Mud, sludge, dredge, blubber… sometimes we try as much as we can to avoid touching this suspension of clay, silt, and water, sometimes we put it on our faces and claim that it is healthy for our skin. Well, one thing is for sure, the muddy soils in Sungei Buloh Wetland Reserve (SBWR) are healthy for the mangrove ecosystem! On the Mangrove Boardwalk in one of the last mangrove ecosystems of Singapore, you can take a close look at the creatures that actually build their homes in the muddy tidal creeks. The most interesting animals hiding in the mud of the reserve are the mud lobster (Thalassina gracilis and anomala) and the tree-climbing crab / mangrove crab (Episesarma singaporense). These crustaceans help to sustain the soil of the Singaporean mangroves.

Figure 1, The observation site where I spotted tree-climbing crabs and homes of the mud lobster.

The altered map is derived from https://butterflycircle.blogspot.com/2019_09_14_archive.html

Nowadays, almost 95% of historical freshwater forest wetlands in Singapore is lost due to urban development and land use change. Fortunately, there are quite some techniques that help us to restore heavily degraded mangrove forest areas, and some of them are natural! A few examples of key factors to measure and calculate in order to develop a restoration are:

The amount of daylight coming through the canopy of a specific area (A healthy mangrove forest should only let 20% of the sunlight through. A thick canopy controls the water temperature and provides organic nutrients for the soil.)

The quality of the water (By measuring the salinity and acidity, it can be determined how well the trees will be growing and wat kind of fish and other animals are housing in the muddy water.)

The biodiversity of a specific area (Supports the whole ecosystem)

The composition of the soil (A healthy soil means that the plants are able to develop better and that the plants in turn provide more organic matter that animals can consume.)

 

By focusing on one of those key factors, a starting point for a restoration project can be established. For example, you can ask yourself, “How can the soil composition remain healthy or even be improved?” And surprisingly, you can find the answer in nature itself:

The mud lobster (Thalassina gracilis and anomala) is an endangered nocturnal species (according to the Singapore Red Book 2008) that lives deep under a mound in a U-shaped tunnel. His house plays a key role in sustaining the mangrove soil and it can be recognized by mud castles that can grow up to 2 meters!

Figure 2, A mud lobster

Photo credit: Ria Tan, 2018 https://wildshores.blogspot.com/2018/01/mud-lobsters-condo-developers-in.html#.YzOppnZBy38

Figure 3, A mound of a mud lobster seen in the intertidal area of SBWR. Plants are growing on top of it.

Photo credit: Joël Moens, 2022

By eating mud, the lobster recycles nutrients from 2 meters depth and brings it up to the surface. Animals and plants feast on these nutrients and the lobster’s dry mound makes a perfect home for plants.

Besides that, the lobster’s digging also loosens the mud and brings oxygenated water into the pores of the soil. They are the farmers of the mangrove soil!

The same applies for the tree-climbing crab (Episesarma singaporense). This species forages for leaf litter in the mud of the Mangrove Boardwalk, oxygenizes the soil and plays a vital role in nutrient cycling. The most fun fact about this crab, is that it can be seen climbing up the mangrove trees at SBWR during high tide! After the tide lowers, new organic material becomes food for the crab.

Figure 4, tree-climbing crabs at SBWR during hight tide

Photo credit: Joël Moens, 2022

Figure 5, tree-climbing crabs at SBWR during hight tide

Photo credit: Joël Moens, 2022

Unfortunately, the lobsters and the crabs are affected by human activities such as land reclamation and pollution. If we keep expanding the urban areas, we might lose not only our crustacean friends, but also their mud and sand condos, and the plants and the animals that are living on it. Only by retaining extensive areas of Singapore’s mangroves, we can conserve these species. So let’s stop invading the land of mud castles, to keep the soil healthy in a natural way!

Written by: Moens Joel Lorenzo

References

Commander. (2019, September 14). Butterfly Photography at Our Local Parks Featuring : Sg Buloh Wetland Reserve (Migratory Bird Trail). Butterflies of Singapore. Retrieved October 2, 2022, from https://butterflycircle.blogspot.com/2019_09_14_archive.html

Loo, J. (2005, February 1). Sungei Buloh Wetland Reserve | Infopedia. Singapore Infopedia. Retrieved October 1, 2022, from https://eresources.nlb.gov.sg/infopedia/articles/SIP_566_2005-02-01.html

Species List (Red Data Book List). (n.d.). National Parks Board. Retrieved October 1, 2022, from https://www.nparks.gov.sg/biodiversity/wildlife-in-singapore/species-list

Tan, R. (2018, January 30). Mud lobsters: “Condo Developers” in the Mangroves. Wild Shores of Singapore. Retrieved October 1, 2022, from https://wildshores.blogspot.com/2018/01/mud-lobsters-condo-developers-in.html#.YzOppnZBy38

Tan, R.,Tree climbing crab (Episesarma) on the Shores of Singapore. (2019, December) Retrieved October 1, 2022, from http://www.wildsingapore.com/wildfacts/crustacea/crab/sesarmidae/episesarma.htm