On Sunday night I found myself down under a local empty lifeguard tower, watching the clouds seeping over the ocean as the sky darkened. The wind pushed me back against the rocks I was sitting on and I instinctively shivered. I quietly took in the scene but kept most of my attention on the relentless waves. The sky went from blue to charcoal over the ocean to glowing orange over the city while the stars and planets switched themselves on in the growing darkness. I still watched the waves intently. Then, I saw it in lazy ripples at the edges of the water, a dim glow. On the next large break, it came into focus. The wave crackled as it crashed ashore. Every facet of its face flickered as it broke on the beach, before receding back into the black ocean. I grinned. Despite its potential harmful properties, the red tide had returned to San Diego and was putting on a small show.
The “red tide” is caused by a large growth of algae – dinoflagellates – in a particular area. The large growth or “blooms” of these organisms cause the water to turn red – or brown in the affected area during the day, but at night, the movement of the water causes the dinoflagellates to emit bright flashes of light. As a result, when one is watching a red tide, one is watching the interaction between water and millions of microscopic creatures – something that is fairly interesting to think about; additionally, it is also interesting to note that bioluminescence of the plankton is not fully understood yet. (http://explorations.ucsd.edu/biolum/). However, there are harmful effects of large algal blooms to both sealife and potentially people in areas where there is a red tide. (http://en.wikipedia.org/wiki/Algal_bloom).
To my untrained eye, I’d say that the red tide that’s occurring in San Diego right now is a somewhat small – while the waves were glowing, it was nothing compared to some of the bigger blooms I have seen during the summers here. One summer when I was working at Torrey Pines State Reserve, the water turned blood red near the coast, and at night, the waves and sand sparkled with light. Compared to that, this red tide is somewhat ethereal and insubstantial. But, if you’re in the greater San Diego region (probably not much further than Oceanside), and you’ve never seen a red tide before, you should head out to the beach just after sunset, preferably somewhere with limited lights, and check it out to see the mystery of nature in action before it fades out completely for now.