01 May 2013

Mangrove and freshwater bryozoans on Singapore's northern shores

A large team explores Lim Chu Kang mangroves to find the intriguing amphibious bryozoans that Dr Dennis has told us about during the Bryozoans and Hydroids Workshop.
We also stopped by Kranji Dam to find freshwater bryozoans. We had a great time with astonishing finds!

We met literally at the end of Lim Chu Kang Road. If we went any further, the car would drown!
Just a short time into the trip, Kwan Siong (in red) found the first amphibious bryozoan! After the search image is imprinted, everyone found lots of them! The bryozoans are found on living leaves and are often high and dry and only submerged at high spring tide. That is why they are called amphibious! We found them on many Avicennia rumphiana leaves with one on Avicennia alba.We checked but didn't find them on Sonneratia alba saplings growing low in the intertidal. In Australia, they grew on Rhizophora stylosa leaves.
This bryozoan was first discovered in Darwin, Australia when someone who was studying everything that grew on mangrove leaves sent specimens to Dr Dennis. He was really keen to seen some in Singapore.
Here's what the amphibious bryozoan looks like under the microscope. Dr Dennis explains it is usually covered in a fine layer of silt and it takes a lot of care to remove the silt without damaging the delicate zooids. The silt probably helps to prevent the bryozoans from drying out when they are not submerged. Read more about Amphibiobeania epiphylla in the paper by Dr Dennis.
Photo by Kwan Siong on facebook.
Soon after, Philip (in maroon shirt) found a small plank and Dr Dennis declares that the bottom is covered in all kinds of bryozoans! After that, we all started finding bryozoans under planks too.
Here's some of the bryozoans we saw. Dr Dennis also found some growing on a Mangrove horseshoe crab!
There were lots and lots of these tiny sausage-shaped bryozoans on everything from rope to litter, to roots. Lim Chu Kang is indeed full of mangrove surprises. My last trip here was in Apr 2011 with Dr Daphne when we saw lots of Bill, the unknown sea anemone.
Thrilled by our success in the mangroves, we decided to make a short stop at Kranji Dam to see if we could find any freshwater bryozoans.
Just a short time stomping around the water's edge looking at plants and stuff soaking in the water, Dr Dennis found some freshwater byrozoans! Since none have been recorded before, these would be new records!
Here's what they look like, growing on a leaf.
It's amazing what we can find if we know what to look for. We couldn't wait to have a closer look at our finds in the lab sessions in the afternoon.


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