Crevice spawning behavior in Dionda dichroma,with comments on the evolution of spawning modes in North American shiners (Teleostei: Cyprinidae)

The crevice spawning behavior of Diondadichroma is described for the first time, andcompared to spawning behavior in the genusCyprinella. The evolution of crevice spawningwith respect to other spawning behaviors ofNorth American shiners is examined usingexplicitly phylogenetic hypotheses for thisgroup. We present evidence that broadcastspawning is plesiomorphic and all otherspawning behaviors are independently derived. There is evidence that crevice spawning hasevolved independently at least three timeswithin the shiner clade. There is no supportfor an evolutionary transition between eggclustering and crevice spawning. Nestassociation, spawning on habitat prepared byother species, has also evolved multiple timeswithin this clade. Evolution of spawning inshiners is best described by phylogeneticstasis with several independent origins ofspecialized spawning stragegies.     

Developmental morphology of the cyprinid fish Tanichthys albonubes

Embryonic, larval, and juvenile development of a small cyprinid species, Tanichthys albonubes, is described from laboratory-reared specimens. The eggs, measuring 1.0–1.2 mm in diameter, were demersal, almost spherical in shape, transparent and unpigmented, with a pale yolk without oil globules. Hatching occurred 45–53 h after fertilization at 25.5°–26.9°C. The newly hatched larvae, measuring 2.2–2.6 mm in body length (BL), had melanophores on the head and body. In particular, a dark vertical streak occurring posterior to the otic capsule and melanophores above the eyes were distinctive. The yolk was completely absorbed at 3.4 mm BL. Notochord flexion was initiated at 5.0 mm BL and finished at 6.0 mm BL. Aggregate numbers of all fin rays were completed at 11 mm BL. Squamation was initiated at 8.4 mm BL and completed at 13 mm BL. Although the eggs of T. albonubes resembled those of other small danionin species, including Aphyocypris chinensis, Chela dadiburjori, Danio rerio, Devario malabaricus, Gobiocypris rarus, Hemigrammocypris rasborella, and Horadandia atukorali, they differed from those of A. chinensis, C. dadiburjori, G. rarus, and Horadandia atukorali in having a wider perivitelline space. The larvae and juveniles of T. albonubes were similar to those of the aforementioned seven species plus Danio albolineatus, Danio kerri, and Devario sp. (cf. D. aequipinnatus) in general morphology. However, the early life stage morphology of T. albonubes differed from them in having a dark vertical streak posterior to the otic capsule and melanophores above the eyes in the yolk sac larval stage, and a dark lateral streak with an unpigmented area just above the former on the body, a dark blotch on the caudal fin, and reddish dorsal, anal, and caudal fins during the postflexion larval and juvenile stages.     

Developmental morphology of the Indian cyprinid fish Barilius canarensis

Embryonic and larval development of an Indian cyprinid fish, Barilius canarensis, is described from laboratory-reared specimens. The eggs, measuring 2.1–2.4 mm in diameter, were demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk without oil globules. Hatching occurred 39–45 h after fertilization at 26.8°–27.4°C. The newly hatched larvae, measuring 4.8–5.1 mm in body length (BL) with 22 + 17 = 39 myomeres, were characterized by melanophores already deposited on the eyes. The eggs of B. canarensis resembled those of the related danionin species Candidia barbatus, Opsariichthys uncirostris uncirostris, Zacco platypus, Z. sieboldii, and Z. temminckii. Although the larvae of B. canarensis were also similar to those of the foregoing species in general morphology, they differed in having a straight notochord tip and pigmentation on the eyes at hatching and the almost entire absence of melanophores on the ventral body surface from the yolk sac to postflexion larval stages. Conversely, melanophores occurred on the anterior abdominal and pericardial cavities from the preflexion to postflexion larval stages.     

Developmental morphology of the cyprinid fish Horadandia atukorali

Embryonic, larval, and juvenile development of a small Indian cyprinid, Horadandia atukorali, is described from laboratory-reared specimens. The eggs, measuring 0.7–0.8mm in diameter, were demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk without oil globules. Hatching occurred 47–54h after fertilization at 26.3–27.5°C. The newly hatched larvae, measuring 2.3–2.6mm in body length (BL) with 16+13=29 myomeres, had no melanophores, except on the eye, a single melanophore occurring on the lower margin, and xanthophores surrounding the pupil. The yolk was completely absorbed at 3.0mm BL. Notochord flexion was initiated at 4.0mm BL and finished at 4.4mm BL. Aggregate numbers of all fin rays were completed at 8.0mm BL. Squamation was initiated at 6.4mm BL and completed at 9.5mm BL. Although the eggs of Horadandia atukorali resembled those of other small danionin species, including Aphyocypris chinensis, Chela dadiburjori, Danio rerio, Devario malabaricus, and Hemigrammocypris rasborella, they differed from those of Danio rerio and Devario malabaricus in having a narrower perivitelline space. The larvae and juveniles of Horadandia atukorali were also similar to those of the latter five species in general morphology, especially in the presence of a melanophore on the lower margin of the eye at hatching, as in C. dadiburjori. However, the early life stage morphology of Horadandia atukorali differed from the other danionin species in having a conical yolk sac at hatching, no cement organ on the forehead in the yolk-sac larval stage, a divided gas bladder in the flexion larval stage, two dark lateral streaks on the head and chevron-like melanophores on the ventral body surface from the preflexion to postflexion larval stages, and xanthophores on the eyes at hatching.     

Developmental morphology of the cyprinid fish Inlecypris auropurpureus

Embryonic, larval, and juvenile development of a Myanmarese cyprinid fish, Inlecypris auropurpureus, is described from laboratory-reared specimens. The eggs, measuring 0.9–1.0 mm in diameter, were demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk without oil globules. Hatching occurred 49–56 h after fertilization at 26.2°–27.3°C. The newly hatched larvae, measuring 2.9–3.1 mm in body length (BL) with 17 + 19–20 = 36–37 myomeres, had melanophores on the head and body. A cement organ on the forehead for adhering to objects during the yolk sac and early preflexion larval stages was distinctive. The yolk was completely absorbed at 3.6–4.0 mm BL. Notochord flexion was initiated at 5.1–5.6 mm BL and finished at 7.1 mm BL. Aggregate numbers of all fin rays were completed at 14 mm BL. Squamation was initiated midlaterally on the anterior trunk at 14 mm BL and completed at 27 mm BL. Although the eggs of I. auropurpureus resembled those of the closely related species Chela dadiburjori, Danio rerio, and Devario malabaricus, they differed from those of Danio rerio and Devario malabaricus in having a narrower perivitelline space. The larvae and juveniles of I. auropurpureus were also similar to those of C. dadiburjori, Danio rerio, and Devario malabaricus in general morphology, but they differed from the latter three species in having a series of dark blotches laterally on the body in the juvenile stage. Moreover, I. auropurpureus differed from C. dadiburjori in having more myomeres and a near-single row of melanophores on the body along the dorsal midline from the yolk-sac to early postflexion larval stages, from Danio rerio in having a cement organ on the forehead during the yolk-sac and early preflexion larvae, and a single melanophore on the lower eye margin in the early yolk-sac larvae, and from Devario malabaricus in having a single melanophore on the lower eye margin in the early yolk-sac larvae. The presence of a cement organ on the forehead indicates a close relationship among the genera Inlecypris, Chela, and Devario.     

Developmental morphology of the cyprinid fish Chela dadiburjori

Embryonic, larval, and juvenile development of an Indian cyprinid fish, Chela dadiburjori, is described from laboratory-reared specimens. The eggs, measuring 0.7–0.9mm in diameter, were demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk and no oil globule. Hatching occurred 50–61h after fertilization at ca. 27°C. The newly hatched larvae, measuring 2.4–2.6mm in body length (BL), had melanophores on the body with 14–16+14–17=29–31 myomeres. Two dark transverse bands on the ventral body surface and one melanophore on the lower margin of the eye in newly hatched larvae were diagnostic. Additionally, a cement organ for adhering to objects was present on the forehead of yolk sac larvae <3.1mm BL. The yolk was completely absorbed at 3.5mm BL. Notochord flexion was initiated at 5.0mm BL and finished at 6.0mm BL. Aggregate numbers of all fin rays were completed at 9.2mm BL. Squamation was initiated on the caudal peduncle at 8.0mm BL and completed at 10mm BL. The eggs of C. dadiburjori resembled those of the closely related species Devario malabaricus and Danio rerio. The larvae and juveniles of C. dadiburjori were also similar to those of the latter species in general morphology, especially the presence of body melanophores in newly hatched individuals and a distinctive lateral streak on the head during the period from yolk sac to postflexion larvae. However, early yolk sac larvae of C. dadiburjori were more similar to those of Devario malabaricus than Danio rerio in having a cement organ on the forehead. Larvae and juveniles of C. dadiburjori differed from those of the latter two species in pigmentation on the ventral body surface at hatching and around the mouth during the period from preflexion to early postflexion larvae and in having a dark lateral streak or band on the body in postflexion larvae and juveniles.     

Reproductive biology and spawning habitat supplementation of the relict darter, Etheostoma chienense, a federally endangered species

We investigated the reproductive biology of Etheostoma chienense in the Bayou du Chien drainage of western Kentucky. Etheostoma chienense is similar in its ecology and reproductive biology to other members of the E. squamiceps complex. However, E. chienense is opportunistic in its choice of egg deposition substrates, as nests were found on a variety of natural and anthropogenic items. Due to an apparent lack of suitable spawning substrates, we added half-cylindrical ceramic tiles to several stretches of stream to increase potential nest productivity. Egg-clutches attached to artificial substrates were twice the size of egg clutches attached to naturally occurring materials. Laboratory experiments were conducted to determine nest rock size and mate choice preferences. Both the size of the male and of the nest rock appeared to be important parameters to spawning females. The life history information gathered here has significant management implications. Artificial spawning substrates should be placed in appropriate microhabitats (i.e., shallow, low-flow reaches in headwaters). Nest cavity vertical height should be about 3.0 cm and tiles should be spaced at least 0.5 m apart. We feel the use of surrogates (e.g., E. oophlyax) to investigate other types of spawning cover, and restoration of riparian buffer zones among other actions, would particularly benefit recovery efforts for this endangered species.     

Direct evidence of a mesopelagic fish,Melanostigma atlanticum (Zoarcidae) spawning within bottom sediments

Synopsis Adult Melanostigma atlanticum were observed living 15 to 32 cm deep within sediment box cores from 350 m depth in the Laurentian Trough of the Maritime Estuary of the St. Lawrence. The fish were found in fluid pockets or burrows of brown-coloured (oxygenated) silty clay within the anoxic zone of the sediment. In August 1983, four individuals (3 male and 1 female) were recovered from pockets located 15 and 32 cm below the sediment surface. All specimens were greater than 100 mm in length, had empty stomachs, and the female carried no eggs. In July 1985, 6 individuals (1 male and 5 females) were found in a head to tail arrangement within a single burrow at 18–20 cm depth. Three of the females carried eggs, while two appeared to have already released their eggs. A cluster of about 50 large eggs, some of which appeared to have been fertilized, was also found in the burrow. Most of the stomachs were empty, but one contained two copepods, another a proceroid cestode, and others contained between 4–22 parasitic hemiurid trematodes. These observations indicate that burrowing into bottom sediments is important in the reproductive behaviour of M. atlanticum.     

Past and present fish species recorded in the estuarine Lake Ichkeul,northern Tunisia

Lake Ichkeul in northern Tunisia is a Ramsar site, a MAB Biosphere Reserve and a UNESCO World Heritage Site. The system is one of the most important coastal wetlands in North Africa, especially as an over-wintering area for migratory birds, particularly Palaearctic waterfowl. The present study was aimed at diagnosing the status of fish species in Lake Ichkeul and documenting their annual and seasonal occurrence within the system. Fish samples were collected monthly at 22 sites from March 2011 to April 2012 using a variety of gears, including a dragnet, gillnet, trammelnet, frynet and beach-seine. Temperature and salinity measurements were taken at each site, while fishes were obtained from only 11 sites, representing mainly lacustrine stations. A total of 18 fish species belonging to 14 genera and 12 families were identified, with Mugilidae dominating with four species, followed by Syngnathidae with three species. This study represents a relative recovery in terms of fish species richness, since only 13 species were recorded here between 2003 and 2007. However, the numbers of fish caught, especially of the commercial taxa, seem to have declined in recent years, and the number of species currently present is much lower than that of several decades ago. Increasing human pressures, particularly reductions in catchment freshwater inputs, a breakdown in ecosystem connectivity, pollution and over-fishing appear to be the principal causes for the decline in fish abundance and diversity.     

Annual cycle of gametogenesis and spawning in a tropical zoanthid,Protopalythoa sp.

Gametogenesis and spawning have been studied since 1986 in a population of Protopalythoa sp. (Anthozoa, Zoanthidea) from Orpheus Island, Great Barrier Reef. Fertile zooids were gonochoric or hermaphroditic with oocytes and sperm vesicles intermingled in the same mesentery; colonies were single sex or mixed. Oocytes arose in macrocnemes below the actinopharynx and were first observed in July. Their mean diameter increased from < 50 µm to 160–240 µm by November, by which time they contained zooxanthellae. Female zooids each produced 800–2400 ova. No testicular vesicles were visible before October but spermatozoa were present in November and December. Spawning in each of three years occurred in November (4th to 6th nights after full moon) simultaneously with mass spawning of scleractinian corals. The buoyant eggs (along with sperm in the hermaphroditic zooids) were released in bundles. Some large oocytes and mature sperm were still present in December.     

Distribution of calbindinlike immunoreactive structures in the optic tectum of normal and eye-enucleated cyprinid fish

Summary Using the ABC immunohistochemical method, we investigated the distribution of calbindinlike immunoreactive structures in the optic tectum of normal fish, Tinca tinca, and from normal and unilaterally eye-enucleated fish, Cyprinus carpio. In nonoperated individuals of both species the optic tectum contained numerous immunoreactive neurons with strongly positive somata located in the stratum periventriculare and a thick immunolabeled dendritic shaft ascending radially toward the stratum fibrosum et griseum superficiale. The retinorecipient layers contained many fibrous immunoreactive structures. Some varicose fibers, isolated or in small bundles, were localized to the stratum album centrale, especially in the dorsal tectal half. Unilateral eye removal produced the disappearance of the immunoreactive fibrous structures located in the retinorecipient layers of the tectum contralateral to the enucleation. The present work shows that calbindinlike immunoreactive substances are localized in specific neural circuits of the fish optic tectum and suggests that the calbindin-like immunoreactive fibers in the retinorecipient strata are of retinal origin.     

Geographic variation of Barbus radiatus Peters,a widely distributed African cyprinid fish

Synopsis Barbus radiatus is a widely distributed, polytypic species with three recognized subspecies: radiatus Peters (1853), aurantiacus Boulenger (1910), and profundus Greenwood (1970). A phenetic analysis of relative similarity was conducted for specimens of B. radiatus from throughout its known range. The study focuses on several large population samples taken recently along the presumed central Zambian interface between the subspecies aurantiacus and radiatus. New data on meristic and morphometric variation in B. radiatus and recent rediscovery of typical radiatus in Lake Victoria demonstrate that profundus is a species distinct from radiatus. With respect to the remaining two subspecies, results indicate a populational mosaic of highly variable morphs rather than two discrete, allopatric morphs. Thus, aurantiacus is placed in synonymy of radiatus. It is hypothesized that the populational mosaic of morphology in radiatus reflects adaptive ecotypic responses to water temperature and current velocity. The characters which accounted for most of the geographic variation of radiatus were body depth, caudal peduncle length, longitudinal meristic counts, dorsal fin height, and orbit diameter.     

Filial cannibalism in a non-brood cycling marine fish

Synopsis Direct observation and the analysis of stomach contents indicate that custodial male Cortez damselfish, Stegastes rectifraenum, regularly eat some of the eggs they fertilize and guard. The pattern of forced starvation and brood cycling by custodial males that is seen in sticklebacks and other fishes for which filial cannibalism is known in the field does not exist for this species. These results indicate that filial cannibalism is likely to be more common among fishes than previously thought, because this behavior is not restricted to species that brood cycle.     

Impact of mass mortality of a mosquito fish,Gambusia affinison the ecology of a fresh water eutrophic lake (Lake Naini Tal,India)

Between 28th March and 4th April, 2000 a fungal infection killed >80% of the most abundant planktivorous fish, Gambusia affinis in Lake Naini Tal, Uttaranchal, India. In response to this mortality, planktonic communities and some eutrophication-related parameters viz., primary productivity, phosphate–phosphorus, nitrate–nitrogen and transparency of the water, were considerably changed. Total zooplankton number more than doubled, phytoplankton number reduced nearly to half, primary production and phosphate-phosphorus was dramatically reduced, while nitrate–nitrogen and water clarity increased. The phytoplankton decline was caused by increased zooplankton grazing (top-down control) rather than phosphorus deficiency (bottom-up control). After 3 months, Gambusia and planktonic communities and nutrient levels reverted back almost to their pre-mortality state. Thus removal of G. affinis could improve water quality of Lake Naini Tal.     

Record of a fatal oomycotic disease of the fresh water fish Anabas cobojius in India caused by Aplanes braunii

The fresh water fish Anabas cobojius (Hamilton-Buchanan 1822), was found to be parasitised by Aplanes braunii de Bary 1888. It is the first and only report of any Aplanes de Bary to cause disease on any fish. A. braunii was found to be a virulent parasite ofA. cobojius causing cotton-wool disease involving the skin and fins. The hyphae also penetrated into the tissues of the infected fish and all of them ultimately died.This revised version was published online in October 2005 with corrections to the Cover Date.     

Food searching decisions in four cyprinid species

Synopsis Four species of cyprinids (vimba, bream, Danubian bleak and roach) which had been incubated and reared under identical conditions differed qualitatively as well as quantitatively in the use of prey search strategies during comparative experiments. While bream and vimba prefer to use sampling techniques under conditions of reduced visibility of benthic prey, roach favor almost exclusively directed search methods. Vimba and Danubian bleak, in contrast to bream and roach, rapidly increase their total search activity in response to successive presentations of novel prey. These results have several ecological implications which are confirmed by field data. It is concluded that food searching cyprinids follow decision rules which are species specific both in the amount of sampling and in the responsiveness to rapidly changing conditions.     

Synchronous spawning in a recently established population of the zebra mussel,Dreissena polymorpha,in western Lake Erie,USA

Seasonal patterns of reproduction in a newly established population of Dreissena polymorpha are described for a site in the western basin of Lake Erie. Reproduction was monitored by histological examination of gonads, analysis of shell length-dry weight relationships, and following abundance of planktonic and settling larvae. Patterns of planktonic larval abundance and settling showed a distinct bimodal pattern in July and August, but conflicted with histological and length-dry weight data that showed spawning was a brief, highly synchronous event occurring in late August. Differences between histological data and abundance of larvae in the plankton can be explained as resulting from drift of larvae from disjunct populations of D. polymorpha which spawned earlier, into the study area. Veliger larvae were present in the plankton at low densities throughout the warm months before and after periods of peak abundances. The presence of these larvae can be explained by a combination of asynchronous spawning among local populations and postponed settlement by planktonic larvae.     

Introduced clupeids in a southern reservoir: more evidence for system-specific reproductive styles

Synopsis Latitudinal trends in reproductive characteristics are evident for some species of Clupeidae. However, selection for life history styles may operate at the population level. The reproductive cycles of alewifeAlosa pseudoharengus and threadfin shadDorosoma petenense in Dale Hollow Reservoir, Tennessee, were monitored over two spawning seasons on the basis of a gonadosomatic index (GSI). Inshore movements normally associated with spawning migrations were monitored using gill nets in spring 1989. GSI values peaked for both species at least one month earlier in 1989 than in 1988 due to warmer water temperatures earlier in the year. Highest GSI values for female alewife occurred each year when surface water temperatures were about 20° C; threadfin shad GSI values peaked at temperatures of 22°–26° C. Trends in male GSI values in both species were similar to those in females. Alewives were not abundant in warm (> 22° C), shallow water after 1 May 1989, but alewife GSI values remained high after this date, suggesting that elevated inshore temperatures limited alewife reproduction. All aspects of alewife reproduction were comparable to other populations of alewife but did not follow latitudinal trends. Threadfin shad reproductive characteristics were similar to other published accounts. We suggest that thermal regimes and reservoir trophic status are important factors for clupeid reproduction and population-level analysis is suggested when considering reproductive styles. Further, our ability to predict the ecology of introduced species in freshwater systems is impaired when species considered have not coevolved or evolved in marine environments.The Tennessee Cooperative Fishery Research Unit is jointly sponsored by Tennessee Technological University, the National Biological Survey, and the Tennessee Wildlife Resources Agency.