太平洋牡蛎同化率的研究

在室内实验条件下,研究了体重、饵料密度和质量对太平洋牡蛎同化率的影响.结果表明,太平洋牡蛎的滤水率、摄食率随个体的增大而增加,并且都符合幂函数模式:FR(IR)=aW^b.太平洋牡蛎同化率与其个体大小的关系不明显.饵料丰度和质量是影响太平洋牡蛎同化率的重要因素.随食物中有机物含量(POM/TPM)的增加,太平洋牡蛎的同化率也增加,随饵料密度的增加而降低.     

不同流速和饵料密度下食蚊鱼与唐鱼的摄食率比较

研究通过比较外来入侵物种食蚊鱼（Gambusia affinis）和土著濒危物种唐鱼（Tanichthys albonubes）在不同流速和饵料密度条件下的摄食特点来评价两者对溪流环境的适应能力。实验共设5 个流速梯度（0 bl/s,1.5 bl/s,3.5 bl/s,5.5 bl/s,7.5 bl/s）和3个饵料密度梯度（500 ind/L, 1 500 ind/L, 3 000 ind/L）。摄食一定时间后通过计数鱼体消化管内的丰年虫无节幼体个数来表示鱼的摄食率。实验结果表明,在不同流速和不同饵料密度下,唐鱼摄食率的变化幅度都小于食蚊鱼。食蚊鱼的摄食率显著受到水流速度和饵料密度以及两者交互作用的影响,表现为随着水流速度的上升而极显著地降低,而随着饵料密度的上升而极显著地升高。而唐鱼摄食率则随水流速度的增大而显著下降,但其摄食率不受饵料密度及其与水流两者交互作用的影响。     

放牧影响下羊草种群生殖生态学的研究

在种群水平上系统研究了放牧对松嫩草原关草种群无性繁殖、有性生殖和生物量的生殖分配的影响。结果表明,放牧制约了羊草种群无性繁殖和有性生殖的更新途径,表现在随放牧强度增加,无性繁殖体营养技密度、根茎牙密度和有性生殖体种子生物量、结实数和生殖枝分化率等指标均显著下降,是生牧后下降迅速。随放牧强度增加,关草种群根茎生物量的分配比例显著增加,而同化器官、非同化器官和种子生物量分配比例都显著下降,极牧阶段几科     

褶皱臂尾轮虫Brachionus plicatilis摄食小球藻Chlorella sp.的碳同化与碳排放

浮游动物在食物链能量流动与物质循环中发挥着重要作用,能将摄入的浮游植物转化为不同形态的碳,在海洋碳循环中发挥重要作用。应用¹⁴C标记示踪方法,定量分析海洋浮游动物褶皱臂尾轮虫Brachionus plicatilis摄入碳的碳同化与碳排放。喂食不同密度小球藻Chlorella sp.（1×10⁵个/mL、5×10⁵个/mL、1×10⁶个/mL）后,褶皱臂尾轮虫对小球藻碳的同化率（AE）为34%-51%,呈现随饵料密度增加而减小的趋势;未被轮虫同化的碳,主要以溶解有机碳（DOC）的形态排放到水体中,DOC占碳排放的比例为37%-51%,随着饵料密度增加而增加;二氧化碳（CO₂）的比例为15%-40%,随着饵料密度增加而减小;颗粒有机碳（POC）占碳排放的比例较少,为23%-34%,随着饵料密度的增加而增加。此外,分析褶皱臂尾轮虫排放DOC的粒径组成,发现低分子量有机碳（LMW,< 3 kDa）的量大于胶体有机碳（COC,3 kDa-0.22 μm）的量,COC占DOC比例为33%-43%;LMW占DOC比例为57%-67%。本研究结果表明,浮游动物可把相当部分食物中的碳转化为DOC,排放到水体中为细菌所利用,在海洋碳循环中发挥重要作用。     

二双斑唇瓢虫对矢尖蚧的捕食作用

研究了二双斑唇瓢虫（Chilocorus bijugus Mulsant)对矢尖蚧（Unaspis yanonensis Kuwana)的捕食作用,结果表明,瓢虫雌成虫对矢尖蚧各虫态的功能反应呈Holling II型,瓢虫对矢尖蚧的捕食效应随捕食者个体间干扰作用的增加而下降,捕食作用率（E）随着瓢虫数增加呈幂函数下降曲线,温度对瓢虫的捕食效应具有显著的影响,寻找效率（a)和处置时间（Th)与温度之间呈二次函数关系,猎物密度对瓢虫生殖力的影响呈Logistic曲线。     

人工红树林中黑口滨螺和黑线蜒螺分布的差异性

研究了福建九龙江河口不同林龄、不同红树种类的人工林中黑口滨螺（Littoraia elanostoma）和黑线蜒螺（Nerita lineata）的分布情况.结果表明,黑线蜒螺主要分布于秋茄林内,且其生物量随林龄增加而增加;桐花树林内黑口滨螺的生物量和密度均大于林龄相近的秋茄林,但个体大小则小于秋茄林.黑口滨螺的生物量在桐花树林内随林龄增加呈现先增加后减少的趋势,而在秋茄林内则随林龄增加而减少.这种差异性反映了人工红树林植物种类及其演替过程对腹足类动物分布的影响.     

幼虫密度对草地螟生长发育及繁殖的影响

为了明确幼虫密度对草地螟Loxostege sticticalis种群增长的影响, 对室内条件下（温度22±1℃, RH 70%±5%, 光周期16L∶ 8D）不同幼虫密度[1, 10, 20, 30和40头/瓶（650 mL）］饲养的草地螟生长发育及繁殖进行了研究。结果表明: 幼虫密度对草地螟幼虫体色、 发育历期和存活率, 以及蛹重和成虫生殖等有显著影响。随着幼虫密度的增加, 幼虫体色黑化程度呈增强趋势, 幼虫密度大于10头/瓶时的体色黑化值均显著大于幼虫密度为1头/瓶时的体色黑化值（P<0.05）。20头/瓶的幼虫和蛹历期最短, 且随幼虫密度的增加而显著延长（P<0.05）。幼虫存活率以10头/瓶最高, 其他幼虫密度的幼虫存活率显著较低（P<0.05）。蛹重以1头/瓶的最重, 并随幼虫密度增加而显著下降（P<0.05）。成虫产卵量和交配率分别以1和20头/瓶的幼虫密度最高, 幼虫密度升高则产卵量、 交配率逐渐降低。成虫产卵历期随着幼虫密度的增加逐渐缩短。雌、 雄蛾寿命分别以10和20头/瓶幼虫密度时最长, 幼虫密度过高时雌雄蛾寿命又显著缩短（P<0.05）。生命表分析表明, 幼虫密度对草地螟种群增长指数有显著影响, 以10头/瓶幼虫密度的种群增长指数最高, 幼虫密度过高或过低时种群增长指数下降。据此认为, 幼虫密度是影响草地螟种群增长的重要因子之一。     

水分和种植密度对干热河谷车桑子生长性状及种内相互关系的影响

水分是干热河谷植物生长过程中最主要的限制因子,种植密度增加也会引起植物生长的资源限制,两者交互作用下植物生长性状及种内关系的变化特征还不清楚。以干热河谷优势植物——车桑子为研究对象,根据元谋干热河谷年均生长季降雨量设置3种水分梯度：高水分、中水分和低水分,同时在各水分梯度下设置4个种植密度：1、2、4、9株/盆,探究水分、种植密度及其交互作用对车桑子生长性状、生物量分配及种内相互作用的影响。结果表明：（1）低水分条件下,车桑子生长和水分生理受到抑制,但车桑子在较低的叶水势下依然能够保持较高的相对含水量;（2）干旱胁迫显著降低了车桑子总生物量和单株生物量,显著增加了枯叶生物量比例,低水分和中水分条件下,增加种植密度对总生物无显著影响;而高水分条件下,增加种植密度显著提高了车桑子总生物量;（3）低水分显著增加了茎、叶生物量的异速生长指数,将更多生物量分配到叶,而种植密度增加显著降低了茎、叶生物量的异速生长指数,增加了茎的生物量分配;（4）通过相对邻体效应的计算,各处理条件下,车桑子种内关系均表现为竞争作用,并且,这种竞争作用的强度随水分的减少和密度的增加而增加。在高密度条件下（9棵/盆）,增加水分不会减轻种内竞争作用。综上,水分和种植密度均会对车桑子个体的生理生长产生影响,在植被恢复过程中,应考虑水分和种植密度对车桑子个体产生的资源限制作用。     

深澳湾太平洋牡蛎养殖容量研究

文章采用方建光模型,通过对广东省南澳县深澳湾养殖环境的水温、叶绿素a、初级生产力和非养殖滤食性动物生物量的调查,结合室内测定的不同规格壳长的太平洋牡蛎(Crassostrea gigas)的滤水率,并参照非养殖滤食性动物相应的滤水率,对深澳湾各月份不同规格太平洋牡蛎养殖容量进行估算。研究发现,深澳湾各规格的太平洋牡蛎最大养殖容量出现在1月份和2月份,最小养殖容量出现在5月份。各规格的太平洋牡蛎年平均养殖容量分别为:壳长3.5～5.0 cm的太平洋牡蛎年平均养殖容量为27 ind/m²,壳长5.5～7.0 cm的太平洋牡蛎年平均养殖容量为16 ind/m²,壳长7.5～9.0 cm的太平洋牡蛎年平均养殖容量为17 ind/m²,壳长9.5～11.0 cm的太平洋牡蛎年平均养殖容量为16 ind/m²。     

三个牡蛎群体遗传多样性的AFLP分析

采用AFLP技术对太平洋牡蛎(Crassostrea gigas)、近江牡蛎(Crassostrea rivularis)和褶牡蛎(Crassostrea plicatula)3个牡蛎群体共60个个体进行了遗传多样性分析。结果表明,14对引物共扩增得到662个位点,其中多态性位点619个,多态性位点比例为93.50%。太平洋牡蛎、近江牡蛎和褶牡蛎多态位点比例依次为73.26%、70.54%和75.08%,Nei氏基因多样性指数分别为0.256 9±0.197 7、0.226 1±0.195 2和0.268 3±0.194 1,Shannon信息指数分别为0.382 3±0.276 2、0.341 4±0.274 1和0.398 8±0.270 9。上述结果表明,3个牡蛎群体的遗传多样性水平褶牡蛎最丰富,太平洋牡蛎次之,近江牡蛎最小。基因分化系数Gst和基因流系数Nm表明这3个牡蛎群体之间存在一定的基因交流。UPGMA聚类分析表明,太平洋牡蛎和近江牡蛎先聚为一支,而后与褶牡蛎聚在一起。     

Sex differences in digestive traits in sexually size-dimorphic birds: Insights from an assimilation efficiency experiment on Black-tailed Godwit

Digestive assimilation efficiency is considered a trait with important implications for animal ecology. However, practically all studies have ignored the importance of sex differences in food assimilation efficiency (AE). Here, we investigated sex differences in dietary and physiological parameters in the Black-tailed Godwit Limosa limosa limosa feeding on rice seeds, a species with sexual dimorphism in body size and body mass. Gross daily food intake, gross energy intake, gross energy output and metabolizable energy intake did not vary significantly between sexes, but godwit females showed lower faeces energy density and higher AE than males. Mass-specific AE was similar in males and females, and the difference in AE could be attributed to the females' greater body mass. We suggest that a differential AE could play a role in explaining sex differences in habitat or micro-habitat selection during the non-breeding season in bird species with sexual dimorphism in size. Finally, we addressed the question about assimilation efficiency accuracy in models that estimate prey acquisitions by declining shorebirds as the Black-tailed Godwit.     

皱纹盘鲍的个体能量收支

对皱纹盘鲍的呼吸、摄食、生长及能量收支等实验研究表明, 鲍的耗氧率与壳长、体重、温度及昼夜变化有关, 耗氧率与壳长、体重均呈幂函数关系, 一天中16~4时(夜间)耗氧率高于4~16时(白天)且在18~20时达峰值.同温度下鲍日摄食率与体重呈幂指数关系, 日(相对)摄食率随温度升高而增加, 而日相对摄食率、日相对生长率均随壳长、体重增加呈下降趋势.鲍在14~20℃内对海带的总转化效率为53%.鲍软体部、海带及鲍粪便干品的比能值分别为19.2、8.57和7.23kJ·g^-1.14~20℃皱纹盘鲍摄入能量的34.6~48.6%为粪能, 22.0~38.2%的能量用于自身代谢, 5.6~28.2%用于贝体软体部的生长.     

皱纹盘鲍的个体能量收支

对皱纹盘鲍的呼吸、摄食、生长及能量收支等实验研究表明, 鲍的耗氧率与壳长、体重、温度及昼夜变化有关, 耗氧率与壳长、体重均呈幂函数关系, 一天中16~4时(夜间)耗氧率高于4~16时(白天)且在18~20时达峰值.同温度下鲍日摄食率与体重呈幂指数关系, 日(相对)摄食率随温度升高而增加, 而日相对摄食率、日相对生长率均随壳长、体重增加呈下降趋势.鲍在14~20℃内对海带的总转化效率为53%.鲍软体部、海带及鲍粪便干品的比能值分别为19.2、8.57和7.23kJ·g^-1.14~20℃皱纹盘鲍摄入能量的34.6~48.6%为粪能, 22.0~38.2%的能量用于自身代谢, 5.6~28.2%用于贝体软体部的生长.     

Die Wachstumskosten vonPorcellio scaber (Crustacea,Isopoda)

The assimilation of food inPorcellio scaber, considered over the entire life cycle, follows a two-phase function with a turning point at a body weight of about 3 mg. It is assumed that an important factor in this relationship is the efficiency of digestion, which should depend on the surface/volume ratio of the mid-gut and on the speed with which food is passed through the intestine. Calculation of these values reveals a size-dependent drop in efficiency of digestion roughly following the “surface rule”. The drop in efficiency of digestion may pose to the system a problem of information retrieval since inefficient digestion increases the “noise” level against which specific “signals” have to be selected — that is, specific molecules have to be absorbed and used in syntheses of cell constitutents. In order to offset decreasing efficiency of digestion, the system would have to increase redundancy, e. g. by assimilating progressively more food and thus, inevitably, increasing “cost” of some kind. The young larvae ofP. scaber, up to a body weight of 3 mg, do, in fact increase the amount of food assimilated in proportion to the calculated increase in redundancy. At about this critical size a switch in metabolism seems to take place, and weight specific assimilation of food decreases despite the continuously dropping efficiency of digestion. The actual use that the organism makes of the food ingested is represented by the ratio assimilation/cost of redundancy. Calculation of this ratio over the whole life cycle shows it to parallel neatly the curve for the monthly growth rate of the species.     

Influence of food density on respiration rate of two crustacean plankters,Daphnia galeata and Bosmina longirostris

Summary The influence of food density on respiration rate was measured for two cladoceran plankton species, Daphnia galeata and Bosmina longirostris, over the range 0 to 2.5 mg C 1^-1, using the modified Winkler technique in order to examine how this affects the respiration rate and whether the functional response is the same in the two species. The respiration rate for animals of equivalent body size did not differ significantly between the two species in the absence of food, but was significantly lower in Bosmina longirostris than Daphnia galeata at high food density. Within a species, the response of respiration rate to changing food density did not differ among individuals of different body size. The respiration rate of D. galeata increased with increasing food density and reached a plateau at a high food density. A similar response curve was also found with the respiration rate of B. longirostris, although the response was less conspicuous. This response curve cannot be explained by the energy cost of known feeding behavior in cladocerans. Since the respiration rate related linearly with the assimilation rate, increase in food density seemed to increase the respiration rate by increasing the energetic cost required to process food biochemically, known as specific dynamic action.     

Food limitation of population density in the orb-wed spider,Nephila clavata

Field studies were conducted to clarify whether variation in food availability among habitats influences population density, and whether population density has a negative effect on foraging success in the orb-web spider, Nephila clavata. Lifetime food consumption per individual (i.e., foraging success) strongly correlated with mean body size of adult females and mean fecundity in populations. Also, there was a positive correlation between foraging success and population density. Since foraging success reflected potential prey availability in the habitat, food resource appeared to be a limiting factor for populations in this spider. Mean fecundity per individual correlated with population density of the following year, suggesting that decreased reproduction is a major component of food limitation on population density. Consistent defferences in mean body size between particular sites were observed over years, while such difference was less obvious in density. Thus, ranking of food abundance among habitats seems to be predictable between years. A field experiment revealed that an artificial increase in population density had no negative effect on the feeding rate of individuals, suggesting that intraspecific competition for food is not important in this species.     

Responses of leaf stomatal density to water status and its relationship with photosynthesis in a grass

Responses of plant leaf stomatal conductance and photosynthesis to water deficit have been extensively reported; however, little is known concerning the relationships of stomatal density with regard to water status and gas exchange. The responses of stomatal density to leaf water status were determined, and correlation with specific leaf area (SLA) in a photosynthetic study of a perennial grass, Leymus chinensis, subjected to different soil moisture contents. Moderate water deficits had positive effects on stomatal number, but more severe deficits led to a reduction, described in a quadratic parabolic curve. The stomatal size obviously decreased with water deficit, and stomatal density was positively correlated with stomatal conductance (g(s)), net CO(2) assimilation rate (A(n)), and water use efficiency (WUE). A significantly negative correlation of SLA with stomatal density was also observed, suggesting that the balance between leaf area and its matter may be associated with the guard cell number. The present results indicate that high flexibilities in stomatal density and guard cell size will change in response to water status, and this process may be closely associated with photosynthesis and water use efficiency.     

Consumption and food utilization by individual larvae and the population of a wood borer Phymatodes maaki Kraatz (Coleoptera: Cerambycidae)

Summary The consumption and the utilization of food by the individuals and the population of a wood borer, Phymatodes maaki Kraatz feeding on the dead wood of a Japanese wild vine, Vitis coignetiae Pulliat were studied at Mt. Daibosatsu, Yamanashi Pref., central Honshu from 1974 to 1976.As for individuals of P. maaki, the estimates of the ratio of growth to consumption and that of assimilation to consumption were very low, amounting to 1.24 and 3.23% in dry weight, 1.23 and 3.12% in carbon weight, and 16 and 13.6% in nitrogen weight respectively. The ratio of growth to assimilation was estimated at 35% in dry weight, 39% in carbon weight and 118% in nitrogen weight. Dry body weight of the adult was correlated with the amount of consumption of the larva.The parasitism by two Ichneumonidae species seemed to be the main mortality factor of the population of P. maaki. A minimum estimate of mortality from egg stage till emergence was 75%.As for the bioeconomy of the population, waste consumption i.e. the consumption of individuals that died before emergence amounted to 75% of total consumption. The growth efficiency (biomass of adults/total consumption) was 0.24% in dry weight, 0.26% in carbon weight and 3.4% in nitrogen weight. The waste efficiency (waste consumption/biomass of adults) was 310 in dry weight, 285 in carbon weight and 22 in nitrogen weight. Approximately 18% of the dead wood of V. coignetiae was decomposed by the feeding of the population.The dry weight of an adult was inversely correlated with density of larvae in the dead wood from which it emerged, but not significantly correlated with the diameter of the wood. The ratio of adult emergence i.e. the survival rate was inversely correlated with density of larvae, but the mortality by parasitism was not density dependent. This seems to suggest that there was an intraspecific competition for the limited food.     

The effect of environmental stress on absolute and mass-specific scope for growth in Daphnia magna Strauss

Daphnids were reared for 2 weeks in different concentrations of food or cadmium, and growth and reproduction were measured as endpoints. At the end of the 14-day experimental period, scope for growth (SFG) was measured and expressed per individual (mJ/ind/h=absolute SFG) and per mg dry weight (mJ/mg/h=mass-specific SFG). Both food deprivation and cadmium stress decreased body size, and absolute SFG decreased with decreasing body size in both exposure scenarios. Also mass-specific SFG decreased with decreasing body size under cadmium exposure, but an increase in mass-specific SFG was observed in the food ration experiment. This suggested that cadmium stress, apart from decreasing energy assimilation, also disturbs energy metabolism. Changes in both absolute and mass-specific SFG were mainly determined by changes in energy uptake, whereas energy loss varied little in response to both environmental stressors. With the cadmium-stressed daphnids, reproduction correlated positively with both absolute and mass-specific SFG. With the food-stressed daphnids however, reproduction correlated positively with absolute SFG but negatively with mass-specific SFG. Mass-corrected SFG still decreased with increasing cadmium stress, but did not differ between ration groups. Thus, mass-corrected SFG provides an indication of metabolic functioning, but appears less suited as an indicator of reproduction.