lecture 16 (Harmful algal blooms)

Question 1

define harmful algal bloom

Answer 1

large increases in numbers of microscopic algae that change the colour of water (to red, brown, green, black, or no discoloration). have toxins or other means of harm

Question 2

algae responsible for HABs

Answer 2

cyanobacteria, haptophytes, dinoflagellates, diatoms, raphidophyceans etc.

Question 3

what is Pseudo-nitzschia australis

Answer 3

a pennate diatom that produces domoic acid, a neurotoxin

Question 4

what algae damages fish gills?

Answer 4

chaetoceros (spiny diatom)

Question 5

what organism causes PSP and what is that

Answer 5

PSP is paralytic shellfish poisoning. caused by dinoflagellates (Alexandrium tamarense and A. catenella which produce saxitoxin)

Question 6

what algae kills fish

Answer 6

heterosigma akashiwo

Question 7

why is “red tide” not used anymore (HAB instead)

Answer 7

because not all cause red algal blooms. can be many colours or colourless

Question 8

describe typical phases of a HAB cycle

Answer 8

initiation (warm temperatures and increased light), development (cells divide germinate, cyst opens and swimming cell emerges), aggregation (cells reproduce within days of hatching, exponentially producing several hundred cells within weeks), decline (nutrients are gone, growth stops and gametes are formed + join to develop into zygote), cyst dispersal (zygotes become cysts, fall to the bottom and lay dormant until correct conditions).

Question 9

What algal group was responsible for the 2004, 2015 massive toxic phytoplankton blooms detected off the west coast of North America?

Answer 9

pseudo-nitzschia -> producing domoic acid causing ASP (amnesic shellfish poisoning)

Question 10

how did domoic acid toxin produced by these diatoms affect top bird predators of the marine ecosystem

Answer 10

caused death, weird behaviour

Question 11

name shellfish/fish poisoning syndroms and what causes them

Answer 11

dinoflagellates:
PSP (paralytic shellfish poisoning) -> Alexandrium
DSP (diarrhetic shellfish poisoning) -> Dinophysis
Neurotoxic shellfish poisoning(NSP) -> karenia
ciguatera fish poisoning (CFP) -> Gambierdiscus
diatoms:
amnesic shellfish poisoning (ASP) -> Pseudonitzschia

Question 12

what toxins are involved in PSP? effects of these on humans?

Answer 12

PSP: saxitoxin (blocks Na channels in nerves and muscle cells)
tingling and numbness of mouth, lips, fingers. general muscle weakness. inhibits respiration (use artificial respiration rather than CPR since heart doesn’t stop). in low doses can remain conscious but paralyzed

Question 13

why are HABs called shellfish poisoning syndroms?

Answer 13

suspension feeding shellfish accumulate these phytoplankton, and eating these causes toxic effects

Question 14

what toxins are involved in DSP? effects of these on humans?

Answer 14

toxin: okadaic acid (affects proteins that control NA secretion by intestinal cells)
causes diarrhea, vomiting, nausea, abdominal pai/cramps. may be accompanied by chills

Question 15

what toxins are involved in NSP? effects of these on humans?

Answer 15

toxin: Brevetoxin (keeps Na channels open)
causes diarrhea, vomiting, abdominal pain, muscular aches, dizziness, anxiety, sweating, peripheral tingling

Question 16

what toxins are involved in CFP? effects of these on humans?

Answer 16

toxins: ciguatoxin and maitotoxin (alter passage of Na and Ca ions, keeps channels open)
causes vomiting, cramps, diarrhea, headache, weakness, numbness

Question 17

what toxins are involved in ASP? effects of these on humans?

Answer 17

toxin: Domoic acid (affects central nervous system)
symptoms: vomiting, abdominal cramps, diarrhea, dizziness, disorientation, short term memory loss (within 48 hours)

Question 18

what toxin and syndrome did the crew of Captain Vancouver’s expedition encounter in the BC coast in the late 1700’s?

Answer 18

PSP, caused by toxin saxitoxin produced by Alexandrium dinoflagellate blooms

Question 19

in what parts of the world is CFP most prevalent?

Answer 19

tropical and subtropical areas

Question 20

briefly explain four consequences of HAB on marine life in addition to toxin production

Answer 20

oxygen depletion/hydrogen sulphide poisoning
shellfish starvation
habitat destruction
physical damage on fish

Question 21

what is food chain magnification?

Answer 21

biological mechanism of concentration
toxins are accumulated in each stage of the food chain, with animals at a given trophic level consuming large quantities of organisms at lower levels

Question 22

what is the algal group mainly responsible for freshwater and brackish water HABs?

Answer 22

cyanobacteria

Question 23

what kinds of toxins are present in feshwater HAB and main effects on humans and animals

Answer 23

Lipopolysaccharides: fever and inflamation in humans from bathing/showering in it
hepatotoxins: animals poisoned from drinking, human death/illness (tumor promoting activity)
neurotoxins: block neuromuscular activity

Question 24

does eutrophication have an impact on incidence of HABs?

Answer 24

yes, can cause HABs since excessive nutrients are present in these coastal waters. (also can cause hypoxia/anoxia)

Question 25

are HABs a recent phenomenon?

Answer 25

no, but they are increasing and becoming more widespread due to climate change (warming)