Red tide in San Diego brings spectacular views as shores glow neon blue at night. Visibility is not guaranteed as red tides are unpredictable and not all of them result in such light displays.

San Diego Glows Blue

On the evening of May 9, San Diego beaches brought spectacular light displays when its waters turned bright neon blue. Evidently, the current red tide event in the area is responsible for the display, as the waters appear red during the day but turn bright neon blue at night in a show of bioluminescence.

According to Michael Latz of the Scripps Institution of Oceanography at UC San Diego, the current red tide is caused by aggregations of dinoflagellates such as Lingulodinium polyedra which is known for its bioluminescent traits. Further, Latz states that such red tides of L. polyedra have been recorded since the early 1900s thanks to observations from Scripps scientists, and they continue to gather information to learn more about the organisms.

Scientists are unsure, however, how long the current red tide will last, but previous similar events lasted from a week to over a month.

Amazingly, many marine organisms actually have bioluminescent capabilities, from those that live in water columns to those that thrive near the bottom of the seafloor. In fact, it is a very common trait among deep sea creatures, whether it is used to attract mates or prey, or to scare off predators.

What Is Red Tide?

Red tides or harmful algal blooms (HABs) happen when simple algae colonies grow out of control and produce harmful toxins that can harm marine mammals, fish, birds, and even humans. The name red tide is attributed to HABs' characteristic of turning the affected water into a red hue.

One of the most known HAB is the nearly annual bloom in the waters along Florida's Gulf Coast that kills fish and makes shellfish dangerous to eat. Sometimes, it can even make the air around the affected area difficult to breathe.

HABs have been recorded in every state, making it a national concern.

Apart from algal blooms that result in the production of harmful toxins, non-toxic algal blooms may also be considered as an HAB when there is a mass die-off of algae and the decaying process leads to the waters being depleted of oxygen. When this happens, the animals in the affected area either leave or are left to die.

However, not all algal blooms are harmful as many also provide food and nourishment for marine animals. In fact, the NOAA states that most blooms are beneficial to marine animals as the tiny plants are a major source of energy for the ocean's food web.