What if you could spend your life sunbathing? – The upside-down jellyfish survey.

A Bermudian mangrove pond, seen from above and under the water.


pond fish

The Walsingham Pond is an anchialine pond, a type aquatic pool lacking surface connection with the open sea, but one that is permanently connected with the sea waters and thus still subject to tidal flushing.  One of the most noticeable features of the pond is the high abundance of the upside down jellyfish. They posess a symbitic algae, which perform photosynthesis. The pond is quite murky in deeper parts and thus the light penetration is limited.

The distribution of jellyfish, their abundance and size should therefore reflect the amount of light reaching the different depths.

pond map


Equipped with a sledge with a mounted GoPro camera, depth logger and a GPS we conducted a survey of the whole pond. It took us half a day of constant swimming, duck-diving and filming. But for the survey to be robust you need to put effort into it, even when it means hurting ears the day later.

Walshingham Pond

An ArcGIS plotted track. The only part of the pond not covered (SE)  is due to the loss of GPS connection.

upside down jellies

an example of a screenshot from the survey video. Shown in the middle are two individuals of Cassiopea sp. jellyfish, upside down, exposing the tentacles with algae. The analysis revealed that both the abundance and bell diameter are dependent on depth, used as a proxy for light.


About Zofia Drapella

I always seek adventures, but want them to be meaningful (usually related to science, marine biology, teaching). I so often find myself in the most amazing circumstances and incredible places with inspiring people. I genuinely consider myself to be the luckiest person in the world... I love nature, oceans, mountains, jungles. I try my best to capture what I have the privilege to see/experience and share it with others.
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