BIEB132_L4_HarmfulBlooms

BIEB132_L4_HarmfulBlooms - Harmful Blooms BIEB 132: Lecture...

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Harmful Blooms BIEB 132: Lecture 4, 10/6/09 I. What is a harmful bloom? II. Causative organisms III. Sequence of a harmful algal bloom IV. Environmental factors V. Monitoring of harmful algal blooms VI. Southern California algal blooms VII. Jellyfish blooms Reading: Levinton pp. 242-243, 557-558; Hallegraeff 2006 article (class web site Readings) I. What is a harmful bloom? A. Bloom – increase in abundance above typical levels, usually short term 1. Seasonal blooms – e.g., diatom spring bloom, not harmful B. Types of harmful blooms 1. High cell abundance – avoided by other organisms, can clog fish gills, block light 2. Noxious – when bloom collapses dying organisms can deplete oxygen (anoxia) 3. Production of toxins – secondary metabolites, usually act as neurotoxins 4. Some blooms are visible (red or brown tides) 5. Harmful algal bloom (HAB) Figures: Southern California red tide of dinoflagellate Lingulodinium II. Causative organisms A. Cyanobacteria 1. Neurotoxins – saxitoxin, blocks sodium channels in nerve cells 2. Hepatotoxins – microcystin, nodularin, inhibit protein phosphatases 3. Freshwater – toxins contaminate drinking water Figures: Freshwater cyanobacterium bloom, Cyanobacterium bloom in Baltic Sea B. Diatom Pseudo-nitzschia 1. Neurotoxin – domoic acid (amino acid) 2. Not all strains are toxic Figures: Pseudo-nitzschia cells, Pseudo-nitzschia bloom sample 3. Accumulates in fish and shellfish, affects birds and marine mammals 4. Activates calcium channels resulting in Ca 2+ influx – damages neurons in the brain 5. In birds – erratic behavior, Hitchcock’s “The Birds” 6. In marine mammals –head weaving, bobbing, bulging from the eyes, mucus from the mouth, disorientation and sometimes seizures 7. In humans –amnesic shellfish poisoning (ASP) (vomiting, diarrhea, stomach cramps, headache, dizziness and confusion, sometimes permanent loss of short-term memory, death) Harmful Algal Blooms p. 1 of 6
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8. 1986 – first reported outbreak from eating shellfish in Canada – 3 people died, > 100 poisoned 9. Domoic acid and ASP in California a) 1991 – first detected in razor clams, crab meat, crab fishery shut down b) 1998 – killed 400 sea lions c) 2001 – poisoned birds in Monterey – ate anchovies that fed on Pseudo-nitzschia d) 2002 – > 500 sea lions with domoic acid poisoning, also affected sea birds, dolphins e) 2004 –first detected in San Diego coastal waters, associated with sea lion strandings Figures: Newspaper articles about domoic acid poisoning of marine mammals and birds C. Dinoflagellates 1. About 2 dozen species produce toxins, wide differences in strain toxicity 2. Paralytic shellfish poisoning (PSP) – some Gymnodinium , Alexandrium , Pyrodinium a) Neurotoxin – saxitoxin, blocks sodium channels in nerve cells
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BIEB132_L4_HarmfulBlooms - Harmful Blooms BIEB 132: Lecture...

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