We couldn’t believe our eyes! Hundreds of tiny dry SAND DOLLARS were folded into the weeds in the highest wrack line at Gulfside City Park Sunday evening. We saw one or two…then another… and another… and another one. Clark and I only had to walk a few yards to collect all of the these.
We knew these were not alive since they were completely dried, mostly white and had little to no “fur” on them. It was so much fun to be able to collect so many in one spot on the beach… but after walking closer to the water to see many LIVE ones in the surf, it was a bit overwhelming. Clark reached down in the water and picked up this many SAND DOLLARS in one scoop. They are all alive! You can tell by the dark color and the cilia or hairs all along their bodies (tests).
Then we started to get worried after seeing thousands of them washing up in the surf.
We could hardly find a place to walk as they got thicker and thicker in density.
Clark walked out to the sand bar and yelled back at me that they were even out there densely covering the sand.
But Dr Jose Leal of the Bailey-Matthews Shell Museum has told us before that it is natural for mass mollusk die-offs or masses of animals exposing themselves (when we had concerns about masses of FIGHTING CONCHS on the beach) in low tide situations like we are having this week with the full moon. So before we jump to any conclusions, y’all, I’m doing some research. I have been in contact with Kristie Anders and research scientist Dr. Richard Bartleson of Sanibel Captiva Conservation Foundation to find out if they might know a reason for this very unusual occurrence. Kristie said “It is possible the sand dollars are trying to move away from water that has little oxygen in it (hypoxia). The little bit of surf agitates the water and increases the oxygen much like a bubbler in an aquarium”. Dr Bartleson said he will try to get some oxygen readings this week and will let us know if that is the reason this is happening.
When I hear anything from SCCF’s research, I will update this post to let you know as well.
UPDATE: July 24, 2013- I received a message from Kristie Anders from SCCF tonight. She said… “The marine lab did salinity studies along the beach. Apparently the water releases and the rain run off from our own area dropped the salinity down to less than a third of was is tolerated by animals like the sand dollars.” So it looks like this unusual situation is because of the freshwater influx rather than the lack of oxygen in the Gulf.
But meanwhile, you can watch this little video I shot while I was in total amazement by this site…
PS- I had a big hat, long sleeve cover-up and sunglasses! I’ve figured out evenings are fine!