The Effects of Hypoxia on Three Sympatric Shark Species: Physiological and Behavioral Responses

Behavioral and physiological responses to hypoxia were examined in three sympatric species of sharks: bonnethead shark Sphyrna tiburo, blacknose shark, Carcharhinus acronotus, and Florida smoothhound shark, Mustelus norrisi, using closed system respirometry. Sharks were exposed to normoxic and three levels of hypoxic conditions. Under normoxic conditions (5.5–6.4mg l^–1), shark routine swimming speed averaged 25.5 and 31.0cm s^–1 for obligate ram-ventilating S. tiburo and C. acronotus respectively, and 25.0cm s^–1 for buccal-ventilating M. norrisi. Routine oxygen consumption averaged about 234.6 mg O₂kg^–1h^–1 for S. tiburo, 437.2mg O₂kg^–1h^–1 for C. acronotus, and 161.4mg O₂ kg^–1 h^–1 for M. norrisi. For ram-ventilating sharks, mouth gape averaged 1.0cm whereas M. norrisi gillbeats averaged 56.0 beats min^–1. Swimming speeds, mouth gape, and oxygen consumption rate of S. tiburo and C. acronotus increased to a maximum of 37–39cm s^–1, 2.5–3.0cm and 496 and 599mg O₂ kg^–1 h^–1 under hypoxic conditions (2.5–3.4mg l^–1), respectively. M. norrisi decreased swimming speeds to 16cm s^–1 and oxygen consumption rate remained similar. Results support the hypothesis that obligate ram-ventilating sharks respond to hypoxia by increasing swimming speed and mouth gape while buccal-ventilating smoothhound sharks reduce activity.     

Comparative residual toxicities of pesticides to the predator Agistemus industani (Acari: Stigmaeidae) on citrus in Florida

Residual toxicities of registered and selected experimental pesticides used on citrus against Agistemus industani Gonzalez (Acari: Stigmaeidae) were compared. Pesticides considered highly toxic to A. industani were: abamectin 0.15 EC at 731ml/ha+FC 435-66 petroleum oil at 46.8l/ha, pyridaben 75WP at 469g/ha, ethion 4EC at 7.01l/ha+FC 435-66 petroleum oil at 46.8l/ha, propargite 6.55 EC at 3.51l/ha, chlorfenapyr 2SC at 1.46l/ha applied alone or in combination with FC 435-66 petroleum oil at 46.8l/ha, sulphur 80DF at 16.81kg/ha, dicofol 4EC at 7.01l/ha, fenbutatin oxide 50WP at 2.24kg/ha, benomyl 50WP at 2.24kg/ha, benomyl 50WP at 1.68kg/ha+ferbam 76 GF at 5.60kg/ha, ferbam 76GF at 11.21kg/ha, neem oil 90EC at 46.8l/ha, and copper hydroxide DF (40% metallic copper) at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha. Pesticides that were moderately to slightly toxic included: copper sulphate 98% at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha, fenbuconazole 2F at 280ml/ha+FC 435-66 petroleum oil at 46.8l/ha, FC 435-66 petroleum oil applied alone at 46.8l/ha or 23.4l/ha, and diflubenzuron 25WP at 1.40kg/ha. Pesticides that were non-toxic included: fenbuconazole 2F at 585ml/ha, malathion 57EC at 5.85l/ha, FC 435-66 petroleum oil at 46.8l/ha, carbaryl 80S at 3.36kg/ha, chlorpyrifos 4EC at 4.68l/ha, and formetanate 92SP at 1.12kg/ha. Understanding the toxic effects of field weathered pesticides against key predacious mite species is important for effective IPM. The results of this study provide a comparison of direct and indirect toxic effects of various pesticides to A. industani under field conditions.     

Optimization of cryopreservation of Artemisia annua L. callus

Cryopreservation of callus tissue of Artimisia annua L. was optimized. Two lines of calli were precultured on MS medium with 5% (v/v) dimethyl sulfoxide, and protected by a cryoprotectant containing 15% (v/v) ethylene glycol, 15% (v/v) dimethyl sulfoxide, 30% (v/v) glycerol and 13.6% (w/v) sucrose. The highest survival rate of callus A201 reached 87% after it was pretreated at 25°C, cryopreserved by liquid nitrogen, recovered in water bath at 25°C and reloaded at 25°C with 34% (w/v) sucrose solution, and that of callus A202 reached 78% after it was treated as callus A201, except pretreated at 35°C, recovered at 35°C and reloaded with 47.8% (w/v) sucrose solution.     

A Cytogenetic Study of the Leaf Beetle Genus Cyrtonus (Coleoptera, Chrysomelidae)

The chromosomes of ten species of Cyrtonus and the genome sizes of six are surveyed. Among the total of 15 chromosomally studied species, 11 have 2n=28 chromosomes and a 13+Xy_p male meioformula, three have 2n=40 and 19+Xy_p and one 2n=46 and 22+Xy_p. All but one species with 28 chromosomes show only metacentric or submetacentric chromosomes, whereas the species with 40 and 46 chromosomes display some telocentrics or subtelocentrics, that are probably derived from the former by centric fissions. However, since the number of major chromosome arms is strikingly higher in these latter species (NF=70 and 78) than in the 28-chromosome species (mostly NF=56), other chromosomal rearrangements such as pericentric inversions or heterochromatin accretions could also be involved. The genome sizes display a narrow range, from 1C=0.6–1.22pg, and they are not significantly correlated with the chromosome numbers. Some possible factors implied in the rough chromosomal evolution of Cyrtonus are discussed in relation to a few other genera of the subfamily Chrysomelinae.     

Uptake of sewage derived nitrogen by<Emphasis Type="Italic"> Ulva rigida</Emphasis> (Chlorophyceae) in Bahía Nueva (Golfo Nuevo,Patagonia, Argentine)

Uptake kinetics of nitrogen derived from sewage–seawater mixtures (2.5–20% v/v effluent) were determined in the laboratory for Ulva rigida (Chlorophyceae) native from Bahía Nueva (Golfo Nuevo, Patagonia, Argentine). In terms of nitrogen concentration, experimental enrichment levels varied between 53.7 and 362.3M of ammonium and between 0.77 and 6.21M of nitrate+nitrite. Uptake rates were fitted to the Michaelis–Menten equation, with the following kinetic parameters: ammonium: V_max = 591.2molg^–1h^–1, K _s=262.3M, nitrate+nitrite: V _max=12.9molg^–1h^–1, K _s=3.5M). Both nutrients were taken up simultaneously, but ammonium incorporation was faster in all cases. The results show a high capability of Ulva rigida to remove sewage-derived nitrogen from culture media. In the field, most of the nitrogen provided by the effluent would be tied up in algal biomass, supporting low nitrogen levels found at a short distance away from the source.     

(T2AG3)n Telomeric Sequence Hybridization Indicating Centric Fusion Rearrangements in the Karyotype of the Rodent Oryzomys Subflavus

Chromosome preparations of 30 specimens of Oryzomys subflavus trapped in eight Brazilian localities were C-, and G-banded and analyzed by fluorescence in situ hybridization (FISH). Two karyotypes were found, 2n=50/FN=64, at three coastal localities of the Atlantic Forest domain, and 2n=58/FN=70 at two sites located in the Cerrado biome, Brazil Central. Two fluorescence in situ hybridization (FISH) patterns of the telomeric sequence (T₂AG₃)_n were observed: in both karyotypes the probes hybridized to the telomeres of all chromosomes and also a hybridization signal in the centromeric regions of two autosome pairs was seen in the 2n=50 karyotype. These results, together with the occurrence of other diploid numbers described in the literature, suggest that O. subflavus is a complex species, bearing fusion/fission rearrangements proper to the different biomes which it inhabits.     

Pullulan production from brewery wastes by Aureobasidium pullulans

The production of pullulan from brewery wastes by Aureobasidium pullulans in shake flask culture was investigated. The maximum pullulan concentration (6.0g/l) was obtained after 72h of fermentation. The external addition of nutrients into the spent grain liquor improved significantly the production of pullulan. In this case, the highest values of pullulan concentration (11.0±0.5g/l), pullulan yield (48.2±1.5%), and sugar utilization (99.0±0.5%) were obtained in the medium (pH 6.5–7.5) supplemented with K₂HPO₄ 0.5%, l-glutamic acid 1%, olive oil 2.5%, and Tween 800.5%.     

Consequences of harvesting for genetic diversity in American ginseng (<Emphasis Type="Italic">Panax quinquefolius</Emphasis> L.): a simulation study

American ginseng, Panax quinquefolius L., is one of the most heavily traded medicinal plants in North America. The effect of harvest on genetic diversity in ginseng was measured with a single generation culling simulation program. Culling scenarios included random harvest at varying levels, legal limit random harvest and legal limit mature plant harvest. The legal limit was determined by the proportion of legally harvestable plants per population (% mature plants per population). Random harvest at varying levels resulted in significant loss of genetic diversity, especially allelic richness. Relative to initial levels, average within-population genetic diversity (H _e) was significantly lower when plants were culled randomly at the legal limit (Mann–Whitney U=430, p<0.001) or when only mature plants were culled (Mann–Whitney U=394, p<0.01). Within-population genetic diversity was significantly higher with legal limit mature plant harvest (H _e=0.068) than when plants were culled randomly at the legal limit (H _e=0.064; U=202, p<0.01). Based on these simulations of harvest over one generation, we recommend that harvesting fewer than the proportion of mature plants could reduce the negative genetic effects of harvest on ginseng populations.     

Early development of the self-fertilizing mangrove killifish <Emphasis Type="Italic">Rivulus marmoratus</Emphasis> reared in the laboratory

The mangrove killifish Rivulus marmoratus was reared at 25°±1°C and 17ppt salinity from 0 to 100 days after hatching (DAH), and its early development was described by examining growth and morphometric parameters, meristic characters (vertebral and fin-ray counts), bone-cartilage development, and pigmentation. Growth was isometric for preanal length, head length, snout length, body depth, pectoral-fin length, dorsal-fin length, anal-fin length, and caudal-peduncle depth. Negative allometric growth was observed in eye diameter and gape size. Meristic counts (mean±SD) for vertebrae (34.2±0.4) and dorsal- (8.6±0.5), anal- (11.4±0.5), and caudal-fin rays (30.2±0.8) were complete at 0 DAH (n=5), whereas pectoral-fin rays and pelvic-fin rays were complete by 30 DAH (14.5±0.4, n=5) and 60 DAH (4.2±0.8, n=5). Full ossification of meristic elements proceeded in the following sequence: vertebrae (by 30 DAH), caudal-, dorsal-, and anal-fin rays (by 60 DAH), pectoral-fin rays (between 60 DAH and 100 DAH), and pelvic-fin rays (by 100 DAH). Both morphological characters and meristic counts indicate that this species can be considered to be a juvenile after 9.8mm in standard length (20 DAH).     

Assessment of within-population genetic structure in <Emphasis Type="Italic">Quercus crispula</Emphasis> and <Emphasis Type="Italic">Q. dentata</Emphasis> by amplified fragment length polymorphism analysis

The spatial genetic structure was assessed by amplified fragment length polymorphism (AFLP) technique for Quercus crispula Blume (37 individuals) and Q.dentata Thunberg (54 individuals) growing along a 550-m transect in Ishikari, Hokkaido, northern Japan. The simple Mantel test revealed significant negative correlation between genetic similarity and geographic distance in Q.dentata and negative but insignificant correlation in Q.crispula. Spatial autocorrelation analysis revealed that Mantels r generally decreased from positive to negative values with the increase of spatial distance in both oak species with significant deviation from zero for the 50–100-m (positive) and 250–300-m classes (negative) in Q.dentata. Thus, significant spatial genetic structure was revealed at least in Q.dentata     

Relation between trace element levels in plasma and myocardium during coxsackievirus B3 myocarditis in the mouse

During most infections the plasma levels of trace elements change, but it is not clear if this reflects changes in the infected tissues. Coxsackievirus B3 (CB3) infection may result in viral replication, subsequent inflammation and changed trace element levels in the myocardium. In the present study, the trace element levels in the plasma and heart of adult male A/J mice were determined during the pre-inflammatory stage (day 4) of CB3 myocarditis for the following trace elements: aluminium (Al), arsenic (As), calcium (Ca), cobalt (Co), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), selenium (Se), silver (Ag), vanadium (V) and zinc (Zn). The severity of the infection was assessed through clinical signs of disease and trace element levels were measured through inductively-coupled plasma mass-spectrometry (ICP-MS). In the heart, the levels decreased for V (59%; p<0.01), Co (38%; p<0.01), Al (81%; p< 0.01), As (66%; p<0.01) and Se (16%; p<0.01). Increased levels were detected for Mn (13%; p<0.05), Fe (48%; p<0.01), Cu (34%; p<0.01) and Ag (46%; p< 0.01). In the plasma, decreases were detected in the level of Zn (32%; p<0.05), whereas increases were seen in Mn (362%; p<0.05), Fe (272%; p<0.01), Co (71%; p<0.05), Cu (25%; n.s.) and Mg (43%; p<0.01) levels. A correlation was found between the levels in plasma and myocardium for Co (r _s=–0.636; p<0.05), Fe (r _s=0.764; p<0.05), Mn (r _s=0.682; p<0.05) and Mg (r _s=–0.791; p<0.05). Thus, determination of some of these trace elements in the plasma may be useful to indicate target tissue involvement in the early pre- inflammatory stage of an infectious disease. Some of these elements are important nutrients for the immune system, while others may be associated with the development of disease complications, such as cardiac arrhythmias.     

Porosity and available water of temporarily waterlogged soils in a Quercus robur (L.) declining stand

Pedunculate oak (Quercus robur L.) is particularly sensitive to decline in clayey soils presenting a high-perched temporary water table. These soils induce two successive constraints in one-year cycle: water excess (and hypoxy) in winter and early spring, and water shortage in summer (water stress being more restrictive to oak). We determined the porosity and water properties of temporarily waterlogged clayey soils supporting forest stands of decliningQuercus robur trees in a 101yr-old oak stand in Belgium (50°06N, 4°16E). Roots unevenly colonized the soil down to 1.6m: fine roots (diameter<5mm) were mostly distributed on the surface horizons (0–0.3 m) and around 1.3m deep, despite dense clayey horizons appearing at 0.35m depth. Clay content below this depth reached 46–51. Illite and vermiculite were the dominant clay minerals. The clayey horizons exhibited marked shrink–swell properties: bulk density at 30kPa increased from 1.41 to 1.88gcm^–3 from the surface to 2m depth. There was also evidence of hypoxic conditions caused by water saturation of pore space in the rooting zone from October to mid-April. Extractable water (EW), calculated between moisture tensions of 5 and 1600kPa was 152.8mm. The level of perched temporary water table strongly depended on the seasonal rhythm of water uptake by trees and on the shrink–swell behaviour of soil.     

Increased erythritol production in Torula sp. by Mn2+and Cu2+

The production of erythritol and the erythritol yield from glucose by Torula sp. were improved, in increasing order, by supplementing with 10 mg MnSO₄4H₂O l^–1, 2 mg CuSO₄5H₂O l^–1, and both 10 mg MnSO₄4H₂O l^–1 and 2 mg CuSO₄5H₂O l^–1. Mn²⁺ decreased the intracellular concentration of erythritol, whereas Cu²⁺ increased the activity of erythrose reductase in cells. These results suggest that Mn²⁺ altered the permeability of cells, whereas Cu²⁺ increased the activity of erythrose reductase in cells.     

Seed dispersal curve of a Mediterranean myrmecochore: Influence of ant size and the distance to nests

Euphorbia characias is a Mediterranean spurge with a diplochorous dispersal system: after a ballistic dispersal that scatters the seeds, some ant species find and retrieve the seeds to their nest (myrmecochorous dispersal). The seed dispersal curve generated by ants in an abandoned field was described and partitioned according to ant size and to the distance to nest entrance from where seeds fell after ballistic dispersal. Both variables (ant size, distance to nest) affected dispersal distance. The seed dispersal curve showed a peak at short distance (median=1m) and a tail extending to 9.4m. The peak and the tail are explained differently. Short distances are usually generated by small ants (Pheidole pallidula and Tapinoma nigerrimum; 0.56±0.41m [n=48]) both from the nearest or farther nest entrances. The tail of the curve is generated disproportionately by big ants (Aphaenogaster senilis and Messor barbarus; 2.09±1.71m [n=61]) from farther nests. Seeds have a much greater probability (P=0.734) of being transported to nests which are not the nearest. This effect is largely due to transportation by big ants.     

Inoculation of sugar mill by-products compost with N2-fixing bacteria

Inoculation of sugar mill by-products compost with N₂-fixing bacteria may improve its quality by increasing total N and available P. Compost was inoculated with Azotobacter vinelandii(ATCC 478), Beijerinckia derxii (ATCC 49361), and Azospirillumsp. TS8, each alone and all three together. Numbers of all N₂-fixing bacteria in compost declined from an initial population of 5×10⁵cellsg^–1 during incubation. The population of Azotobacter declined to approximately 2×10²cellsg^–1 and the population of Beijerinckia and Azospirillum declined to approximately 9×10³ and 3.5×10⁴cellsg^–1 respectively, at day 50. Inoculation with N₂-fixing bacteria increased acetylene reduction, total N by 6–16 and available P by 25–30% in comparison to the uninoculated control. Increasing the N content and P availability of compost increases its value and there may be additional benefit from providing N₂ fixing bacteria.     

<Emphasis Type="Italic">In vitro</Emphasis> screening of sugarcane to evaluate smut susceptibility

Tissue-cultured plantlets of three sugarcane (Saccharum spp.) cultivars having a known field smut reaction were screened for susceptibility to Ustilago scitaminea H&P Sydow. Plantlets were inoculated with 0.5 l of a suspension of equally mixed quantities of plus and minus mating type sporidia of U. scitaminea at concentrations ranging from 1×10¹ to 1×10⁶ cells. Fungal sori (whips) were produced in cultivar N12 (intermediate) 6weeks following inoculation with 1×10⁵ mixed sporidia and thereafter in cultivar NCo310 (susceptible) but not in cultivar N19 (resistant). Sori bearing teliospores were produced up to 3months following inoculation and incubation at 26°C. No sori were produced at mixed sporidial concentrations lower than 1×10⁵cells. The in vitro soral production in cultivars N19, N12 and NCo310 was 0, 27.5 and 47.5% respectively. Plantlets inoculated with 1×105sporidia of only one mating-type did not produce sori in any of the three cultivars tested. Blind scoring of an unknown sugarcane cultivar by this method corresponded exactly with its field smut rating.     

The temperature-dependent duration of development and parasitism of three cereal aphid parasitoids, Aphidius ervi, A. rhopalosiphi, and Praon volucre

Temperature dependencies were established for the egg-to-mummy and mummy-to-adult phases, for mummy mortality, and for parasitism of Aphidius ervi Haliday, Aphidius rhopalosiphi De Stefani-Perez, and Praon volucre (Haliday) (Hymenoptera, Aphidiidae), three parasitoids of Sitobion avenae (Fabricius) (Homoptera, Aphididae), at 8°C, 12°C, 16°C, 20°C, and 25°C on winter wheat (cv. Haven). A physiological model described temperature-dependent development over the full temperature range, whereas a linear model was fitted for data above 8°C and used to estimate the lower temperature thresholds and day-degrees (° D) required for development. The thresholds for A. ervi were 2.2°C for egg-mummy development and 6.6°C for mummy-adult development, those for A. rhopalosiphi were 4.5°C and 7.2°C, and those for P. volucre were 3.8°C and 5.5°C. The time to develop into mummies and adults differed significantly between the three species: A. ervi development into mummies required an average of 159 ° D, while development into adults took an average of 73 ° D. The corresponding average times required for A. rhopalosiphi and P. volucre to develop mummies were 124° D and 126° D, while their development into adults required an average of 70° D and 150° D, respectively. Mummy mortality was 25–35% at 8°C and less at the higher temperatures tested, but began to increase again at 25°C, showing a quadratic relationship between mortality and temperature. Parasitization was very low or, in the case of P. volucre, absent up to 12°C and thereafter increased with increasing temperature. The relationship between parasitization, recorded as percent aphids mummified, and temperature was linear at the temperatures tested and depended on species. A. ervisuperparasitized 11.1% aphids at 20°C and 16.6% aphids at 25°C, whereas superparasitism was low in A. rhopalosiphi and absent in P. volucre. From 16°C to 25°C the P. volucre sex ratio increased. For A. ervi and A. rhopalosiphi there was no trend with temperature, but at 20°C and 25°C it was close to even. Field data for 1996 and 1997 allowed for a comparison of actual and expected emergence of overwintering mummies. In both years, parasitoids were predicted to have emerged from overwintering mummies well in advance of the onset of aphid infestation, and more than a month earlier than the first parasitized aphids were found in winter wheat. Observations from trap plants in other crops supported the predictions of the models. Other factors that can affect biological control by cereal aphid parasitoids are discussed.     

Growth,acetylene reduction activity and localization of nitrogenase in relation to vesicle formation in Frankia strains Cc1.17 and Cp1.2

A comparative study was conducted on the effect of NH₄Cl on growth, vesicle formation and formation of nitrogenase of Frankia strains Cc1.17 and Cp1.2, derived from root nodules of Colletia cruciata and Comptonia peregrina, respectively. On a medium without combined nitrogen (P-N), both strains formed spherical cells, called vesicles, like many other Frankia strains. Data are presented on the number of vesicles per mg protein, after cultivation in media with sodium propionate as C-source without combined nitrogen (P-N) or with 0.2 g NH₄Cl/l (P+N). Strain Cp1.2 as may other Frankia strains, showed on P+N medium a very strong reduction of vesicle formation of 99% relative to the number of vesicles formed on P-N medium, after 11 days growth. However, in strain Cc11.17 this reduction was only 70%. The occurence of relatively large numbers of vesicles in P+N media has not yet been reported for other Frankia strains. No acetylene reduction activity was found in NH ₄ ⁺ -grown cells. The regulation of induction of nitrogenase in Frankia by NH₄Cl was tested by immuno-gelectrophoresis using antisera against nitrogenase of Rhizobium leguminosarum PRE. The component I of the enzyme showed crossreactivity while the component II had only a weak crossreaction. The experiments indicated that no nitrogenase was detectable in the NH ₄ ⁺ -grown cells. For the localization of nitrogenase, relative amounts of the enzyme were compared in whole cells and vesicle-enriched fractions. Western blots showed a significant enrichment of nitrogenase in the vesicle fractions, which indicated that most of the nitrogenase was localized in the vesicle.     

Summer forage biomass and the importance of litterfall for a high-density sika deer population

The biomass of summer forage and their contributions were surveyed to show that litterfall supported a high-density population of sika deer (Cervus nippon Temminck) in summer on Nakanoshima Island, Toya Lake, Japan. In July 1974, the grassland had the highest productivity among understory vegetations (228±55kgha^–1: mean±SE). In deciduous forests, palatable plants occupied only 0.1% of the biomass of 0.872±0.366kgha^–1, and deciduous leaves within the reach of deer (=220cm at height) produced 0.208±0.070kgha^–1. However, litterfall during this period had the highest productivity, 28.7± 5.3kgha^–1. The deer consumed litterfall (75.6% in dry weight), short grasses (17.2%), deciduous forest understory (4.1%), deciduous leaves within the reach of deer (3.0%) and conifer plantation under story (0.1%). It is suggested that the high-density deer population would be maintained by litterfall through the year instead of browsing in deciduous forests, which has been overlooked.     

Competition between <Emphasis Type="Italic">Eucalyptus victrix</Emphasis> seedlings and grass species

Competition in a natural system may be interspecific or intraspecific. In semiarid ecosystems, competition for resources between established neighboring grass species and newly recruited seedlings is very high. To examine the effects of grass species density, growing space and time of establishment on Eucalyptus victrix seedlings (interspecific competition), and the effect of density and growing space within E.victrix (intraspecific competition) we conducted an experiment under controlled conditions. We tested four hypotheses (i) E.victrix seedling growth is not affected by grass density; (ii) there is no difference in E.victrix survival and growth between early and later grass establishment; (iii) interspecific competition is not more intense than intraspecific competition in E.victrix; and (iv) growth of E.victrix seedlings is not dependent on available growing space. In a monoculture of E.victrix, seedling mortality was higher (10%) in large pots. In mixed culture pots, where E.victrix seedlings and grass seedlings were planted on the same day, E.victrix seedlings survived for up to 4weeks, but started to die after week five in the smallest pots. However, mortalities occurred in pots of all sizes when grass was established before E.victrix seedlings. Results also indicated that the resources necessary for the growth of individual E.victrix seedlings were more limiting under conditions of increased density of neighboring grass species rather than intraspecific competition. In particular, photosynthetic area of E.victrix seedlings was drastically reduced in mixed cultures. Although density, pot size and time of planting had impacts on E.victrix seedlings, the patterns of these impacts were variable.