Parthenogenetic reproduction of Diaphanosoma celebensis (Crustacea: Cladocera): influence of salinity on feeding, survival, growth and neonate production

 Effect of salinity on the feeding rate and parthenogenetic reproduction of asexual females of the cladoceran Diaphanosoma celebensis Stingelin was studied. Short-term (10 h) grazing experiments were conducted using Isochrysis galbana as feed at 5, 17, 25 and 30 psu salinity. Gut pigment concentration showed a significantly higher rate of feeding at lower salinities. Survival, growth, maturity attainment and neonate production of asexual females reared in the above four test salinities indicated preference for lower salinities (5 and 17 psu). The mean size of adult females decreased from 909 to 593 μm, mean life span from 24 to 5 d, mean neonate production from 12 to 2 and mean size of neonates from 434 to 400 μm as the salinity increased from 5 to 30 psu. Salinity variations also affected the size and age of primiparous females. Resting egg formation and sexual reproduction did not occur at the tested salinities. The results indicate that D. celebensis is adapted to low saline, estuarine environments. Received: 14 January 2000 / Accepted: 24 March 2000     

Genetic differentiation in a pelagic crustacean (Meganyctiphanes norvegica: Euphausiacea) from the North East Atlantic and the Mediterranean Sea

Meganyctiphanes norvegica (M. Sars)is a pelagic crustacean that plays a key role in marine food webs of North Atlantic Ocean and marginal seas. We studied eight population samples collected in the European Atlantic and Mediterranean Sea. By means of single strand conformation polymorphism analysis (SSCP) and direct sequencing, we investigated a segment of 158 base pairs of the mitochondrial gene coding for the subunit 1 of NADH dehydrogenase. We found 12 sequence variants among the 385 individuals studied. Analysis of molecular variance (AMOVA) showed that 14.75% of the total genetic variability was explained by differences between populations, thus indicating absence of panmixia for these populations. Pairwise comparisons revealed three distinct genetic pools: the first one represented by Cadiz Bay, the second one by the Ligurian Sea, and the third one included all the NE Atlantic samples. We also investigated one population from the Alboran Sea (within the Mediterranean basin, east of the Strait of Gibraltar). This population was found to be genetically intermediate between the NE Atlantic samples and the Ligurian sample, suggesting that the restriction to the gene flow is not associated with the Strait of Gibraltar, but possibly with the Oran–Almeria oceanographic front. The present work indicates that M. norvegica, although endowed with a high dispersal capacity because of its pelagic habit, can develop separate breeding units inside the same oceanic basin (the Atlantic). Furthermore, the Ligurian sample should be considered as a distinct evolutionary entity, separated from the Atlantic population. Received: 2 May 1999 / Accepted: 26 November 1999     

Grazing rates of organic matter and living fungal biomass of decaying Spartina alterniflora by three species of salt-marsh invertebrates

 The pathway for the flow of salt-marsh grass production into marsh food-webs is still not well defined. We compared the abilities of three marsh macroinvertebrates [salt marsh periwinkles, Littoraria irrorata (Say) (=Littorina irrorata), salt-marsh coffee-bean snails, Melampus bidentatus (Say); and a talitrid amphipod, Uhlorchestia spartinophila Bounsfield and Heard] to access standing-dead leaves of smooth cordgrass (Spartina alterniflora Loisel). The invertebrates were incubated with naturally-decaying leaves, and the rates of removal of organic matter and living fungal biomass (ergosterol) were measured. The impact of invertebrate activity upon fungal growth rates was measured as rates of fungal-membrane synthesis (incorporation of radioacetate into ergosterol). The removal rates of organic leaf biomass per mg individual biomass were highest for amphipods (700 μg mg⁻¹ d⁻¹) and lowest for periwinkles (90 μg mg⁻¹ d⁻¹), but the relatively large biomass of the snails made their removal rates per individual greater than those of amphipods. Net removal of ergosterol by all three invertebrates was >50% for yellow-brown (early-decay) leaf blades. For fully-brown (advanced-decay) blades, >50% removal of ergosterol was found only for periwinkles; exposure to coffee-bean snails and amphipods resulted in a net ergosterol reduction of ≤20%. The lower net reduction of living fungal biomass by coffee-bean snails and amphipods may have been due to fungal-growth stimulation (2.3-fold stimulation in coffee-bean snails and 1.5-fold stimulation in amphipods). Grazing by periwinkles did not stimulate fungal growth, possibly because of its high intensity. Grazing by these three salt-marsh shredders may affect marsh-grass shoot-decay in different ways. Periwinkles may abbreviate the period of fungal production, and incorporate the decaying material relatively quickly into snail biomass and fecal-pellet rain to the sediments. Coffee-bean snails and amphipods may enhance and prolong fungal production, along with the formation of fecal-pellet rain. All three invertebrates fed preferentially on leaf blades rather than leaf sheaths, and feeding rates of gastropods were higher during the night than during the day. Received: 25 November 1998 / Accepted: 4 November 1999     

Metabolic differences between “demersal” and “pelagic” development of the Antarctic sea urchin Sterechinus neumayeri

 Early development of the Antarctic sea urchin Sterechinus neumayeri was examined under two differ-ent culture regimes: one to simulate development near-bottom (“demersal development”) and the other to simulate the development of embryos in the water column (“pelagic development”). When embryos of both treatments reached the hatching blastula stage at 5 d post-fertilization (−1.5 °C), the blastulae that had undergone demersal development evidenced significant differences (by ANOVA or suitable non-parametric comparison) in the following: a thicker blastoderm layer (12%, P < 0.001), higher ash-free dry weights (19%, P < 0.01), lower mass-specific respiration rates (50%, P < 0.001), higher incorporation rates of ³⁵S-methionine into protein (23%, P < 0.003), and a differential pattern of protein synthesis. When embryos developed demersally, they remained in the jelly-coat material released with the eggs at spawning. Quantitative isolation of this jelly-coat material in S. neumayeri demonstrated that it contained a significant amount of organic matter, 115 ng ash-free dry mass per egg, equivalent to 17% of the egg's initial organic mass. Uptake of external nutrients during embryogenesis may be a significant component of the physiological energetics of this polar invertebrate by allowing the utilization of jelly-coat material released by a female during spawning. Received: 21 April 1999 / Accepted: 5 June 2000     

Simultaneous hermaphroditism in the marine shrimp Lysmata wurdemanni (Caridea: Hippolytidae): an undescribed sexual system in the decapod Crustacea

Simultaneous hermaphroditism with outcrossing, a previously unconfirmed sexual system in decapod crustaceans, is documented in the shrimp Lysmata wurdemanni (Gibbes), using time-lapse video observations on mating in pairs of “female-phase” (FP) individuals. Copulations between FPs resulted in successful spawning and development of embryos. However, female-phase hermaphrodites maintained in isolation were unable to self-fertilize spawned eggs. All smaller individuals possessed characters typical of caridean males, including male gonopores, appendices masculinae, ejaculatory ducts, and cincinnuli on the first pleopods. However, the gonad of these male-phase (MP) individuals was an ovotestis with an undeveloped ovarian portion. FPs, which spawn eggs and incubate embryos, also had male gonopores and an ovotestis terminating in ejaculatory ducts containing sperm. In FPs, male pleopod characters were absent or reduced, and a female incubatory character, expanded pleopod flanges, showed a greater relative size. Smaller size classes of the population were composed only of MPs while larger size classes consisted of both MPs and FPs. “Transitionals,” individuals with MP characters but an ovotestis containing vitellogenic oocytes, were rare and overlapped completely in size with FP and larger MP individuals. It is suggested that not all MPs transform into FP hermaphrodites. Social interactions may mediate MP change into FP hermaphrodites in L. wurdemanni. The social system of L. wurdemanni and other Lysmata spp. may determine the exact form of the sexual system in these species. Received: 26 October 1997 / Accepted: 21 April 1998     

羊角月芽藻摄取磷形态的动力学研究

将湖水中的磷分成总溶解磷,溶解反应磷,总反应磷、溶解的水解性磷,溶解的光解性磷。研究其在羊角月芽过程中的变化。     

氯酚与富里酸的缔合作用

本文用超滤膜方法证实氯酚与富里酸之间存在缔合作用,并计算出表观缔合常数在２．７＊１０＾３－－１２１＊１０＾３ｍｌ．ｇ＾－１范围内。实验结果表明”ＰＨ、富里酸含量,氯酚取代氯原子个数都能够影响Ｋ值的大小。     

亚铵法制浆黑液作肥料对水环境影响的研究

通过亚铵法制浆蒸煮黑液直接作农肥施于水稻田的研究,给出了不同施肥方式连续数天田间水和渗滤水中黑液污染物变化情况,定量描述了黑液作肥料直接施于水稻田对水环境的影响。     

用废腈纶制备高分子增稠剂

以废腈纶为原料，经碱法水解反应和扩链反应制取乳液用高分子增稠剂。水解工艺条件为水解温度95℃，水解时间4h；水解配方为m(PAN)：m(NaOH)：m(H2O)=1：0．6：5；扩链反应温度95℃，扩链反应时间约4h。对不同乳液体系进行的增稠性能评价及应用表明，利用该技术制备出的高分子增稠剂性能优良，应用范围广泛。现已建成一套生产能力为1000t/a的工业装置。     

环境民事法律责任与环境损害赔偿

环境民事责任是环境法律责任的一种形式,是解决和处理环境损害赔偿中重要的法律依据。