Comparative oogenesis in cardinal fishes (Apogonidae,Perciformes), with special focus on the adaptive structures of the egg envelopes

The present study compares gonad structure and oogenesis in 30 species of cardinal fish (Apogonidae) from the Indo-Pacific region. In all of the species studied the ovaries are bilobed, with each lobe possessing ovigerous lamellae whose numbers and dimensions increase concomitantly with growth of the fish and reproductive stage, and correlate with the total dimensions of the particular species. In species of the genus Siphamia, the ovarian lobes are associated with a fat body that is not found in species of the other genera studied. Some of the species studied (Siphamia spp.; Archamia spp.) demonstrate group-synchronized maturation of eggs, possibly with only one spawn per reproduction season. However, most of the Apogon spp., and other genera, have unsynchronized cycles, a characteristic of multiple spawners. The various stages of previtellogenic and vitellogenic development are similar in the different species, but differ in timing and dimensions of the oocytes around which the morphogenesis of the egg envelope (chorion) and follicle begins. Differentiation of the egg envelope and follicle cells parallels the vitellogenic stages of egg development. The number of eggs was found to correlate positively with the length of the body and ovary of the fish, whereas egg diameter was found to correlate negatively with body length. The surface of the egg envelope bears ridges that form patterns of various types, whose structures and dimensions seem to be species-specific, and which in most species converge upon the single micropyle on the animal pole. The exposed ridge mazes include a special fibrous web that anchors in the micropyle. The production and importance of these ridges, as well as the correlations between egg numbers per spawn, egg dimensions, and the oral dimensions of the paternal male, are discussed.     

Communal Spawning in the Common Frog Rana temporaria– Egg Temperature and Predation Consequences

Females of the common frog, Rana temporaria, spawn synchronously at communal breeding sites, forming a communal egg mass of individual spawn clumps. A total of four spawning sites were studied. In the centre of the communal egg mass, daily maximum temperature was higher and minimum temperature lower than further out. Spawn clumps in the centre of the communal egg mass developed faster than single spawn clumps. In the centre of the egg masses, some spawn clumps suffered almost total egg mortality. This was probably the consequence of a cold spell with sub‐zero temperatures in combination with a tendency for low minimum temperatures in the centre. In a laboratory study, worm leeches, Erpobdella spp., fed readily on eggs of common frog, while horse leeches, Haemopis sanguisuga, hardly ate any eggs. At the spawning sites, most worm leeches were found in single spawn clumps, far from the communal egg mass. Females which spawned late, when most of the spawning was over, preferred to spawn in the centre of the communal egg mass. This suggests that there is a net advantage for eggs in spawn clumps laid in the centre.     

Reproductive morphology, mating behavior, and spawning ecology of cephalaspid sea slugs (Aglajidae and Gastropteridae)

Abstract. Several recent experimental studies have assessed the behavioral reproductive ecology of four opisthobranch species belonging to the families Aglajidae and Gastropteridae (Cephalaspidea). In order to extend the scope of this earlier work, here we document the reproductive morphology and behavior of 36 taxa belonging to the same two sea slug families. Measurements focus on insemination patterns, spawning characteristics, as well as the size and shape of male and female reproductive organs (i.e., prostate, penis, bursa copulatrix, seminal receptacle). We found that behavioral and morphological traits vary considerably between species, even between closely related taxa. Mating behavior covers the full spectrum from unilateral to simultaneously reciprocal insemination and includes putatively antagonistic mechanisms such as hypodermic injection in some cases. With respect to morphology, particularly great variation was present in traits related to the male sexual function, such as prostate size and penis type. In traits associated with the female function, noticeable variation in those traits accessible for measurement was limited to the relative size of the sperm‐digesting bursa copulatrix. These data provide the basis for future comparative analyses on the evolution of reproductive characters in a phylogenetic context. We further explore the relationship between characteristics and body size. Our data corroborate previous findings that in species with exclusively planktotrophic development, investment per embryo (using mean egg diameter per species as a proxy) is independent of mean species body size. In contrast to egg size, spawn weight and the number of eggs per spawn tightly increased with body size, both within and among species. Hence, larger individuals among planktotrophs increased reproductive investment by increasing offspring quantity rather than investing more into each single offspring. Comparably large eggs with few eggs per spawn in our only two species with facultatively intracapsular metamorphosis are also consistent with findings in other opisthobranchs.     

Genetic, spatial, and temporal components of precise spawning synchrony in reef building corals of the Montastraea annularis species complex

When organisms release gametes into the sea, synchrony must be precise to increase fertilization and decrease hybridization. We tagged and genotyped over 400 spawning corals from the three species in the Montastraea annularis species complex. We report on the influence of species, individuals, and genotypes on timing of spawning from 2002 through 2009. During their annual spawning event M. franksi spawns on average 2 h after sunset, whereas M. annularis and M. faveolata spawn 3.5 h after sunset. Only M. franksi and M. annularis have compatible gametes. Individual colonies of the same genotype spawn at approximately the same time after sunset within and across years (within minutes), but different genotypes have significantly different spawning times. Neighboring colonies, regardless of genotype, spawn more synchronously than individuals spaced further apart. At a given distance, clone-mates spawn more synchronously than nonclone-mates. A transplant experiment indicates a genetic and environmental influence on spawn time. There is strong, but not absolute, concordance between spawn time, morphology, and genetics. Tight precision in spawning is achieved via a combination of external cues, genetic precision, and perhaps conspecific signaling. These mechanisms are likely to influence reproductive success and reproductive isolation in a density-dependent manner.     

Forest farming of shiitake mushrooms: Aspects of forced fruiting

Three outdoor shiitake (Lentinula edodes (Berk.) Pegler) cultivation experiments were established during 2002–2004 at the University of Missouri Horticulture and Agroforestry Research Center, in central Missouri. Over three complete years following a year of spawn run, we examined shiitake mushroom production in response to the temperature of forcing water, inoculum strain, substrate host species and physical orientation of the log during fruiting. Forcing compressed the period of most productive fruiting to the two years following spawn run. Further, chilled forcing water, 10–12 °C, significantly enhanced yield, particularly when ambient air temperatures were favorable for the selected mushroom strain. The temperature of water available for force-fruiting shiitake logs depends on geographic location (latitude) and source (i.e., farm pond vs. spring or well water). Prospective growers should be aware of this effect when designing their management and business plans.     

Observations on the hypophysation of murrels (Ophicephalidae)

The four common Indian species of murrels, viz., Ophicephalus striatus (Bloch), Ophicephalus marulius (Hamilton), Ophicephalus gachua (Hamilton) and Ophicephalus punctatus (Bloch) were hypophysed, the former three for the first time.The characters by which sexes in murrels can be distinguished, basis of selection of breeders, hormone doses administered and response, percentage of fertilization of eggs, techniques adopted for hatching of eggs and rearing of larvae and the total developing eggs and spawn produced are reported and discussed.     

Rana temporaria metamorph production and population dynamics in the field – Effects of tadpole density,predation and pond drying

This study investigates factors of importance for tadpoles survival and metamorph production in the common frog Rana temporaria. It also assess the importance of this for the population dynamics of the species. Eighteen ponds were studied for up to 8 years. Data collected each year included: number of spawn clumps deposited, tadpole number and metamorph number. The permanency of the ponds was also recorded each year. Measures were taken of predator density. There was no suggestion of density dependence in the survival of tadpoles. In contrast, the number of spawn clumps deposited per pond area was highest for ponds with high survival. Density of predators (sticklebacks, newts and invertebrates) was negatively correlated to tadpole and metamorph survival. This was true both within (among years) and among ponds. Several of the study ponds dried completely before metamorphosis in some years. However, those ponds also were those with the smallest number of predators and in years with successful metamorphosis, these ponds produced more metamorphs than more permanent ponds. An analysis of the year to year dynamics showed that population size (number of deposited spawn clumps) was correlated to that in the previous year, suggesting a fairly high adult survival, but also on the number of metamorphs emerging two or three years before (corresponding to the age of sexual maturity of the species). It is concluded that the aquatic stage is not strongly limiting in these ponds but conservation efforts should be focused on the terrestrial habitat. Also, the study stresses the value of temporary ponds, despite the fact that recruitment often fails totally in these.     

Combined analysis of Perca fluviatilis reproductive performance and oocyte proteomic profile

The success of reproduction depends greatly upon gamete quality, especially oocytes which carry most of the molecular material necessary for early embryogenesis. However, it remains difficult to find relevant morphologic and/or biochemical parameters to assess oocyte quality and thus have a reliable prediction of the reproduction performance. To understand which criteria are the most reliable to assess the reproductive success of the Eurasian perch (Perca fluviatilis), we measured 14 parameters characterizing female, spawn, oocyte, and embryonic or larval development on 20 independent spawn. A data analysis allowed the definition of two clusters of spawn with different larval characteristics: the first cluster was composed of spawn which led mainly to strong large larvae presenting a low deformity rate, while the second cluster rather corresponds to spawn leading to smaller and weaker larvae with a higher deformity rate. Moreover, a third cluster (unfertilized spawn) was studied. Our analysis revealed that most of the prefertilization biological traits that we studied appeared poorly relevant to predict larval features, proper embryonic development and deformity occurrences. We thus performed a large scale proteomic analysis to highlight proteins differently expressed in each spawn cluster. A 2D-DIGE study followed by an MS/MS spectrometry allowed the identification of 32 proteins involved in several biological functions and differently expressed between spawn clusters. Among them, proteins involved in cell response to the oxidative stress, as well as energetic metabolism, heat shock proteins and Vitellogenins are of particular interest. Several functions appear specific to a spawn cluster and could thus explain their corresponding reproduction performance. In the future, proteins involved in those cellular mechanisms may constitute molecular markers predictive of the reproduction performance in Perca fluviatilis.     

Features of gametogenesis and sexual cycles of six notothenioid fishes from East Antarctica

Summary Some features of gametogenesis and sexual cycles of three species of the genus Trematomus (fam. Nototheniidae)-Trematomus centronotus Regan, T. eulepidotus Regan and T. scotti (Boulenger) and three species of icefishes (fam. Channichthyidae)-Chionodraco hamatus (Lönnberg), Ch. myersi Tyler and Neopagetopsis ionah Nybelin-were studied at Davis and Mawson Seas during austral autumn (March–April), 1983. Two peculiarities of the sexual cycles of Trematomus species may be noted: the uniform state of gonads of mature specimens of each species, and differences in time of spawning (austral summer and autumn for T. centronotus and T. eulepidotus, and, evidently, beginning of spring or the end of winter for T. scotti). Among the features of gametogenesis of icefishes are the early accumulation of yolk in oocytes, and the beginning of polarization and homogenization of yolk in oocytes, which are far from definitive sizes. Some differences in spawning time were registered in first maturing and repeatedly maturing specimens of Ch. hamatus. Repeatedly maturing specimens probably begin to spawn in December–January; those maturing for the first time evidently still spawn in March–April. Ch. myersi and N. ionah, judging by singular mature specimens, supposedly spawn during austral autumn.     

Mechanisms of reproductive isolation among sympatric broadcast-spawning corals of the Montastraea annularis species complex

Many coral species spawn simultaneously and have compatible gametes, leading to controversy over the nature of species boundaries and the frequency with which hybridization occurs. Three western Atlantic corals, Montastraea annularis, M. faveolata, and M. franksi, typify this controversy; they all spawn sympatrically on the same evenings after the fall full moons. Here we show, in both Panama and the Bahamas for multiple years, how a variety of mechanisms may act in concert to reproductively isolate all three species. Field studies indicate that M. franksi spawns two hours earlier than the other two species, and the eggs released during this earlier period disperse an average of 500 m by the time the other species spawn. Field measures of fertilization indicate that peak fertilization occurs when spawning synchrony is high and that corals that spawn at the tails of the spawning distributions have greatly reduced fertilization success. Laboratory studies indicate that there is a gametic incompatibility between M. faveolata and the other two species. There are regional differences in the gametic compatibility of M. franksi and M. annularis. In Panama, the two species are completely compatible, whereas in the Bahamas, M. franksi sperm can fertilize M. annularis eggs but the reciprocal cross often fails. Gamete age influences patterns of fertilization, such that very young eggs seem resistant to fertilization and old sperm lose viability after two hours. In sum, the combination of temporal differences in spawning, sperm aging, gamete dispersal and dilution, and gametic incompatibility act in various combinations among the three species, making it unlikely that hybrid fertilization would occur.     

The biological characteristics of micromycetes isolated from fish roe

The fungi Aspergillus fumigatus Fres., and Fusarium sporotrichiella Bilai were studied for their effect on certain biochemical indices of two-year carp and spawn of grass carp under laboratory conditions. The intraperitoneal introduction of A. fumigatus in a dose of 5 and 20 min conidia per individual to two-year carp decreased significantly the protein level in blood serum, the decrease being more considerable with the introduction of the smaller dose of fungal conidia. Joint incubation of the grass carp spawn and F. sporotrichiella induced changes in the protein level, amylolytic and phosphate (acid phosphatase) activity in spawn. In that case the time of the fungus action on grass carp spawn was a decisive factor. Activity of certain hydrolytic enzymes in mycelium and conidia of A. fumigatus and F. sporotrichiella was determined. The amylolytic activity was not revealed in the checked samples. The proteolytic activity was established in all samples of fungi and culture liquid, the highest level being observed in mycelia and conidia of A. fumigatus. The alkaline and acid phosphatase activity was found in F. sporotrichiella: the acid phosphatase activity was higher in mycelium, the acid phosphatase one in the fungus conidia. The problem on the A. fumigatus ability to produce extracellular enzymes is under discussion.     

Preliminary observations on the spawning conditions of the European amphioxus (Branchiostoma lanceolatum) in captivity

Members of the subphylum Cephalochordata, which include the genus Branchiostoma (i.e. amphioxus), represent the closest living invertebrate relatives of the vertebrates. To date, developmental studies have been carried out on three amphioxus species (the European Branchiostoma lanceolatum, the East Asian B. belcheri, and Floridian-Caribbean B. floridae). In most instances, adult animals have been collected from the field during their ripe season and allowed (or stimulated) to spawn in the laboratory. In any given year, dates of laboratory pawning have been limited by two factors. First, natural populations of these three most studied species of amphioxus are ripe, at most, for only a couple of months each year and, second, even when apparently ripe, animals spawn only at unpredictable intervals of every several days. This limited supply of living material hinders the development of amphioxus as a model system because this limitation makes it more difficult to work out protocols for new laboratory techniques. Therefore we are developing laboratory methods for increasing the number of amphioxus spawning dates per year. The present study found that a Mediterranean population of B. lanceolatum living near the Franco-Spanish border spawned naturally at the end of May and again at the end of June in 2003. Re-feeding experiments in the laboratory demonstrated that the gonads emptied at the end of May refilled with gametes by the end of June. We also found that animals with large gonads (both, obtained from the field and kept and fed at the laboratory during several weeks) could be induced to spawn in the laboratory out of phase with the field population if they were temperature shocked (spawning occurred 36 hours after a sustained increase in water temperature from 19 degrees C to 25 degrees C).     

Insemination of the salmon spawn by Micromycetes at the fish-rearing farm "Pushcha-Voditsa"

Fungi of 21 species attributed to 11 genera of three classes--oomycetes, zygomycetes, deuteromycetes--have been isolated from the surface of the Salmo gairdneri Rich. spawn and from water samples of incubation apparatuses of the fish-rearing farm "Pushcha-Voditsa" (the Kiev Region). Among the revealed micromycetes only Saprolegnia parasitica C o k e r is a fish parasite. Most of isolates are imperfect fungi; they dominate among the hyphal forms in the mycobiota of fish and water and in natural water bodies. Fusarium sporotrichiella. B i l a i, one of the isolates, is slightly toxicogenic. It affects the fish spawn viability and biochemical indices: the joint incubation of spawn and fungi induces changes in the level of water-soluble protein, amylolytic and phosphatase activity. The disturbance of the spawn envelope integrity has been observed in the experiment.     

Life history correlates and extinction risk of capital-breeding fishes

We consider a distinction for fishes, often made for birds and reptiles, between capital-breeding and income-breeding species. Species that follow a capital-breeding strategy tend to evolve longer intervals between reproductive events and tend to have characteristics that we associate with higher extinction risk. To examine whether these ideas are relevant for fishes, we assembled life history data for fish species, including an index of extinction risk, the interval between spawning events, the degree of parental care, and whether or not the species migrates to spawn. These data were used to evaluate two hypotheses: (1) fish species with a major accessory activity to spawning (migration or parental care) spawn less often and (2) fish species that spawn less often are at greater risk of extinction. We tested these hypotheses by applying two alternative statistical methods that account for phylogenetic correlation in cross-taxon comparisons. The two methods predicted average intervals between spawning events 0.13–0.20 years longer for fishes with a major accessory activity. Both accessories, above-average parental care and spawning migration, were individually associated with longer average spawning intervals. We conclude that the capital-breeding paradigm is relevant for fishes. We also confirmed the second hypothesis, that species in higher IUCN extinction risk categories had longer average spawning intervals. Further research is needed to understand the relationship between extinction risk and spawning interval, within the broader context of life history traits and aquatic habitats. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: S. Dufour, E. Prévost, E. Rochard & P. Williot Fish and diadromy in Europe (ecology, management, conservation)     

On the biology of Amphibia in the ecosystem of Lake Glubokoe

In Lake Glubokoe, the Amphibia are represented by five species. Two numerous species, Rana temporaria L. and Bufo bufo L., spawn in the lake and appear to be a significant component of its ecosystem. Thus, in autumn R. temporaria is a common food for predatory fish (pike, perch). During their wintering R. temporaria participate in the consumption of oxygen from the water. They may be a source of dangerous infections. Their tadpoles and those of B. bufo feed in the lake and annually remove substances from it. Adult R. temporaria in autumn, and the young of the year of R. temporaria and of B. bufo influence the population numbers of small littoral invertebrates. Several dozen pairs of Rana terrestris Andrzejw are observed to spawn regularly. Rana esculenta L. and Rana ridibunda Pallas are scarce. The influence of introducing a nature preserve on the numbers of Amphibia in Lake Glubokoe is discussed.     

Visual discrimination by the spraying characid,Copeina arnoldi Regan

Visual discrimination by male spraying characids, Copeina arnoldi, during spawn splashing was studied. Apparently the spawn is not used per se in directing parental splashing. Males discriminated between the standard 12·7-cm disc and a square, a triangle, a white disc, and a small disc in successive and/or simultaneous presentations. They did not discriminate between the standard disc and a large disc in succession, nor between the standard (green) disc and a white disc presented simultaneously. Although they can discriminate between objects differing in shape, colour, and/or brightness, these are probably not the major cues used in nature for selecting the spawn substrate from other proximal stimuli. However, large size differences may be important in spawn substrate discrimination.     

What is normal? A characterization of the values and variability in reproductive endpoints of the fathead minnow, Pimephales promelas

Jensen et al. [Jensen, K.M., Korte, J.J., Kahl, M.D., Pasha, M.S., Ankley, G.T., 2001. Aspects of basic reproductive biology and endocrinology in the fathead minnow (Pimephales promelas). Comp. Biochem. Physiol. C 128, 127-141.] investigated aspects of the normal reproductive biology of the fathead minnow (FHM, P. promelas), and subsequent studies have generated a large amount of additional reproductive data for endpoints such as plasma steroid hormone and vitellogenin concentrations, spawn interval, and secondary sex characteristics (i.e., nuptial tubercle score and fat pad weight). These data were analyzed and fitted with statistical distributions to improve understanding of the variability in normal, unexposed, adult male (n=154) and female (n=186) FHM. Summary statistics for most endpoints were consistent with results from other more limited studies of FHMs. Male fat pad weight, and in both sexes gonad and liver weights were found to be proportional to body weight. Multiple statistical distributions were found to characterize each endpoint with the exception of spawn interval. Based on one of the largest datasets ever compiled for controlled studies, results presented herein provide a robust point of reference for the quantitative assessment of reproductive processes in the fathead minnow.     

Distribution of mycosporine-like amino acids in the sea hare Aplysia dactylomela: effect of diet on amounts and types sequestered over time in tissues and spawn

We investigated the interaction of diet and accumulation of UV-absorbing mycosporine-like amino acids (MAAs) in body tissues and spawn of the sea hare Aplysia dactylomela to determine if MAA accumulation reflects type and level of dietary intake. Food sources were the red algae Acanthophora spicifera, Centroceras clavulatum, and Laurencia sp., and the green alga, Ulva lactuca. Adults were maintained on these foods for 40 days, after which feces were collected and tissues separated by dissection. Field animals were similarly sampled at this time. All spawn from experimental and field animals was collected over the study period. Samples, including seaweed foods, were analysed for six MAAs. Overnight consumption experiments using a variety of common seaweeds and one seagrass from A. dactylomela's habitat showed that the four seaweeds selected as foods were among those best-eaten by Aplysia. After 40 days levels of specific MAAs in the tissues of experimental animals showed excellent correlation with those in their diets, suggesting that the MAAs were dietarily-derived. Relative MAA contents in spawn from all diet groups correlated well with those in spawn from field animals. Commonest MAAs in spawn were porphyra-334, shinorine, and palythine, in this order. Concentrations of these MAAs were maintained at constant levels over time in spawn from all diet groups eating red algae and from field animals. Spawn from the Ulva dietary group showed an initial significant decline in MAA concentrations, but levels stabilized after the first 2 weeks. Skin was rich in porphyra-334 and shinorine, and levels of these in experimental animals correlated well with comparable levels in the skin of field animals. Digestive glands contained high levels of asterina-330, particularly those of the Centroceras dietary group, where concentrations reached a maximum of 21 mg dry g(-1).     

Contrasting effects of dams with and without reservoirs on the population density of an amphidromous goby in southwestern Japan

Ichthyological Research - Dam construction affects the distribution and abundance of freshwater fishes, particularly for diadromous species. Amphidromous fishes spawn in rivers, and hatched larvae...     

Systematics and Ecology of Shell-Boring Polychaetes from New England

In a survey of shell-boring polychaeles of New England, representativesof five families were found: Spionidae, Cirratulidae, Capitellidae,Terebellidae, and Sabellidae. The five spionid species were studied extensively. These includePolydora commensalis Andrews, found only in shells occupiedby hermit crabs, P. concharum Verrill, P. socialis (Schmarda), P. websleri Hartman, and Boccardia hamata (Webster) , foundin various types of shell. Breeding periods were defined andthe larval development described for each species. Polydoraconcharum deposits egg capsules inwinter months, while the oilierpolydorids spawn in spring or summer. Morphology of planktoniclarvae is distinct in each species, although P. websteri larvaemay be confused with non-boring species such as P. ligni Webster.Polydora socialis adults are found in both shells and sedimentand have a unique grinding apparatus, a gizzard, between theesophagus and intestine. The cirratulid, Dodecaceria sp., follows an asexual mode ofreproduction. The syslematics of Dodecaceria is complex owingto multiple modes of reproduction. No sexually mature individualswere observed during the course of this study. Asexual budswerefound in the Fall. A sabellid, Pseudopolamilla reniformis (Miiller), is commonlyfound in theshells of Placopeclen magellanicits (Gmelin) inMaine waters. Its reproductionis unknown.