Red Tide

Why in news?

• Red tide outbreak kills thousands of fish on South Florida shore in the United states

About Red tide:

• Red tide is a marine environmental event where protists, including algae and dinoflagellates, go through a tremendous growth period, called a bloom, or an algal bloom.
• In a 2- to 3-week period, it is possible for each algal cell to produce 1 million daughter cells.
• This growth may cause the water to change colors, causing what is commonly known as a Red Tide

Causes:

• Terrestrial runoff containing fertilizer, sewage and livestock wastes transport abundant nutrients to the seawater and stimulate bloom events.
• Natural causes, such as river floods or upwelling of nutrients from the sea floor, provide nutrients and trigger bloom events as well.
• Increasing coastal developments and aquaculture also contribute to the occurrence of red tides.

Areas prone to Red Tides: 

• Harmful algal blooms can occur worldwide, and natural cycles can vary regionally.
• The growth and persistence of an algal bloom depends on wind direction and strength, temperature, nutrients, and salinity.
• Red tide species can be found in oceans, bays, and estuaries, but they cannot thrive in freshwater environments.

Effects:

• Red tides produce extremely dangerous toxins that can sicken or kill people and animals.
  • Most species contributing to algal blooms are harmless; however, some of the toxins produced by certain species are highly toxic.
  • Often, the algae and the shellfish that consume them are unaffected. However, further up the food chain, these toxins can be fatal
  • Brevetoxins are potent ichthyotoxins and have been responsible for the death of billions of fish over the years.
• Prevent sunlight penetration:
  • Algal Blooms deprive aquatic organisms of sunlight and oxygen and negatively impact a variety of species that live below the water surface.
• Red tides also creates ‘Dead Zones’ in the water
  • Dead zone is a more common term for hypoxia, which refers to a reduced level of oxygen in the water.

PRACTICE QUESTION:

Which of the following statements are correct regarding ‘Red Tide’?

1. Red Tide species cannot generally thrive in fresh water environment.

2. Terrestrial runoff containing fertilizer and livestock wastes can stimulate Red Tide events.

Select the correct answer using the code given below:

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Answer