Nonpoint Source Pollution- A Recent Study

Introduction

Who would have thought that the health of rivers would be considered an essential factor in the effort to preserve coral reefs globally? Recently it has been identified that rivers and streams play a crucial role in the overall health of coastal coral reefs and marine ecosystems. Rivers carry nutrients, minerals, and sediments downstream providing marine life with the nutrients required to sustain a healthy ocean biome. Rivers, however, can also pick up and transport a multitude of harmful pollutants as the water flows through a range of environments between the mountain watersheds and the oceans.  According to the National Oceanic and Atmospheric Administration (NOAA), “Over 80% of all global marine pollution comes from nonpoint sources”. Nonpoint source pollutants refer to the large number of contaminants in water or air that accumulate from many unidentifiable sources that becomes a collective issue. This can include garbage, agricultural waste, soil runoff, excess sediments from erosion or wildfire, and organic wastes that are not properly disposed of. The stresses imposed by nonpoint sources in combination with current environmental imbalances are increasing the threats facing all marine ecosystems. These threats include rising ocean temperatures, harmful forever chemicals and plastics, and ocean acidification, which is where the pH levels of the water become more acidic, and marine animals such as coral and invertebrates cannot generate their skeletal structures. These variables are creating the perfect storm in many regions that are leading to the destruction of coral reef ecosystems that the world depends on directly and indirectly in numerous ways. The risks facing aquatic environments are furthering the imbalance within these valuable ecosystems and threatening their ability to provide the ecosystem services essential for marine life, people, and the planet. All global ecosystems contribute essential ecological services to the collective whole, including people, and coral reefs are no exception to this. Healthy coral reefs provide life-sustaining values such as coastal protection from storms, habitat for a wide range of marine life, food security for coastal communities, and jobs and revenue from tourism that supports millions globally. 

Nonpoint Source Pollution and its Threats

To shed some light on this horrific situation, I will explain how nonpoint source pollution can harm coral reef ecosystems. For example, a septic tank on a developing island may malfunction and break, causing the contaminated water to impact the surrounding area. Leaching into a nearby freshwater source that channels it to the sea or being released directly from a location on the coast to the offshore coral reefs. When this happens, the nutrients in the waste give algae a catalyst to grow and start a bloom. An algal bloom is where all of the excess nutrients in the surrounding water are available to algae colonies in the water column and they accumulate in the area and continue to grow on the top of the water. The excess nutrient-filled water from human-made nonpoint sources allows the algae to thrive and the colonies consume all of the available oxygen and nutrients in the water, which reduces the available oxygen for the marine life below. Another significant issue that can arise is the coral not receiving sunlight due to the dense algae colonies above. Without the sun, coral cannot photosynthesize (create food from the light of the sun), and without oxygen, the water surrounding the bloom becomes more acidic which is not suitable for any marine life to live. A recent study conducted in May of 2023 discusses how local stressors such as nonpoint source pollution and global stressors such as ocean rise both contribute to coral loss, but local stressors are more important to consider in the short term. 

The Study

This issue is often not at the forefront of conservation efforts which is why scientists from the University of Tokyo decided to conduct a study about Anthropogenic nitrogen pollution threats of South Asian coral reef systems. Their study discusses the gap in research that nonpoint source pollution, in this case, nitrogen wastes, plays more of a role in the death of coral reef ecosystems than previously considered in past studies. An increased global population and an increase in land usage globally, have increased the amount of anthropogenic nutrients which is nutrient waste produced by humans. In this study, the main sources of nitrogen waste were listed as sewage discharge, wastewater discharge, terrestrial runoff, and agricultural runoff. Coral ecosystems thrive in waters that are clear, shallow, warm, and usually lack lots of nutrients and this is perfect for them. But when these anthropogenic nutrients seep into the waterways and groundwater, they end up in the coastal waters and can be severely harmful not only to the marine habitats below but to human health. One of the key reasons for this study was the lack of research on anthropogenic pollutants and how they directly affect coral reef ecosystems and all the marine life in them. Coral reef ecosystems are more complex than many may think on the surface and when there are changes in the surrounding water conditions, the foundation of a highly interconnected system becomes unbalanced. If an imbalance remains in place for too long the entire ecosystem is at risk of fully collapsing, thus eliminating the crucial ecosystem services provided to humans and the planet. 

Findings

Due to the dire situation of coral reefs currently, this study aimed to open the door by quantifying the amount of anthropogenic nitrogen nonpoint pollution that humans are creating and how that in addition to other environmental factors are increasing the rate of loss of coral ecosystems. This is done through an extensive analysis of current knowledge about nonpoint sources and using that as a guide to design water testing criteria in certain areas around the South Asian region. This study was very extensive with a breakdown, country by country, of the condition of their coastal coral reefs and the different measurements of nitrogenous wastes that were tested in the water. Through each location, the researchers gave recommendations for addressing the levels of nitrogenous wastes that were present. Through this process, a lot of information gaps were noted leaving room for future studies to fill and several questions to be answered on the cumulative effects of nonpoint source pollutants.

Conclusion 

Little resources have been dedicated to monitoring coastal waters to properly measure the impacts of anthropogenic nitrogen wastes on coral reef ecosystems and this study was able to shed light on their attempt to quantify the amount of anthropogenic nitrogen that was being transferred to coastal marine ecosystems of coral reefs via runoff and watershed. The researchers discuss the damage that nitrogenous wastes can cause to the ecosystems and give a breakdown of the different findings from each South Asian Country to determine the significant amounts of nitrogen pollutants ending up in coastal waters but also the state that coastal coral reef ecosystems are in. This study opens a new door for studies in quantifying how much nitrogen waste humans create and how that can be reduced in combination with introducing conservation efforts to give these ecosystems a fighting chance against their current environmental threats.