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Sea lion and Algal Blooms


Recently, hundreds of sea lions are found dead or sick on California beaches due to toxic offshore algae blooms.


GS III: Environment and Ecology

Dimensions of the Article:

  1. About Sealion
  2. Algae Bloom

About Sealion:

  • Sealion is a marine mammal belonging to the family Otariidae, which also includes fur seals.
  • They are known for their semi-aquatic lifestyle, spending significant time both on land and in the water.
  • Seals have a streamlined body with a large head and a long, flexible neck.
  • They typically have a brown or tan coat, and adult males develop a thick mane of hair around their necks.
  • Seals inhabit rocky shorelines, islands, and sandy beaches, where they create breeding colonies.
  • They can be found in various regions, including the Pacific Ocean, the Atlantic Ocean, and parts of the Indian Ocean.
  • Seals are carnivorous and primarily feed on fish, including herring, anchovies, sardines, and squid.
  • Currently, there are six recognized subspecies of sea lions: Australian sea lions, California sea lions, Galapagos sea lions, New Zealand sea lions, South American sea lions, and Steller sea lions.

Algae Bloom

  • An algal bloom or algae bloom refers to a rapid increase or aggregation in the population of algae in freshwater or marine water systems, often characterized by water discoloration.
  • Algae encompass various types of aquatic photosynthetic organisms, including macroscopic organisms like seaweed and small, single-celled organisms like cyanobacteria.

Causes of Algae Bloom:

Excess of Nutrients:
  • Algal proliferation is primarily caused by the accumulation of large quantities of phosphorus and nitrogen in the water.
  • Runoff from fields and farmland containing nitrogen and phosphorus fertilizers contributes to nutrient load in water bodies.
  • Rainfall carries these leachable nutrients from the soil into streams, rivers, and eventually larger water bodies like oceans.
  • Untreated sewage and poorly treated sewage containing nitrogen compounds like ammonia and nitrates can lead to algal blooms.
  • Industrial waste, when improperly treated or untreated, can introduce contaminants and substances such as lead, nitrogen, and phosphorus into water systems, promoting the growth of algae.
Presence of Dead Organic Matter:
  • Bacteria present in the atmosphere and water require suitable growth and nutrition sources.
  • Dead organic matter in the water provides nutrients that activate algae growth.
  • Nutrients combined with dead organic matter promote the proliferation of algae and subsequent blooming.
High Temperatures:
  • Global warming and depletion of the ozone layer contribute to accelerated algal bloom growth.
  • Certain bacteria require favorable temperatures for growth, both in and out of the water.
  • High temperatures resulting from global warming accelerate nutrient decomposition, providing simpler forms of nitrogen compounds that bacteria can use and proliferate.
Slow Moving Water:
  • Algae blooms require large quantities of water to grow.
  • Slow-moving waters provide an environment conducive to algal growth and explain their confined growth in fast-flowing streams and rivers.

-Source: The Hindu

December 2023