red tide

*Red Tide/Algal Bloom*

*Definition:* Phenomenon caused by microscopic algae blooms, discoloring coastal waters.

*Key Points:

•  Unrelated to tidal movements.
• Not all blooms produce toxins.
• Approximately 4,000 algae species, with 300 identified as blooming.
• algal blooms can discolor water (red, brown, yellow, purple, green, or white).
• Harmful Algal Blooms (HABs) pose risks to humans and marine life.

*Types of Algal Blooms:*

1. *Non-toxic blooms*: No harm to humans or marine life.

2. *Toxic blooms*: Produce toxins harmful to humans and marine life.

3. *Harmful Algal Blooms (HABs)*: Toxic or cause harm through other mechanisms.

*Health Effects:*

1. Paralysis

2. Diarrhea

3. Amnesia

4. Neurological problems

5. Respiratory issues

*Toxic *

1. *Paralytic Shellfish Poisoning (PSP)*

2. *Neurotoxic Shellfish Poisoning (NSP)*

3. *Diarrhetic Shellfish Poisoning (DSP)*

4. *Amnesic Shellfish Poisoning (ASP)*

*Consequences:*

1. Economic impacts (fishing, tourism)

2. Environmental damage (marine life, habitats)

3. Human health risks

_Key Points:_

1. Dinoflagellates often cause red tides, but not all red tides are caused by dinoflagellates.

2. Not all dinoflagellates cause red tides.

3. Not all red-tide forming algae are toxic.

4. Color variability: red, brown, yellow, green, etc.

5. Toxic blooms harm marine life, including fish and invertebrates.

_Toxic Blooms Categories:_

1. Fish-killing blooms

2. Invertebrate-killing blooms

3. Non-lethal blooms

_Toxin Accumulation:_

1. Filter-feeding bivalve molluscs (clams, oysters, escallops)

2. Siphons, digestive glands, or mantle cavities

3. Paralytic Shellfish Poisoning (PSP)

_Notorious PSP-Causing Dinoflagellate:_

1. Gonyaulax catenella (Pacific coast, North America)

2. Neurotoxin: Saxitoxin (100,000 times more potent than cocaine)

3. Mechanism: Interferes with sodium ion movement across neuromuscular synapses

_Toxicity Thresholds:_

1. 100-200 cells/mL: Mussels toxic for human consumption

2. 23-30,000 cells/L: Bloom visible to the unaided eye

_Toxicity Retention:_

1. Normally 2-3 weeks after a bloom

2. Longer retention times possible

 

*Causes of Algal Blooms:*

1. Nutrient-rich waters

2. Warm water temperatures

3. Changes in ocean currents

4. Human activities (pollution, coastal development)

Natural Factors:

1. Upwelling: Nutrient-rich waters from deep ocean

2. Coastal currents: Nutrient-rich waters from ocean movement

3. Seasonal changes: Temperature, salinity, and light fluctuations

4. Humic substances: Organic compounds from soil and salt-marsh areas

5. Vitamin B12: Essential nutrient for dinoflagellates, washed into sea from soil

Human-Induced Factors:

1. Farm runoff: Excess nutrients (e.g., phosphates, nitrates)

2. Nutrient loading: Increased nutrients from human activities

3. Pollution: Industrial, agricultural, and municipal waste

4. Climate change: Altered ocean temperatures and chemistry

5. Coastal development: Habitat destruction, altered water circulation

*Impacts of Red Tides and Harmful Algal Blooms (HABs)*

*Contributing Factors:*

1. Coastal water pollution (human activities)

2. Sea water temperature increase (climate change)

3. Climatic oscillations (El Niño events)

*Global Distribution:*

Countries affected:

1. Argentina

2. Australia

3. Brazil

4. Canada

5. Chile

6. Denmark

7. England

8. France

9. Guatemala

10. Hong Kong

11. India

12. Ireland

13. Italy

14. Japan

15. Netherlands

16. New Zealand

17. Norway

18. New Guinea

19. Peru

20. Philippines

21. Romania

22. Russia

23. Scotland

24. Spain

25. Sweden

26. Thailand

27. United States

28. Venezuela

*Human Health Impacts:*

1. Respiratory issues (inhalation)

2. Skin irritation (contact)

3. Gastrointestinal problems (consumption of contaminated shellfish)

4. Amnesia

5. Memory loss

6. Paralysis

7. Death

*Environmental Impacts:*

1. Fish kills

2. Physical damage to fish (barbs lodging in gill tissues)

3. Financial losses (farmed fish mortality)

4. Economic impacts on coastal communities

5. Loss of tourism

6. Impacts on commercial fishing

*Economic Consequences:*

1. Loss of livelihoods (fishing, aquaculture)

2. Decreased tourism revenue

3. Economic burdens on coastal communities

4. Costs associated with cleanup and mitigation