A Warning Sign of Impending Caulerpa Sporulation by Gene Schwartz

A Warning Sign of Impending Caulerpa Sporulation

I'm sure most hobbyists that have kept Caulerpa in their refugium or display tank know about or have experienced this algae's reproductive activity. "Going sexual," as we all like to call it. This has happened to me as well. I have had the displeasure of waking up to a cloudy tank three times in the past, and I assure you I definitely know what a mess it is to deal with. However, this time, I happened to document the events leading up to the event with some photographs. These photos clearly show some warning signs of the imminent sexual activity. Distinctive and noticeable changes take place in the algae prior to the release of the spores. Upon noticing these changes, a bit of quick action can head off the potential problems of sporulation.

Figure 1. This picture shows the gametangia formed on the thallus of the Caulerpa.

Figure 2. A close-up shot of the gametangia.

The night before the last time my Caulerpa released gametes, I noticed something strange on the alga and decided to take some pictures so I could ask Ron Shimek about it the next day. It turned out that I should have, instead, "gone to town" removing that alga because I woke up to a cloudy mess in the tank. In running around and replacing carbon Polyfilters® and preparing for water changes, I totally forgot that I had taken photos the night before. After I had caught up and decided to catch my breath, I remembered them and decided to look at them and post my question. It turns out that I captured some changes in the alga that were distinctive and can probably be used to forewarn of any future "Caulerpa orgies." My pictures serve as a warning to pay attention to your Caulerpa and if something similar to what I've seen is found, be sure to act quickly. I would suggest removing all the alga, as that individual or "bunch" will go sexual once the gametangia are formed, no matter what one does. Once the nuclei begin subdividing and form gametangia, the thallus, or main body of the alga will release spores and die regardless of what is done. Earlier pruning of the alga may delay or prevent gametangia formation. However, from my experience with the process, it is apparent that it cannot be stopped simply by removing part of the algae, once the gametangia have begun forming.

Figure 3. A view of the tank the morning Caulerpa serrulata went "sexual."

Figure 4. A close-up view of the Caulerpa after sporulating. Note the
discolored thallus of the algae that had released the spores.

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