Tidal Flushings & Algal Bloom



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Naturally Decomposing Coralline Algae Reappears

If you have surfed, swam or walked the shores in Cardiff-by-the-Sea lately, you might be wondering, What is that smell?  Seaweed in the lagoon’s inlet is doing its thing — decomposing — and creating a sulfur-like scent.

Click on the previously recorded video below to learn more about this naturally occurring event with Doug Gibson, Conservancy Executive Director and Principal Scientist:

Kelp and red corraline algae often get pushed into the inlet. Once it gets in here, it settles out and starts to decay. When that happens, it creates hydrogen sulfide or an egg smell. Like other algal blooms, this will soon dissipate. The water is safe. If you want to take a look at the natural process, come down to the inlet and see the algae.

Decomposing kelp, and red coralline algae (Calliarthron sp.), in the lagoon inlet channel

Graceful wetland birds, like the Great Blue Heron, wade through the algae at the inlet in search of a next meal.

The next full tidal flushing will begin on Friday, September 7 during a series of 6′ and higher tides. Neighbors can expect nighttime lighting during this tidal flush, nearest to the temporary dike, located in front of the nature center. This weekend’s flushing should help dissipate some of the decomposing algae.

Come out to the trails this weekend to view the full lagoon flushing. A great vantage point is from the overlook at Annie’s Canyon Trail or the Gemma Parks Loop off Rios Avenue Trail.

View from Annie’s Canyon Trail, approximately 200-feet above sea level. Notice the new mudflat in the middle of the channel.

*This post was adapted from the May post: Natural Ocean Events at the Inlet and the Beach.

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