West Coast HABs affect:

Transcription

1 West Coast HABs affect: Fish (both wild and penned Marine Birds Marine Mammals Humans & Invertebrates Five West Coast Harmful Algal Bloom Species ϑ Dinoflagellate, Alexandrium spp. ϑ Pennate diatom, Pseudo-nitzschia spp. ϑ Raphidophyte, Heterosigma akashiwo ϑ Dinoflagellate, Dinophysis spp.? ϑ Dinoflagellate, Lingulodinium polyedrum (basionym Gonyaulax polyedra) 1

2 HARMFUL ALGAL BLOOMS The definition of a HAB is not clear-cut, since it is a societal term, not a scientific term, that describes a diverse array of blooms (both macroscopic and macroscopic) that can cause detrimental effects to national economies. HARMFUL ALGAL BLOOMS The definition of a HAB is not clear-cut, since it is a societal term, not a scientific term, that describes a diverse array of blooms (both macroscopic and macroscopic) that can cause detrimental effects to national economies, including: Toxic effects on humans and other organisms generally caused by biotoxins Physical impairment/death of fish/shellfish Nuisance conditions odors and discolouration affecting recreation/tourism Overwhelming effects on ecosystems 2

3 Red Tides Blooms of single-celled microorganisms (phytoplankton) that attain such densities that they discolour the seawater; the most common red tides are motile, dinoflagellates Red Tides Blooms of single-celled microorganisms (phytoplankton) that attain such densities that they discolour the seawater; the most common red tides are motile, dinoflagellates A poor term since they have: Nothing to do with tides (although always coastal), Not necessarily red in colour (can be red/brown/green/orange) 3

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5 Dinoflagellates Blooms of motile dinoflagellates are the most common red tides Normally dinoflagellates are found in concentrations of ~ 100 cells per litre During blooms, concentrations are 1-2 X 10 6 cells/litre discolouration is size-dependent (ranges from cells/l up to 10 8 cells/l) blooms may be also harmful at low densities due to toxin production 5

6 Red Tides are not New! Written reports have suggested red tides since biblical times (1,000 BC) Exodus, Chap. 7, Vs all the water that were in the river were turned to blood. And the fish that were in the river died; and the river stank, and the Egyptians could not drink of the water of the river; and there was blood throughout all the land of Egypt. Describes the first of the 10 great plagues of Egypt Most Red Tides are Harmless! Remember of the ~ ,100 extant marine phytoplankton species: only 300 species reach densities for water discolouration - red-tides (7%) species of these 300 spp. are harmful (2%), and only half of these have the capacity to produce toxins (1%) 6

7 HABs are found world-wide in coastal regions 7

8 Three Basic Types of Harmful Algal Blooms ν Indiscriminate Kill of Marine Fauna (Marine Fauna Mass Mortality) ν Selective Fish (Marine Fauna) Killers (usually toxins produced) ν Toxic Vectoring Through Food Chain ( i.e., paralytic shellfish poisoning) Indiscriminate Kill of Marine Fauna (Marine Fauna Mass Mortality) This type of HAB is due to the creation of anoxic conditions: Resulting in the indiscriminate mortality of marine fauna, including fish and invertebrates. Any phytoplankton species could potentially cause such a HAB in a coastal environment 8

9 The series of events leading to such a HAB: phytoplankton grow and multiply, increase in density - a flowering or bloom event cells become concentrated physically onshore winds, semi-enclosed bay nutrients needed for their continued growth are eventually exhausted phytoplankton cells die, and are decomposed (which requires oxygen) by bacterial respiration waters become low in oxygen or become oxygen depleted (anoxic) The series of events leading to such a HAB: phytoplankton grow and multiply, increase in density cells become concentrated physically onshore winds, semi-enclosed bay nutrients needed for their continued growth are eventually exhausted phytoplankton cells die, and are decomposed (which requires oxygen) by bacterial respiration waters become low in oxygen or become oxygen depleted (anoxic) indiscriminate death of marine fauna 9

10 Factors contributing to dinoflagellate blooms A seed population (resting cysts or hyphocysts) High surface temperature and lower salinities Winds - Strong offshore winds aid upwelling - advect inorganic nutrients from deeper waters to the surface - Gentle onshore winds concentrates bloom near coastline - VERTICAL STABILITY IN WATER COLUMN Light - usually during periods of bright, sunny, calm weather Nutrients - Blooms usually occur when upwelling has ceased - Nutrients themselves not necessarily cause of blooms, Species succession (generally after diatom blooms) The 1995 late winter bloom of Lingulodinium polyedrum... Pacific Ocean California was observed from Monterey Bay, CA in the north to upper Baja, Mexico in the south over a several month period in 1995 and

11 Red tide with Bioluminescence Display at Butterfly Beach, Santa Barbara July 2000 (Dinoflagellate Lingulodinium polydrum) Santa Barbara News-Press (non-intensified digital camera photo) 11

12 Selective Fish (Marine Fauna) Killers Chaetoceros convolutus and C. concavicornis Spiny diatoms have long siliceous (glass) setae with short secondary spines. Chains of these cells become lodged in gills Trigger massive amounts of mucus by fish KILLS PENNED FISH! Continuous irritation exhausts the supply of mucus and mucous cells Causing lamellar degradation, & eventual death from reduced oxygen exchange The raphidophyte secretes excess mucous Mucous lodges in fishes gills Impairs respiratory & osmoregulatory capabilities Hydrogen peroxide &/or superoxide hydroxyl radicals have been suggested, Kills both penned and wild salmon in the Pacific Northwest Also found in Southern California And San Francisco Bay 12

13 Toxic Vectoring Through the Marine Food Chain Diarrheic Shellfish Poisoning (DSP) caused by species of the dinoflagellate genus Dinophysis. Until very recently DSP was not found on the west coast, but the causative organism is commonly found here. On-going research now shows DSP. Paralytic Shellfish Poisoning (PSP) caused by a saxitoxin (>18 different types of these neurotoxins) released by species of the dinoflagellate genus, Alexandrium, e.g., A. tamarense and A. catenella Human Symptoms of Paralytic Shellfish Poisoning Symptoms appear rapidly (within ~ 30 min), and the onset is dose related. 1. Initially one feels a prickly, itchy sensation; Firstly, oral-facial numbness, Secondly, numbness to the extremities. 2. Rapid fall in arterial blood pressure (hypotension): Dizziness, General numbness and weakness. 3. Loss of coordination of voluntary muscles. 4. Respiration inhibited. 5. Death from asphyxiation (usually within 12 hr). If the patient survives the first 12 hrs, then s/he will survive, so seek immediate medical treatment should these symptoms appear. 13

14 Other issues of interest regarding PSP: The 18 (+) nerotoxins (saxitoxins) are not neutralized by heat, so cooking will not help. Shellfish containing the PSP saxitoxin do not look or behave differently from non-toxic shellfish. Females are more sensitive than men to this toxin There is no specific antidote to saxitoxin poisoning from PSP. The medical profession treats the symptoms of PSP with purgatives and symptomatic artificial respiration. Alkaline fluids are often useful in destabilizing the toxin. Responsible for Paralytic Shellfish Poisoning (PSP) 14

15 Pseudo-nitzschia species a toxigenic diatom which produces domoic acid - responsible for Amnesiac Shellfish poisoning (ASP) in local waters Very difficult to identify toxic from non-toxic Pseudo-nitzschia spp. Dr.Vera Trainer (NWFSC, Seattle, WA) 15

16 Centrifuge sea lion blood !g/mL 33% Long Term Exposure Causes? < 0.10!g/mL 11% !g/mL 19% > 0.50!g/mL 2% Not Detected 35% 55 animals tested, more than half (65%) had measurable concentrations of domoic acid. About 20% of the animals had very high concentrations. 16

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18 Useful HAB Websites