A detailed 2,000-year late-Holocene pollen record from Lower Pahranagat Lake, southern Nevada, USA [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Preliminary analysis of 128 pollen samples and 7 radiocarbon dates from a 5-meter-long, 10-centimeter-diameter sediment core retrieved from Lower Pahranagat Lake (elevation 975 meters), Lincoln County, Nevada, gives us a rare, continuous record of vegetation change at 14-year intervals over the past 2,000 years.

Progress of modern aquaculture

The development of the aquaculture industry worldwide is discussed in detail with respect to activities conducted by various international organizations, considering in particular the leading role played by the FAO and its regional agencies. A brief examination is also made of the current situation regarding the industry in India and the potential for further development and improvement.

典型草原优势植物养分回收特性对养分和水分梯度变化的响应

养分回收是植物衰老时，养分从衰老组织向活的组织体转移的一种过程。该过程延长了养分在植物体内的滞留时间，提高了植物保持养分的能力，因此是植物适应养分贫瘠生境的策略之一。全球气候变化，包括降水格局改变和氮（N）沉降增加，改变了生态系统正常的生物地球化学循环，因此可能会对植物的养分回收特性产生影响。研究不同N、磷（P）、水梯度上，植物物种养分回收特性的响应格局，对于预测N沉降增加和降水格局改变对物种养分利用策略的潜在影响，具有一定的理论与实践意义。本研究以中国科学院植物研究所多伦恢复生态学实验站长期施N肥实验（0，1，2，4，8，16，32，64 g N m-2 yr-1等8个水平）为研究平台研究了克氏针茅（Stipa krylovii）群落中优势植物养分回收随N素添加梯度的变化，同时结合三个盆栽控制实验（施N肥实验：0，0.5，1，2，4，8，16，32，64，128 g N m-2等10个水平;施P肥实验：梯度同施N肥实验;控水实验：3600，4000，4500，5143，6000，7200，9000，12000，18000，36000 mL pot-1等10个水平），主要探讨了羊草（Leymus chinensis）养分回收效率（从衰老组织中回收转移的养分百分数，RE）和养分回收度（以枯叶中养分浓度衡量，RP）以及其它叶片养分特性(绿叶养分浓度和比叶面积SLA)对环境因子改变的响应格局。同时，我们还调查了枯叶C:N比和C:P比等参数，研究环境因子改变对凋落物分解的影响。 1）连续4年施N肥显著降低了五个物种叶片N素回收度（NRP），对P素回收度（PRP）的影响在各物种间差异较大，但低N提高了多数物种的PRP;物种间，冷蒿（Artemisia frigida）RP（枯叶N和P浓度分别为14.3±2.0 mg g-1和0.68±0.09 mg g-1）最低，砂韭（Allium bidentatum）（N：5.2±0.2 mg g-1，P：0.12±0.01 mg g-1）最高。沿施N梯度，N素回收效率（NRE）的变化趋势在物种间差异较小但在方法间（叶干重水平，叶面积水平和单株水平）差异较大，而P素回收效率（PRE）的变化在物种间和方法间差别都较大。叶干重水平和叶面积水平上，NRE在四个物种中表现出显著降低的趋势，PRE只在糙隐子草（Cleistogenes squarrosa）和星毛委陵菜（Potentilla acaulis）中显著降低，其它三个物种变化不显著。单株水平上，所有物种NRE（除了克氏针茅）和PRE均与施N量梯度无显著性关系。物种间，砂韭的RE最高（＞80.0%），冷蒿和星毛委陵菜最低（＜60.0%）。方法间，叶片水平上的RE均高于单株水平上。沿施N肥梯度，两个禾本科物种SLA无显著变化规律，而其它三个物种SLA表现出先增加后变化不大的趋势。物种间，最高和最低的SLA分别表现在冷蒿和克氏针茅。沿施N肥梯度，五个物种C:N比呈先显著降低后缓慢降低的趋势。物种间，最大和最小的C:N比分别出现在砂韭和冷蒿。 2）盆栽施N肥实验中，一定范围内，施N肥显著提高了羊草地上地下生物量、SLA和绿叶N浓度，显著降低了C:N比、NRP、NRE和PRE，但对绿叶P浓度、叶片PRP和C:P比无明显影响。平均枯叶N浓度和枯叶P浓度分别为16.2 mg g-1和1.01 mg g-1，平均NRE和PRE分别为46.1﹪和58.1﹪。10月时，地下生物量和养分积累均高于地上部分。 3）盆栽施P肥实验中，一定范围内，施P肥显著地提高了羊草地上地下生物量、SLA、绿叶N浓度和绿叶P浓度，显著降低了C:N比、C:P比、NRP、PRP和PRE，但对NRE无显著影响。平均枯叶N浓度和枯叶P浓度分别为9.9 mg g-1和7.43 mg g-1，平均NRE和PRE分别为58.2﹪，平均PRE为56.1﹪。10月时地下部分生物量和N库积累均高于地上部分，而P库在两个部分间差别不大。 4）盆栽控水实验中，一定范围内，供水量增加显著增加了羊草地上地下生物量、SLA、NRP、PRP、PRE、C:N比和C:P比，显著降低了绿叶N浓度，但对绿叶P浓度和NRE无显著性影响。平均枯叶N浓度和枯叶P浓度分别为10.4 mg g-1和0.32 mg g-1，平均NRE和PRE分别为54.4﹪和76.8﹪。10月时，地下部分生物量和养分积累均高于地上部分。 以上结果表明，N、P和水分因子的改变影响了植物生物量和养分分配、叶片养分特性、养分回收能力以及枯叶分解质量等，且不同梯度影响程度也不同。因此，未来全球变化包括N沉降增加和降水格局改变可能影响植物养分利用策略和凋落物分解特性，进而可能对植被-土壤系统养分循环产生影响。

Feeding trials of green seaweed Ulva fasciata

For the nutritional evaluation of green seaweed Ulva fasciata, a feeding trial was performed in albino rats. The results indicated that the 20% replacement of seaweed U. fasciata instead of carrot or lettuce in rad diet causes no harmful effects, as evident by a non-significant change in blood constituents and serum enzyme levels. The weight gain observed in rats with U. fasciata diet was same as that of control diet. The true digestibility ratio of U. fasciata was 80.20% with carrot and 83.4% with lettuce. The data suggest that the green seaweed U. fasciata could be used as an alternative dietary component in animal fodder.

Blackening of canned prawn and its prevention

The paper gives an account of the types of blackening associated with canned prawn in brine and their control. It was found that blackening caused by iron sulphide could be controlled by maintaining proper titratable acidity of fill brine in cans. The paper also elaborates on the factors responsible for or governing this critical titratable acidity. In regard to copper sulphide blackening, control was found to be difficult by maintaining the acidity or by additives such as EDTA when the copper content in the material went above the critical level.

Performance of paddy-cum-prawn culture in rainfed low land ecosystem of Sunderbans

Performance of both paddy (Var. NC 492) and prawn Penaeus monodon were assessed for two years during wet-season in rainfed lowland ecosystem with a view to study the economic viability of paddy-cum-prawn culture in the coastal saline zone of West Bengal. Both mono and dual culture of paddy and prawn were tried in the study. Fingerlings of prawn (α 35,000 haˉ¹) of 10-15 mm size were reared for about three and half months with and without fish feed. It was observed that addition of fish feed resulted in higher (57.7%) production of prawn (2.65 mg/haˉ¹) but not rice. Such increase in prawn production was 1.6 times higher when no feed was provided and 1.4 times higher when grown as sole crop. However, paddy, whether grown as mono or mixed culture, did not differ in yield significantly. In dual culture, the benefit - cost ratio was higher (6.83) when prawn was grown with feed and it was maximum (36.0) when grown without feed as sole crop. The study, therefore, indicates that paddy-cum-prawn culture under low land ecosystem of the coastal saline zone is enterprising particularly for small and marginal farmers who fear to take risk of growing prawn alone at the cost of paddy.

Comparative account of growth rate of body parts with total length in Rita pavimentata (Gunther)

The paper deals with sex-wise growth rate of different body parts in relation to total length in Rita paviinentata (Gunther). Growth rates calculated on pooled data by using the common regression coefficient 'b' reveals isometric and homogeneous nature in sexes.