FISH KILL
1. Context
Days after tens of thousands of dead fish washed up on multiple beaches of southeast Texas, USA, last week, authorities have removed the carcasses from several spots. The corpses first began to surface on June 9, leading officials to ask the public to stay away from the affected beaches until the time they had been cleared, due to the risk of being exposed to bacteria and sharp fins.
2. What led to the massive die-off of fish in Texas?
- Fish kill is the sudden death of many fish or aquatic animals over a short period, mainly caused by low levels of dissolved oxygen in the water.
- The massive die-off of fish in Texas was attributed to a fish kill phenomenon.
- Warm water temperatures make it difficult for fish to breathe as oxygen dissolves less easily in warmer water compared to colder water.
- When fish get trapped in shallow water, which warms up quickly, they act erratically and further deplete oxygen from the water, leading to suffocation.
- Calm seas along the Texas Gulf Coast prevented oxygen from entering the water through wind and waves, exacerbating the oxygen depletion problem.
- Overcast weather hindered photosynthesis by phytoplankton, reducing the production of oxygen in the water.
- The combination of warm water, calm seas, and overcast weather contributed to the low oxygen levels and the subsequent fish kill in Texas.
3. Fish Kills in Texas Summers
- Fish kills in Texas are a recurring phenomenon during the summer months.
- The rise in sea surface temperatures during summer leads to fish kills.
- Menhaden, a common fish species, is particularly affected and experiences mass die-offs.
- Menhaden serves as an important food source for other fish, making its death crucial to the regional ecosystem.
- The recent fish kill incident in Texas is a part of this annual occurrence, affecting primarily menhaden.
4. Impact of Climate Change on Texas Fish Kill
- While the recent fish kill in Texas is not directly linked to climate change, experts suggest that rising ocean temperatures could make such incidents more common in the future.
- Warmer oceans result in lower levels of dissolved oxygen, leading to fish suffocation and death.
- Katie St Clair from Texas A&M University highlights the concern of rising seawater temperatures and the need for monitoring the situation.
- Climate Change also has other negative effects on fish populations, such as smaller size and the migration of species to cooler waters, disrupting the fish industry.
| For Prelims: Fish Kill, Fish Kill Phenomenon, Photosynthesis, Phytoplankton, Biological oxygen demand (BOD), Chemical Oxygen Demand(COD). |
Previous year Question
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1. Biological Oxygen Demand (BOD) is a standard criterion for (UPSC 2017)
A. Measuring oxygen levels in the blood
B. Computing oxygen levels in forest ecosystems
C. Pollution assay in aquatic ecosystems
D. Assessing oxygen levels in high-altitude regions
Answer: C
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Source: The Indian Express
