Research on abalone (Haliotis midae L.) cultivation in South Africa

Although abalone fisheries in South Africa have existed since 1949, cultivation started by successful spawning of captured specimens in 1981 to produce spat and juveniles. Twelve abalone farms, with an estimated investment of US$12 million, have since been established on the coast of South Africa, with a projected production of 500–800 tons. While Haliotis midae could reach a maximum size of about 200 mm shell length at an age of over 30 years in the wild, farm production is concentrating on an average size of 100 mm after 5 years. Growth rates of 0.08–4.5% body weight day ^?1 for abalone of 10–17 mm shell length have been found under stimulated farming conditions on formulated diets, while the corresponding feed conversion ratio (FCR) was 0.9–2.4. Growth rate, FCR and protein efficiency ratio decline at water temperatures above 20 °C. Anaesthetics, for example magnesium sulphate, are used to prevent injury during removal from tanks. Prostrate diatoms, such as Cocconeis sublittoralis (Hendey), Amphora proteoides (Hustedt) and Achnanthes brevipes (Agardh) are preferred after the larval stage (5–7 days, depending on temperature) are finished. South Africa abalone growers prefer formulated feeds in pellet form, which is convenience and cost favourable to farm operations and management. Although fish meal has been found to be the most suitable protein source for inclusion in formulated diets, plant proteins such as soy bean meal, cottonseed meal and sunflower meal presented good growth and apparent protein digestibility. The parasite sabellid polychaete, Terebrasabella heterouncinata, recently named by Australian and American researchers, is indigenous to a variety of South African intertidal molluscs and impedes growth by causing irritation beneath the mantle in abalone. Prevention to some degree is possible by high standards of hygiene and husbandry of abalone in the tanks, but new techniques to control large infestations now include ultrasound. In spite of a reputation for toughness, abalone meat frozen immediately after shucking is tender relative to red meat. The success of abalone farming in South Africa has been as a result of a high degree of cooperation between the private sector and government‐backed research institutions, and it is anticipated that this collaboration will continue.     

新疆淡水藻类研究：乌鲁木齐南山八一林场绿藻初报

本文首镒报道乌鲁木齐南山八一林场山区的绿藻１１属，１２种，其中１０属，１０种为新疆新记录。这些结果是对１９９１年７月采集的２０号标本经鉴定后获得的。     

值得在华南地区推广应用的3种野生观赏樱属植物

通过对华南地区野生樱属植物进行深入的调查,从形态特征、生态习性、繁殖、观赏价值、园林应用等方面,介绍了钟花樱桃、尾叶樱桃和海南樱桃3种适合在华南地区推广应用的樱属植物。     

物理农业工程技术在南药发展中的应用现状

近年来，物理农业在我国北方地区受到重视，并在一些农业产业投入和运用，其技术价值和优点在生产过程已显示出来。随着物理农业工程技术在国际与国内市场的不断完善和发展，有可能成为我国第四代农业发展方向。以云南为例，分析当前南药发展现状，充分论述利用当地气候资源、地理优势及物理农业工程技术优势发展云南南药的必要性。并预测在发展过程中将要面临的各种困难，最后提出运用物理农业工程技术发展南药产业的建议。     

一次连续性暖区暴雨过程的诊断分析

利用常规气象观测资料和ERA5逐时再分析资料,对2019年4月18-19日华南地区出现的一次连续性暖区暴雨过程进行了诊断分析。结果表明：此次暴雨过程主要是受气旋性环流切变、西南低空急流影响而形成的暖区对流性强降水天气过程。500hPa副高呈带状分布,强度偏弱,位置偏南,气旋性环流自西向东影响了江南地区；华南地区地面呈东高西低的形势,广东始终处在地面低压前部偏南风的控制下；850hPa和700hPa受西南低空急流的影响,配合以风速或切变形成的低层辐合,高空200hPa对应强的辐散流场；华南至江南一带南低北高的地势,对地面偏南风或西南风起到了很好的抬升作用,这些因素共同作用,形成了这次连续性暖区暴雨过程。     

秦岭南麓新分布小太平鸟迁徙期食性初步观察

2011-2013年冬季,作者采用分组全天跟踪的方法,调查小太平鸟迁徙期活动特征和食性。结果证明:小太平鸟冬季由北向南成群迁徙过程中,会在某个生境优良的区域停留取食9~15日、成群活动在树冠上部。小太平鸟在迁徙期停留区域取食植物果实种类有20种,有人工栽培树种果实,也有野生树种果实。今后应持续迁移路线、停歇地、种群动态监测。     

Prevalence,molecular characterization and risk factor analysis of Ehrlichia canis and Anaplasma platys in domestic dogs from Paraguay

This is the first study to investigate the prevalence and risk factors associated with Ehrlichia canis and Anaplasma platys positivity in dogs from Paraguay. Conventional PCR assays for the E. canis 16SrRNA gene and A. platys p44 gene were carried out in blood samples from 384 dogs from Asunción city, Paraguay. Sequencing and phylogenetic analysis were performed in selected positive E. canis and (16SrRNA gene) and A. platys (16S and p44 genes) samples. The overall prevalence of E. canis and A. platys in dogs in Paraguay was 10.41% (40/384) and 10.67% (41/384), respectively. Older dogs without veterinary care had higher odds for E. canis positivity and a higher number of dogs in the same household, as well as absence of anti-tick treatment were considered risk factors for A. platys. Ehrlichia canis and A. platys circulate in the dog population from Asunción, and are described for the first time in Paraguay.