桂南葡萄夏果成熟过程中的品质变化规律

[目的]探索桂南地区葡萄夏果成熟过程中果实品质变化规律,为桂南生产优质葡萄提供参考依据.[方法]以维多利亚、赤霞珠、雷司令和优株玫瑰4个品种为试材,在其果实转色前2周、转色开始(5％转色)、转色结束(100％转色)、采收前4个时期采样,测定其可溶性糖、可滴定酸、可溶性固形物、花色素含量、pH和糖酸比,分析4个品种夏果果实成熟过程中品质的变化规律.[结果]维多利亚、赤霞珠、雷司令、优株玫瑰夏果在成熟过程中果实的可溶性糖、可溶性固形物、果皮花色素含量、pH和糖酸比呈上升趋势,可滴定酸含量呈先上升后下降变化趋势.维多利亚和优株玫瑰夏果果实的可溶性糖和可溶性固形物含量在果实发育过程中最先迅速积累,随后花色素含量迅速增加,可滴定酸含量随之迅速降低,糖酸比迅速增加.[结论]鲜食葡萄品种维多利亚和优株玫瑰在生产上可通过枝梢修剪扩大其叶片光合作用面积,促进夏果糖分增加而生产出优质葡萄;酿酒葡萄品种赤霞珠和雷司令夏果品质在桂南地区表现较差,不适合用于酿制葡萄酒.     

松针提取物对广西麻鸡血液生化指标、抗氧化能力及免疫功能的影响

为研究松针提取物对广西麻鸡血液生化指标、抗氧化能力和免疫功能的影响,试验选取1日龄广西麻鸡1 600只作为试验动物进行120 d的饲养试验。试验鸡群随机分为2组,每组2个重复。在饲养过程中,对照组饲喂基础饲粮;试验组全程在基础饲粮中添加松针提取物。结果表明,试验组显著提高血清中谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)的活性、提高总抗氧化能力(T-AOC)和降低血清中丙二醛(MDA)的含量(P0.05);显著提高IgA、IgG、IgM、补体C3和补体C4的含量(P0.05);显著提高血清中钙、磷的含量,降低血清中胆固醇的含量(P0.05)。因此,松针提取物能够显著改善广西麻鸡的血液生化指标,提高广西麻鸡的抗氧化能力和免疫功能。     

基于问卷调查的广西北部湾居民对废弃土地的响应--以钦州市钦南区为例

采用问卷调查的方式,以钦州市钦南区为例,调查广西北部湾经济开发区荒废土地现状以及当地村民的反应。调查结果表明,在接受调查范围内有55%的村民有荒废土地;针对荒废土地的处理,45%的村民表示将荒废土地转让,33%的村民表示任其自由发展;面对被荒废的土地,28%的村民迫切想改变现状,41%的表示无能为力,31%的持无所谓态度。针对上述情况,分析了原因并提出了一定的措施,以期为当地的土地规划和利用提供参考。     

广西规模化猪场2种主要排污模式的指标测定

应用常规的化学分析技术,测定了广西地区具有代表性的2个规模化猪场不同污水处理阶段的污染物含量,并与国家排放标准进行比较,研究每个处理环节污染指数的变化,从而为畜牧养殖业节能减排采取针对性的整改措施提供参考。污染物指标包括:悬浮物(SS)、氨氮(NH3-N)、五日生化需氧量(BOD5)和化学耗氧量(CODcr)。结果表明,2个规模化猪场排出的污水经过一定的污水处理工艺后,猪场1排放的污水不达标,猪场2排放的污水达标;植物塘对污水有明显的净化作用;沉淀调节池和二沉池环节都能有效降低悬浮物(SS)的指标。     

广西稻田养鱼对农业资源利用效率的宏观影响

统计广西稻田养鱼主要分布的桂北、桂西北、桂东南三个区域中的8个长期开展稻田养鱼的县和11个基本未开展稻田养鱼的县在1995~2004年间与农业资源利用效率有关的数据。对比分析表明:在同区域和同季稻条件下,稻田养鱼县的稻谷单产量普遍高于非稻田养鱼县,而单位化肥、农药的用量仅处于同区域的中低水平;非稻田养鱼县取得较高的稻谷单产水平是使用了大量化肥、农药的结果;部分非稻田养鱼县使用了比同区域的稻田养鱼县更多的化肥、农药,但稻谷单产仍低于稻田养鱼县。结论:广西稻田养鱼提高农业资源利用效率的作用显著。     

辽东湾斑海豹线粒体苏氨酸和脯氨酸及控制区部分序列分析

通过PCR产物测序法,测定了46只辽东湾斑海豹线粒体DNA的一段包括部分苏氨酸和脯氨酸tRNA基因及部分控制区的717 bp序列,得到17个序列单元型。与港海豹相比,所有辽东湾斑海豹17个单元型在控制区序列中都有2处缺失,是区分港海豹和斑海豹的种间分子标记。与日本海和鄂霍次克海区斑海豹m tDNA相同片段进行比较研究,发现辽东湾斑海豹的线粒体控制区DNA的单元型比例相对较少,遗传多样性水平相对较低。辽东湾斑海豹m tDNA的16296位点即苏氨酸tRNA基因序列的最后一位有1个C碱基的插入,16607位点存在T/C转换,这两个变异位点是鉴别辽东湾斑海豹与日本及鄂霍次克海区斑海豹的重要分子标记。初步表明,辽东湾斑海豹与日本海、鄂霍次克海斑海豹是属于不同的地理种群,或者辽东湾斑海豹同这两个海区斑海豹未发生基因交流或者雌性个体的相互交流。     

自然环境变动对北部湾渔业资源的影响

根据1949~1985年广西渔获量、捕捞努力量,以及降雨、风速和盐度等统计资料,分析了自然环境的变动对广西渔获量年际变化的影响,由于捕捞努力量的难以转换性,采取以时间系列代替捕捞努力量的变动,并建立了渔获量对时间序列和环境变量的回归模型,以此来反映北部湾渔业资源的变动情况。分析结果表明,渔获量波动与时间序列显著相关,还与广东沿岸平均降雨量、北部湾沿岸平均降雨量、涠洲岛盐度以及香港季候风等环境因素显著相关。包含时间序列和环境变量的渔获量模型的回归系数为0·93,其置信水平达到99%以上。研究的结果说明,除捕捞因素外,环境因素的变动对北部湾渔业资源的波动有显著的影响。     

Bluefin tuna (Thunnus thynnus) distribution in relation to sea surface temperature fronts in the Gulf of Maine (1994–96)

Fishery‐linked aerial surveys for bluefin tuna (Thunnus thynnus) were conducted in the Gulf of Maine (GOM) from July through October, 1994–96. Each year, from 507 to 890 surface schools were detected and their locations examined in relation to oceanographic conditions. Correlations between bluefin tuna presence and environmental variables were explored for sea surface temperature (SST), distance to a SST front, frontal density (relative density of all SST fronts seen in a given 1 km area for 2 weeks prior to each tuna sighting), and bottom depth and slope. Mean SST associated with bluefin schools was 18.1°C (±2.8). Schools were located at a mean distance of 19.7 km (±19.6) from SST fronts, and in water masses with an average frontal density of 28.2 m km^?2 (±35.7). Mean bottom depth of detected schools was 139.0 m (±70.3), and mean bottom slope was 0.7% rise (±0.7). A binomial generalized linear model fit to these variables indicated that bluefin are seen closer to fronts than locations in which no tuna were seen. Using simple and partial Mantel tests, we investigated the spatial correlation between bluefin tuna presence and the environmental variables, controlling for spatial autocorrelation. For each day that schools were sighted, we performed 24 Mantel tests, on a combination of response and predictor variables. The spatial relationship between bluefin tuna and SST fronts was inconsistent. Our analysis identified significant spatial structure in the bluefin school locations that had no significant correlation with any of the measured environmental features, suggesting that other untested features, such as prey density, may be important predictors of bluefin distribution in the GOM.     

Drivers for spatial modelling of a critically endangered seabird on a dynamic ocean area: Balearic shearwaters are non-vegetarian

1. Spatial modelling is an important research tool to improve our knowledge about the distribution of wildlife in the ocean. Using different modelling techniques (MaxEnt and a generalized linear mixed model), a predictive habitat suitability model was developed for one of the most threatened seabirds in the world: the Balearic shearwater, Puffinus mauretanicus.
2. Models were developed using a 10-year dataset from the Gulf of Cádiz (on the south-western Iberian Peninsula), a key foraging area for Balearic shearwaters during migration and the non-breeding season.
3. Predictive habitat maps strongly matched the observed distribution patterns, pointing to bathymetric features as the main modelling drivers. The species was concentrated on shallow areas (up to approximately 100 m in depth) of the continental shelf, very close to the mouth of the Guadalquivir River. In contrast with previous studies, Balearic shearwater distribution in the highly dynamic Gulf of Cádiz was not correlated with areas of high chlorophyll a concentration.
4. This lack of spatial correlation probably arises from the delay between the phytoplankton bloom and the response of the zooplankton and small fish that are preyed upon by Balearic shearwaters, which may result in important displacements of this trophic chain across the Gulf of Cádiz.
5. The analysis presented contributes to a better understanding of the spatial distribution and ecology of the critically endangered top predator in the Gulf of Cádiz and offers important information to improve management plans.

     

Effects of fishing practice changes on pelagic shark longline captures in the Gulf of Gabes,Tunisia

1. In order to increase their catches, longliners targeting sharks in the Gulf of Gabes, Tunisia, have increased the number of hooks per basket and have included new bait types instead of mackerel (Scomber scombrus). This paper reports the effects of these changes on catch composition, catch rates, size distribution, life‐stage captures, and mortality at haulback.
2. Data from 48 and 96 longline sets, carried out during the shark fishing seasons of 2007 and 2008, with two hooks per basket, and 2016 and 2017, with five hooks per basket, respectively, were examined to assess the effect of gear change. Moreover, the effects of bait types were inspected based on 33 fishing sets using whole mackerel, 19 using salema (Sarpa salpa) halves, and 27 using pieces of stingray (Dasyatis spp.), sampled during 2016 and 2017.
3. The species composition indicated that longliners expand the vertical distribution of their hooks to operate from the surface to the bottom. The catches with both longline designs were dominated by sandbar shark (Carcharhinus plumbeus). Despite gear changes, the catch rate of C. plumbeus decreased by 42.21%, suggesting population decline. The size composition indicated a shift towards larger specimens, mainly adult females, which could jeopardize the shark population. Moreover, the mortality of the main species at haulback seems to be affected by the design of the longline.
4. The bait used, mainly pieces of stingray, significantly increased the catch rate of sandbar shark, which suggests a greater attractiveness of the new bait; however, fish size and mortality rates at haulback were unchanged in response to bait variation.
5. The fishery operates in shark nursery grounds, which exposes these fish (principally C. plumbeus) to considerable exploitation pressure. The new fishing practices intensified the pressure and thus the risk of a rapid depletion of populations. To preserve the shark species in the area, the use of new gear and attractive bait should be banned.