Harmful Algal Blooms (HABS) OCEA 101

Transcription

1 Harmful Algal Blooms (HABS) OCEA 101

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 microscopic and macroscopic) that can cause detrimental effects to national economies.

3 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

4 Harmful algal blooms (HABS) affect upwelling regions worlwide, and are likely to respond similarly because of the common dynamics.

5 Benguela Current

6 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

7 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)

8 Phytoplankton Nano and picoplankton Picoplankton -most abundant in ocean Common members: -diatoms - dinoflagellates - coccolithophorids -cyanobacteria -green algae Both may be responsible for HABs

9 Dinoflagellates Some Facts Autotrophic, heterotrophic and mixotrophic members. Three broad groups: - Gymnodiniades (unarmored) - Peridiniales (armored) - Dinophysiales (armored) Possess two flagellates and are motile: - one flagellum encircles cell (the cingulum) - one at flagellum angles to cingulum (the sulcus) Some are capable of diel migration They double in number about once per day Dinoflagellates are responsible for harmful algal blooms

10 Noctiluca scintillans Dinophysis tripos Gonyaulax polyedra

11

12

13

14 Not all mortality is a result of toxins. In some areas the blooms result in near anoxic conditions.

15 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

16 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 Trichodesium?

17 Trichodesium Filamentous cyanobacteria Nitrogen gas fixer Forms colonies and rafts Red blooms are common The Red Sea Also important for nitrogen fixation in subtropical gyres Trichodesium colony Trichodesium

18 Most Red Tides are Harmless! 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%)

19 HABs are found world-wide in coastal regions Worldwide occurence of reported Paralytic Shellfish Poisoning (PSP) in 1970 and The increase over time may be caused by spread of reponsible dinoflagellates via the bilge of container ships.

20

21 Five West Coast Harmful Algal Bloom Species Dinoflagellate, Dinoflagellate, Alexandrium Alexandriumspp. spp. (PSP) (PSP) Pennate Pennate diatom, diatom, Pseudo-nitzschia Pseudo-nitzschia spp. spp. (ASP) (ASP) Raphidophyte, Raphidophyte, Heterosigma Heterosigma akashiwo akashiwo Dinoflagellate, Dinoflagellate, Dinophysis Dinophysisspp. spp. (DSP) (DSP)? Dinoflagellate, Dinoflagellate, Lingulodinium Lingulodinium polyedrum polyedrum (basionym (basionymgonyaulax polyedra) polyedra) (PSP) (PSP)

22 Pennate Navicula cuspidata

23 Five West Coast Harmful Algal Bloom Species Dinoflagellate, Dinoflagellate, Alexandrium Alexandriumspp. spp. (PSP) (PSP) Pennate Pennate diatom, diatom, Pseudo-nitzschia Pseudo-nitzschia spp. spp. (ASP) (ASP) Raphidophyte, Raphidophyte, Heterosigma Heterosigma akashiwo akashiwo Dinoflagellate, Dinoflagellate, Dinophysis Dinophysisspp. spp. (DSP) (DSP)? Dinoflagellate, Dinoflagellate, Lingulodinium Lingulodinium polyedrum polyedrum (basionym (basionymgonyaulax polyedra) polyedra) (PSP) (PSP)

24 The 1995 late winter bloom of Lingulodinium polyedrum... Paralytic Shellfish Poisoning 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 1996.

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

26 West Coast HABs affect: Fish (both wild and penned Marine Birds Marine Mammals Humans & Invertebrates

27 Three Basic Types of Harmful Algal Blooms Indiscriminate Kill of Marine Fauna (Marine Fauna Mass Mortality) Selective Fish (Marine Fauna) Killers (usually toxins produced) Toxic Vectoring Through Food Chain ( i.e., paralytic shellfish poisoning)

28 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

29 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

30 Harmful algal blooms (HABS) affect upwelling regions worlwide, and are likely to respond similarly because of the common dynamics.

31

32 Factors contributing to dinoflagellate blooms A seed population (resting cysts (algal spores)) High surface temperature and lower salinities (stratified surface waters) 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, although increased nutrient supply is a factor

33

34 Offshore changes in organisms I phytoplankton poor (newly upwelled < 10C, low Chl, high N) II diatom dominated (maturing upwelling > 10C, moderate Chl and N) III dinoflagellates (aged upwelling 12-16C, high Chl, low N) Wind III II I Variations in physical forcing can lead to interuption of this succession and HABs Upwelling front

35 What do we know about HABs in coastal upwelling regions? Spring dominated by diatoms. Summer dominated by heterotrophs Autumn appearance of dinoflagellates

36

37

38

39 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 Continuous irritation exhausts the supply KILLS PENNED FISH! of mucus and mucous cells Causing lamellar degradation, & eventual death from reduced oxygen exchange

40 Chaetoceros

41 Close up of shark gills showing lamellae (plate-like structures)

42 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

43 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

44 Toxic Vectoring Through the Marine Food Chain this HAB mechanism is an indirect poisoning via the food chain (i.e., initial filter feeder is unaffected) illness or death? Filter feeder/plankton eater Predator (sensitive) Toxin producer Predator (insensitive) (Toxins are concentrated in predator tissues and organs) OK

45 Alexandrium catennela (responsible for PSP)

46

47 Responsible for Paralytic Shellfish Poisoning (PSP)

48 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.

49 Other issues of interest regarding PSP: The 18 (+) neurotoxins (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 males 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.

50 Many but not all HABS are due to dinoflagellates: Pseudo-nitzschia is a toxigenic diatom which produces domoic acid - responsible for Amnesiac Shellfish poisoning (ASP) in local waters (nausea, muscle weakness, disorientation, organ failure, and short-term memory loss in humans) Very difficult to identify toxic from non-toxic Pseudo-nitzschia spp.

51 ~100 sea lions died from feeding on infected anchovies and sardines. Reason for sudden appearance is unknown. Dr.Vera Trainer (NWFSC, Seattle, WA)

52 Neurotoxic Shellfish Poisoning (NSP) Toxin brevitoxin Dinoflagellate, Karenia brevis Common in Gulf of Mexico LysedK.brevisrelease toxin into atmosphere respiratory problems and eye irritation

53 Karenia brevis Karenia brevis bloom, west FL

54 Diarrhetic Shellfish Poisoning (DSP) Toxin okadaic acid Dinoflagellates Dinophysis and Prorocentrum lima Widespread worldwide Gastrointestinal problems (mild)

55 Dinophysis norvegica

56 Prorocentrum lima

57 Ciguatera Fish Poisoning Toxin Ciguatera Dinoflagellates Gambierdiscus toxicus Lives attached to seaweed Transmitted to herbivorous reef fish Affects > 400 species of tropical reef fish Toxins concentrated in liver Common in FL, HI, and Caribbean Cyclic outbreaks triggered by reef disruptions

58 Parrot fish

59

60 Pfisteria Dinoflagellate Pfisteria piscida Major fish kills in U.S. estuaries

61 Vibrio cholerae Cholera Bacteria associated with phytoplankton blooms Carried by cyanobacteria, diatoms, dinoflagellates, seaweeds, and zooplankton eggs sacks

62 Anomalously high sea-level during IOZM years prevents monsoon rains in Ganges from draining into Bay of Bengal. Cholera carrying zooplankton are carried upstream from ocean.

63 Increased coastal flooding during El Nino years Cholera and ENSO

64 Centrifuge sea lion blood

65 µg/ml 33% Long Term Exposure Causes? < 0.10 µg/ml 11% µg/ml 19% > 0.50 µg/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.

66 Useful HAB Websites