Description

Disclaimer: Copyright infringement not intended.

Context:

A toxic algal bloom off South Australia has caused a natural disaster, killing marine life and disrupting tourism and fishing.

About Karenia mikimotoi:

Aspect	Details
What is it?	A toxic dinoflagellate species responsible for harmful algal blooms (HABs) globally.
Toxins Produced	Produces reactive oxygen species and ichthyotoxins – deadly to marine life, not directly harmful to humans.
Genus & Relatives	Part of the Karenia genus; relatives include K. brevis (causes Florida red tides).
Toxicity to Humans	Low; no direct illnesses reported, but severe indirect impacts via marine food chain.
Toxicity to Marine Life	Highly lethal to fish, shellfish, echinoderms, invertebrates via oxygen depletion and gill damage.
Key Morphological Trait	Athecate (lacks cellulose cell wall); fragile and easily ruptured in water.
Environmental Impact	Causes hypoxic/anoxic conditions during bloom decay; linked with massive fish kills.
Trigger Conditions	Marine heatwaves and nutrient changes intensify bloom formation.
Symptoms in Fish	Gill damage, stress, disorientation, and mortality.

About South Australia

Aspect	Details
Location	South-central Australia; bordered by WA, NT, QLD, NSW, and VIC.
Southern Boundary	Opens to the Great Australian Bight (part of the Southern Ocean).
Capital City	Adelaide
Area	~983,482 sq. km (4th largest Australian state)
Climate	Driest state in Australia; Mediterranean near coasts, arid inland
Highest Point	Mount Woodroffe – 1,435 m above sea level
Lowest Point	Lake Eyre – ~15 m below sea level
Key Landforms	Nullarbor Plain, Eyre Peninsula, Mount Lofty Ranges, Flinders Ranges
Major River	Murray River – state’s only significant perennial river

ALSO READ- https://www.iasgyan.in/daily-current-affairs/plankton-bloom

Source: ddnews

PRACTICE QUESTION

Q. Karenia mikimotoi, recently in the news, is:

A. A coral species affected by ocean acidification

B. A marine bird native to the Great Australian Bight

C. A toxic dinoflagellate causing harmful algal blooms

D. A deep-sea fish discovered off the coast of South Australia

Answer: C

Explanation:

Karenia mikimotoi is a toxic dinoflagellate that causes harmful algal blooms (HABs), leading to mass marine life mortality due to oxygen depletion and gill-damaging toxins. While not directly harmful to humans, its blooms are ecologically devastating, especially during marine heatwaves.