, -26-

and these areas are to include aquatic or mesic habitats, planning should be on a "basin-wide" approach. It will be necessary to main- tain a substantial, "up-to-date" file on water and land developments in the area, especially upstream from sites of natural interest. And, most importantly, public information exchange and mutual understanding must be developed and maintained.

Conclusion

The Sonoita Creek basin in Santa Cruz County, Arizona, has suffered considerable modification since man's influence spread to include the

American Southwest. The relative isolation of the area, both the stability and change in vegetation, and a fortuitous combination of natural springs, streams, and artificial ponds, has allowed much of the native terrestrial and aquatic fauna of the region to persist; many of the species are now restricted to isolated parts of the drainage.

Projected development of the area for man's use, some of which is as yet speculative, makes the probability of maintaining "natural areas" that include aquatic habitats unlikely at best. I recommend that the part of the Sonoita Creek basin that now is protected be carefully developed to include as many of the former habitats (cienegas, for example) as is possible, and that planning be initiated immediately to compensate for probable changes in land and water use in the vicinity.

Perhaps the concept of the "living museum" should be applied. If projected developments are realized, and considering the quality of the Sonoita Creek basin as an area for human use, such an approach is

presently dictated. -27-

Literature Cited

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

Barlow, G. W. 1958. Daily movements of the desert pupfish, Cminodon macularius, in shore pools of the Salton Sea, California. Ecology, 39: 580-587.

. 1961. Social behavior of the desert pupfish, gyprinalpm macularius, in the field and in the aquarium. Amer. Midi. Nat.,

65: 339-359, Cole, G. A. 1968. Desert Limnology. In, Desert Biology, Voldme I. Academic Press, Inc., New York (in press). Girard, C. 1856. Researches upon the cyprinoid fishes inhabiting the

fresh waters of the United States of America, west of the Mississ- ippi Valley, from specimens in the Museum of the Smithsonian Institution. Proc. Acad. Nat. Soi,, Phila., 8: 165-213. . 1859. Ichthyology of the boundary. In, U. S. and Mexican Boundary Survey, 2: 1-85.

Hastings, J. R., and R. M. Turner. 1965. The Changing Mile. Univ. Arizona Press, Tucson.

John, K. IL 1963. The effect of torrential rains on the reproductive

cycle of Rhinichthys osculus (Girard) in the Chiricahua Mountain; Arizona. Copeia, 1963: 241-252.

1964. Survival of fish in intermittent streams of the Chir-

icahua Mountains, Arizona. Ecology, 45: 112-119. Miller, R. R. 1952. Bait fishes of the lower from , Nevada, to Yuma, Arizona, with a key for their identification. -28-

Calif. Fish and Game, 38: 7-42.

. 1961. Man and the changing fish fauna of the American

Southwest. Pap. Mich. Acad. Sc., Arts, Lett., 46: 365-404. , and C. H. Lowe, Jr. 1964. Part 2, An annotated check-list of the fishes of Arizona. In, The Vertebrates of Arizona. Univ. Arizona Press, Tucson.

Minckley, W. L. 1968. Introductions of the Gila topminnow, Poecilion-

sis occidentalis, within its native range. Copeia, in press.

, and J. E. Deacon. "Endangered species," examples in western

freshwater fishes. Science, in press.

Myers, G. S. 1965. Gambusia, the fish destroyer. Tropical Fish Hobby- ist, 13: 31-32, 53-54. Snyder, J. 0. 1915. Notes on a collection of fishes made by Dr. Edgar

A. Mearns from rivers tributary to the Gulf of California. Proc.

U. S. Nat. Mus., 49: 573-586.

Winn, H. E., and R. R. Miller. 1954. Native postlarval fishes of the lower Colorado River basin, with a key to their identification.

Calif. Fish and Game, 40: 273-285.