The selective advantage of host feminization: a case study of the green crab Carcinus maenas and the parasitic barnacle Sacculina carcini

Male crabs infected by parasitic barnacles (Rhizocephala) are known to be morphologically feminized. Here, we investigate morphological chances in green crabs, Carcinus maenas, induced by the parasitic barnacle Sacculina carcini. Infected males acquire a broader, longer and segmented abdomen, fringed with marginal setae. Copulatory appendages and pereopods are reduced in length, and the chelae become smaller. The feminization show great individual variation. Males with scars from lost externae, the parasites reproductive organ situated under the abdomen, are less modified than males carrying an externa, and the feminization is more pronounced in smaller than in larger males. No super-feminization is evident in female crabs that remain morphologically unaffected by infection. The protective value of a parasitically induced enlargement of the male abdomen may constitute an adaptation that increases parasite longevity. The additional effects on male morphology are viewed as pleiotropic side effects of the main adaptive value of enlarging the abdomen.     

江苏水源地型水库异味物质发生风险及影响因素

为认知水源地型水库异味发生风险及其规律,本研究于异味风险高危期(夏季),对江苏17个省级水源地型水库开展了水质、浮游生物和异味物质状况调查.结果表明,本次调查的17个水库普遍存在富营养化程度偏高(如藻类生物量偏大和水体透明度偏低)的问题,约三分之一的水库出现部分水层异味物质2-甲基异莰醇(MIB)浓度超标,MIB平均浓度为(13. 7±20. 7) ng·L-1,表明江苏省水库型水源地普遍存在MIB风险;多个水库检出土臭素(GSM),但其浓度均没有超过10ng·L-1的饮用水标准浓度(最大浓度为4. 6 ng·L-1);同步水质调查及统计分析表明,MIB浓度和水体叶绿素a浓度、水体透明度、悬浮颗粒物浓度、富营养化指数等重要水质指标及浮游植物生物量(特别是蓝藻生物量)相关性显著(P 0. 05),其中MIB与叶绿素a、富营养化指数呈极显著的相关关系(P 0. 01).因此,水源地型水库的异味物质风险与水库的富营养化密切相关;实施营养盐外源输入削减、提高流域植被覆盖度、科学调控渔业养殖规模等水体富营养化控制措施是水库异味物质控制的关键.     

Production and fate of copepod fecal pellets across the Southern Indian Ocean

The vertical distribution of copepods, fecal pellets and the fecal pellet production of copepods were measured at seven stations across the Southern Indian Ocean from productive areas off South Africa to oligotrophic waters off Northern Australia during October/November 2006. We quantified export of copepod fecal pellet from surface waters and how much was retained. Furthermore, the potential impact of Oncaea spp. and harpacticoid copepods on fecal pellets degradation was evaluated and found to be regional substantial. The highest copepod abundance and fecal pellet production was found in the western nutrient-rich stations close to South Africa and the lowest at the central oligotrophic stations. The in situ copepod fecal pellet production varied between 1 and 1,000 μg C m⁻³ day⁻¹. At all stations, the retention of fecal pellets in the upper 400 m of the water column was more than 99% and the vertical export of fecal pellets was low (<0.02 mg m⁻² day⁻¹).     

Ontic openness: An absolute necessity for all developmental processes

The physicist Walter M. Elsasser is mostly known for his work on the Earth's magnetism. Less attention has been paid to his efforts toward identifying what are the real differences between physical and biological systems. One essential distinction he recognized was that physical systems are largely homogenous while biological systems always revealed what he called ordered heterogeneity. Calculation of the possible configurations of such heterogeneous systems almost always leads to combinatorial explosions and to what Elsasser referred to as immense numbers. Such calculations have the consequence that any such systems are necessarily unique - mathematically speaking they represent one-sets.Another consequence is that immense numbers automatically introduce enormous uncertainty and indeterminacy into the system. Such systems are said to be ontically open. Applying this perspective to the genome and employing the notion of informational entropy reveals a common drive behind all development. This means that both conventional Darwinian evolution as well as the genomic mistakes that are believed to lie behind processes like aging and diseases can be interpreted against the background of one and the same process.At the same time the approach demonstrates how Darwinian evolution encompasses other notions such as Kauffman's “adjacent possible” ( [Kauffman, 1995] and [Kauffman, 2000]) and Eldrege's and Gould's “evolution via punctuated equilibria” (e.g., [Eldredge and Gould, 1972] and [Gould and Eldredge, 1977]).     

How to Consider the Value of Farm Animals in Breeding Goals. A Review of Current Status and Future Challenges

The objective of this paper is to outline challenges associated with the inclusion of welfare issues in breeding goals for farm animals and to review the currently available methodologies and discuss their potential advantages and limitations to address these challenges. The methodology for weighing production traits with respect to cost efficiency and market prices are well developed and implemented in animal breeding goals. However, these methods are inadequate in terms of assessing proper values of traits with social and ethical values such as animal welfare, because such values are unlikely to be readily available from the product prices and costs in the market. Defining breeding goals that take animal welfare and ethical concerns into account, therefore, requires new approaches. In this paper we suggest a framework and an approach for defining breeding goals, including animal welfare. The definition of breeding goals including values related to animal welfare requires a multidisciplinary approach with a combination of different methods such as profit equations, stated preference techniques, and selection index theory. In addition, a participatory approach involving different stakeholders such as breeding organizations, food authorities, farmers, and animal welfare organizations should be applied. We conclude that even though these methods provide the necessary tools for considering welfare issues in the breeding goal, the practical application of these methods is yet to be achieved.     

离子色谱法同时测定土壤中可溶性Na^、K^＋、Mg^2＋、Ca^2＋

应用离子色谱法（IC）同时测定土壤中可溶性Na^、K^＋、Mg^2＋、Ca^2＋。以CS12A阳离子交换柱分离,稀硫酸为淋洗液,电导检测器检测,对土壤中的Na^、K^＋、Mg^2＋、Ca^2＋进行同时测定。方法具有较宽的线性范围和较高的灵敏度。在0～40mg／L内呈良好的线性关系,土壤中Na^、K^＋、Mg^2＋、Ca...     

Growth of plankton algae as a function of N-concentration,measured by means of batch technique

Employing a special batch technique which involves extremely low concentrations of the alga Selenastrum capricornutum, it is shown that a growth rate of ca. 75% of optimum growth occurs at a concentration of 0.02 g-at N(NH₄ ⁺) l^-1. The low concentrations of this N-source in the oligotrophic parts of the oceans (ca. 0.06 g-at l^-1) thus give rise to a borderline deficiency. As the half-saturation constant (K _S) for growth was recorded at 0.05 g-at N(NO₃ ^-), this ion can hardly be of much importance at the low concentrations present in these parts of the oceans. It is wrong to assert that N is the primary limiting nutrient. Phosphate also is found at concentrations giving rise to a borderline deficiency.     

Annual population development and production by small copepods in Disko Bay,western Greenland

The population of small copepod species (approximately <1 mm) were investigated during an annual cycle in Disko Bay, western Greenland. The small species considered were Acartia longiremis, Pseudocalanus spp., Oithona spp., Oncaea spp., Microsetella spp., and Microcalanus spp. Most of the small species were present in the surface waters year round and numerically dominated the community, and in biomass from late summer and throughout winter. Oithona spp. was numerically the main contributor, while Pseudocalanus spp. dominated in terms of biomass. In the uppermost 50 m, maximum abundance, biomass and secondary production were observed in late September after the phytoplankton production practically had terminated and the winter initiated. The free spawning Acartia longiremis showed a strong seasonal fluctuation in biomass and egg production, in contrast to the egg carrying species Pseudocalanus spp. and Oithona spp. These had a long spawning season and maintained a more stable biomass year round. Secondary production was estimated by three different ways: (1) based on the obtained specific egg production rates, (2) a temperature dependent equation, and (3) a multilinear regression taking temperature, body weight and chlorophyll into consideration. The contribution of the small species was insignificant when compared to the large Calanus species during the spring- and post-bloom. However, during late summer and winter, where Calanus had left the upper water strata for hibernation, the small species played a crucial role in the pelagic carbon cycling.     

Improving the risk–risk trade-off method for use in safety project appraisal responses

Environmental Economics and Policy Studies - The risk–risk trade-off method is a technique used to elicit the relative trade-off between changes in morbidity and mortality risks in stated...