Effects of kelp Ecklonia maxima inclusion in formulated feed on the growth,feed utilisation and gut microbiota of South African abalone Haliotis midae

The effect of kelp Ecklonia maxima inclusion in formulated feeds on abalone growth and gut bacterial communities has not been previously investigated in South Africa. An eight-month on-farm growth trial was conducted with sub-adult Haliotis midae (～43 mm shell length) fed graded levels of kelp in formulated feeds. Kelp inclusion (0.44–3.54% of pellet dry mass) promoted faster growth (65.7–74.5% total mass gain), with better feed and protein conversions (apparent feed conversion ratio [FCR] 1.4–1.8, apparent protein efficiency ratio [PER] 2.3–2.7), as compared with the non-supplemented feed (52.3% total mass gain, FCR 2.1, PER 1.9; p < 0.001). Abalone-gut bacterial DNA was sequenced using 16S rRNA gene pyrosequencing and the sequences were clustered into operational taxonomic units (OTUs) at a 97% similarity level. A supplementary 16S rRNA gene denaturing gradient gel electrophoresis (DGGE) analysis was employed. The dominant OTUs differed in terms of their relative abundances, with an autochthonous Mycoplasma strain being significantly more abundant (p = 0.03) in the gut of abalone fed a kelp-supplemented feed. The DGGE band patterns displayed higher within-group variability for abalone fed the control diet, suggesting that dietary kelp inclusion promotes gut-bacteria homeostasis. This may contribute to better feed utilisation and growth in abalone fed kelp-supplemented feeds.     

Use of probiotic bacteria to improve growth and survivability of farmed New Zealand abalone (Haliotis iris)

The effects of two probiotic feeds containing two and three bacterial isolates were evaluated on the growth performance of New Zealand abalone (Haliotis iris). Probiotic bacteria were isolated from the guts of healthy adult abalone. The isolates were screened qualitatively and quantitatively according to their ability to hydrolyse nutrients (i.e. proteins, starch and alginate), produce acid and resist bile salts. Based on the screening results, we developed a multi-strain conglomerate of 2- and 3- probiotic bacterial strains that were supplemented into a commercial abalone feed to use in our experiments. The 2-probiotic conglomerate consisted of Exiguobacterium JHEb1 and Vibrio JH1, and the 3-probiotic conglomerate consisted of Exiguobacterium JHEb1, Vibrio JH1 and Enterococcus JHLDc. The probiotic feeding trial involved abalone juveniles (20–30 mm in maximum shell length). Both probiotic feeds significantly improved abalone growth compared to that of the unsupplemented feed. The 3-probiotic supplemented feed produced a significant shell length increase of 20.9%, a wet weight gain of 19.8% and a five-fold reduction in mortality compared to the controls. The 2-probiotic supplemented feed resulted in significant increases in shell length (15.4%) and reduced mortality (five-fold), but not in weight gain, compared to controls.     

The effect of low-level kelp supplementation on digestive enzyme activity levels in cultured abalone Haliotis midae fed formulated feeds

Previous studies have found that macroalgal inclusion in formulated diets for cultured abalone improves feed utilisation, and it was suggested that seaweed-associated bacteria supply enzymes that aid in the animal's digestion. In the present study, we hypothesised that kelp supplementation in formulated feed affects the profile of digestive enzymes in farmed Haliotis midae. Commercially reared sub-adult abalone fed a kelp-supplemented (Ecklonia maxima; 0.88% dry weight) or kelp-free control feed were collected for analysis of the amylase, alginate lyase, laminarinase, fucoidanase and protease activities in the gut. Levels of polysaccharidase and protease activity did not significantly differ between the diet treatments. However, enzyme-activity levels were more variable in abalone fed the kelp-free diet as compared with those fed the kelp-supplemented diet (coefficients of variation: 73%, 48.3–60.2% and 31.9% [control diet] versus 42.7%, 13.6–33.8% and 14.6% [KS diet] for amylase, macroalgal polysaccharidases and acid protease activity, respectively). We suggest that the presence of dietary kelp modulates the abalone's gut bacteria and their nutrient exchange. Proteomic identification of proteins in abalone gut sections showed that exogenous enzymes associated with the gut microbiome aid in bacterial utilisation of digested molecules, whereas abalone endogenous enzymes degrade the macronutrients in formulated feeds.     

Integrated culture of silver kob Argyrosomus inodorus and bloodworm Arenicola loveni loveni in abalone farm effluent

South African abalone Haliotis midae farms utilise large volumes of seawater (c. 500–1 500 l s^–1) and produce relatively dilute effluents that are potentially suitable for the integrated culture of other species. To test this hypothesis, a marine finfish, silver kob Argyrosomus inodorus, and a detritivorous polychaete, bloodworm Arenicola loveni loveni, were cultured in abalone farm effluent and the results compared to controls reared in unused seawater. The silver kob were fed a nutritionally complete pelleted diet whereas the bloodworm were placed in shallow tanks with a low water velocity that allowed suspended organic solids to settle for the detritivorous worms to feed on. Silver kob growth rate (0.48% body weight d^–1; SE = 0.01%), mortality (1.8 ± 0.5%), feed conversion ratio (3.0 ± 0.2) and protein efficiency ratio (1.0 ± 0.1) did not differ significantly between the effluent and control treatments. Bloodworm reared in abalone effluent grew well on the particulate organic waste matter in the effluent (0.39% body weight gain d^–1; SE = 0.07%), whereas those in the seawater control lost weight at 0.19 ± 0.04% body weight d^–1 over the experimental period. Bloodworm mortality did not differ significantly between effluent (6 ± 3%) and unused seawater (11 ± 8%) treatments. The faster growth of bloodworm in the abalone farm effluent was ascribed to the higher deposition rate of enriched organic solids (182 ± 56 g m^–2 d^–1) compared with those grown in the seawater control (46 ± 13 g m^–2 d^–1). It was concluded that abalone farm effluent is potentially suitable for the culture of both bloodworm and silver kob.     

杂色鲍种苗用试验配合饵料

随着鲍的人工育苗数量的不断增多,以及幼鲍从室内培养池移入海区的养殖阶段,直到成为种苗的规格(壳长1—1.5厘米),其饵料仍然是养殖成败的关键之一。福建南部海区杂色鲍(Haliotis diversicolor Reeve)的种苗培育阶段,正值夏季水温升高,采集天然海藻比较困难,鲍的饵料发生短缺;而且为了进一步弥补和提高鲍的饵料中所含蛋白质等营养成分,以提高幼鲍和种苗鲍存活率,加快生长速度,除积极开发利用天然海藻资源外,必须广开饵料新途径,因而研制种苗鲍用试验配合饵料,适当增加能促     

Evidence for a positive relationship between juvenile abalone Haliotis midae and the Sea urchin Parechinus angulosus in the South-Western Cape,South Africa

Previous field observations have suggested an association between the urchin Parechinus angulosus and juveniles of the abalone Haliotis midae. To test the generality and nature of this association, surveys were carried out at five sites between Cape Point and Danger Point in the kelp beds of the South-Western Cape, South Africa. These showed that both species occupy primarily hard substrata, showing preferences for encrusting coralline algae. They also confirmed a strong, positive relationship between urchins and juvenile abalone. Of the juvenile abalone sampled, more than 98% were found beneath sea urchins. All small (3–10 mm) and medium-sized(11–20 mm) juvenile abalone were under urchins, whether on flat or vertical reef, or in crevices. A small proportion (～10%) of larger juveniles(21–35 mm) was not found under urchins, and in these instances they occupied crevices instead. These findings are of particular importance in terms of their implications for the lucrative commercial abalone fishery in South Africa, indicating that urchins are of critical importance to the continued survival of viable abalone populations. There has been a dramatic decrease in natural populations of sea urchins over the past five years in the heart of the abalone fishing grounds, and the present findings suggest that this will lead to recruitment failure of abalone, because juvenile abalone seem dependent on the urchins. The long-term consequences for the industry may be crucial.     

Polydorid polychaetes (Spionidae) on farmed and wild abalone (Haliotis midae) in South Africa: an epidemiological survey

Although there has been an increase in our understanding of the shell-boring polydorids that infest abalone Haliotis midae in South Africa, abalone from a limited number of farms, and wild populations from east of Cape Agulhas only, have been examined. To gain further knowledge and a more complete understanding of the local distribution of polydorids, we examined up to 30 abalone from each of 14 farms in the Northern, Western and Eastern Cape provinces, and five wild sites in the Western Cape, west of Cape Agulhas. Farm and wild communities were significantly different from each other (ANOSIM, r = 0.632, p < 0.002) and Bray–Curtis cluster analysis showed that most farms clustered separately from wild sites. Boccardia proboscidea was present on all but one of the infested farms, whereas some were also infested by Dipolydora capensis. By contrast, D. capensis was present at all wild sites sampled, whereas B. proboscidea was absent from these sites. Polydora hoplura, a common shell-boring pest, was present at only two farms and two wild sites. There appeared to be some exchange of polydorids among farms and between farms and wild abalone. The farm on the East Coast did not cluster with any other sites, indicating a unique composition of polydorids on that coast. No new, potentially problematic, species was encountered, although four species showed an increase in their known distribution.     

海带雌性原生质体的分离与培养

于1993年1月 - 1993年4月，为了制备遗传性纯一的基因工程受体，用酶法从海带雌配子体单性生殖系分离雌性单倍体原生质体。从皱纹盘鲍消化腺及消化器官提取出鲍酶，在25°C下、1％（W／V）的鲍酶与2％（W／V）的纤维素酶（Onozuka R－10）合用能有效解离单细胞和原生质体。海带雌性原生质体经2d培养再生了细胞壁。     

Boulders or urchins? Selecting seeding sites for juvenile Haliotis midae along the Namaqualand coast of South Africa

The extent to which the relationship between juvenile abalone Haliotis midae and sea urchins Parechinus angulosus is induced by their physical habitat along the Namaqualand coast of South Africa was investigated. Correlation analyses between the proportion of abalone utilising sea urchins for refuge and the proportion of habitat defined as exposed were computed from 28 experimental seeding sites in Port Nolloth on the north-west coast of South Africa. A highly significant positive correlation was found (r = 0.72, p < 0.05). It was concluded that, along the Namaqualand coast, under-boulder habitat was the most important factor determining the survival of juvenile abalone (size 12–26mm). Site selection should therefore be based on the suitability of the physical substratum to provide shelter for juvenile abalone along that coast.     

粤东养殖区分离的2株海洋弧菌及其胞外产物对皱纹盘鲍致死毒性的初步分析

2011年秋,福建和广东地区养殖的皱纹盘鲍(Haliotis discus hannai)相继暴发死亡。同年12月,我们从广东汕头病区取样分离得到2株弧菌,其中bb3为溶藻弧菌(Vibrio alginolyticus), bb4为哈氏弧菌(V. harveyi)。本研究以bb3、bb4作为供试菌株对1龄皱纹盘鲍进行侵染实验,获得如下结果：20℃条件下,供试菌及其胞外产物粗提液注射处理均可致受试鲍死亡,浓度2.5×107 cfu/mL 的 bb3与2.0×107cfu/mL的bb4悬液注射可分别引发43.33%和78.02%的受试鲍死亡;供试菌株的致死毒性与注射弧菌的总量正相关,与受试幼鲍的壳长、全湿重负相关;注射或浸泡-创伤两种处理方式均可导致受试鲍死亡,并且因注射供试弧菌而死亡的幼鲍软体部组织被健康鲍取食后也可引发取食者死亡;从侵染实验死亡的受试鲍软体部组织中可重新分离得到这2种供试弧菌。上述结果表明,溶藻弧菌 bb3和哈氏弧菌bb4是皱纹盘鲍的病原菌。药敏试验表明, bb3、bb4均已对抗生素具有一定程度的耐药性,在测试的20种抗生素中,仅有头孢曲松和丁胺卡那霉素是这2株弧菌同时高度敏感的抗生素,但bb3和bb4却对8种抗生素同时表现出抗性。     

Comparison of assemblages and some life-history traits of seabirds in the Humboldt and Benguela systems

There are 21 and 15 species of seabirds that breed in the Humboldt and Benguela upwelling systems respectively. Only two species of gull are common to both systems, one as an endemic subspecies to the Benguela system. Eleven species and two subspecies are endemic (or nearly so) to the Humboldt system; seven species and one subspecies to the Benguela system. Each system has an endemic penguin, sulid, cormorant and tern that feed mainly on anchovy Engraulis spp., sardine Sardinops sagax or both these fish. The Peruvian pelican Pelecanus thagus also feeds primarily on these prey items. A plentiful availability of food has resulted in many of these seabirds attaining high levels of abundance. For the four pairs of species that feed on anchovy and sardine, those in the Humboldt system all have a biology that enables them to increase more rapidly than their Benguela counter-parts. This reflects the higher frequency of environmental perturbations that depress seabird populations in the Humboldt system. In addition, both systems have a small endemic cormorant that feeds near the coast and a small endemic tern that breeds in the adjacent mainland desert and feeds at the sea surface. Several seabirds endemic to a system have no obvious ecological equivalent in the other system: the pelican, a diving-petrel, four storm-petrels and a gull in the Humboldt system; a cormorant and a gull in the Benguela system. Some species with tropical or subantarctic affinities breed at the boundaries of the systems. Others breed also in freshwater systems. The grey gull Larus modestus, which feeds in the Humboldt system, breeds in montane deserts.     

南海岛礁羊鲍(Haliotis ovina)资源及其栖息地环境研究

鲍是重要的海珍品,羊鲍(Haliotisovina)是主要生活在热带岩岸潮间带大型经济鲍类底栖动物。为了研究南海岛礁羊鲍资源及其栖息环境,我们在宣德群岛的永兴岛和七连屿,永乐群岛的羚羊礁、甘泉岛和晋卿岛进行了羊鲍资源分布及其栖息水环境研究。按照《海岛调查技术规程》中潮间带岩岸大型底栖生物调查方法,对羊鲍进行取样调查。按照《海洋调查规范第4部分:海水化学要素调查》(GB T 12763.4-2007),对羊鲍栖息地水环境的总无机氮、活性磷酸盐、悬浮物和叶绿素a等海水化学要素进行分析。结果表明,羊鲍在永乐群岛和宣德群岛都有分布,这些岛礁按永兴岛、七连屿、羚羊礁、甘泉岛和晋卿岛的顺序,分布密度依次增加,个头大小依次增大,总体来说羊鲍资源量小,有的岛礁海区几乎绝迹,亟需开展生态增殖和资源养护研究工作。水质调查表明,除永兴岛站位的悬浮物指标因填海作业未达标外,各站位的水质指标均达一类水标准且具有一定稳定性。因此,尽管南海岛礁受人类活动的影响,但该海域仍适合羊鲍栖息,是羊鲍资源养护、底播生态增殖和生态养护的适宜场所,符合建立海洋保护区的国家水质标准和环境条件。     

A spatial- and age-structured assessment model to estimate the impact of illegal fishing and ecosystem change on the South African abalone Haliotis midae resource

The management of abalone stocks worldwide is complicated by factors such as illegal fishing combined with the difficulties of assessing a sedentary (but not immobile) resource that is often patchily distributed. The South African abalone Haliotis midae fishery is faced with an additional problem in the form of a relatively recent movement of rock lobsters Jasus lalandii into much of the range of the abalone. The lobsters have heavily reduced sea urchin Parechinus angulosus populations, thereby indirectly negatively impacting juvenile abalone which rely on the urchins for shelter. A model is developed for abalone that is an extension of more standard age-structured assessment models because it explicitly takes spatial effects into account, incorporates the ecosystem change effect described above and estimates the magnitude of substantial illegal (‘poached’) catches. The model is simultaneously fitted to catch per unit effort and Fishery-Independent Abalone Survey abundance data, as well as to several years of catch-at-age (cohort-sliced from catch-at-size) data for the various components of the fishery and different spatial strata. It constitutes the first quantitative approach applied to the management of this commercially valuable resource in South Africa and has provided a basis for management advice over recent years by projecting abundance trends under alternative future catch levels.     

不同饵料对两种帘蛤科贝类生长性能的影响研究

为探讨不同饵料对青蛤(Cyclina sinensis)与文蛤(Meretrix meretrix)生长和存活的影响,本实验选用紫菜(Pyropia)、浒苔(Enteromorpha prolifera)、海带(Laminaria japonica)、小球藻(Chlorella vulgaris)和人工配合饲料5种饵料,采用单一饵料投喂方式进行饲养.结果表明:小球藻组中特定生长率、存活率及饲料转换率与各饵料组均有显著性差异(P<0.05),青蛤的增质量率显著低于紫菜组、海带组及人工配合饲料组(P>0.05).在人工配合饲料组中青蛤与文蛤的特定生长率与各饵料组均有显著性差异(P<0.05),青蛤的增质量率与各饵料组无显著性差异(P>0.05),文蛤的增质量率显著高于紫菜组、浒苔组及人工配合饲料组(P<0.05).在3组大型藻中,海带组中青蛤的特定生长率为0.07％,增质量率为4.59％,饵料转换率为7.09％,存活率为74％;文蛤的特定生长率0.13％,增质量率为8.36％,饵料转换率为1.41％,存活率为55.6％.综上,小球藻和人工配合饲料有利于青蛤和文蛤的生长,在3组大型藻中,投喂海带有利于文蛤和青蛤的生长和存活.     

A decade of illegal fishing in Table Mountain National Park (2000–2009): trends in the illicit harvest of abalone Haliotis midae and West Coast rock lobster Jasus lalandii

Illegal fishing activities are reported to be on the increase in South Africa, including in its marine protected areas (MPAs). Research is presented on the nature and the scale of illegal fishing in Table Mountain National Park (TMNP) by analysing the numbers of abalone Haliotis midae and West Coast rock lobster Jasus lalandii confiscated from fishers operating in the park's marine protected area between 2000 and 2009. Data were collected from offence logbooks maintained by South African National Parks rangers and managers, the South African Police Services, and interviews with alleged or self-confessed illegal fishers. The research findings indicate that the annual numbers of illegally fished abalone and rock lobsters have increased significantly over time. Spatial analysis suggests that confiscations of abalone occur predominantly on the east coast of the park, whereas higher confiscations of illegally fished rock lobsters occur on the west coast. It is clear from this research that new and more efficient approaches will need to be designed and implemented to minimise illegal fishing in the TMNP MPA. Context-specific conservation targets that acknowledge and integrate social as well as developmental needs are required, and may be essential for limiting biodiversity loss in the longer term, which will ultimately ensure the success of fisheries management and conservation in TMNP.     

皱纹盘鲍(Haliotis discus hannai)肠道潜在益生菌的筛选及对幼鲍生长的影响

采用体外实验筛选益生菌结合16SrDNA序列分析法,从124株不具有溶血作用的皱纹盘鲍(Haliotis discus hannai)肠道细菌中筛选得到5株潜在益生菌并进行了分子鉴定,进一步对5株潜在益生菌进行了安全性实验及体内饲喂实验。结果表明,2株具有拮抗哈维弧菌和灿烂弧菌能力的潜在益生菌分别被鉴定为Shewanella sp.(WA64)和Shewanella sp.(WA65),一株产海藻酸酶和淀粉酶的潜在益生菌被鉴定为Vibrio sp.(WA51),产蛋白酶潜在益生菌被鉴定为Bacillus sp.(FA12),产琼脂酶潜在益生菌被鉴定为Tamlana sp.(FA86);安全性实验表明5株潜在益生菌在107cfu/ml下对皱纹盘鲍没有明显的毒害作用;通过体内饲喂实验发现,潜在益生菌WA64、WA65的复合作用能够显著提高幼鲍增重率和存活率(P<0.05),并在生产条件下能够明显降低幼鲍的死亡量。经抗生素敏感性实验,WA64菌株对15种抗生素均敏感或中度敏感,WA65菌株仅对庆大霉素和链霉素2种抗生素产生耐药。     

Population structure and growth of polydorid polychaetes that infest cultured abalone Haliotis midae

Polydorid polychaetes can infest cultured abalone thereby reducing productivity. In order to effectively control these pests, their reproductive biology must be understood. The population dynamics and reproduction of polydorids infesting abalone Haliotis midae from two farms in South Africa is described using a length-based, age-structured model. Shells were infested mainly by introduced Boccardia proboscidea. Polydora hoplura and Dipolydora capensis were also present but in numbers too few to identify factors influencing infestation. At both farms, B. proboscidea lived for a minimum of 12 months. Growth rate, size at maturity, maximum size, infestation intensity, recruitment, percentage of the population brooding and mortality appear to be affected by abalone feeding regime and water temperature, and these factors need to be considered in controlling infestation. Brooders and recruits were present throughout the year, but increased significantly during mid- to late winter/early spring when water temperature and day length increased. Treatment measures should therefore be implemented throughout the year but with increased effort when water temperature increases.     

开放海区水下悬浮延绳式PVC 管养鲍新技术研究

为拓展养殖空间,发展开放海区鲍养殖产业,在福建兴化湾新开发海区进行了抗风浪养鲍新技术的研究,对开放海区与传统遮蔽养殖海区、延绳式PVC管养技术与传统筏架式筐养技术进行了分析比较.结果表明,经19个月的养殖,开放海区PVC管养组鲍的日均增质量以及成活率分别为(106.41±5.33)mg/d和82.75％,显著大于处在开放海区和遮蔽海区的2个筐养组(P＜0.05).冬春季为鲍的最佳生长时期,其日均增长表现为PVC管养组大于筐养组(P＜0.05);开放海区大于传统遮蔽养殖海区(P＜0.05).养殖器具的污损生物附着量则表现为所有筐养组均显著大于PVC管养组(P＜0.05).夏秋季采用水下延绳式PVC管养模式还能有效地避免高温、污损生物和台风的侵袭与危害.     

Laboratory-scale evaluation of the potential of chemical containment for farmed abalone larval escapees

The sensitivity of abalone Haliotis midae larvae to low levels of toxicants was used to conduct a laboratoryscale experiment to determine the possibility of using chemical containment to prevent the escape of larvae from land-based culture systems, thereby reducing the environmental impact of farming operations. The cryoprotective agent, dimethyl sulphoxide or DMSO (Me₂SO), was used as a toxicant and embryos were exposed to increasing concentrations (0–25.60 mol l^–1) of DMSO for a period of 24 hours. Hatch-out rates of the control group (0.0% DMSO) did not differ from those obtained at 0.2% (2.56 mol l^–1) and 0.4% (5.12 mol l^–1) DMSO. An exposure level at and above 0.6% DMSO resulted in a significant decrease in the number of normal larvae. At an exposure concentration of 0.6% (7.68 mol l^–1) DMSO, 65% (SE 3.0) of the fertilised eggs hatched, compared to only 10% (SE 2.0) at a concentration of 1.0% (12.80 mol l^–1) DMSO. This study indicates the potential for use of DMSO as a form of chemical containment of abalone larvae, even at very low doses. It presents South African abalone farms with a chemical containment method that could potentially be used to prevent the unintentional escape of H. midae larvae from land-based operations.     

A review of the assessments of the major fisheries resources in South Africa

The waters off South Africa's coastline boast a rich mix of commercially fished species. Quantitative assessments of these marine resources have developed from simple methods first applied in the 1970s, to models that encompass a wide range of methodologies. The more valuable resources have undergone regular assessments in recent decades, with frequencies closely related to the management approach employed for each fishery. Many of these assessments form the operating models used to simulation-test candidate management procedures. This paper provides a comprehensive review of the assessments of 11 of the most important fisheries resources in South Africa. Some assessments use simple biomass dynamics models, whereas others are a hybrid of age- and length-based models, each designed to model the specific characteristics of the resource and fishery concerned. Many of the assessments have been disaggregated by species/stock and/or area as related multispecies/stock/ distribution hypotheses have arisen. This paper explores the similarities and differences in the data available and the methods applied. The review indicates that, whereas the status of three of these resources cannot be estimated reliably at present, the status of six resources is considered to be reasonable to good, whereas that of abalone Haliotis midae and West Coast rock lobster Jasus lalandii remains poor.