Kelp forests in False Bay: urchins vs macroalgae in South Africa’s southwest coast biogeographical transition zone     

《African Journal of Marine Science》2013,35(4):395-406

Kelp forests along South Africa's southwest coast occur in a region of biogeographical overlap. Commonly referred to as transition-zone kelp forests, these dynamic ecosystems are particularly susceptible to grazing from species such as urchins. This study explores relationships between urchins and macroalgae in transition-zone kelp forests along the western side of False Bay. Six kelp forests in this region were sampled. At each site, the urchin Parechinus angulosus and kelp Ecklonia maxima were counted, percentage cover of understorey algae was recorded, and drift algae were collected. Despite variability in urchin and algal cover across sites, kelps generally increased from north to south, while urchins did the opposite. Urchins were negatively associated with macroalgae, although this relationship was weak. A localised threshold of 50 urchins m^–2 was identified, above which kelp density failed to increase above 10 m^–2 and percentage cover of understorey algae usually remained below 20%. Surprisingly, no relationship was discovered between drift algae and attached algae. The findings highlight the complexity of these cool-water environments. To better understand the role of urchins in this system, particularly under changing climate trends, experimental research into the feeding behaviour and possible effects of urchins on attached algae in the presence/absence of drift algae is advised.  相似文献   

Molecular evidence for three separate cryptic introductions of the red seaweed Asparagopsis (Bonnemaisoniales,Rhodophyta) in South Africa     

《African Journal of Marine Science》2013,35(2):263-271

The red seaweed genus Asparagopsis Montagne (Bonnemaisoniales) contains two widely introduced species that are considered notorious seaweed invaders worldwide, Asparagopsis armata and A. taxiformis, both characterised by heteromorphic, diplo-haplontic life histories. To uncover cryptic introductions of Asparagopsis along the South African coastline and identify ‘Falkenbergia’ isolates (i.e. tetrasporophytic life-history phase morphologically identical between species), the mitochon-drial cox2–3 spacer was sequenced from gametophytes of Asparagopsis taxiformis from Scottburgh, KwaZulu-Natal, on the East Coast, Knysna Lagoon on the South Coast and from tetrasporophytes, otherwise unidentifiable to species level, collected from False Bay near Cape Town on the South-West Coast and Tsitsikamma on the South Coast. Only tetrasporophytes of the temperate Asparagopsis armata were encountered from the Cape Peninsula (Cape Town) probably as far east as to Port St Johns, Eastern Cape province. This is considered an introduced species, and was first collected at Kommetjie (Cape Peninsula) in 1935. Gametophytes of the warm-temperate to tropical A. taxiformis were first collected at Reunion Rocks near Durban in 1984; the KwaZulu-Natal material studied here belongs to an Atlantic Mediterranean cryptic lineage. This taxon is an ecological dominant in some intertidal and shallow subtidal areas in northern KwaZulu-Natal, and is thus considered ‘introduced’ and ‘invasive’. In contrast, A. taxiformis gametophytes, collected in Knysna Lagoon in 2008, clustered with individuals of Indo-Pacific lineage 2. The latter is considered a major invasive lineage in the western Mediterranean, but at present is categorised as introduced in South Africa. This study provides molecular evidence of three independent, cryptic introductions in South Africa, one of them probably very recent, and this is discussed with respect to potential vectors responsible for transport.  相似文献   

Seaweed cultivation: Traditional way and its reformation   总被引：4，自引：0，他引：4  

费修绠  鲍鹰  卢山 《中国海洋湖沼学报》1999,17(3):193-199

INTRODUCTIONSeaweedcultivationisthemosteffectivewayforobtaininglargeamountofseaweedproducts.Thoughseaweedcultivationhasahistoryofonlyafewdecades,itsdevelopmentisfast (Fei,1 996) .Thetotalproductionofcultivatedseaweedatpresentisabout 62 50× 1 0 3tonsfreshweight,ofwhichLaminariaaccountsfor 3 1 0 0× 1 0 3tons,Undaria 2 2 0 0x 1 0 3tons,Porphyra 750× 1 0 3tons,Gracilariasp .1 0 0× 1 0 3tons,EucheumaandKappaphycus 1 0 0× 1 0 3tons,otherkindofseaweeds 1 0 0× 1 0 3tons.Theestimatedtotal…  相似文献   

红藻多糖的化学

Ⅰ.五种琼胶海藻的研究          下载免费PDF全文

李智恩  史升耀  黄家刚  徐祖洪  刘万庆  郭玉彩  张星君 《海洋与湖沼》1993,24(1):93-99

分析了鸡毛菜、易曲凹顶藻热带变种、三叉仙菜、海萝和多管藻(1979—1989分别采自广东山东和海南省)未碱处理与碱处理的多糖产率、凝胶强度、粘度、凝固点、融点、硫酸酯和3,6-内醚-半乳糖含量,同时用红外光谱和~(13)C-核磁共振波谱测定了它们的组成和结构。结果表明它们都具有琼胶的基本结构,鸡毛菜是制造琼胶的很好原料,易曲凹顶藻热带变种也可用于制造琼胶,三叉仙菜是制造低凝固点琼胶的原料。此外还发现海萝和多管藻也有一些凝固性。  相似文献   

硇洲岛大型海藻场软体动物群落的季节演替及其与环境因子的关系     

姚昕  孙省利  张才学  廖海晴  彭宇航 《海洋与湖沼》2022,53(5):1258-1268

广东湛江硇洲岛是典型的潮间带生态系统,属于热带气候,适宜底栖生物生存。底栖动物作为生态指标的一部分,可以反映出地理环境的多样性。于2011~2012年在硇洲岛潮间带五个位点进行底栖软体动物采样,以研究软体动物的季节演替变化,结果检出软体动物有4纲49科71属共104种。其中双壳纲39种,占总数的37.50%;腹足纲59种,占总数的56.73%;多板纲4种,占总数的3.85%;头足纲2种,占总数的1.92%。种类数秋季最多共61种,春季32种,夏季51种,冬季55种。各季节间共有种类数为19~33种。有8个种类为3个季节共有种,有12个种类为4个季节共有种,季节种间更替率为0.58~0.76,春秋季种间更替率最高,夏秋季种间更替率最低。优势种10种,其中1个物种为全年优势种,有2个物种为3个季节共有种。不同物种在潮间带分异明显,中潮区软体动物有58种,低潮区软体动物有44种,高潮区软体动物只有3种。调查显示各季节软体动物栖息密度变化明显,按降序排列为春季、夏季,秋季、冬季。季度Shannon-Wiener多样性指数变化范围为2.45~3.42,年均值为2.99;季度Pielou物种均匀度指数变化范围为0.53~0.66,年均值为0.58;季度Margalef物种丰富度指数变化范围为2.42~4.61,年均值为3.73; Simpson指数变化范围为0.69~0.80,年均值为0.76。调查显示各断面均受到不同程度的人为干扰,相关性分析发现栖息密度与悬浮物和总有机碳正相关(P<0.05)。优势种的转变与沿岸上升流的强弱以及养殖废水的不规则排放有关。软体动物的栖息密度与大型海藻的分布呈相反趋势,低潮区软体动物栖息密度小,与其结构和食性有关。  相似文献   

摄食紫菜粉等4种单一饵料的蚤状潘脂肪酸组成的比较     

刘飞  徐善良  王丹丽  周伟  程亮 《台湾海峡》2014,(1):90-95

用GC／MS法分析比较了紫菜粉、小球藻、酵母、Banta液（牛粪1．5g＋干稻草2g＋沃土20g＋水1000cm3）4种食物条件下蚤状潘的脂肪酸组成．结果表明：4种食物培养下,蚤状潘的总脂含量依次为39．80、60．10、44．60、52．30mg／g．一共检测出脂肪酸14种,其中8种饱和脂肪酸（SFA）,2种单不饱和脂肪酸（MUFA）,4种多不饱和脂肪酸（PUFA）．紫菜粉培养组与小球藻组PUFA含量显著高于酵母组和Banta液组（P〈0．05）,占总脂肪酸的1／3以上,酵母组MUFA质量分数最高（P〈0．05）,达55．73％,Banta液组以SFA质量分数最高（P〈0．05）,为52．45％．其中紫菜粉组的PUFA中缺乏C18：3,但C20：5（EPA）和C20：4（AA）质量分数高达22．67％和9．02％是小球藻组的1．6倍和4．5倍（P〈0．05）,而且EPA和AA的实际含量也显著高于小球藻组（P〈0．05）,达到9．02mg／g和3．59mg／g;比较得出,紫菜粉培养组的20碳以上必需不饱和脂肪酸含量丰富,明显高于其他3组．本实验证实蚤状潘的脂肪酸组成与食物脂肪酸成正相关．分析认为,用紫菜粉培养枝角类用于海水育苗会取得更佳的营养效果．  相似文献   

The appearance of Ulva laetevirens (Ulvophyceae,Chlorophyta) in the northeast coast of the United States of America     

Yunxiang Mao  Jang Kyun Kim  Roderick Wilson  Charles Yarish 《中国海洋大学学报(英文版)》2014,13(5):865-870

Introduced species may outcompete or hybridize with native species, resulting in the loss of native biodiversity or even alteration of ecosystem processes. In this study, we reported an alien distromatic Ulva species, which was found in an embayment (Holly Pond) connected with Long Island Sound, USA. The morphological and anatomical observations in combination with molecular data were used for its identification to species. Anatomy of collected specimens showed that the cell shape in rhizoidal and basal regions was round and the marginal teeth along the basal and median region were not found. These characteristics were primarily identical to the diagnostic characteristics of Ulva laetevirens Areschoug (Chlorophyta). The plastid-encoding tufA and nucleusencoding ITS1 were used for its molecular identification. Phylogenetic analysis for the tufA gene placed the specimens from Holly Pond in a well-supported clade along with published sequences of U. laetevirens identified early without any sequence divergence. In ITS tree, the sample also formed well-supported clades with the sequences of U. laetevirens with an estimated sequence divergence among the taxa in these clades as low as 1%. These findings confirmed the morpho-anatomical conclusion. Native to Australia, this species was reported in several countries along the Mediterranean coast after the late of 1990s. This is the first time that U. laetevirens is found in the northeast coast of United States and the second record for Atlantic North America.  相似文献   

Aquaculture of Sarcothalia atropurpurea tetraspores in New Zealand for carrageenan production     

S. E. McNeill 《新西兰海洋与淡水研究杂志》2013,47(4):528-542

The endemic red seaweed Sarcothalia atropurpurea is a potentially valuable source of carrageenan, but no information is available on growing this species as a crop in New Zealand. Tetraspores released from wild-harvested reproductive thalli were settled onto strings and grown initially in tanks under two different day-lengths. Seeded strings were transplanted to open water at 2, 6 and 10 weeks after spore release. Gametophytic biomass was harvested twice by pruning plants approximately six and nine months after spore release. Sporeling length was correlated with day length during tank culture but these differences were not apparent after a period of open-water culture. Spores cultured with medium day-length for 6–10 weeks before transfer to open water grew into harvestable plants that contained similar amounts and types of carrageenan to that from wild material. These results demonstrate for the first time that aquaculture of gametophytic S. atropurpurea from tetraspores is possible.  相似文献   

Calorific content of New Zealand marine macrophytes     

Miles D. Lamare  Stephen R. Wing 《新西兰海洋与淡水研究杂志》2013,47(2):335-341

Calorific content was measured in 28 species of New Zealand macroalgae. Values ranged from 1.04 to 3.34 kcal g‐1 dry weight (wt), 3.03–5.18 kcal g‐1 ash‐free dry wt, and 0.13–1.75 kcal g‐1 wet wt. Seasonal variation in calorific content was measured in two of these species, Macrocystis pyrifera and Ulva lactuca, both of which showed clear changes in energy content over a 1‐year period. Factors affecting variation in calorific content between species and during the year are discussed, and the application of the current findings to ecological and aquacultural research on New Zealand seaweeds are considered.  相似文献   

海洋植物组织和细胞培养研究进展   总被引：3，自引：0，他引：3  

徐礼根  阮积惠 《海洋学研究》1999,17(2):1-9

对海藻组织和细胞培养研究进行了综述。认为我国在该领域的研究起步晚、人员少,但在经济海藻应用研究如紫菜体细胞育苗上具有国际领先水平。为促进海藻组织和细胞培养技术的产业化,应加强藻类组织培养工作者与高等植物组织培养工作者之间的交流和合作,以组织培养技术中较为成熟的离体快繁为突破口,进行市场急需商品苗的快速生产。利用海藻组织和细胞培养进行次生物质合成和特殊药物转化的研究亦具有潜在的应用价值。  相似文献