The effects of light intensity and algae-induced turbidity on feeding behaviour of larval striped trumpeter

Striped trumpeter larvae reared in algal cell‐induced turbid water (greenwater) fed equally well in clearwater in a light intensity range of 1–10 μmol s^‐1 m^‐2, when evaluated in terms of both the proportion of larvae feeding and larval feeding intensity. An ontogenetic improvement in photopic visual sensitivity of larvae was indicated by improved feeding at 0·1 μmol s^‐1 m^‐2, from 26±5% of larvae feeding and 0·027±0·005 rotifers consumed per feeding larva min^‐1 on day 8, to 96±2% and 0·221±0·007 rotifers consumed larva^‐1 min^‐1 on day 23 post‐hatching. Algal cell‐induced turbidity was shown to reduce incident irradiance with depth, indicated by increasing coefficients of attenuation (1·4–33·1) with increasing cell densities (0–2×10⁶ cells ml^‐1), though light intensities in the feeding experiment test chambers, at the algal cell densities tested, were within the optimal range for feeding (1–10 μmol s^‐1 m^‐2). Algae‐induced turbidity had different effects on larval feeding response dependent upon the previous visual environment of the larvae. Young larvae (day 9 post‐hatching) reared in clearwater showed decreased feeding capabilities with increasing turbidity, from 98±1% feeding and 0·153±0·022 rotifers consumed larva^‐1 min^‐1 in clearwater to 61±10% feeding and 0·042±0·004 rotifers consumed larva^‐1 min^‐1 at 56 NTU, while older clearwater reared larvae fed well at all turbidities tested. Likewise, greenwater reared larvae had increased feeding capabilities in the highest algal cell densities tested (32 and 66 NTU) compared with those in low algal cell density (6 NTU), and clearwater (0·7 NTU) to which they were naïve.     

Diel and spatial drifting patterns of silver perch Bidyanus bidyanus eggs in an Australian lowland river

Densities of silver perch Bidyanus bidyanus eggs drifting in the Murray River, Australia, suggested a peak spawning time between 2100 and 0100 hours, and a propensity to drift in higher densities near shore and at the bottom of the water column. The results highlight the need to consider such spatial and temporal patterns when estimating species-specific drift abundances.     

Effects of river red gum, Eucalyptus camaldulensis, litter on golden perch, Macquaria ambigua

Aquaria with added river red gum, Eucalyptus camaldulensis , litter became hypoxic, with decreased pH and contained up to 30 mg 1⁻¹ tannin and lignin. Survival of golden perch, Macquaria ambigua , larvae in aquaria treated with a simulated annual litter density of 450 g m⁻² for 72 h was 14·9% for 15-day-old larvae and 0% for 8-day-old larvae. A litter density of 1223 g m⁻² resulted in total mortality for both age groups of larvae. Aeration increased survival of larvae to a minimum of 68·8% in 1223 g m⁻² litter treatments compared to 89·8% in aerated controls and 86·8% in non-aerated controls. A kinetic behavioural assay was used to detect alarm responses in golden perch larvae and juveniles exposed to leachates from river red gum bark, leaves and wood. Eight-day-old larvae exposed to bark and wood leachates (0·001–10 g 1⁻¹) exhibited an initial period of hyperactivity, followed by a concentration-dependent decrease in spontaneous activity. Larvae exposed to leaf leachates displayed only a decrease in spontaneous activity. Four-month-old juveniles exposed to wood leachates were also initially hyperactive, then progressively developed mild hypoactivity at increasing leachate concentrations. Juveniles exposed to wood leachates at 20g 1⁻¹ for 30min suffered 97·5% mortality in 96 h. Wood leachates induced dose-dependent lamellar fusion, epithelial dissociation and necrosis in the gills. The presence of toxic leachates and low oxygen availability in flooded river red gum forests may make these habitats unsuitable as nursery areas for native fish.     

Effects of two oil dispersants on phototaxis and swimming behaviour of barnacle larvae

The effects of two oil dispersants (Vecom B-1425 GL and Norchem OSD-570) mixed with diesel oil on the survival and behaviour of the stage II nauplii of the barnacle Balanus amphitrite were investigated. The24 and 48-hour LC₅₀ values for Vecom B-1425 GL:diesel mixture were 514 and 48 mg l₋₁ respectively, while respective values for Norchem OSD-570:diesel mixture were 505 and 71 mg l₋₁. Under sublethal concentrations, increased levels of the dispersant:diesel mixtures caused a reduction in phototactic responses. Balanus amphitrite nauplii failed to exhibit phototactic responses when exposed to Vecom B-1425GL:diesel mixtures of 400 mg l₋₁ and higher for 24 hours. A longer exposure time of 48 hours further reduced the Lowest Observable Effect Concentrations (LOECs) to 60 mg l₋₁. The LOECs for Norchem OSD-570:diesel mixtures under exposure periods of 24 and 48 hours were 400and 80 mgl₋₁ respectively. The curvilinear velocities (VCL) and straight-line velocities (VSL) of the stage II nauplii ranged from 0.7–1.1and 0.2-0.4 mms₋₁ respectively. Increased concentrations of dispersant:diesel mixtures caused a significant change in the curvilinear and straight-line velocities. Both oil dispersants, dispersant:diesel mixtures of 20 to 40 mgl₋₁ caused significant increases in VCL, but no significant change in VSL. Dispersant:diesel mixtures of 100 mg l₋₁ and higher resulted in a reduction in VSL for both dispersants. This revised version was published online in August 2006 with corrections to the Cover Date.     

Influence of light intensity and photoperiod on embryonic development,survival and growth of threatened catfish Ompok bimaculatus early larvae

Larval growth and survival of catfishes are largely influenced by the various biotic and abiotic factors. The present study investigated the effect of different light intensities and photoperiods on growth and survival of Ompok bimaculatus larvae. Three separate trials of 21 days each were carried out in an aquarium tank. The first trial investigated the embryonic changes (based on hatching rate and time) upon exposure to varied light intensity (0, 300, 500, 900 and 1200 lx) and photoperiodic regime (24l:0d, 16l:8d, 12l:12d, 8l:16d and 0l:24d). Subsequently, hatched-out larvae were subjected to the aforementioned intensities (Trial II) and photoperiod (Trial III, intensity of 300 lx) for growth and survival attributes. Eight hundred healthy larvae (average body weight = 0.003 g) were randomly distributed into five treatment groups for the last two trials. Results suggest a higher embryo hatching rate and larval survival at 0 and 300 lx, whereas the largest larval growth was observed at 900 lx. In Trial III, survival was highest in 0l:24d and growth in 24l:0d and 16l:8d was higher (P < 0.05). Performance index was higher (P < 0.05) in both 0 and 300 lx light and decreased at higher intensities. The overall interpretation from the present study concludes that a completely dark rearing environment is recommended for better survival of O. bimaculatus although growth was compromised.     

The effect of light intensity and spectrum on the incidence of first feeding by larval haddock

Under full–spectrum white light, feeding success of haddock Melanogrammus aeglefinus first feeding larvae, as measured both by proportion of larvae feeding and mean prey consumed, peaked at 1·7-18 μmol s^-1 m^-2. Feeding was significantly reduced at lower and higher intensities. A similar result was observed for larvae feeding under blue (470 nm) light, with significantly greater feeding success at intermediate light intensity (1·8 μmol s^-1 m^-2). When different light qualities were compared, larvae had significantly greater feeding success when exposed to blue (470 nm) light than either full-spectrum white or green (530 nm) light. Haddock larvae were capable of prey capture under all light treatments tested, indicating a necessary degree of adaptive flexibility in feeding response. The results are consistent with predisposition of haddock larvae to optimal feeding in a visual environment comparable with open ocean nursery grounds. Information on the impact of light on haddock first feeding can be incorporated into models of larval growth, survival, year-class strength and recruitment, and assist in developing husbandry protocols to maximize larval survival in aquaculture.     

Sublethal effects of angling and release on golden perch Macquaria ambigua: implications for reproduction and fish health

The present study tested the hypothesis of no delayed sublethal effects of mild angling and release on the feeding, growth, somatic condition and gonadal development of golden perch Macquaria ambigua during gametogenesis. Subsamples of adult M. ambigua (n = 17–21 of 207), originally captured from the wild and stocked into ten 0·1 ha earthen ponds, were angled and released during early and late gametogenesis. Wild samples that were concurrently collected throughout the experiment underwent rapid and synchronous gonadal development and many spawned. While no spawning occurred in the ponds, most M. ambigua underwent normal gonadal development to maturity, including the angled fish. Angled fish also fed, maintained condition and actually grew faster than non‐angled captive controls. Although females that were angled during late gametogenesis more readily ingested and retained baited hooks, neither their subsequent condition nor gonadal development was significantly affected. The predominance of null results was attributed to the combined effects of the flexible reproductive strategy of M. ambigua, the benignness of mouth hooking and immediate release, and possible methodological issues arising from differential hooking success of more aggressive and resilient individuals. The findings support earlier catch‐and‐release research, but contrast with reports of acute reproductive effects following capture and handling for aquaculture broodstock. This discrepancy highlights the need for research to specifically address welfare questions relevant to recreational fisheries across various species and angling scenarios.     

Effects of salinity on the growth and nutrient retention in silver perch, Bidyanus bidyanus (Mitchell 1838) (Teraponidae)

The silver perch, Bidyanus bidyanus, is a native Australian freshwater fish of the highest aquaculture potential. The species is known to tolerate a certain extent of salinity. Silver perch juveniles were fed a commercial diet (45% protein) and reared at salinities 0, 4, 8 and 12 in order to assess weight gain, specific growth rate (SGR), food conversion ratio (FCR) and nutrient retention at these four salinities. Fish reared at salinity 4 (P < 0.05) showed the best weight gain, SGR, FCR and a significantly better performance. Nitrogen and phosphorus retention were also significantly better in fish reared at salinity 4 (P < 0.05).     

光照强度对水鬼蕉(Hymenocallis littoralis)生长及生理生态特性的影响

研究了4个光照强度水平对水鬼蕉(Hymenocallis littoralis (Jacq.) Salisb.)在土壤和碎石基质人工湿地中生长的影响.4个光处理平均光照强度(μmol m-2 s-1)是:701(全光照,光强I)、495(全光照的71.4%,光强Ⅱ)、304(全光照的44.7%,光强Ⅲ)、141(全光照的20.2%,光强Ⅳ).研究表明,在较弱光强(III、IV)下,水鬼蕉的株高、叶生物量、叶片长度、叶绿素含量通常显著高于较高光强(I、II)下的植物.较低光强植株的生物量通常高于较高光强的植株,但差异一般不显著.光合作用和根生物量虽以全光照的植株较高,但不同光强之间差异不显著.可见,水鬼蕉具有一定的耐阴性,适度的荫蔽(全光照的约50%)有利于其生长.水鬼蕉在土壤和碎石基质对光照强度的反应不完全相同.在相同的光照强度下,生长于碎石基质的水鬼蕉的测定指标(除叶绿素含量外)通常都显著高于生长于土壤基质的植物.水鬼蕉100 cm左右的高度、较慢的生长速度、在碎石基质适度遮荫有利于生长等特点使其适合用于构建多种植物人工湿地群落的中下层植物,是一种在污水处理人工湿地有较好应用潜力的植物.     

Effects of temperature, photoperiod, and light intensity on the calling rhythm in Arctiid moths

Mean times of onset for calling in Haploa clymene (Brown), Spilosoma virginica (Fabricius), Pareuchaetes insulata (Walker), Cycnia tenera (Hübner), and Euchaetes egle (Drury) advance to earlier times in the photoperiod at lower temperatures. Temperature has no apparent effect on the calling period in Pyrrharctia isabella (J. E. Smith), Spilosoma congrua Walker, and Apantesis nais (Drury). The relationship between the temperatures experienced by each of these species as adults and the response of their calling rhythms to temperature is discussed. Lights-on can elicit calling behaviour in C. tenera, although it is not an absolute requirement because calling eventually begins when lights-on is delayed 4 h and calling also begins prior to lights-on at lower temperatures. Calling periods lengthen in C. tenera and S. congrua when the scotophase is prolonged and in S. congrua after the onset of a lower photophase light intensity (40 lux), suggesting that a higher photophase light intensity (450 lux) inhibits calling and thus causes its termination.

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Résumé Aux faibles températures le moment moyen de déclenchement de l'appel apparaît plus tôt au cours de la photopériode chez Haploa clymene Brown, Spilosoma virginica Fab., Pareuchaetes insulata Walk., Cycnia tenera Hübn. et Euchaetes egle Drury. La température n'a apparemment pas d'effet sur le moment où l'appel débute chez Pyrrharctica isabella J.E. Smith, S. congrua Walk. et Apantesis nais Drury.L'analyse porte sur les relations entre les températures subies par les adultes de ces espèces et leurs réactions d'appel aux différentes températures. L'apparition de la lumière peut induire le comportement d'appel chez C. tenera, bien que ce ne soit pas indispensable puisqu'il peut éventuellement commencer à des températures plus basses avant l'illumination quand celle-ci est retardée de 4 heures. Les périodes d'appel sont prolongées avec la scotophase chez C. tenera et S. congrua, et même après l'apparition d'une photophase à faible intensité lumineuse (40 lux), l'appel de S. congrua se poursuit, ce qui suggère que les photophases à intensité lumineuse plus élevée (450 lux) inhibent l'appel et ainsi en provoquent la fin.

     

光强度对大草蛉成虫感光性和趋光性行为的影响

运用视网膜电位（electroretinogram, ERG）技术和行为学方法研究了大草蛉Chrysopa pallens Ramber成虫的光强度反应。结果显示: （1）白光（Log I= 4.5~0.0）可引发2 h暗适应的大草蛉复眼的电位反应。随光强增强其ERG值呈近线性增大, 最强时未出现高端平台, 表明该光强范围内其感光性基本一致, 且可感受更强的光; （2）一定光强度（Log I= 4.0）以上的白光可引发大草蛉较明显的趋光性行为, 该行为具有光强域值特征和较明显的光强度依赖性。弱光时（Log I=4.5）无趋光性行为, 随光强增大趋光性反应率增大, 光较弱（Log I= 4.5~1.5）时增大缓慢, 较强（Log I=1.5~0.0）时迅速增大, 至最强（Log I=0.0）时最大（37.1%）, 呈一近“J”型式样。避光行为无或很低, 且无规律, 最大值仅为4.5%。这些结果表明: 光强度是大草蛉感光性与趋光性行为的重要决定因素, 强光时感光性电位反应与趋光性行为反应基本一致, 弱光时则不同, 暗示了光强度信息在感光性和趋光性间作用的有条件性和复杂性。     

Influence of larval feeding history on the body condition of Amphiprion melanopus

The cellular condition of liver hepatocytes and the height of gut epithelium cells of larval Amphiprion melanopus were sensitive indicators of feeding condition. Muscle fibres of the trunk showed marked separation in fish fed every third day just prior to settlement. Low feeding regimes also caused reductions in growth, increases in larval duration and reductions in size at metamorphosis. Gut epithelium cell height was also influenced by fish standard length and age. This study suggests that gut epithelium cell height is a useful index for an examination of the importance of starvation of larvae in tropical waters; however, size and age standardization is required prior to comparisons of wild caught fish through time or with laboratory samples.     

Schooling behaviour and retinomotor response of juvenile Pacific bluefin tuna Thunnus orientalis under different light intensities

Schooling behaviour and histological retinal light adaptation in juvenile Pacific bluefin tuna Thunnus orientalis were examined under various light intensities to determine the effect of light intensity on behaviour. After monitoring the schooling behaviour of juveniles 35–36 and 45–46 days post hatching, schooling variables such as nearest neighbour distance and separation swimming index were measured under different light intensities. Furthermore, retinal indices of light adaptation were investigated histologically for each experimental light intensity. Under intensities >5 lx, schooling variables in the two juvenile growth stages were nearly constant, allowing schooling. In contrast, the schooling variables indicated that the fish gradually swam more widely and randomly with decreasing light intensities <5 lx. The retinal indices also showed a shift from light adaptation to dark adaptation at light levels <5 lx. From 5 to 0·01 lx, retinal adaptation and fish schooling behaviour changed with light intensity. These data suggest that the schooling behaviour of juvenile Pacific bluefin tuna is greatly affected by retinal adaptation.     

Effect of light intensity on broiler behaviour and diurnal rhythms

Light intensity manipulation is an important management tool affecting broiler behaviour and physiology but still there is a debate regarding the optimum level to be used in confinement barns. Two experiments were completed to study the impact of light intensity (1, 10, 20 and 40 lx) on behaviour and diurnal rhythms of broilers raised to 35 d of age. For each experiment, 950 Ross × Ross 308 chicks were housed per room with replication of individual light intensity treatment in two environmentally controlled rooms. Within each large room, a small pen with 25 male and 25 female chicks was used for recording behaviour. Data were analyzed as a randomized complete block design with experiment acting as a block. All chicks were provided with 40 lx intensity and 23 h light until shifting to treatment light intensity and 17 h daylength at 7 d of age. For each replicate, behaviour was recorded for a 24 h period, starting at 16 or 17 d of age. At 23 d of age, three birds per room were bled at the start, middle and end of light and dark periods for melatonin estimation using RIA. When summarized over the 24 and 17 h observation periods, birds exposed to a light intensity of 1 lx rested more (P = 0.01) and preened (P < 0.05) and foraged (P < 0.05) less in comparison to other light intensities. Birds from all treatments exhibited diurnal rhythms for feeding, resting, drinking, walking, standing, foraging and preening behaviours with little or no activity during the 7 h dark phase. The serum melatonin levels at the start, middle and end of light and dark phases were unaffected by light intensity (P > 0.1). In conclusion, light intensity ranges from 1 to 40 lx did not affect melatonin levels or behavioural diurnal rhythms, but birds exposed to a light intensity of 1 lx rested more and preened less, potentially indicating a reduced welfare state.     

光强对烟草幼苗形态和生理指标的影响

通过白纱布遮荫模拟不同光生境条件(透光率分别为100%、68.2%、35.4%和16.7%),研究了光强因子对烟草幼苗形态和生理指标的影响.结果表明:随相对光强的减弱,幼苗高度增加,茎粗、干鲜比、叶片厚度和单位叶面积质量均呈降低趋势,幼苗干物质积累减少,但其对叶数的影响不大.弱光条件下,叶片自由水、叶绿素、总氮和蛋白质含量增加,束缚水含量降低,叶绿素a/b值减小,转化酶活性降低;烟草幼苗根系相对不发达,根冠比和根生物量减小,根系活力降低.表明弱光条件不利于培育烟草壮苗,生产中应尽可能改善苗床的光照条件.     

光照强度对曼陀罗和紫花曼陀罗生长发育的影响

以曼陀罗(Datura stramonium)及其变种紫花曼陀罗(Datura stramonium var. tatual)为研究材料, 采用光照培养箱对盆栽苗进行5个光照强度的处理, 研究其生长发育、叶片解剖结构、叶片及茎色素含量对不同光照强度的响应。结果表明: (1)在试验设置的光照强度范围内, 增强光照强度有利于曼陀罗和紫花曼陀罗的发育及茎、叶生物量的积累; 13 000和18 000 lx两个光照强度下两供试曼陀罗长势最好; 同等光照强度下紫花曼陀罗的株高、基茎粗、叶片数目、茎叶生物量大于曼陀罗, 但差异性不显著。(2)两供试曼陀罗叶片厚度、栅栏组织厚度、海绵组织厚度及气孔密度、气孔指数均随着试验光照强度的增强而增加; 紫花曼陀罗气孔密度及气孔指数明显高于曼陀罗。(3)两供试曼陀罗叶片中叶绿素含量均随试验设置光照强度的增强呈先升后降的趋势; 随试验设置光照强度的增强, 两供试曼陀罗茎中叶绿素a、b及类胡萝卜素含量变化趋势不一致; 茎中花色素苷、类黄酮及总酚含量的变化情况是: 两供试曼陀罗均与光照强度呈正相关, 但紫花曼陀罗比曼陀罗含量高, 这也是紫花曼陀罗花、茎等器官呈紫色的物质基础, 加上气孔密度和气孔指数较大等特性, 使紫花曼陀罗较曼陀罗适应性更强。     

光照强度与光周期对虎斑乌贼胚胎发育的影响

为探究光照对虎斑乌贼受精卵孵化的影响,确定其胚胎发育的最佳光照条件,本研究采用单因子试验方法,分析了不同光照强度(10、30、50、70、90 μmol·m^-2·s^-1)和光周期L∶D(24 h∶0 h、18 h∶6 h、12 h∶12 h、6 h∶18 h、0 h∶24 h)对虎斑乌贼胚胎发育的影响.结果表明: 不同光照强度对虎斑乌贼胚胎发育的孵化率、卵黄囊断裂率、培育周期、初孵幼体体质量与胴长均影响显著;而对孵化周期和幼体出膜7 d后存活率无显著影响.其中孵化率、培育周期、初孵幼体体质量与胴长随着光照强度的增强先增大后减小,而卵黄囊断裂率则逐渐增大.最适光照强度为30 μmol·m^-2·s^-1,此光照强度下孵化率为(90.0±4.1)%,卵黄囊断裂率为(7.3±1.5)%,培育周期为(25.50±0.35) d,孵化周期为(8.10±0.89) d,初孵幼体体质量为(0.213±0.011) g,胴长为(1.013±0.022) cm,出膜7 d后存活率为(97.1±4.0)%.不同光周期对虎斑乌贼胚胎发育的孵化率、培育周期、孵化周期均影响显著,而对卵黄囊断裂率、初孵幼体体质量、胴长和幼体出膜7 d后存活率无显著影响.其中孵化率和孵化周期随着光照时间的增加呈现先增大后减小的变化.最适光周期为LD(12 h12 h),此光周期下孵化率达(88.7±1.8)%,卵黄囊断裂率为(8.7±1.8)%,培育周期为(25.00±0.50) d,孵化周期为(7.00±3.20) d,初孵幼体体质量为(0.209±0.005) g,胴长为(0.998±0.026) cm,出膜7 d后存活率为(96.8±7.1)%.说明弱光照强度30 μmol·m^-2·s^-1和半日光照强度L∶D(12 h∶12 h)更有利于虎斑乌贼的胚胎孵化.在实际生产中,应避免阳光直射,采取适当的遮光措施.     

The effect of light intensity on the drift of young-of-the-year cyprinid fishes

Density, but not body size, of drifting young-of-the-year cyprinid fishes was negatively correlated with light intensity. As an ability to resist the water current develops gradually with size, the results support the view that drift in cyprinid fishes is a behavioural decision, triggered by light level, rather than passive displacement of visually disoriented fishes.     

Influence of photoreactivating light intensity and incubation temperature on photoreactivation of Escherichia coli following LP and MP UV disinfection

Aims:  To investigate the effects of fluorescent light intensity, sunlight intensity and temperature on photoreactivation of Escherichia coli after low-pressure (LP) and medium-pressure (MP) ultraviolet (UV) disinfection.
Methods and Results:  Two E. coli strains were irradiated with LP and MP UV lamps, and exposed to various fluorescent light (0–23 kLux) and sunlight intensities (1–80 kLux), and temperatures (4–50°C). Escherichia coli concentrations were enumerated at hourly intervals to determine photoreactivation rates and final photoreactivation levels. Higher photoreactivation rates and levels were observed with increasing fluorescent light intensities, while high sunlight intensity (>12 kLux) caused a one-log decrease in E. coli concentrations. When exposed to near-optimum growth temperatures (23–37°C), photoreactivation levels were higher than those with too high (50°C) or too low (4°C) temperatures. Overall, photoreactivation following MP UV disinfection was lower than that following LP UV disinfection.
Conclusions:  Photoreactivation of bacteria following UV disinfection can be a problem in tropical countries where sunlight is abundant and temperatures are high, unless high sunlight intensity is present or if MP UV disinfection is employed.
Significance and Impact of the Study:  With the increased use of UV disinfection, it is imperative that photoreactivation be taken into account in the design of reactors based on site-specific conditions of temperature and light intensity exposure.     

Effects of water level and light intensity on capsule production dynamics of Sphagnum capillifolium

 选取尖叶泥炭藓(Sphagnum capillifolium)为试验材料, 在模拟水位与光强条件下, 对人工构建的苔藓植物群落进行室内培养, 每隔1-3天观察并记录植株高度、孢蒴变化过程及变化时间, 分析了不同水位与光强条件对孢蒴生产的植物功能属性动态的影响。水位上升促进了蒴柄伸长及植株高增长, 增加了孢蒴开裂率及遮蔽率。光强增加有助于孢蒴生长, 并提高了孢蒴开裂率。在孢蒴直径以及植株高增长性状上, 水位与光强存在交互作用。水位与光强对孢蒴增长率均没有影响。此外, 水位升高与光强增加使孢蒴成熟及蒴柄伸长时间提前, 总体上使孢子释放时间分别提前了4.0 d和4.8 d, 由此可能减小了孢子体因受夏季干旱影响而败育的风险。孢子释放后, 繁殖株高增长加速, 可为未来的再次繁殖奠定基础。