Understanding the Decline of Hard Corals in 2023

Hard corals: An Overview

Recent findings from the Global Coral Reef Monitoring Network (GCRMN) indicate a significant decline in hard coral populations throughout the Caribbean. This alarming trend poses severe implications for marine biodiversity.

What are Hard Corals?

Hard corals, commonly referred to as stony corals, are vital marine organisms that construct the limestone frameworks essential for reef formation. They exist in colonies and are often labeled as “reef-building corals.”

Key Features of Hard Corals

Hard corals consist of numerous tiny polyps that secrete calcium carbonate. This process leads to the formation of sturdy skeletons, which gradually evolve into rock structures. These rocky foundations are crucial for the habitation of juvenile corals, providing them with a stable environment.

A pivotal aspect of hard corals is their symbiotic relationship with tiny algae known as zooxanthellae. The corals offer shelter to these algae, while the zooxanthellae, in turn, supply nutrients to the corals through photosynthesis.

Threats to Hard Corals

The health of hard corals is increasingly jeopardized by several factors:

• Bleaching Events: Rising sea temperatures lead to coral bleaching, a phenomenon where corals expel their symbiotic algae, resulting in loss of color and vitality.
• Stony Coral Tissue Loss Disease: This disease has spread across 30 countries, causing unprecedented mortality among coral populations.
• Declines in Herbivores: The decline of key herbivores, such as the Diadema sea urchin, has resulted in an 85% increase in macroalgae, further threatening coral health.

Given the critical role of hard corals in marine ecosystems, their decline is a pressing environmental concern. Immediate action is required to address these challenges and promote reef conservation.

Frequently Asked Questions (FAQs)

Q1. What are the main threats to hard corals?
Answer: Hard corals face threats from rising sea temperatures causing bleaching, diseases like Stony Coral Tissue Loss, and declines in herbivore populations, leading to increased macroalgae.

Q2. Why are hard corals important for marine ecosystems?
Answer: Hard corals provide structural habitats for various marine species, contribute to biodiversity, and play a crucial role in protecting coastlines from erosion.

Q3. How does coral bleaching occur?
Answer: Coral bleaching occurs when corals expel the algae living within them due to stress from high temperatures, resulting in loss of color and essential nutrients.

Q4. What is the role of zooxanthellae in coral health?
Answer: Zooxanthellae are crucial for coral health as they perform photosynthesis, providing nutrients to corals while benefiting from the shelter offered by the corals.

Q5. How can we protect hard coral populations?
Answer: Protecting hard coral populations requires reducing carbon emissions, establishing marine protected areas, and promoting sustainable fishing practices to enhance coral resilience.

UPSC Practice MCQs

Question 1: What is one major factor contributing to coral bleaching?
A) Increased pollution
B) Rising sea temperatures
C) Overfishing
D) Eutrophication
Correct Answer: B

Question 2: What disease has significantly impacted hard corals globally?
A) coral reefs Syndrome
B) Stony Coral Tissue Loss Disease
C) Coral White Syndrome
D) Sea Fan Disease
Correct Answer: B

Question 3: Which organism is essential for coral health due to its symbiotic relationship?
A) Sea Turtle
B) Zooxanthellae
C) Diadema sea urchin
D) Sea Cucumber
Correct Answer: B

Question 4: What percentage increase in macroalgae has been observed due to the loss of herbivores?
A) 50%
B) 70%
C) 85%
D) 90%
Correct Answer: C

Question 5: What is the primary composition of hard coral skeletons?
A) Silica
B) Calcium Carbonate
C) Magnesium
D) Organic Matter
Correct Answer: B

Question 6: The relationship between corals and zooxanthellae is described as?
A) Parasitic
B) Commensal
C) Symbiotic
D) Competitive
Correct Answer: C

Question 7: Which of the following is a significant consequence of coral bleaching?
A) Increased biodiversity
B) Coral mortality
C) Enhanced reef structure
D) Decreased sea temperature
Correct Answer: B