Ammocrypta pellucida

The most elongate species of the subgenus Ammocrypta. Adults usually 46-71 mm in total length (TL) (longest 81 mm), young of year 28-53 mm TL in October. Facey (1997) discerned three age classes: Age 0, 18.8-41.2 mm; Age 2, 34.2-52.6 mm; Age 3, 45.5-52.8 mm. Body depth contained 7.0-11.2 times in standard length. Williams (1975) provided ranges based on analyzed specimens. In live specimens, the body is translucent with a yellowish or greenish cast, especially dorsally, with a narrow metallic gold to olive-gold band passing subcutaneously along the line of lateral blotches. The dorsum is marked with 11-19 small olive spots along the dorsal ridge which beomce rows of paired spots along base of dorsal fins, with one row on each side of fin. Along lateral line is a series of 8-15 oblong, dusky-olive spots that may form a faint band posteriorly (Trautman 1981). In alcohol, the dorsum is variously marked by 11-19 dusky to brown blotches, extremely variable in size, shape and position. Where these extend across the dorsum, they are broken along the midline forming rows of paired spots, particularly along the base of the dorsal fins. Laterally, the body is marked with 9-15 dusky to dark brown longitudinal blotches of variable size, shape and horizontal position becoming larger and darker posteriorly. Lateral line is complete with 65-84 scales. Belly, cheek and opercle are unscaled; breast is unscaled except for embedded scales near and on prepectoral area (Williams 1975). Organs, vertebrae, and lateral blotches on opposite side of body are visible through flesh in live fish (Spreitzer 1979). Sexual dimorphism is subtle. Pelvic fins have melanophores concentrated on the basal half to two-thirds in males, while females have no pigmentation or occasional melanophores along margins of pelvic rays (Williams 1975). During spawning season, genital papillae of males (which are smaller than females) remain a distance from anal-fin spine while papillae of female encroach on or touch anal-fin spine base (Spreitzer 1979). Type specimens were documented by Jordan and Evermann (1896), Linder (1959), and Collette & Knapp (1966). Protolarvae are 5.5 mm TL at hatching, and possess a stomodeum, 23-26 (x = 24.4) preanal myomeres, and 18-19 (x = 18.4) postanal myomeres (Simon et al. 1992).

The most elongate of the subgenus Ammocrypta, and the only Etheostoma with both the long axis of the lateral blotches horizontal and 4-7 rows of scales below the lateral line at the caudal peduncle (Williams 1975). Ammocrypta meridiana (southern sand darter) achieves a maximum size of 58 mm and is pale yellow-orange. Ammocrypta vivax (scaly sand darter) is primarily a coastal plain species of the Mississippi embayment (Williams 1975).

Generally this sand darter prefers habitats within small creeks to large rivers and lake shores, with slow to medium current, and lakes and lake-like expansions of rivers with fine sandy substrate (0.1-1.0 mm) (Daniels 1993, Trautman 1981, Scott and Crossman 1973, Williams 1975, Adams and Burr 2004, Grandmaison et al. 2004, and many others).

Sandy areas are generally depauperate of flora and other fauna so that both competitors and predators may be lacking. Sand particles (0.1-1.0 mm) are deposited at low velocities relative silt and clay (which tend to move as aggregates) or larger stones and cobbles. Unconsolidated silts and clays erode at lower velocities than sand, but remain in suspension unless stream velocity decreases (Morisawa 1985). Sand runs form in depositional areas where current slows on the inside of a bend in the river. Such runs can be stable, though sand particles are eroded and deposited with storm events (Gordon et al. 1992). Burrows into sand bottom. Eggs are buried in the substrate. Simon et al. (1992) reported collecting eggs and larvae from the Tippecanoe River (Indiana) from sand and gravel in slight to moderate current at temperatures of 20-23 C.

Ohio: most abundant in larger, sandy areas of sections of moderate or large-sized streams where silting-over of sand was at a minimum and current was not strong enough to wash away the sand (Trautman 1981). Pennsylvania: taken over sandy riffles (Lachner, Westlake and Handwerk 1950). Kentucky: captured over clean sand along the margins of a Dianthera riffle (Branson and Batch 1974). Quebec: Vladykov (1942) reported unusual captures over limestone with a thin layer of mud, and clay mixed with some sand. Sand at one French Creek site was approximately 2-4 dm deep (Criswell 1992), and Barnes (1979) reported substrate depths of 100-500 cm at a sand darter site on Federal Creek. Water depths ranged from 2 dm (Criswell 1992) to 14.6 m (Scott and Crossman 1973). Minimum stream widths reported were 7-9 m (Barnes and Carline 1977). In the Tippecanoe River, greatest abundance occurred where water was approximately 30 cm deep over a substrate of 80% sand and 20% gravel (Johnston 1989). In general, medium and coarse sand co-dominated the substrate in Salt Creek, with fine sand being third most prevalent by weight, and with some silt also present. The dynamic nature of this habitat was documented by percent composition of various particle sizes changing monthly, and by observations of changes in size, shape, topography, and degree of silt cover at study sites (Spreitzer 1979). Daniels studied habitat within the Mettawee River in (New York) and within an artificial stream environment. Greatest abundance (75%) of observed darters was less than 20 m downstream of channel bend (depositional side of stream), 90% on sand 5 m from shore and in less than 0.5 m depth. Vegetation and debris were greater than 5 m; i.e. Measured water velocity was 10-20 cm/sec water column velocity. Artificial stream data corroborated field data. Sand substrate at the riffle site reported by Lachner et al. (1950) is no longer present in sufficient quantity to support A. pellucidum, although the site is otherwise intact and still supports all other riffle inhabitants reported (Criswell 1992). Maximum water temperature reported for a capture site was 26 C (Johnston 1989). Vladykov (1942) reported pH readings of 8.2 and 8.6 in Quebec. Specific data on other water parameters quality are lacking.

In Lake Erie, A. pellucida occupied clean sandy shores, shallow bays, and the island region of the lake (Van Meter and Trautman 1970). Langlois (1954) reported it from sandy shoals at the narrows of Middle Bass Island, and noted that some were captured by local boys at a bathing beach on South Bass Island in 1952. It occupies unconsolidated, sandy bottom along the shoreline of Presque Isle in waters 1-5 feet in depth. Although there is little specific data on water quality requirements, a report by Beeton (1961) concluded the change in bottom fauna of Lake Erie, which corresponds to reported declines in A. pellucida (Trautman 1981, Van Meter and Trautman 1970), indicated an increase in the organic component of the sediments. In the western basin island area the bacteria load increased threefold between 1913 and 1946, average total nitrogen increased from 0.265 ppm in 1942 to 0.83 ppm in 1958, free ammonia from 0.013 in 1930 to 0.092 in 1958, and total phosphorous increased from 14.4 ppb in 1942 to 36 ppb in 1959.

Annulus formation is weak, but discernable. Maximum age in the Salt Creek study was 2+ years. Mean standard lengths for 135 specimens analyzed were: age 0, 33.4 mm (range 18.8-41.2); age I, 44.4 mm (range 34.2-52.6); age II, 48.8 mm (range 45.5-52.8). There was little size difference between males and females, and the sex ratio was 1:1 (Spreitzer 1979).

Information on population structure, density and age composition information is lacking. Studies of other darter species indicate near constant mortality rate throughout life (beyond the larval stage) or a relatively high death rate at advanced age, as opposed to high juvenile and low adult mortality found in most fish species (Page 1983). At one French Creek Station, 34 specimens were captured in a 510 square meter area in good habitat in 24 minutes with electro-fishing gear (Criswell 1992). Bouton (1986) reported capturing 45 individuals in a 4-mile section of the Poultney River, 95% of which had clean sand bottom, and considered this a healthy population.

Parasites identified from Lake Erie specimens included the nematodes: Camallanus oxycephalus and Agamonema sp.; and trematodes: Neascus sp., Tetracotyle sp., and Lebouria cooperi (Bangham and Hunter 1939). Those from Salt Creek and incidence of infestation were: C. oxycepahlus 9.2%; the trematode Uvulifera ambloplitis 79.8%; the copepod Lernaea cyprinaceae 5%; and the cestode Protocephalus ambloplitis 80%. The infected Salt Creek specimens showed no evidence of decline in physical condition (Spreitzer 1979).

Burying Behavior: A. pellucida was reported to bury itself in sand substrate by several authors. Clay (1975) and Trautman (1981) reported a tail-first burying sequence, which no longer appears credible. Jordan and Copeland (1877) first reported a head-first burying sequence in aquarium fish. Spreitzer (1979) and Daniels (1989) reported detailed accounts of head-first burying behavior. The darter swims slightly above stream bottom for 0.3-2 mm, then plunges into the substrate at an angle of 20-60 degrees, then travels through the sand in a shallow V-shaped path. Elapsed time from first contact with sand to final resting position was 0.12-0.75 sec. Spreitzer (1979) reported two types of burying behavior. The more common "casual" behavior resulted in the snout and eyes being exposed at termination of the sequence, while the less common "avoidance" behavior left the fish completely buried. Daniels (1989) tested three hypotheses (predator avoidance, prey ambush, and maintaining position) to explain burying behavior and concluded that predator avoidance or presence of prey in the water column (larval food items) did stimulate burying. Darters may actively uncover within the sand (Daniels, personal communication). The ability of the darter to maintain itself in an apparently homogeneous microhabitat (by burying) during high or low flows was important, though low oxygen levels in substrate may limit such behavior. Some fish remained buried for at least 18 hours. The temperature at the bottom of the water column was found to be approximately 10 C higher than at 2 cm into the substrate, illustrating the potential advantage for thermoregulation during low flows and hot weather. Simon (1991) concluded that burying behavior appears to be a resting response used during occupation of homogeneous sand habitats, and that incidences of complete burial and, burial with head and snout exposed, corresponded to long and short resting periods, respectively. Individuals that remained in the sediment longer than one hour were usually completely buried.

Associates: In Salt Creek (Spreitzer 1979), fish species considered associated with A. pellucida were Etheostoma nigrum in the transition zone between silt and sand, (where both were observed feeding non-aggressively), Notropis stramineus and Ericymba buccata (which may compete with the sand darter for food), and Noturus miurus (where cover exists). In French Creek, western Pennsylvania, E. blennoides, E. zonale, Percina maculata, Hypentilium nigricans, Ichthyomyzon sp. (ammocetes), Notropis stramineus, N. volucellus, and Noturus miurus were taken with A. pellucida (Criswell 1992). In the Mettawee in New York, Daniels found only E. olmstedi abundance positively correlated in darter sampling stations (p=0.25). He attributed co-occurrence of other species to their wide-spread distribution rather than because they shared habitat (Daniels 1993.

Predation: Definitive information on predation is lacking. Because A. pellucida is apparently somewhat active during periods of darkness (Daniels 1989, Johnston 1989) the possibility of losses to predatory fishes exists. Species that overlap with the sand darter in habitat and range (Trautman 1981) and should be considered potential predators are Lepisosteus osseus, Micropterus dolomieu, M. punctulatus, Stizostedion vitreum, and S. canadense. Daniels (1989) concluded that even if a darter buried, a wading bird could pick the fish from the substrate if it observed the point of entry. Field observations in French Creek (Criswell 1992) during low flows and bright sunlight, when the darters were quite visible, indicated they were reluctant to bury immediately when pursued by investigators, preferring to dart at least 2 m before plunging. One specimen was chased 10 m before burying. This behavior would tend to make the fish susceptible to avian predators such as the belted kingfisher (Megaceryle alcyon), which nest along streams.

Spawns in June and July in Ohio basin, 2-3 weeks later in Great Lakes and St. Lawrence River populations (Kuehne and Barbour 1983. In Vermont, spawning apparently began in mid-June in 1995 (Facey 1995). Spreitzer (1979) reported the spawning period as extending from May through mid-August, based on female fecundity, with most spawning occurring in June and July; eggs hatch in less than 7 days; fry begin to feed about 9 days after hatching

The only description of spawning behavior is based on observations of captive specimens in aquaria that were captured from the Tippecanoe River (Johnson 1989). During sampling in July, 23 males and 4 females were captured, suggesting males had congregated in that area. In captivity, 11 A. pellucida were monitored in a 37.8 liter tank with water 30 cm in depth and 5 cm substrate (gravel to fine sand). Four males pursued one female around the tank, often resting their pelvic fins and chins on her back. The female was mounted by a male in a position directly on top of her. Egg deposition occurred when the pair vibrated, with their tails and caudal peduncles buried in the substrate. In 3 of 12 episodes, a second "sneaker" male joined the pair, positioned himself on one side of the female, and vibrated with the pair. Eggs were buried singly in the substrate. Spawning occurred both day and night at water temperatures of 20.5-23 C. Small tubercles on the ventral surface of the first few outer pelvic rays of the male apparently hold or stimulate the female during spawning. Eggs are translucent, sperical, and slightly adhesive. Spreitzer (1979) found that the diameter of mature ova varied greatly (mean 1 mm, range 0.74-1.2 mm), larger females produced more ova than smaller specimens, and females having more ova produced more mature ova, the mature ova compliments per female being quite low (mean 71; range 30-170) which is similar to A. BEANI (22-71) and A. BIFASCIA (12-69) (Williams 1975). It appeared that yearling females that had not attained a standard length of 36 mm by May did not spawn in that year. In Salt Creek, the lowest silt levels in the habitat occurred in June and July, coinciding with peak spawning activity and raising the possibility of a relationship, perhaps to ensure greater egg survivability. Maximum longevity apparently is only a few years (Facey 1995).