User:Abhishekram99/National Marine Sanctuary of American Samoa

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The National Marine Sanctuary of American Samoa (formerly the Fagatele Bay National Marine Sanctuary ) is one of many federally-designated underwater areas protected by NOAA's Office of National Marine Sanctuaries. This sanctuary is the largest and most remote in the national Marine Sanctuary system. Spanning 13,581 sq mi, it is home to the greatest biodiversity of aquatic species of all marine sanctuaries. Among them are expansive coral reefs, including some of the oldest Porites coral heads on earth, deep-water reefs, hydrothermal vent communities, and rare archeological resources. It was established in 1986, and then expanded and renamed in 2012.

The American Samoa archipelago is located in the mid-south Pacific ocean, halfway between Hawaii and New Zealand. It is the only American Territory south of the equator. The Park has one visitor center in Tutuila, known as Tauese P.F. Sunia Ocean Center. There are exhibits for all ages, and it is open year-round.

Climate Change
An increase in greenhouse gas emissions have caused a rise in global temperatures. This phenomenon, known as global warming or climate change, is beginning to impact Earth’s most treasured natural spaces, and the Samoan Islands are among the most vulnerable regions. This rise in CO2 and temperature causes an imbalance in the Samoan reef ecosystem in a myriad of ways, which will be described below.

Ocean Acidification
Since 1750, the acidity of the ocean has increased by 30%. An increase in ocean acidification destabilizes Samoan reefs by impacting crustose corraline algae, a calcareous species that consolidates and cements reefs together. A reduction in coral calcification impairs coral growth and density, increasing vulnerability to erosion and damage. The increase in acidification also makes it difficult for clams in all stages of life to grow their shells, and for the larvae of corral reef fish to grow, survive, and make it back to the reef. It is projected that by 2060, the aragonite (CaCO3) saturation state that is crucial to coral growth will fall below the optimal threshold of 4.0 to 3.5, and continue deteriorating in the future.

Rising Water Temperatures
The oceans absorb much of the heat caused due to increase in global temperature. Waters in American Samoa have risen 1.8F in the past 30 years, and are projected to increase 4.7F by 2090. Extreme temperature events, also known as heatwaves, have also increased in frequency. Coupled with the rise in ocean temperature, these heatwaves cause coral bleaching events, wherein symbiotic algae are expelled from the coral, causing the corals to appear white. These algae provide food and process waste from the corals, hence are extremely essential to their survival. Five mass bleaching events have occurred from 1994 to 2017, with the 2015 event causing the most damage. These events are projected to become more frequent and intense in the future. It is estimated that the reefs of the American Samoa could experience yearly bleaching by the year 2040.

By the year 2115, under extreme warming, it is projected that water temperatures in this region may be too high for species currently living in the reefs. Due to the isolation of the Samoan reefs, species may not be able to find another suitable habitat. Warming temperatures may also worsen coral diseases and favor invasive species, such as the outbreaks of the crown-of-thorns sea star, a predator of the coral.

Algal blooms will also become more expansive and longer-lasting. Some of these blooms may also be Harmful Algal Blooms (HABs) and become toxic to life around it.

Changing Weather Patterns and Storms
In the American Samoa, climate change is estimated to increase rainfall by about 10% by 2100, while extreme precipitation events are also projected to increase in frequency. These extreme events cause large amounts of sediment runoff, which bury corals, suffocating and killing them. This sediment also clouds up the water, making photosynthesis challenging. Nitrogen from fertilizers increase coral disease and contribute to coral bleaching.

Tropical cyclones drive harsh winds and towering waves that cause damage to coral systems, sometimes causing persistent decrease in coral cover. These storms are expected to increase in intensity, but decrease in frequency over the next 70 years.

Actions Being Taken
The NOAA Ocean Acidification Program placed a very scientifically powerful buoy in Fagatele Bay in May 2019. This buoy records real-time values of water temperature, acidity, and other relevant parameters, that can then be used to assess trends. NOAA also tackles non-climate stressors that can make the reefs more resilient as a whole. The population of crown-of-thorns sea star, a natural predator of corals, is closely monitored and controlled to prevent outbreaks. The sea stars are injected with ox bile that painlessly kills them and does not harm the rest of the ecosystem. A coral nursery project was also piloted in 2020. In the future, corals from the nursery could be used to restore reefs after devastation due to weather or other events.

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