A Summertime Jellyfish Collection Trip

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Tommy Knowles
Senior Aquarist
Monterey Bay Aquarium

The abundance of jellyfish in Monterey Bay is well known. The bay is sometimes so thick with sea nettles (Chrysaora fuscescens) that it seems like you can walk on them. But the local sea water temperature has been slightly warmer than usual over the past year, and this has created some unusual conditions. Jellyfish seem to be seeking out colder waters. In our surface collections, we have not been able to find jellyfish as reliably as in the past. The moon jellies showed up briefly a few months ago, but they didn’t stay long. Occasionally I hear that someone saw a sea nettle, but these sightings are rare, and the jellies do not wait for me to come collect them. Perhaps they are deeper than I can see or collect, or perhaps they are offshore or in cooler waters to the north.

At the Monterey Bay Aquarium we culture jellies in the laboratory to fill most of our exhibits, but wild jellies are always great for starting new polyp cultures or for filling out an exhibit. And of course there are jelly species that we cannot culture yet, so when they appear we collect them and put them on exhibit for the public to see. So, I was very excited when a few months ago a few more jelly species began to show up again nearby.

The weather in the summertime around Monterey is often foggy & cold, and our nice “summer” days are spread out across the spring, winter, and fall, showing up for a week or two at a time unexpectedly. But much of this summer has been an actual summer—sunny, and even hot! A few Tuesdays ago was such a day, and the ocean was flat. A perfect day to search the ocean for jellyfish.

I left early, before the wind picked up, on our 19′ Boston Whaler with Mackenzie Bubel. Mac is a new jelly aquarist, but her attitude is a perfect fit for the job–serious about the work of culturing challenging species, but also laid back enough to have fun & not get too upset when something doesn’t work out.

We headed west from the aquarium past Point Pinos, the southern edge of Monterey Bay, and turned south. We cruised past the world famous golf courses of Pebble Beach until we reached Cypress Point, the western-most tip of the Monterey Peninsula and a place where an abundance of jelly species can sometimes be found. One of our collectors, Kevin Lewand, is always scouting for us, letting us know which jellies are showing up where. Kevin had seen “a little bit of everything” while diving at Cypress Point a few days earlier, so we headed down there to see what we could find.

At first, we found nothing. The boat ride down to Cypress Point is a long one, so coming back with nothing would have been quite a disappointment. On the way down, we had stopped at a few promising slicks—strips of calm water where plankton and jellies may collect—but all we saw was clear, black water. No jellyfish. And now, there was more of the same at Cypress Point. However, I recalled that when, a year earlier, I had made the trip to Cypress Point in much less favorable sea conditions looking for Egg Yolk jellies for culturing, we had also encountered empty slicks at first. However, as we ventured in closer toward the canopy of giant kelp, we found the jellies we were looking for.

Mac & I steered the Whaler east & turned our search closer to shore. Sure enough, just as we entered a slick on the edge of the kelp canopy, we began to see jellies. Specifically, the delicate Cross jellies (Earleria cellularia). We can culture this species, but the wild, adult medusae also have very good longevity in our 10ºC exhibits. These medusae were quite large (7 cm), and, if collected carefully, they could nicely fill up the window of an exhibit. The medusae were spread out enough that we had to spend an hour or so patrolling the slick, but eventually we had collected enough to stock an exhibit.

After a while, we came across several Egg Yolk jellies as well. This species can grow to a rather large size, but some of them were more medium-sized—around 20 cm—the perfect size for our exhibit. This find was especially fortuitous since my nice, cultured Egg Yolks had just recently been eaten by the screen in the exhibit, and I was currently relying on some back up animals that were a little less impressive. We collected 5 wild Egg Yolks that will do well in the exhibit until I am able to grow up new, cultured Egg Yolks in the lab.

Egg Yolks are the top medusivores in our area. They eat all the other jellies. In fact, they were eating loads of Cross jellies when we collected them. Mac and I were very pleased to be returning to the aquarium with full buckets of jellyfish, especially since days like this have become less frequent in recent months. But the arrival of the Egg Yolks also means that the other jelly species could disappear, becoming Egg Yolk food until their polyps release another bloom. We hope that those blooms come soon.


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