珠江口海域3种重要有害藻类的溶血毒性研究

从珠江口海域分离、鉴定出3种重要有害藻类小普林藻JX12(Prymnesium parvum)、剧毒卡尔藻JX24(Karlodinium veneficum)、红色赤潮藻JX14(Akashiwo sanguinea),在实验室条件下研究了不同反应温度和pH值对小普林藻溶血活性的影响,在此基础上对海洋微藻溶血活性的测定方法进行了优化,并进一步分析比较了不同藻株以及不同生长时期溶血毒性的变化特征。研究结果显示,在实验温度范围内(4~50°C),小普林藻的溶血活性随温度的升高而增大,37℃为其最佳反应温度,pH 8和50 min为其最佳反应条件。不同生长时期的小普林藻溶血毒性具有显著差异,对数期溶血活性(5.67×10~(-7)HU·cell~(-1))显著高于稳定期(2.32×10~(-7)HU·cell~(-1))和衰亡期(3.40×10~(-7)HU·cell~(-1))。分离自珠江口海域的3种微藻均检测出溶血毒性,单个细胞溶血活性由强到弱分别为红色赤潮藻(976.20×10~(-7)HU·cell~(-1))、小普林藻(5.67×10~(-7)HU·cell~(-1))、剧毒卡尔藻(2.58×10~(-7)HU·cell~(-1))。值得注意的是,红色赤潮藻中国株JX14的单位细胞溶血活性显著高于美国株AS2,是后者的2倍以上。本研究首次确认珠江口海域红色赤潮藻、小普林藻和剧毒卡尔藻均具有较强的溶血毒性,这些有害藻类一旦形成赤潮可能对河口生态系统安全以及水产养殖业造成严重危害。     

Prymnesium parvum: The Norwegian Experience1

Johnsen, Torbjørn M., Wenche Eikrem, Christine D. Olseng, Knut E. Tollefsen, and Vilhelm Bjerknes, 2010. Prymnesium parvum: The Norwegian Experience. Journal of the American Water Resources Association (JAWRA) 46(1):6-13. DOI: 10.1111/j.1752-1688.2009.00386.x Abstract: In Norwegian waters, Prymnesium parvum has been reported from Oslofjorden in the south to Spitzbergen in the north. However, blooms of P. parvum have only been reported from the Sandsfjorden system in Ryfylke, Western Norway where the salinity of the permanent brackish layer (2-5 m) typically is in the range of 4-7 psu during the summer months. The first bloom on record occurred in 1989, and it killed 750 metric tons of caged salmon and trout which was a significant economic loss to the fish farming industry. Toxic blooms occurred as well in subsequent years and the number of fish farms in the area decreased considerably as did the occurrence of P. parvum. In 2005, fish farming was reintroduced to the area and again, in 2007 a toxic bloom of P. parvum killed 135 metric tons of caged fish. The Norwegian Institute for Water Research has, in collaboration with “Erfjord Stamfisk” fish farm, set up a monitoring program that includes light microscopy cell counts of Prymnesium, water quality measurements, and observation of the caged fish. A submergible fish net was mounted over the fish pens and during the toxic outbreak of P. parvum in July-August 2007, which was as previous years confined to the upper brackish water layer, the fish nets were lowered to 10 m depths below the surface and fish feeding was temporarily stopped. Despite substantial weight loss, the fish survived the toxic bloom and the economic loss was minimal. Monitoring of P. parvum bloom dynamics in 2007 revealed that populations were initially dominated by the nonmotile forms which were gradually replaced by the flagellated forms. Toxicity was observed when the flagellated cells dominated populations in the summer. Chrysochromulina, solitary small Chaetoceros species, and small centric diatoms co-existed with P. parvum during the monitoring period (June-October).     

Prymnesium parvum Control Treatments For Fish Hatcheries1

Barkoh, Aaron, Dennis G. Smith, and Gregory M. Southard, 2010. Prymnesium parvum Control Treatments for Fish Hatcheries. Journal of the American Water Resources Association (JAWRA) 46(1):161-169. DOI: 10.1111/j.1752-1688.2009.00400.x Abstract: In 2001, the ichthyotoxic microalga Prymnesium parvum caused massive fish kills and adversely affected fish production at the Texas Parks and Wildlife Department (TPWD) Dundee State Fish Hatchery. Since then, we have investigated several P. parvum bloom and ichthyotoxicity control treatments to develop management strategies that allow fish production and prevent the spread of the alga into unaffected hatcheries and impoundments. Current control successes include treatments for ponds, water supply, and a hazard analysis and critical control point program. For pond treatment, ammonium sulfate (as 0.14-0.25 mg/l un-ionized ammonia nitrogen for temperatures above 15°C), copper sulfate (2 mg/l), Cutrine^®-Plus (0.2-0.4 mg/l as copper), or potassium permanganate (3 mg/l above the potassium permanganate demand) controls P. parvum blooms. Copper sulfate at 1 mg/l controls P. parvum but is unable to eliminate ichthyotoxicity whereas potassium permanganate at 2 mg/l above the potassium permanganate demand controls ichthyotoxicity. For water treatment, ultraviolet (UV) light at 193-220 mJ/cm² doses or ozone at 0.4-1.2 mg/l for 6 min destroy P. parvum cells and reduce or eliminate ichthyotoxicity. A combination UV and ozone treatment appears to provide the best results; however, successful treatments depend on dosage relative to cell density and toxin concentration. To prevent the spread of the alga, hatchery fish delivery units and equipment are cleaned with household bleach (10% solution for 15 minutes) or hydrogen peroxide (62.5-12,500 mg/l for 0.25-24 hours). These treatments are tailored to water quality conditions and the fish species cultured at affected TPWD hatcheries. We recommend that other users test these treatments before applying them to ponds or other impoundments containing fish or other aquatic life.     

Potential Methods for Managing Prymnesium parvum Blooms and Toxicity,With Emphasis on Clay and Barley Straw: A Review1

Hagström, Johannes A., Mario R. Sengco, and Tracy A. Villareal, 2010. Potential Methods for Managing Prymnesium parvum Blooms and Toxicity, With Emphasis on Clay and Barley Straw: A Review. Journal of the American Water Resources Association (JAWRA) 46(1):187-198. DOI: 10.1111/j.1752-1688.2009.00402.x Abstract: Harmful algal bloom (HAB) control and mitigation is a complex problem in ecosystem management. Phytoplankton play an important role in aquatic ecosystems as primary producers and food sources for many commercially important shellfish and there are limited options for targeting just a single species within the community. Chemical treatments (e.g., algaecides), rotting barley straw, nitrogen and phosphorus manipulation, and clay and/or flocculants are but a few techniques tested or used to reduce fish kills or shellfish contamination during a HAB event. Prymnesium parvum control has focused on the use of chemicals, nutrient manipulation, and clay flocculation. However, many HAB control methods have been rejected due to their effects on ecosystems, high costs, or limited effects on target organisms. For example, rotting barley straw (Hordeum vulgare) is considered to be an environmentally friendly alternative, but has been found to have very different results on the phytoplankton community depending on the dominating taxa and is ineffective against P. parvum and dinoflagellate blooms. Clay flocculation is a useful control/mitigation technique during fish kills in marine aquaculture sites in South Korea and can be effective in freshwater if the correct combination of clay and flocculent is used. Toxins produced by P. parvum and Karenia brevis also bind to phosphatic clay, thereby removing and/or neutralizing the toxins, but there is concern that the clay will have a negative effect on sessile organisms. Some shellfish suffer high mortalities and significant impacts on somatic and reproductive tissue growth at high clay loads; however, benthic communities appear to be unchanged after five years of clay treatment in South Korea. There are likely site-specific and ecosystem-specific characteristics that make generalizations about control options difficult and require careful assessment of options at each location.     

Mini Review: Probes for Detecting Prymnesium parvum and Preliminary Results From Gene Expression Studies1

Medlin, Linda K., Sonja Diercks, and Sara Beszteri, 2010. Mini Review: Probes for Detecting Prymnesium parvum and Preliminary Results From Gene Expression Studies. Journal of the American Water Resources Association (JAWRA) 46(1):144-152. DOI: 10.1111/j.1752-1688.2009.00398.x Abstract: Prymnesium parvum is common in brackish and marine coastal waters within temperate zones, world-wide. P. parvum forms recurrent blooms causing fish kills in many parts of the world. Harmful blooms are formed in nutrient rich, low salinity lakes, ponds, river systems, or estuaries. Probes made to this species and to the genus Prymnesium have been tested in dot blot and fluorescent in situ hybridization (FISH) and used with a solid-phase cytometer using a tyramide signal amplification (TSA) enhanced FISH hybridization to provide a means to identify the cells before blooms develop with automated counting. Field counts from light microscopy have been compared with solid-phase cytometer counts. Additional detection systems, such as biosensors and microarrays, have also been developed to identify rapidly this species without resorting to electron microscopy. Advantages and disadvantages of each detection system are discussed. A study of the genes expressed by P. parvum under environmental conditions that can induce blooms or stress was undertaken to try to understand the ecology behind toxic blooms.     

Global Genetic Relationships Among Isolates of Golden Alga (Prymnesium parvum)1

Lutz-Carrillo, Dijar J., Gregory M. Southard, and Loraine T. Fries, 2010. Global Genetic Relationships Among Isolates of Golden Alga (Prymnesium parvum). Journal of the American Water Resources Association (JAWRA) 46(1):24-32. DOI: 10.1111/j.1752-1688.2009.00388.x Abstract: Prymnesium parvum is considered among the most harmful algal species in the world for finfish and other gill breathing organisms. Although it is globally distributed, with the exception of Antarctica, P. parvum is usually associated with coastal and brackish waters. Historically, P. parvum incidents were recorded in the eastern hemisphere; however, in 1985 it was detected in inland Texas waters. We used DNA sequence variation of the first internal transcribed spacer in the nuclear ribosomal operon (ITS1) among multiple samples of P. parvum from Texas and other locales to address the possible origins of P. parvum in Texas and the United States (U.S.). With the exception of a sample from Diversion Lake, other samples from Texas, South Carolina, and Wyoming exhibited limited genetic variation and were similar in sequence to a sample from Scotland. The Diversion Lake sample was similar in sequence to samples from Denmark and Norway, and the Maine sample was highly similar to samples from England. These results suggest multiple independent introductions of P. parvum to the U.S.     

Comparison of Three Algaecides for Controlling the Density of Prymnesium parvum1

Rodgers, John H., Jr., Brenda M. Johnson, and West M. Bishop, 2010. Comparison of Three Algaecides for Controlling the Density of Prymnesium parvum. Journal of the American Water Resources Association (JAWRA) 46(1):153-160. DOI: 10.1111/j.1752-1688.2009.00399.x Abstract: Prymnesium parvum has become more prevalent in water resources of the southern United States. As the potential impacts of P. parvum are relatively well known, especially its capability to severely affect fish, managers have sought efficacious, environmentally sound, and socially acceptable strategies for mitigating this noxious species. Laboratory testing was used to identify an effective algaecide for control of P. parvum from Texas, Arizona, Florida, North Carolina, and South Carolina. Cutrine^®-Plus at 0.2 mg Cu/l significantly decreased the density of P. parvum in samples from all of these locations. Both copper sulfate and Phycomycin^® were less effective for controlling the population growth of P. parvum. The predicted response from the laboratory study was confirmed in the field at the Arizona site. Strategic use of Cutrine^®-Plus in larger water resources could provide toxin-free refugia to allow some fish to survive and repopulate the water resource when the golden alga infestation abates.     

Phaeocystis globosa核糖体大亚基(28SrDNA)的序列分析与分类学意义

对一株Phaeocystisglobosa的28SrDNA基因序列测定,共得到碱基大小为1795bp的两个序列片段,其中序列一的长度为970bp,序列二的长度为825bp。将Ph.globosa与Ph.antarctica和Prymnesiumpatelliferum同源序列进行对比,发现Ph.globosa与Ph.antarctica仅在序列二中有一个碱基插入/缺失,同源性为99.99%,而与Pr.patelliferum相比,有7处插入/缺失,碱基总变异率为6.13%;研究发现序列一中有一个比较明显的高度保守区和两个高变区;序列二中有两个比较明显的高变区、一个保守区和一个高度保守区。对28SrDNA基因RNA二级结构分析发现,DNA序列保守区在RNA二级结构上也非常保守,与DNA序列分析结果一致,都证明28SrDNA基因只适用于种以上水平的分类研究,不宜用于种间和种下水平的研究。