LIBRARY OF THE UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAICN NOTICE: According to Sec. 19 (a) of the University Statutes, all books and other library materials acquired in any man- ner by the University belong to the University Library. When this item is no longer needed by the department, it should be returned to the Acquisition Department, University Library. ILLINOIS NATimAL HISTORY SURVEY \ HE LIFE HISTORY OF THE LEAST DARTER, Etheostoma microperca, IN THE IROQUOIS RIVER, ILLINOIS BROOKS M. BURR and LAWRENCE M. PAGE ■:■;■:■:■:/ ' . ~ fi,i.^ '^ ^ :.■.■.■.■■■- Biological Notes No. 112 State of Illinois IHinois Institute of Natural Resources Natural History Survey Division Illinois Natural History Survey Urbana, Illinois- August 1979 Fig. 1. — The distribution of Etheostoma microperca. Questionable records were not plotted. The study area is enclosed within the square. THE LIFE HISTORY OF THE LEAST DARTER, ETHBOSTOMA MICROPERCA, IN THE IROQUOIS RIVER, ILLINOIS Brooks M. Burr and Lawrence M. Page This report on Etheosloma microperca in a small tributary of the Iroquois River is the second life his- tory report on the subgenus Microperca in Illinois. The first was on E. proeliare (Burr k Page 1978). Included here are comparisons of the two Illinois species and E. fonticola, a third member of the sub- genus recently studied by Schenck R: Whiteside (1976, 1977a, 19776). Etheostoma microperca was described by Putnam in 1863 (as Microperca pimctiilata) from specimens collected from localities in Michigan, Wisconsin, Illi- nois, and Alabama. Those from Alabama presum- ably represented the closely related but then imnamed E. prorliarc. The range of E. microperca (Fig. 1) extends from Moira River in northeast Ontario, through much of the Great Lakes ihainage, north- west to the Red River of the North in Minnesota, and soiuh through the middle Ohio River Valley. Disjimct populations occur in tlie Ozark Uplands and in the Blue River, Oklahoma. A detailed mor- phological description and comparisons with related species are found in Burr (1978). We are indebted to John A. Boyd, Patti A. Burr, and Michael A. Morris for aid in collecting spec- imens; to Edward A. Lisowski, John K. Bouseman, Jos^ A. Mari Mutt, and Donald W. Webb, all pres- ently or formerly of the Illinois Natural History Sur- vey (INHS), for identification of stomach contents; to David F. Oetinger and William L. Cinrent, Uni- \ersity of Nebraska-Lincoln, for identification of parasites; and to Philip W. Smith, Illinois Natural History Survey, for coiuisel and advice. We are grateful to the following curators and their institiuions (abbreviations are used in the text and Table 2) for granting specimen loans, laboratory space, and other courtesies: Branley A. Branson, East- ern Kentucky University (EKU); Frank B. Cross, Uni- versity of Kansas (KU); Max A. Nickerson, Milwaukee Public Museum (MPM); Neil H. Douglas, Northeast Louisiana University (NLU); Loren G. Hill, Univer- sity of Oklahoma (OAM); Ted M. Cavender, Ohio State University Museum (OSM); E. }. Crossinan, Royal Ontario Museum (ROM); Carter R. Gilbert, University of Florida, Florida State Museum (UF); Reeve M. Bailey and Robert R. Miller, University of Michigan Museum of Zoology (UMMZ); Albert P. This paper is published by .luthority of the State of Illinois, and is a contribution from the Section of Faiinistic Surveys and Insect Identificalion of the Illinois Natural History Survey. Dr. Brooks M. Burr, formerly a Research Assistant at the Sur\'ey, is Assistant Professor, Department of Zoolog> . Southern Illinois University, Carbondale. Dr. Lawrence M. I'age is an Associate Taxonomist at the Survey. Blair (.\PB) and Hague Lindsay, University of Tulsa (UTULSAC); and Wayne C. Starnes (WCS), Univer- sity of Tennessee. This study was supported in part by a grant from the Tiieodore Roosevelt Memorial Fund of the Amer- ican Museum of Natural History and NSF grant DEB 76-22387, both to Brooks M. Burr. The illus- trations were prepared by Illinois Natural History Sinvey illustrators Lloyd LeMere and Craig W. Ronto and Survey Photographer Larry Farlow. The cover illustration and Fig. 4 are from a drawing by Alice A. Prickett, Staff Artist for the University of Illinois School of Life Sciences. William L. Pflieger, Missouri Department of Conservation, served as guest reviewer. The manuscript was edited by Shirley Mc- Clelian, Assistant Technical Editor at the Survey. STUDY AREA Etheostoma microperca occurs sporadically in northern Illinois and is common at certain localities in the Rock, Fox, and Kankakee river systems. A small, unnamed tributary of Iroquois River (Kanka- kee system) northeast of Watseka in Iroquois County was selected for the life history study. The Iroquois River lies within the area of Wisconsinan Drift, and tiie watershed was originally sandy marsh (especially in Indiana) and tall-grass prairie (Forbes & Richard- son 1920:xxxviii) but is now mostly farmland. The tributary in which E. microperca was studied is a short (6 km long) direct tributary of the Iroquois River, meandering through cultivated fields upstream and forested land downstream. The study area (Fig. 2), at a bridge 6 km northeast of Watseka, is sur- rounded by cultivated fields. One small, rock riffle and a few mud-bottom pools are present, but the rest of the study area is a sinuous channel of nearly uni- form width (0.5-1.0 m), depth (< 0.5 m), and sub- strate (mixed sand and silt). The water current is slow. Stream banks are grassy and devoid of trees. Water temperatures varied during the study period from 4°C in February to 24°C in July. In summer and fall some rooted vegetation was present, and filamentous algae dominated large stretches of the stream. At this site and for a moderate distance up- stream and downstream E. microperca was the most common fish. Seventy-three species of fishes occur in the Illinois portion of the Kankakee River system. At the study area the most common, in addition to E. microperca, are Pimephales notatus, Semotilus atromaculatus, No- •«3*' ^i «i«>. Fig. 2. — The EtliL'ostoma microperca life history sliuly site, an unnamed tribtilaiy of the Iroquois River, 6 km northeast of Walscka, Iroquois County, Illinois. Photo taken 3 July 1978. tropis straminexis, Campostoma anomalum, Lepomis cyanellus, Fundulus notatus, and Etheostoma nigrum. METHODS Methods of study were those employed by Page (1974:4-5) except as noted below. Observations and minnow-seine collections were made at approximately monthly intervals from 5 August 1975 to 27 Septem- ber 1976. Additional data on reproduction were ac- quired on 26 March 1977 and 19 May 1977. Aging to month was done, using May, the month of the greatest breeding activity in tlie study area, as month zero. A total of 700 specimens was preserved and stored in 10-percent formalin. Because the study site was pliysically uniform and E. microperca was found to be rather evenly distrib- uted throughout, no attempts were made to sample by habitat. However, quantitative samples were made to monitor variations in the popidation density of E. microperca. Nearly all E. microperca from museum collec- tions were examined to determine probable spawn- ing periods in other localities and other years. In- dicators of spawning preparedness were the same as those listed by Burr & Page (1978:5). Specimens in a collection were considered to be in spawning con- dition if any of the specimens was in peak reproduc- tive condition. HABITAT Adults of E. microperca were consistently found in submerged vegetation along overhanging grassy banks and among filamentous algae. Rarely were they found in midstream away from any vegetation. During high water they avoided strong current and were foimd almost exclusively in quieter water under overhanging banks. Juveniles were found in thick growths of algae at the edge of the stream. Comparative collections made by the authors in Oklahoma, Missouri, Indiana, and Michigan indicate that the species prefers quiet waters rich in vegeta- tion (most often filamentous algae, Elodea, Myrio- phylhim, or Ceratophylhim) with sand or muck bot- toms. E. microperca is abundant in some Ozark springs, spring runs, and spring-fed creeks. In Ohio it is present in clear pothole lakes and prairie streams of low gradient with bottoms consisting of soft muck, sand, or gravel (Traiitman 1957:604). The preferred habitats of E. microperca are heavily vegetated, low- gradient water bodies, including small to large streams and margins of lakes and vegetated springs. REPRODUCTION Reproductive Cycle of the Male By early January the genital papilla of the male begins to swell noticeably, and by late March or early April it is thick and stout (Fig. 3). Testes of breeding Fig. 3. — Genital papillae of Etheostoma microperca. A, nonbreeding male; B, breeding male; C, nonbrecding female; D, breeding female. The breeding specimens were 1 year old, collected on 23 May 1976. The nonbreeding specimens were H- years old, collected on 30 August 1976. males are greatly enlarged, opaque white, and spongy; those of nonbreeding males are small and translucent. All spring-collected males— including the smallest, a 22.0-mm male collected in April— were sexually ma- ture and thus were potential spawners. In all three species of the subgenus Microperca males were found to be sexually mature at 1 year. Males began to develop lateral flaps of skin on the pelvic fins as early as late January, but it was not until mid-March that breeding colors were ev- ident and not until April that breeding tubercles ap- peared. By mid-March the pelvic-fin flaps were de- veloped nearly to their maximum, and the color of the first dorsal, anal, and pelvic fins had intensified. From about the second week of April to the end of June, male breeding colors and structures were at their peak development (Fig. 4). The body was dark Fig. 4. — Breeding male (upper) and breeding female (lower) Etheostoma microperca collected in the Iroquois River on 23 May 1976. Both the male and female were 30 mm. Nuptial tuberculation is not shown. Drawings by Alice A. Prickett. green with 8-10 intense mid-lateral black blotches interspersed with spots of metallic green. The pre-, post-, and suborbital bars were intense black. The opercle, belly, and pectoral fin bases were metallic green. The flesh overlying the top of the head and the second dorsal and caudal fins was thick and milky white. The iris of the eye was red. Distally and bas- ally the first dorsal fin was charcoal gray; medially in each membrane was an intense red-orange spot sur- rounded by flecks of metallic green. The second dorsal fin had four or five charcoal gray bands; the caudal fin had six or seven charcoal gray bands. The pectoral rays were sharply outlined by melanophores. The throat, breast, and belly had large black blotches of pigment. The pelvic and anal fins were a deep red-orange. Tubercles developed on all the pelvic fin rays, and were most heavily concentrated on the distal por- tions of the rays. Pelvic fin flaps were developed to their maximum, with the skin greatly expancled on both sides of the pelvic spine and between pelvic rays one through three. Winn (195Brt, 1958bj indicated that during the breeding season small stationary areas about 30 cm in diameter are defended as territories by E. micro- perca. Plants are apparently used in the delimita- tion of territories. At the study site on 19 May 1977 agonistic encoiuiters were observed between males, and in aquaria certain males appeared to establish territories. Pugnacious behavior was observed on nu- merous occasions between rival males. Evidence for the establishment of territories was not found in E. procUnrc (Burr & Page 1978:11) or E. fonticola (Strawn 1956). Reproductive Cycle of the Female The genital papilla of the female enlarged over several months and by the spawning period was a swollen conical structure (Fig. 3) much larger than the papilla of the male. The conical shape of the female papilla of E. microperca is different from the bulbous and bilobed shape of the papilla of E. proeUare and E. fonticola (Burr 1978:7). The female color and pattern (Fig. 4) changed lit- tle prior to and during the breeding period. The pelvic and anal fins became amber in color and some- times developed a light yellow or orange cast. In a few females there was some orange in the medial portions of the first dorsal fin membranes and in the iris of the eye. The second dorsal and caudal fin bands were charcoal gray, and the pectoral fins were sharply outlined by melanophores. Ovaries in July and August were small. From September through February ovaries were small and pink, and ova were small and white. By March, some yellow ova were discernible, and from .^pril to June large dark-yellow ova were present. Prior to spawning the large, dark-yellow ova transformed into translucent, prominently indented eggs 0.8-1.1 mm across and with one or t^\o large oil droplets (see Burr S: Page 1978:fi for an illustration of indented eggs). Prominently indented eggs are characteristic of the three species of Microperca. The indentation, involving both the chorion and egg plasma mem- Iirane, disappears soon after fertilization and does not facilitate attaching eggs to the substrate nor pack- ing eggs in the ovaries (Burr 8; Ellinger 1980). All females collected from April to Jiuie had large, maturing or translucent ova and apparently woidd have spawned. The smallest spring-collected female was 23.2 mm and was collected 27 April 1976. In 16 females collected in April-Jime 1976 the niun- ber of mature ova ranged from 31 to 240 (Table 1). For these females there was no significant correlation between the number of mature ova and the standard length, nor between the number of mature ova and the adjusted body weight; for both relationships the 6 Table 1. — Relationship between size, age, and ovary weight of Elheosloma microperca females and the number of mature ova. All females were 1 year (11-13 months) old. Number of Standard Adjusted Month Ovary Mature (Dark Length Body Weight of Weight Yellow or in mm in Grams" Collection in Grams Translucent) Ova 28 0.20 April 0.04 54 28 0.27 April 0.04 62 23 0.21 May 0.05 102 24 0.18 May 0.04 92 24 0.20 May 0.06 104 25 0.19 May 0.05 84 25 0.23 May 0.09 180 26 0.24 May 0.06 112 27 0.24 May 0.07 154 28 0.24 May 0.06 101 30 0.32 May 0.08 240 30 0.32 May 0.09 174 29 0.18 June 0.04 31 29 0.33 June 0.03 78 30 0.28 June 0.03 36 30 0.29 June 0.04 106 • Adjusted body weight is the specimens weight after re- moval of the ovaries, stomach, intestine, and liver. correlation coefficient (r) was less than 0.12. The same lack of correlation was found in E. proeliare and is discussed by Burr Sc Page (1978:6-7). Because eggs are laitl over a relatively large area, spawning in E. proeliare and E. microperca is likely to be inter- rupted; thus an accurate estimate of the number of eggs produced during the spawning season is difficult. Egg counts presented on these species and on E. fon- ticola, which lays eggs throughout the year (Schenck & Whiteside 1977n:367), may not be of the total num- bers produced. Petravicz (1936:81) reported that a female E. microperca lays about 30 eggs during 1 day of spawning. Winn (1958^:182) who counted all ova (believing that all are normally laid in a season), re- ported 455-1,102 eggs laid by E. microperca. From August until the spawning period, ovaries increased in size relative to the body of the female (Fig. 5). For the females examined, the relationship between the mean weight of the ovaries divided by the adjusted body weight (Y) and the month (X), with August = 1 and May (the inonth of the greatest spawning activity) = 10, was log Y = 0.799 + 0.158 X, with r = 0.779 (Fig. 5). The proportionally largest ovaries (equalling 38.9 percent of the adjusted body weight) were found in a 25-mm female collected on 23 May 1976. In the 16 females represented in Table 1, ovary-weight-to-adjusted-body-weight ratios ranged from 0.092 to 0.389 and averaged 0.230. Spawning At the study area E. microperca in breeding con- dition were found from April to June. Individuals transferred from the Iroquois River on 27 April 1975, 23 May 1976, 31 May 1976, and 19 May 1977 spawned in aqtiaria on those days and/or for a few days there- after. Stream temperatures at the time of the capture of ripe E. microperca individuals ranged from 16° to 20°C; aquaria temperatures ranged from 20° to 23°C. Petravicz (1936:78) gave stream temperatures of 12°-15.5°C for ripe E. microperca; Winn (19586: 158) listed spawning temperatures as 16°-18°C. Spawning was observed in the Iroquois River on 19 May 1977 along the shallow margins of the stream in dense beds of filamentous algae; this spawning hab- itat agrees with the observations of Petravicz (1936) and Winn (1958a, 19586). Examinations of preserved museum specimens from throughout the range of the species indicated that spawning occurs early (February-May) in the Blue River, Oklahoma, and certain Ozark streams and later (May-July) in more northern areas (Table 2). Populations o/ E. microperca that occur in or near constant-temperature springs in the Ozarks (see Ni- angua River, Missouri, Table 2) possibly spawn through much of the year, as does the related E. jonlicola (Schenck &: Whiteside 1977a: 367-368) which occurs in a large constant-temperature spring in Texas. Geographic variation in spawning periods is almost certainly related to warmer water on earlier dates at more southern latitudes. In addition to the probable spawning dates listed in Table 2, the fol- lowing are from ptiblished literature: May (Mich- 500n 200' 100- 50- 20- 10- LOG y = 0.799 + 0.158 X "T" "T" I SEPT. I NOV, I JAN. I MAR, I MAY I AUG, OCT, DEC, FEB, APR, JUNE Fig. 5. — Monthly variations in ovarian weight relative to adjusted body weight of 3- to I3month-old Elheostoma micro- perca females. The vertical axis is a logarithmic scale. Table 2. Frequency distribution bv montli of the collection of Elheostoma microperca in breeding condition from throughout the range of the species. Drainages are arranged primarily by latiiiulc and geographic propinquity where possible. Numbers in parentheses are numbers with specimens in reproductive condition as explained under Methods. Museum collection abbreviations are given in the introduction. Drainages Feb. Mar. Apr. May June July Aug. Collection Dates Blue R., OK (7— EKU 614; INKS 75678; KU 12924: OAM 1597, 7157, 9158, 10015) lllinois-Neosho R., OK, AR. MO (8— APB uncat; KU 10735, 10749; NLU 25892; UTULS.^C 1171, 2571, 2522; WCS AK/NSl-1) Gasconade R., MO (3— INHS 75828; KU 8029, 10989) Sac R., MO (1— INHS 75822) Niangua R., MO (3— INHS 75817: UMMZ 108728. 150283) Great Miami R., OH (1— OSM 14249) Scioto R., OH (2— OSM 22980; UMMZ 159856) Kankakee-Fox R., IL, IN (10— INHS 4168, 5402, .5491, 73838: Iroquois River collections) Rock R.. IL, WI (4— INHS 206, 3201, 3248; MPM 7932) Upper Missis>ippi R., MN (2— UF 21046; UMMZ 95001) L. Michigan. MI, \VI (10— MPM 9886: U.MMZ 82012, 84222, 90033, 90123, 90380, 97950, 97994, 139002. 164398) L. Huron, MI, ONT (9— UMMZ 61723, 66702, 67927, 67986, 68991, 69114, 73187, 8.5.530: ROM 30.505) Thames R., ONT (4— ROM 30135, 30138, 30996: UM.MZ 8.5567) Maumce R.. south L. Erie, OH. MI, ONT (10 — OSM 9957: ROM 30636, 30843; UMMZ 56858, 66516, 87504, 89872, 89961, 118501, 162222) 5 1 February-27 April 3 2 I 1 6 February-9 June 1 1 1 1 1 1 2 1 I 3 4 1 1 18 18 1 20 27 18 27 March-1 May March March-19 .\ugust March .^pril-6 May April-12 July 1 2 1 4 2 4 I 1 8 14 26 May-11 June May^ July April-16 July 3 2 4 2 May-IO July 1 5 3 4 1 26 2 Mav-19 June May-21 July igan)-Hankinson 1908:216; 26 April and 5 May (Michigan)— Petravicz 1936:78: mid-April to mid- June (Michigan)-'\Vinn 1958^:165; 27 May (^ridl^gan)- AVinn 1958^:201; .SO June (Oklahoma)-Branson 1970: 460; May to early June (Missouri)-Pflieger 1975:323. The first reference to spawning in E. microperca is that by Hankinson (1908:216) who observed breed- ing pairs in \\'alnut Lake. Michigati. with a female below and a male aljove in "what may have been the spawning act." Petravicz (1936) later gave a more de- tailed account of breeihng habits of the species based on field and laboratorv obsenations on a popidation in Bell Branch, Detroit, Michigan. AVinn (1958rt, 1958/)) gave the most complete account of reproduc- tion in E. microperca based on field and laboratory observations on individuals from t^vo lakes in Wash- tenaw County. Michigan. Our observations of spawn- ing in E. microperca agree closely with those of the above authors. Spawning was observed at the study site at 1030 hours on 19 Mav 1977. Spawning in aquaria occurred at various times throughout the day and was obser^-ed on numerous occasions. Field obsen-ations agreed with those made on aquaria-held specimens. The description that follows is from laboratory observa- tions. Males ^vere much more active in aquaria than males of the related E. proeliare or E. fonticola (Strawn 1955:412) and constantlv pursued females. They courted females by hanging vertically in mid- water for several seconds while vibrating their fins vigorously. Occasionally a male mounted a female, clasped her with his pelvic fins, and bore down on her nose, head, or nape with his chin and throat as if to stimulate her. No actual "chin rubbing" was obser\'ed as in E. proeliare (Burr 8: Page 1978:8) and E. gracile (Braasch S; Smith 1967:7). The female selected the site of egg deposition and, with the male close behind, elevated to the site (Fig. 6), .\t the egg site the male mounted the back of the female, the two quivered intensely for a few seconds while curved in a loose S-shaped fashion such that the female genital papilla was on the selected spot, and 1-3 adhesive eggs were laid. The S-shaped position presumably facilitated the release of milt close to the eggs. .\t the instant of egg laying both the male and female always had their mouths wide open; in E. proeliare only the female had her mouth open at the instant of egg laying. Eggs ranged from 0.8 to 1.1 mm across and were attached to twigs, leaves, algae and the sides of the aquarium. On several occasions spawning pairs swam the depth of the water (30 cm) in the aquarium, stuck their snouts just above the water surface, and deposited eggs on the side of the aquarium. Usually several eggs were laid at one site (e.g., a chnnp of twigs). In contrast to E. proeliare, E. micro- perca would perform three or four spawning acts in succession with only a brief period of rest in between. Spawning pairs of E. proeliare usually separated and rested up to a minute before they resumed spawn- ing. Typically a pair would lay several eggs at one site and then move 5-15 cm from the first site and lay several more eggs. On a few occasions eggs were not laid during mounting and quivering. In an aquarium in which were placed four females and three males, 96 eggs were laid on a plastic substrate Fig. 6.—Etheostoma microperca spawning in aquaria. Top: Male bearing down on nape of female illustrating a typical part of courtship behavior. Middle and lower: Male and female in vertical position as egg and sperm are released on twigs. Note in- tensity of pigmentation in male and gaping mouths of both sexes. and 29 eggs were found on a piece of leaf after 5 hours. Laving eggs on tlie sides of aquaria and on leaves and twigs required the spawning pair to assume ver- tical positions. These positions were maintained by rapid vibrations of the caudal and pectoral fins. The expanded pehic fins of the male enabled him to grip tightly the middorsum of the female. Fin positions for the two sexes were virtually identical to those described for E. proeUare (Burr & Page 1978:10). AVhile the spa^sning position of E. microperca was almost always vertical, horizontal positioning during successful egg-laying was observed occasionally. Some spawning males did not have pelvic or anal fin tubercles. The lack of tubercles on those indi- viduals indicates that the structures are not necessary for maintenance of body contact but probably aid in the stimidation of the female. In aquaria, males spawned with several females and often attempted to mount other males. All the males held in aquaria during the spawning season spawned. Neither sex gave any attention to the eggs after spawning. Parental care is absent in all tliree species of Microperca. Winn (1958^:163-164) reported that E. micro- perca moved from the deeper portions of lakes and streams to shallow areas to spawn, and that males often arrived 1-2 weeks earlier than females. Petra- vicz (1936:79) stated that samples of E. microperca taken from mid-stream generally yielded many more females than males, but that haids made near shore residted in a more evenly distribiued sex ratio. He concluded that females remained in deeper water until readv to spawn, at which time thev entered the inshore spawning territory occupied by males. Spawn- ing migrations were not observed at the study site because tiie small size and vegetated nature of the stream probably negated the need for the invasion of a new habitat. The spawning behavior of the three species of Microperca is similar. Spawning position is usually vertical or inverted and male-female positioning is nearly itlentical. Only 1-3 eggs are laid at each spawning act (Burr S: Page 1978:8, Strawn 1956:14), and egg deposition sites are much the same. Sexual Dimorphism Sexual tlimorphism in tuberculation, pelvic fin structure, coloration, and genital papillae are dis- cussed elsewhere in this paper and by Burr (1978:25- 32). A taxonomic study of E. microperca from throughout its range revealed that 8 of 16 morpho- nietric characters measured on breeding specimens showed highly significant (P < 0.005) sexual dimor- phism (Burr 1978:51). Males had significantly longer lieads, wider interorbital widths, longer postdorsal lengths, deeper caudal peduncles, and longer pelvic. pectoral, anal, and second dorsal fins. E. proeliare was sexuallv dimorphic (P < 0.005) for 7 out of the 16 morphometric characters measured and E. fon- ticola 5 out of the 16 (Burr 1978:48, 50). DEVELOPMENT AND GROWTH Eggs incubated in aquaria at 15.5^C (60°F) hatched in 264 ± 13 hours (11 days), at 20"C (67°- 68T) hatched in 181 ± 7 hours (7.5 days), and at 22=-23"C (71°-74°F) hatched in 144^12 hours (6 ilavs). Eggs incubated at 27''C (80°F) spoiled after a few days. Petravicz (1936:82) and Winn (1958fc:182) reported hatching time at 18°-20°C (64°-67''F) to be G.0-6.2 days. A hatchling 3.5 mm in total length was mostly translucent but had individual melanophores on the head, yolk sac, and some of the myomeres (Fig. 7: top). The pectoral fins were larger than in other Fig. 7. — Top: Ethcosloma microperca hatchling (3.t mm total length). Middle: 3-day-old larva (4.0 mm total length). Bottom: 7-davold juvenile (4.7 mm total length). species of Etiieostoma studied (e.g., E. gr ac He— Br aasch R: Smith 1967:9; species of Catonotus-Page 1974:11, 1975:8-9: Page & Burr 1976:8) and the tail had an unusual shape. Petravicz (1936:82) reported a hatch- ling 3 mm in total length. Three-day old larvae (Fig. 7:middle) averaged 4.0 mm in total length and had 10 pectoral fin rays, several caudal fin rays, and melanopiiores concentrated on the yolk sac remnant, heail, antl myomeres. At 7 days a juvenile was 4.7 mm in total length: the yolk sac had nearly disap- peared, the caudal fin had many rays developed, and the pectoral fins were large (Fig. 7:bottom). The pelvic, dorsal, and anal fins had not differentiated at 7 days. A series of 20 young E. min'operca ranging from 10 7 to 13 mm was collected at the study site on 27 June 1976. At 7 mm all fins, fin rays, and branchiostegal rays were well developed; scales and the lateralis sys- tem were nonexistent; pigment was limited to dis- crete melanophores scattered over the head and body, and outlining fin rays and myomeres. At 8-9 mm 10 vague lateral blotches and 6-7 dorsal saddles were present, and more pigment was visible on the head, gill covers, and snout. At 10-11 mm the lateral blotches and dorsal saddles were well defined; pig- ment outlined the anal fin rays; scales were visible on the top and sides of the body; melanophores were beginning to outline the scales; the undersides, nape, and head were still devoid of scales; and the cephalic lateralis system was developed to its maximum. At 12-13 mm body squamation was complete, but no scales were present on the opercles; pigmentation on the head was like that of the adult, and the opercular spine was well developed. Males and females grew at nearly the same de- creasing rate (Fig. 8). The relationship between 35-1 30 25 20 15 10 S-\ 0- • Y = 11.34 + 15.09 LOG X (Hales) OY = 12.84 + 13.86 LOG X (Females) 10 12 — I 1 1 16 18 20 MONTHS OF AGE Fig. 8. — Size distribution by age of Etheostoma microperca collected in the Iroquois River between 5 August 1975 and 27 September 1976. Black dots represent sample means for males; circles represent sample means for females. Regression line is for both sexes. A total of 700 specimens is represented. Standard length (Y) and age in months (X) for males is Y= 11.3 -f 15.09 log X, with r = 0.857, and for fe- males is Y = 12.84 -f 13.86 log X, with r = 0.899. The largest specimen examined from the study area was a 32.4-mm female collected on 1 1 December 1975; the largest male was 31.5 mm collected on 27 September 1976. The largest specimen known is a 36.9-mm female from Spring Creek, Mayes County, Oklahoma. In general females reach a greater max- imum size than do males, probably because females live longer. At I year (12 months) males (N = ll) averaged 28.4 mm and females (N = 24) averaged 28.1 mm. E. microperca reached one-half of the first year's mean growth in about 6 or 7 weeks. E. proeJiare required aljout 8 weeks to reach one-half of the first year's mean growth (Burr & Page 1978:11). DEMOGRAPHY Density Quantitative samples of E. microperca were taken at the study area every month by repeatedly seining an area until no more individuals were present in some seine hauls. The number collected was trans- posed into the number per square meter (Table 3). The greatest density was 33.09 darters/m^ collected on 14 October 1975. The considerable variation in density (Table 3) seems to follow a seasonal trend and also emphasizes Table 3. — Number of Etheostoma microperca per square meter in the Iroquois River by month o£ collection. Collection Date Number Collected Number per Square Meter 14 October 1975 92 33.09 13 November 1975 70 11.78 11 December 1975 58 4.00 20 January 1976 26 2.33 12 February 1976 13 0.93 27 March 1976 13 0.84 27 April 1976 17 2.44 23 May 1976 12 0.83 27 June 1976 IS 2.12 27 July 1976 29 3.81 30 August 1976 31 13.90 27 September 1976 40 26.85 certain life history phenomena. From late summer through fall the species reached its greatest density at the study area. This is presumably due to a con- centration of individuals by the extremely low water levels and the presence of both —1 and 1-f year classes. During winter months the density decreased; few individuals in the 1-f year class survived, and there was a rise in the water level due to fall rains and winter snows. In spring the density remained low. In late siunmer the nimibers in the population began to build to the maximum attained in the fall. E. microperca was the most common species of fish at the study area and it reached greater densities than those reported for other darters studied. The highest density found for E. proeJiare was 5.5 indi- viduals/m2 (Burr & Page 1978:11). Schenck & White- side (1976:702) reported that the highest density found for E. fonticola at San Marcos River, Hays County, Texas, was 4.7 individuals/m^. Composition Of the 700 E. microperca collected in the Iroquois River between 5 August 1975 and 27 September 1976, 82.0 percent were up to 1 year of age and 18.0 per- cent were between 1 and 2 years of age (Table 4). I II There was no sifrnificant deviation from a 1 to 1 sex ratio in the first year (—1) age class but because of greater longevity females predominated [1.7 fe- males to 1 male (x" = 8.12; P < 0.005)] in the 1+ yeiu- class. Survival Of the 314 males collected, 85.0 percent were up to 1 year of age and 15.0 percent were over I year of age. Of the 386 females collected 79.5 percent were up to 1 year of age and 20.5 percent were over 1 year of age. Assuming that each year class was col- lected in proportion to its relative number in the population, 17.6 percent of the first-year males and 25.7 percent of the first-year females survived to a second year. For males and females combined, the survival to a second year was 21.9 percent. These survival values and those of E. procliare (Burr 8: Page 1978:11) are lower than those for other darters stud- ied, and the short life span of the species of Micro- perca is a distinctive feature among percids. E. srnithi is also a short-lived species: the oldest individual re- corded was a 24-month old male (Page il- Burr 1976:9). The oldest E. microperca examined from the Iro- quois River (assuming a May hatching) was a 20- month old female collected in December 1975. The oldest males examined were five 18-month old indi- viduals collected in October 1975. Winn (19586:182) reported seven 2-year-old specimens of E. microperca collected from his study sites in Michigan. His method for determining the age of specimens was not given. Although E. microperca is short-lived, it can sur- vive extreme environmental conditions. In a study of stream desiccation in Tenmile Creek, Lucas County, Ohio, Tramer (1977:475) found that E. mi- croperca survived periods of drought by burrowing into the substrate. When rain refilled the dry pools in the creek, E. microperca reappeared. Migration £. microperca was common in the study area dur- ing most months of the study period and there was no indication of any mass movements up or down stream. Reference to breeding migrations observed in other populations was made under Spawning. Territoriality Territorial behavior, as discussed briefly under Reproductive C\cle of the Male, was observed in the field and laboratory. The aquaria used in this study could have been overcrowded, which, according to "W^inn (1958n:202), results in abnormal behavior and possibly inhibits full expression of territoriality. Petravicz (1936) did not observe territorial behavior and it was not observed in the related E. proeliare (Burr & Page 1978:11) and E. fonticola (Strawn 1956). Table 4 Distribution of sexes and year classes in samples of Ellieostoma microperca collected in the Iroquois River be- tween 5 .August 1975 and 27 September 1976. Sex Number by Year Class -1 l-h Total Males Females Total 267 307 574 47 79 126 314 386 700 According to Winn (19586:168) E. microperca de- fended a small (ca. 25-30 cm) "stationary" territory which had three dimensions. The three dimensional tenitory of E. microperca included the vertical height of the plant as the third dimension. According to Winn territorial defense was not maintained at night. DIET Stomachs of 120 E. microperca contained mostly chironomid larvae and small crustaceans (Table 5). Gastropods, annelids, and insects other than chiron- omiils made only small contributions to the diet. Compared to other darters studied, e.g., Pcrcina sciera (Page & Smith 1970), P. phoxocephala (Page & Smith 1971), P. nigiofasciata (Mathur 1973), Etheostoma scjuamiceps (Page 1974), E. kennicolli (Page 1975), and E. srnithi (Page &: Burr 1976), the three species of the subgenus Microperca fed more on small crus- taceans and less on insects other than chironomids (Burr S: Page 1978:11; Schenck S; Wiiteside 19776). Reasons for this were discussed by Burr &: Page (1978: 11-12) and Schenck &: Whiteside (19776:490). Isopods, cladocerans, copepods, and chironomids \vere major components of the diet of E. microperca of all sizes. Gastropods, plecopterans, and several kinds of dipterans were important to large (22-30 nun) E. microperca. In darters which attain a larger maximum size than do species of Microperca, small crustaceans are important to smaller individuals but decreasingly so with an increase in the size of the darter. Chironomids and copepods were important diet items every month of the year (Table 6). Isopods and cladocerans were important diet items several months of the year. Fish eggs were consumed during spring months. Strawn (1956:17) and Schenck &: Whiteside (19776) reported that E. fonticola cannibalized newly hatched larvae and eggs. Petravicz (1936:81) indicated that supernumerary males of E. microperca may de- vour eggs fertilized by rival males. Forbes (1880:26) and Forbes &: Richardson (1920: 318) concluded that in Illinois small crustaceans made up 64 percent of the diet of E. microperca, Chiron- omus 34 percent, antl ephemerids (Neuroptera) 2 per- cent. Forbes (1888: 516, 517, 524, 527, 529, 531) gave some indication of seasonal feeding habits with the groups mentioned above being eaten during May and June. Cahn (1927:56) reported that E. microperca 12 Table 5 Stomach contents of Etheostoma microperca from the Iroquois River, by size class of darter. Figures in parentheses are numbers of stomachs examined. Percent of Stoma iclis in Which Mean Number of Food Organisms Food Organism Occurred per Stomach 1 Food Organism <16 16-21 22-27 >27 <16 16-21 22-27 >27 mm mm mm mm mm mm mm mm (10) (20) (45) (45) (10) (20) (45) (45) Gastropoda 5.0 13.3 4.0 0.10 0.22 0.04 Aimelida Lumbricidae 8.0 024 Crustacea Cladocera 10.0 45.0 37.8 24.0 0.80 2.10 2.80 1.14 Ostracoda 4.0 0.04 Copepoda 90.0 1 00.0 73.3 60.0 2720 14.35 10.22 8.96 Isopoda Asellidae Asellus 40.0 15.0 17.8 38.0 0.70 0.55 0.56 1.30 Insecta Plecoptera 1 0.0 6.7 4.0 0.10 0.07 0.04 Odonata 5.0 0.05 Collembola Entomobryidae 2.0 0.02 Diptera Chironomidae G0.0 75.0 73.3 68.0 3.30 3.25 4.91 5.98 Tabanidae 4.4 4.0 0.04 0.04 Ephydridae 6.0 0.10 Simulidae 22 0.38 Lepidoptera Pyralididae 2.0 0.02 Fish eggs 4.4 6.0 0.07 0.14 Empty 2.2 4.0 0.02 0.04 in southern Wisconsin (Waukesha County) ate insect larvae, nymphs, and entomostraca. INTERACTIONS WITH OTHER ORGANISMS Competition Pflieger (1971:280-281) suggested that the comple- mentary distribution of E. microperca and E. proe- liarc in Missouri was a result of competition. The two species have been collected together in a stream in Oklahoma in years past but recent collections have produced only specimens of E. proeliare. Similarly, E. microperca was known by an old collection from a creek in southwestern Arkansas. Numerous recent collections in the creek have again produced only specimens of E. proeliare. Because the habitat re- quirements of the two species are similar, their com- plementary distributions may be due at least in part to competition. Other than E. microperca the only darter captured in the study area was E. nigrum. E. nigrum usually inhabited the central portion of the stream in sandy stretches and was never common. No evidence of competition involving E. microperca was found at the study area. Predation As potential predators of E. microperca, eight Semotilus atromaculatus (73-90 mm) and three Le- pomis cyancUus (49-82 mm) were preserved and later examined. No fish remains were found in their stomachs. Hankinson (1911:204) found remains of E. micro- perca in the stomachs of yoimg "black bass" 2.5 inches long from Walnut Lake, Michigan. Cahn (1927:56) reported that the species was eaten by Po- moxis annularis and Micropterus salmoides. In an analysis of the feeding habits of two species of trouts from Birch Lake, Cass County, Michigan, Leonard & Leonard (1949:304) found that E. microperca was not eaten although it was present in the lake. i Parasitism Of the 120 E. microperca in which stomach con- tents were examined, two each contained one spiny- headed worm (Acanthocephahis sp.). Parasitic nema- todes were found in the stomachs from every month of the year except August and February. A total of 32 nematodes was found in the stomachs examined and up to 4 nematodes were found in an individual stomach. The only external infestation was a par- asitic copepod (Lernaea sp.) found on a specimen col- lected in August. In specimens examined from throughout the range of E. microperca external fluke infestations were found in four collections: OSM 16617 (Scioto River, Ohio); ROM 26803 (AuSable River, Ontario); UMMZ 136999 (Bad River, Michigan); UMMZ 139765 (Sa- line River, Michigan). In a study of parasites in Lake Erie fishes Bang- ham k Hiniter (1939:406) examined four specimens of E. microperca and found no infestations. The only published report of parasitism in this species is by •a V e a O 3 s c c 8 a o 1 tA s (A 1 o o 2 u o < ^ « o 0.0 n o s o o oi OO d o on o CO s CO ■^ d § S s e< to d o 80 g s c4 00 d g s o 00 o o s; ■^ d o s o g o o ? s o Q =^ ^2 n o o<2 < ^ ■82 c S- O T3 O o o - «) o — o o ^ i5 o d o d s o d o o d d o o o odd lo " o o d o d o o o o d o o d o o o d o o d d o o c o o P =! d : O o «5 ■ CO OT o d o o d P o o o a o -H o m o o 82 S •a Xi 8,^ 2--S e 3 w C rt c o< = u •a T3 a, (o O O U 2 ^a V 3 •a 5: < t- o 2 H. n E 2 i3 S gii = t; o -3 -g W S^ CuOU 3 oj rt , i rs -ii e 3 ' ^ 3 O -S .a -a 2 § S "S a. - ._ ^ 5-U H td 'cfl g-o. a. a 14 Evermann k Clark (1920:450-457) who found that some individuals from Lake Maxinkuckee, Indiana, were infected with trematodes. SUMMARY The life-history information on E. microperca in Iroquois River is summarized in Table 7. Table 7 Summary of life-history information on the Iroquois River Etheostoma microperca . Characteristic Life-History Data Principal habitat Age at reaching sexual maturity Age at first spawning Size at reaching sexual maturity Sexual dimorphism Breeding tubercles Description of genital papillae Number of mature ova in preserved females Description of egg Spawning period Spawning habitat Egg deposition sites Number of eggs laid per spawning act Spawning position Egg guarding Incubation period Influence of sex on growth rate Density Sex ratio among first year (—1) age class Sex ratio among I-|- year age class Longevity Maximum size Migrations Territoriality Principal diet Vegetated, sluggish water bodies with a bottom of sand or muck 1 year 1 year All spring-collected individuals regardless of size were potential spawners Adult males average smaller, have red-orange in their first dorsal, anal, and pelvic fins, develop cuplike appendages on their pelvic fins, and have longer heads, wider inter- orbital widths, longer postdorsal lengths, deeper caudal peduncles, and longer pelvic, pectoral, anal, and second dorsal fins Present on undersides of pelvic fins in males only (none found on anal fin in this population) Females have a swollen, conical papilla; males have a pointed, tubular papilla 31-240 j 0.9 mm across, translucent (1-2 oil droplets) and prominently indented on one side 1 From April to Jime Shallow, sluggish edges of stream in dense beds of filamentous algae Dead leaves, twigs, debris, filamentous algae 1-3 Both male and female in vertical position (rarely horizontal), male mounted on back of female None observed 264 ± 13 hours at 15.5°C, 181 ± 7 hours at 20°C, 144 ± 12 hours at 22°-23°C Both sexes grew at approximately same rate Up to 33.09 darters/ m- during fall along vegetated stream edges 1 male; 1 female 1 male; 1.7 females 20 months for females; 18 months for males 32.4 mm standard length for females; 31.5 mm standard length for males None observed Males establish territories about plants at least during breeding season Chironomid larvae and small crustaceans LITERATURE CITED Bangham, R. v., and G. W. Hunter, III. 1939. Studies on fish parasites of Lake Erie. Distribution studies. Zoologica 24: 385-448. Braasch, M. E., and P. W. Smith. 1967. The life history of the slough darter, Etheostoma gracile (Pisces, Percidae). Illinois Natural History Survey Biological Notes 58. 12 p. Branson, B. A., J. Triplett, and R. Hartmann. 1970. A partial biological survey of the Spring River drainage in Kansas, Oklahoma and Missouri. Part II. The fishes. Kansas Academy of Science Transactions 72(4):429-472. Burr, B. M. 1978. Systematics of the percid fishes of the sub- genus Microperca, genus Etheostoma. Alabama Museum of Natural History Bulletin 4. 53 p. , and M. S. Ellinger. 1980. Distinctive egg morphology and its relationship to development in the percid fish Etheos- toma proeliare. Copeia. In press. , and L. M. Page. 1978. The life history of the cypress darter, Etheostoma proeliare, in Max Creek, Illinois. Illinois Natural History Survey Biological Notes 106. 15 p. Cahn, A. R. 1927. An ecological study of southern Wisconsin fishes; the brook silversides (Labidesthes sicculus) and the Cisco (Leucichthys artedi) in their relations to the region. Illinois Biological Monographs 11:3-151. Evermann, B. W., and H. W. Clark. 1920. Lake Maxinkuckee, a physical and biological survey. Indiana Department of Con- servation 1:1-600; 2:1-512. Forbes, S. A. 1880. The food of fishes. Illinois Slate Laboratory of Natural History Bulletin I(3):I8-65. IS On the food relations of freshwater fishes: a summary and discussion. Illinois State Laboratory of Natural History Bulletin 2:475-538. and R. E. Richardson. 1920. The fishes of Illinois. 2nd ed. Illinois Natural History Survey, cxxxvi -f 357 p. Hankinson, T. L. 1908. A biological sui-vey of Walnut Lake, Michigan. Pages 157-288 in Michigan State Board Geological Survey Report tor 1907. . 1911. Ecological notes on the fishes of Walnut Lake, Michigan. American Fisheries Society Transactions 40:195-206. Leonard, J. W., and F. A. Leonard. 1949. An analysis of the feeding habits of rainbow trout and lake trout in Birch Lake, Cass County, Michigan. American Fisheries Society Transac- tions 76:301-314. Mathur, D. 1973. Some aspects of life history of the black- banded darter, Percina nigrofasciata (Agassiz), in Halawakee Creek, Alabama. American Midland Naturalist 89(2):381-393. Page, L. M. 1974. The life history of the spottail darter, Etheostnina squamiceps, in Big Creek, Illinois, and Ferguson Creek, Kentucky. Illinois Natural History Survey Biological Notes 89. 20 p. . 1975 The life history of the stripetail darter, Etheos- toma kennicotti, in Big Creek, Illinois. Illinois Natural His- tory Survey Biological Notes 93. 15 p. -, and B. M. Burr. 1976. The life history of the slabrock darter, Etheostoma smithi, in Ferguson Creek, Kentucky. Illi- nois Natural History Survey Biological Notes 99. 12 p. 15 , and P. W. Smith. 1970. The life histon of the dusky darter, Percina sciern, in the Embanas River. Illinois Natural History Suney Biological Notes 69. 15 p. , and . 1971. The life history of the slendcrhead darter, Percina phoxocephala, in the Embarras River, Illinois. Illinios Natuial History Survey Biological Notes 74. 14 p. Petravicz, J. J. 1936. The breeding habits of the least darter, Microperca punctulata Putnam. Copeia 1936(2):77-82. Pfliecer, W. L. 1971. A distributional study of Missouri fishes. University of Kansas Publications, Museum of Natural His- tory 20(3): 225-570. . 1975. The fishes of Missouri. Missouri Department of Conservation, Jefferson City. 343 p. ScHENCK, J. R., and B. G. Whiteside. 1976. Distribution, habitat preference and population size estimate of Etheosloma fon- ticola. Copeia l976(4):697-703. , and . 1977a. Reproduction, fecundity, sexual dimorphism and sex ratio of Etheosloma fonlicola (Ostcich- thyes: Percidae). American Midland Naturalist 98(2):365-375. , and . 19776. Food habits and feeding behavior of the fountain darter, Etheosloma fonticola (Osteichthyes: Percidae). Southwestern Naturalist 21(4);487^92. Str.\wn, K. 1955. A method of breeding and raising three Texas darters. Part I. Aquarium Journal 26(1 2): 408-4 12. . 1956. A method of breeding and raising three Texas darters. Part II. Aquarium Journal 27(1):11, 13-14, 17, 32. Tramer, E. J. 1977. Catastrophic mortality of stream fishes trapped in shrinking pools. American Midland Naturalist 97(2):469-}78. rkALT.\i.\N, M. B. 1957. The fishes of Ohio. The Ohio State University Press, Columbus. 683 p. Winn, H. E. 1958a. Observations on the reproductive habits of darters (Pisces-Percidae). American Midland Naturalist 59(1): 190-212. . 1958/). Comparative reproductive behavior and ecology of fourteen species of darters (Pisces-Percidae). Ecological Monographs 28(2): 155-191. Printed by authority of the State of Illinois (P.O. 12919-4M-8-79) us ISSN 0073-490X 12919-4M- i 1 ^ ^^' vy?lt»