三个种群有尾和断尾丽斑麻蜥的选择体温、表面活动和摄食量

用2006年4-6月捕自长安(陕西)、共和(青海)、哈尔滨(黑龙江)三个地理隔离种群尾部完整的丽斑麻蜥(Eremias argus)成年雄体检测断尾对选择体温、表面活动(表面调温个体数)和摄食量的影响。各种群个体均分为实验和对照组,在距尾基部10 mm处切除实验组蜥蜴尾部,获得断尾个体。实验和对照组个体饲养在相同的实验室条件下收集相关数据,历时四周。表面活动的种群间差异是不同种群个体对其所处区域热环境长期适应的结果。断尾个体减少表面活动见于所有三个种群,表明尾自切能导致丽斑麻蜥活动水平的改变。同一种群断尾和有尾个体表面活动的时间格局无显著差异,不同种群表面活动的时间格局无显著差异,这些结果表明丽斑麻蜥白天活动节律具有种的特异性,不受断尾影响。丽斑麻蜥选择体温随纬度或海拔升高而降低,这种变化趋势可能是热环境制约的结果。所有三个种群断尾个体的选择体温均低于有尾个体,表明断尾可改变丽斑麻蜥的体温调定点。丽斑麻蜥摄食量存在种群间差异,长安种群蜥蜴的摄食量显著大于共和种群蜥蜴。三个种群断尾个体均未增加摄食以满足尾再生的额外能量需求,表明增加摄食不是该种蜥蜴补偿断尾能量代价的对     

Interactive effects of haloclines and food patches on the vertical distribution of 3 species of temperate invertebrate larvae

In laboratory experiments, we examined the effect of haloclines and determined whether the presence of food patches overrides this effect on larval vertical distribution of the sea star Asterias rubens, the sea urchin Strongylocentrotus droebachiensis and the mussel Mytilus edulis. We experimentally constructed haloclines in which the salinity of the bottom water layer was 35 and that of the top layer was 21, 24, 27, and 30 (21/35, 24/35, 27/35, and 30/35) for A. rubens and S. droebachiensis, and 24, 27, 30 and 32 (24/35, 27/35, 30/35, and 32/35) for M. edulis. For each species and stage, additional halocline treatments (A. rubens: 24/32 and 27/32; 4-arm S. droebachiensis: 21/29 and 24/32; 6-arm S. droebachiensis: 24/29 and 24/32; M. edulis: 27/32 and 30/32) were used to determine whether the larval response to inhibitory salinity gradients was due to the absolute salinity of the top layer or the relative salinity difference between the two layers. Also, we measured the density of A. rubens and M. edulis to determine whether the specific gravity of larvae can explain the observed vertical distributions. Larvae aggregated at and below the halocline and these aggregations were more pronounced with increasing strength of the vertical salinity gradient. Threshold salinities in the top layer which inhibited ~ 100% of the larvae from crossing the halocline were 24 for A. rubens and M. edulis, and 21 for S. droebachiensis. These distributional patterns were not the result of larval density, which was greater than all treatment water densities for M. edulis and S. droebachiensis and lower for A. rubens. The effect of the presence of a food patch at inhibitory haloclines (A. rubens: 24/35 and 27/35; 4-arm S. droebachiensis: 21/34 and 24/34; M. edulis: 27/35) was determined by using three algal densities: 0, 5000 or 10 000 cells ml^- 1Thalassiosira pseudonana in either the top or the bottom water layer. For both A. rubens and M. edulis, the number of larvae at the halocline increased in the presence of a food patch, but this effect did not depend on algal density in the patch. For 4-arm S. droebachiensis, there was no effect of the presence of a food patch on larval vertical distribution. Our results suggest that low salinity may act as a barrier to vertical movement and that the presence of food patches above the halocline may strengthen the larval aggregation response to inhibitory haloclines.     

Does food quality influence thermoregulatory behavior in the intertidal fish Girella laevifrons?

Algal and invertebrate species are less abundant towards higher zones of the intertidal, where the greatest variations in physical environmental conditions occur. Mobile predators such as fishes that inhabit high intertidal rockpools are thus exposed to wide variations in physical conditions and to a low abundance and quality of food. We used an aquarium with a temperature gradient in the laboratory to assesed whether dietary quality differences modify temperature preferences of Girella laevifrons, one of the most abundant transitory fishes inhabiting rocky shores along the coast of Chile. Our results indicate that food quality clearly modifies temperature preferences in this species. Animals fed on high quality bivalves selected intermediate temperatures (16–18°C) while those fed on lower quality algae selected lower temperatures (10–12°C). Control fish not subjected to the temperature gradient did not select portions of the aquarium differentially. The thermal selectivity of G. laevifrons in relation to the optimization of digestive processes and mechanisms of energy conservation are discussed.     

湖泊放流二龄河蟹的食性

在保安湖一围栏区（3.3hm^2）周年采样,共获得可供食性和的二龄河蟹362只（壳宽1.99-6.24cm）。胃含物分析表明,河蟹为杂食性,兼具肉食性倾向,以底层群落为食,食谱极为复杂,包括水生大型植物、藻类（47个属）、原生动物、轮虫、节肢动物、环节动物、动物、鱼类和颗粒碎屑,各大类食物的出现频率分别为87.3%、82％、0.3%、0.6%、48.2%、28.2%、0.3%、28.7%、88.7％。而不可分辨物在食物团中较为常见,出现频率达46.1%。植物性饵料（大型植物＋藻类）出现频率为87.7%,动物性饵料出现频率89.8%;食物团完全由动物性饵料组成的占5.8%,完全由大型植物组成的占5.3%,完全由藻类组成的占0.3%。T－检验表明二龄雌、雄蟹在食性方面不存在显著差异。细胞计数表明,胃含物中大型植物在数量上比藻类多2个数量级。作者最后讨论了在河蟹食性分析中的一些难点问题。     

Benthos as the basis for arctic lake food webs

Plankton have traditionally been viewed as the basis for limnetic food webs, with zooplankton acting as a gateway for energy passing between phytoplanktonic primary producers and fish. Often, benthic production has been considered to be important primarily in shallow systems or as a subsidy to planktonic food web pathways. Stable isotope food web analyses of two arctic lakes (NE14 and I minus) in the Toolik Lake region of Alaska indicate that benthos are the primary source of carbon for adults of all species of benthic and pelagic fish present. We found no effect of turbidity, which may suppress benthic algae by shading, on food web structure. Even though Secchi transparency varied from 10.2 m in NE14 to 0.55–2.6 m in I minus, food webs in both lakes were based upon benthos, had four trophic levels, and culminated with omnivorous lake trout. We suggest that the importance of benthos in the food webs of these lakes is due to their extreme oligotrophy, resulting in planktonic resources that are insufficient for the support of planktivorous consumers.     

The seasonal hippocampus of food-storing birds

Food storing is seasonal in birds like chickadees, nuthatches and jays, occurring at high levels in fall and winter and low levels in spring and summer. Memory for cache sites is hippocampus dependent in chickadees and both the recruitment of new neurons into the hippocampus and the total size of the hippocampus change seasonally. Unlike seasonal change in the vocal control nuclei of songbirds, however, change in the hippocampus appears not to be controlled by photoperiod. The annual timing of hippocampal neuronal recruitment and change in hippocampal size is quite variable, reaching maximum levels at different times of year in different studies. The amount of food-storing activity by chickadees is known to be influenced by flock dominance structure, energy balance, food availability, and other seasonally varying factors. The variable timing of seasonal change in the hippocampus may indicate that the hippocampus of food-storing birds changes annually in response to change in the intensity of food storing behaviour itself.     

The annual reproductive pattern of the Antarctic clam, <Emphasis Type="Italic">Laternula elliptica</Emphasis> from Marian Cove,King George Island

The annual reproductive cycle of the Antarctic soft-shelled clam, Laternula elliptica, in Marian Cove, King George Island was studied over a 2-year period from February 1998 to January 2000. Annual changes in the gametogenesis were investigated by measuring the percentage of area occupied by oocytes in a follicle [follicle index (FI)] and the oocyte size. In 1998, the monthly mean FI increased significantly from October to November, peaked in December, and decreased rapidly from December to January. In February and March 1999, degenerated eggs were observed in the spent follicles. Degeneration and resorption of residual eggs by phagocytosis occurred mostly in February and March in both 1998 and 1999, although the resorption process was observed year-round. The histology indicated that complete vitellogenic growth of L. ellpitica at Marian Cove takes at least a year and the clams spawn annually during the austral summer. The ripening and subsequent spawning of clams at Marian Cove in 1998 and 1999 coincided with the algal blooming (September–October 1998 and December and January 1999–2000) suggesting that in coastal Antarctica food supply is a crucial factor that governs gonad maturation and subsequent spawning along with the water temperature.     

Nitrogen-stable isotopic signatures of basal food items, primary consumers and omnivores in rivers with different levels of human impact

We examined how nitrogen-stable isotopic signatures of food web components (basal resources, primary and lower consumers, and omnivores) in rivers change with increasing levels of human population density (HPD) in their watersheds. Samples were collected from 22 rivers flowing in the Lake Biwa basin, Japan. Among three potential resources at the base of food webs (epilithon, benthic and suspended particulate organic matter), the mean isotopic values (δ¹⁵N) of the epilithon (4.5–7.8%) were consistently higher than those of other items (1.9–4.2%) and displayed the most pronounced elevation (by 3.3%) with increasing HPD. The mean δ¹⁵N values of the individual taxa of lower consumers (bivalve, snail and caddisfly) tended to increase with increasing HPD, although the pattern and the extent of the elevation were highly variable among the taxa. These results suggest a taxon-specific feature in the N source (or sources) of lower consumers. Our data suggested that human activities (e.g. nutrient loading) potentially induce changes in the N baselines of river food webs. The major N source of bivalves appeared to be shifted from suspended particulate organic matter to other items with increasing HPD. Trophic levels of goby fish (Rhinogobius sp. OR) and shrimp (Palaemon paucidens), being estimated to be at 2.4–3.8 and 2.1–3.4, respectively, did not differ significantly among rivers with different HPD levels. An erratum to this article can be found at     

Buffer requirements for enhanced hydrogen production in acidogenic digestion of food wastes

The requirements for pH buffer addition for hydrogen production and acidogenesis in batch acidogenic digestion of a food waste (FW) feedstock with limited alkalinity was studied at various initial pH conditions (6.0–8.0). The results showed that, without buffer addition, hydrogen production from this feedstock was insignificant regardless of the initial pH. With buffer addition, hydrogen production improved significantly if the initial pH was greater than 6.0. Substantial hydrogen production occurred when the pH at the end of the batch digestion was higher than 5.5. The maximum hydrogen production was found to be 120 mL/g VS added when the initial pH was 6.5 and buffer addition was in the range of 15–20 mmol/g VS. The effect of pH buffering on the formation of volatile fatty acids (acetic acid, propionic acid and butyric acid) was similar to its effect on hydrogen production. The results of this study clearly indicated shifts in the metabolic pathways with the pH of fermentation. The changes in metabolic pathways impacted upon the dosage of buffer that was required to achieve maximum hydrogen generation.     

Effect of ID ACE gene polymorphism on dietary composition and obesity-related anthropometric parameters in the Czech adult population

The aim of this study was to investigate the possible associations between insertion/deletion (ID) polymorphism in angiotensin-converting enzyme (ACE) (dbSNP rs 4646994) with the food intake and body composition in the Czech non-obese, obese and extremely obese populations. A total of 453 various-weighted individuals were enrolled in the study and were according to their BMI assigned into following subgroups, such as obese (30 ≤ BMI < 40), morbidly obese (BMI ≥40) and non-obese (20 < BMI < 30) subjects. Both the obese cases and the non-obese controls underwent the identical subset of standardized examinations (BMI, % body fat, waist-to-hip ratio, skin fold thickness, native dietary composition examined by 7-day food records, etc.). No significant case–control differences in genotype distributions or allelic frequencies were observed. There were no differences in genotype frequencies between males and females either. The prevalence of obesity was significantly higher among subjects with the II genotype (42 %) when compared with those with DD (36%) and those with ID (37%) genotypes (P = 0.04). When compared with carbohydrate intake in the whole studied cohort, the odds ratios of carrying the DD allele in the morbidly obese cohort were 0.84 (95% CI 0.34, 2.10, P = 0.17), 0.27 (0.07, 0.98, P = 0.02), and 4.25 (1.44, 12.51, P = 0.005) in those individuals consuming <210, 210–260, and >260 g of carbohydrates/day, respectively. Based on our findings, the ID ACE polymorphism could represent a gene modulator of carbohydrate intake in morbidly obese Czech population; the strong significant effect of DD genotype was observed in the phenotypes of extreme obesity with the highest carbohydrate intake.