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Coral Bleaching and the Carbon Cycle

Coral Bleaching and the Carbon Cycle Notes

Coral Bleaching Overview

  • Definition: Coral bleaching is a phenomenon where corals expel the symbiotic algae (zooxanthellae) living in their tissues, often due to stress factors such as temperature changes.

  • Causes of Bleaching:

  • Elevated water temperatures, often measured as 1°C above the Maximum Monthly Mean (MMM).

  • Other stress factors can include ocean acidification, pollution, and loss of water clarity.

Recent Events in Florida Keys

  • July 2023 Incident:

  • Southern Florida Keys experienced severe coral bleaching due to record high sea temperatures.

  • Record temperatures reached as high as 33.60°C on July 13, exceeding the bleaching threshold.

  • This has raised concerns for mass mortality events among the coral populations.

  • Temperature Measurements:

  • MMM for Florida Keys: 29.63°C

  • Bleaching Threshold: 30.63°C

  • Start of Bleaching: June 14, 2023 (crossed threshold).

Coral Reef Basics

  • Coral Location: Typically found within 23 degrees north and south of the equator.

  • Significance: These regions are known as biodiversity hotspots, often referred to as the "rainforests of the sea."

Important Facts About Corals

  • Classification:

  • Corals are marine animals belonging to the class Anthozoa (related to jellyfish and anemones).

  • Over 6,000 species exist.

  • Structure: Corals are colonial invertebrates that consist of numerous tiny animals called polyps.

  • Symbiosis:

  • Coral polyps engage in a symbiotic relationship with algae (zooxanthellae), which perform photosynthesis and provide essential nutrients.

  • Algae live within the coral's tissues offering glucose and oxygen, vital for coral health.

Effects of the Carbon Cycle on Coral Bleaching

  • Relationship Between Carbon Cycle and Coral: Elevated CO2 levels lead to ocean acidification, affecting coral growth and resilience to bleaching.

  • Importance of Monitoring: Understanding how carbon emissions impact coral reefs is crucial for mitigating risk and managing reefs effectively.

Coral Bleaching Activities: Research and Data Analysis

  1. Task Overview: Identify coral bleaching trends across four different locations for insights and comparisons.

  • Locations: Asuncion Island, Abul Thama (Bahrain), Clipperton Island (France), Martin (Florida).

  1. Data Collection and Analysis:

  • Temperature data and heat stress measurements for three periods: 2001-2002, 2009-2010, and 2013-2014.

  • Higher heat stress correlates with significant bleaching events.

  1. Key Measurements:

  • Heat Stress is quantified as the area under the sea surface temperature curve exceeding the MMM line.

  • Trends over the given years should be assessed to compare how coral reef locations respond differently to temperature changes.

Conclusion

  • Ongoing monitoring and research are essential for understanding coral bleaching and developing strategies to protect these vital ecosystems amidst changing carbon levels and temperature extremes.