Decomposition temperature sensitivity of isolated soil organic matter fractions

The general consensus is that a warming climate will result in the acceleration of soil organic matter (SOM) decomposition, thus acting as a potential positive feedback mechanism. However, the debate over the relative temperature sensitivity of labile versus recalcitrant SOM has not been fully resolved. We isolated acid hydrolysis residues to represent a recalcitrant pool of SOM and particulate organic matter (POM) to represent a labile pool of SOM, and incubated each at different temperatures to determine temperature sensitivity of decomposition. Short-term incubations of POM generated results consistent with published experiments (i.e., greater proportion of C respired and lower Q₁₀ than whole soil), while incubations of acid hydrolysis residues did not. The contrasting results illustrate the difficulty in assessing temperature sensitivity of labile versus stable SOM decomposition, partly because of the inability to quantitatively isolate labile versus stable SOM pools and to be sufficiently certain that respiration responses to temperature are not masked by processes such as enhanced stabilization or microbial inhibition/adaptation. Further study on the temperature sensitivity of decomposition of isolated SOM fractions is necessary to better explain and predict temperature responses of bulk SOM decomposition.     

Invertebrates increase the sensitivity of non-labile soil carbon to climate change

The fate of global soil carbon stores in response to predicted climate change is a ‘hotly’ debated topic. Considerable uncertainties remain as to the temperature sensitivity of non-labile soil organic matter (SOM) to decomposition. Currently, models assume that organic matter decomposition is solely controlled by the interaction between climatic conditions and soil mineral characteristics. Consequently, little attention has been paid to adaptive responses of soil decomposer organisms to climate change and their impacts on the turnover of long-standing terrestrial carbon reservoirs. Using a radiocarbon approach we found that warming increased soil invertebrate populations (Enchytraeid worms) leading to a greater turnover of older soil carbon pools. The implication of this finding is that until soil physiology and biology are meaningfully represented in ecosystem carbon models, predictions will underestimate soil carbon turnover.     

提高低温敏感型甘蓝型油菜雄性不育三系制种杂交率的途径

1990～1994年，以两个低温敏感型甘蓝型油菜细胞质雄性不育系为材料，探讨了提高制种杂交率的途径。结果表明：（1）在平丘区秋播制种条件下，不育系的不育度在70％以下，平均制种杂交率为62．0％，在自然生态条件下，难以筛选到秋播制种的适宜区域。（2）采用平丘区晚直播制种途径，不育系的不育度可提高到90％以上，但制种亲本个体发育不良，综合性状差，制种产量受影响。（3）高海拔区（2600～3200m）春播制种途径，其制种杂交率达93．0％以上，两年制种产量达到607．5～1939．5kg／hm2，平均1298．3kg／hm2，超过平丘区秋制水平。     

温度对鲫血液生化指标和消化酶的影响

采用室内模拟方法,研究了鲫(Carassius auratus)在9℃、16℃、25℃、30℃温度条件下的血液学指标和消化酶活力的变化。结果显示,鲫血清无机成分中的镁、磷在16℃时存在最大值,而其它成分变化不显著。在9～25℃水温范围内,甘油三脂、总胆固醇、总蛋白、白蛋白、球蛋白等均随水温上升而上升,并在25℃时达到最大值,而超过25℃后,甘油三脂、总胆固醇、总蛋白、白蛋白、球蛋白等含量均随水温升高而下降。在9～30℃水温范围内,血清中谷丙转氨酶和谷草转氨酶活性随水温上升先升高、后下降,在25℃时达到最大值。鲫肠道中,蛋白酶和脂肪酶活性在9～25℃阶段升高,25～30℃时下降,蛋白酶和脂肪酶的活性均在25℃时最高;而肝胰脏中蛋白酶和脂肪酶活性随温度变化不明显。     

黑鲪的标准代谢率及其与温度和体重的关系

在11.2~23.6℃ 之间的4个实验温度下,采用流水式呼吸仪测定了不同体重黑鲪(29.6～358.1g)的标准代谢率。结果表明,各测定温度下的标准代谢率均随体重增加而增大,二者之间的关系可用幂函数Rs = a lnWb描述,标准代谢率的组间均数差异显著,但b值却无显著性差异;修正为标准体重后的标准代谢率随温度升高而减速增大,二者之间的关系可用函数RＳＷ = m e－b/T描述,且当标准体重分别为48.6g、147.9g和243.1g 时,标准代谢率的组间均数也有显著差异;黑鲪的标准代谢率(Rs, mg/ｉｎｄ·h)和相对标准代谢率(Rs, mg/g·h)与体重和温度之间的交互作用数学模型分别为：Rs = 1.160 W0.752 e－9.494/T 和 Rs= 1.160 W－0.254 e －9.494/T 。     

半滑舌鳎hsd11b1l和hsd11b2基因的克隆及其温度响应的表达规律

皮质醇在鱼类应对外界环境压力的过程中起到重要调控作用,而hsd11b1l和hsd11b2具有调节体内皮质醇浓度的重要功能.本研究克隆了半滑舌鳎(Cynoglossus semilaevis)hsd11b1l和hsd11b2基因的cDNA全长序列,分析了其序列特征,研究了其时空表达特征及温度响应的表达规律.结果显示,hs...     

The effects of a temperature rise on oxygen consumption and energy budget in gilthead sea bream

The rates of daily average, minimum and maximum oxygen consumption, specific dynamic action (SDA), ingestion and digestibility in gilthead sea bream, Sparus auratus L., were measured before, during and after a gradual rise of water temperature from 20 to 28 °C at a rate of 1 °C day-1. The relationship between energy gain and the metabolic costs has also been investigated. Oxygen consumption of juvenile sea bream had a clear daily rhythmicity, with low levels during darkness and higher levels during the light period. Both light and feeding processes raised the metabolism of sea bream, but fish fasted for 2 days also showed an increase in oxygen consumption during the light period. Acclimation to 28 °C was complete for the minimum oxygen consumption rate in 12 days, but daily average and maximum oxygen consumption rates on the 19th day after the change were still 33% higher than at 20 °C mainly due to increased SDA. The digestibility of food components did not change significantly throughout the experiment. These relationships are discussed with respect to the potential for growth when fish are reared at 28 °C, although the energy costs are high.     

Salinity tolerance of cultured Eurasian perch, Perca fluviatilis L.: Effects on growth and on survival as a function of temperature

Eurasian perch is generally only considered to be a candidate for freshwater aquaculture even though wild populations are found in estuarine and brackish water habitats. Little knowledge exists on two issues a) the effect of temperature on the salinity tolerance of perch and b) the long-term effects of brackish water on their overall growth performance. The present study addresses these two questions.

Firstly, the effect of temperature (12, 15, 20 and 25°C) on perch survival of a salinity challenge at either 13 or 18‰ was determined. Survival was unaffected by 13‰ at the two lowest temperatures whereas higher temperature and higher salinities had a dramatic detrimental effect (at 25°C, 50% mortality was reach at 62h and 39h for 13‰ and 18‰, respectively). Secondly, we examined the effect of salinity on growth, which was assessed by measuring standard length and body weight at regular intervals for 130days. In addition, Specific growth rate (SGR), Fulton's condition factor (K) and food conversion ratio (FCR) were also calculated as was the effect of salinity on plasma osmolality, blood ion content (Na⁺, Cl⁻, K⁺) and muscle water content at the termination of the experiment. The optimum growth for this study was seen in the lowest salinities at 0 and 4‰. Surprisingly, even small increases in salinity were detrimental to perch growth. At 10‰, growth in terms of body weight was reduced by about 50% after 130days compared to perch reared in freshwater.

Interest in brackish water production of perch would be most likely served best by selecting a strain of perch that is adapted to saline conditions, as found in the lower Baltic region. Further studies are required to understand the potential for brackish water perch production.     

菲律宾蛤仔摄食率与温度、壳长和饵料浓度的关系

以等边金藻3011为饵料,采用室内流水法,在12、20和24℃3个温度和不同的壳长、饵料浓度下,测定并计算了温度、壳长和饵料浓度与菲律宾蛤仔摄食率的关系,并建立了相关数学模型。结果显示,在实验条件范围内,摄食率随着饵料浓度的增大而增大,且符合幂函数方程。摄食率可以用温度、壳长和饵料浓度的自然对数方程表示,其模型为：IR=21．2LnT＋20．06LnL＋7．10LnC-97．95,经协方差分析结果表明,其相关系数呈非常显著水平。     

极北海带对氮、磷吸收和砷、镉、铅吸附的研究

极北海带(Laminaria hyperborea)分布于大西洋东北海域,有很高的经济和生态价值,有望成为我国海藻资源增值的对象。本研究通过分析极北海带在不同温度下对N、P营养盐的吸收,以及对不同重金属离子的吸附,研究其对富营养化和重金属的去除能力。结果显示,1)温度为9℃~13℃时,极北海带对N、P的吸收率均最高,其中72 h后其对P的吸收率达到了95%~98%,对氨氮的吸收率为96%,对硝酸氮的吸收率约为42%,表明其对N、P有显著的去除作用。2)极北海带对As5+的富集量为168.33 mg/kg,藻体表面和内部As5+含量无显著差异,分别占藻体As5+总量的55%和45%,As5+处理6 d后极北海带的相对生长速率为–0.92%/d,极北海带生长不正常。极北海带对Cd2+的吸附量为15 mg/kg,且91%的Cd2+位于藻体表面,仅9%的Cd2+位于藻体内部,相对生长速率为5.78%/d,说明其对极北海带生长有抑制。极北海带对Pb2+的吸附量为320 mg/kg,其中96.5%的Pb2+被吸附于藻体表面,3.5%的Pb2+位于藻体内部,其相对生长速率为6.73%/d,表明Pb2+对极北海带的生长无显著影响。