This blog post examines the causes of red tide and the damage it inflicts on marine ecosystems, exploring fundamental solutions to prevent and mitigate it.
The ocean has always been closely intertwined with human life. It provides food, transportation, and even influences climate, playing a vital role. However, in recent times, the abnormal signals sent by the ocean have become increasingly frequent. One such signal is the phenomenon where the sea turns red—known as red tide. Red tide is one of the prime examples illustrating the negative impact humanity has on marine ecosystems, worsened not only by natural factors but also by human activities. We must thoroughly understand this phenomenon of the sea turning red and identify its root causes and solutions.
What is a red tide, why does it occur, and how can it be prevented? Red tides can be caused by red tide organisms such as phytoplankton, bacteria, and ciliates. In most cases, it refers to the phenomenon where the color of the sea, rivers, or lakes turns red or brown due to a rapid increase in the number of phytoplankton. This phenomenon is not merely a change in water color; it has diverse impacts across the entire ecosystem.
Even if phytoplankton numbers surge dramatically, the water may not change color if they remain widely dispersed. However, when the volume density of red tide organisms exceeds 3ppm, the color change becomes pronounced enough to be visible to the naked eye. When red tide organisms concentrate intensely, the ocean’s red hue deepens, evolving beyond a mere biological phenomenon into an environmental issue.
So how does a red tide occur? While several theories exist, they commonly cite adequate sunlight, water temperature, and eutrophication as the causes. Since phytoplankton obtain energy through photosynthesis, their numbers surge rapidly in waters where photosynthesis is active. These conditions naturally align most frequently in spring and summer, with water temperatures between 15°C and 25°C being optimal for red tide organisms’ growth. While red tides can occur as part of natural cycles, human activities are identified as the primary factor increasing their frequency.
Just as we fertilize plants to promote growth, eutrophication in the ocean supplies excessive nutrients to red tide organisms like phytoplankton. While eutrophication can occur naturally, it is primarily caused by increased levels of nitrates and phosphates in the ocean due to waste from human activities. This eutrophication acts as a key factor, making red tides more frequent and intense.
When a red tide occurs, it causes various damages. Mass mortality of aquatic organisms is one of the most significant impacts. When harmful algal blooms proliferate excessively, dissolved oxygen levels decrease, causing aquatic life like fish to suffocate or suffer direct harm from toxic blooms. Algae like Cochlodinium, in particular, can secrete mucus substances that clog fish gills, hindering respiration, or release toxic substances that paralyze nerves, leading to death. This damage extends beyond simple fish mortality, adversely affecting the entire ecosystem.
Furthermore, red tides are lethal to aquatic plants. When red tide organisms cover the water surface, sunlight cannot penetrate the water, inhibiting photosynthesis in aquatic plants and ultimately leading to their death. This acts as a significant factor disrupting the ecosystem balance and can cause the long-term collapse of marine ecosystems.
To mitigate the damage caused by red tide phenomena, a red tide warning system must be implemented, and practical prevention measures must be established. Through the red tide warning system, farmed fish can be moved to safe areas in advance to minimize damage, or the growth of red tide organisms can be suppressed by installing shade nets. However, these methods are only temporary countermeasures and cannot serve as fundamental solutions.
Therefore, to fundamentally prevent red tide phenomena, regulation of human activities is necessary. It is necessary to regulate nitrogen and phosphorus emissions and prevent excessive nutrient supply through dredging of sediment. Furthermore, improvements to sewage treatment facilities and manure processing facilities must prevent organic matter and heavy metals from entering the sea. These measures will not only prevent red tides but also play a crucial role in restoring marine ecosystems and protecting the global environment.
This blog post examined the causes of red tide, its damage, and prevention strategies. Appropriate quantities of red tide organisms serve as prey for predators in the ecosystem and are themselves part of the cycle. However, excessive amounts collapse ecosystems and disrupt the ocean’s balance. We must recognize that red tide is not merely a natural phenomenon but a problem caused by human activity. If we dedicate our efforts to preventing red tides, the ocean will once again return its blue light to us.
