At Surface Value

The next time you are at a marina, don’t just admire the vessels on the water. Look also at the pontoons that serve as docks for yachts and small boats!

Besides “housing” boats, pontoons provide shelter for a variety of marine organisms. The submerged sides of pontoons provide homes for immobile life forms near the water’s surface where light can penetrate more easily than at greater depths. The immobile life forms in turn serve as habitat for mobile organisms. Thus, the pontoons create conditions for a variety of marine life to thrive.

The seawalls of marinas are also ideal for the establishment of marine organisms. The cracks and crevices on the seawalls provide stable places for marine plants and animals to attach themselves to and grow.

Find out more about the variety of unique organisms that can be found just beneath the water’s surface in our City in Nature.

One of the best-known kinds of surface marine life, seaweed is found throughout our marinas. Green seaweeds, like the species that we consume, can actually be found in a diverse array of forms. While some have soft tissue, others have a more rigid structure due to calcium in their cell walls; some have smooth edges while those of others are serrated. They also come in a variety of shapes, with some even resembling grapes.

It may surprise some to know that species of red seaweed contain chlorophyll and are able to photosynthesise. Compared to their green counterparts, however, red seaweeds contain additional pigments that allow them to be better adapted to lower light levels. Hence, they can be found not only in shallow bright areas near the water’s surface, but also in deeper waters where green seaweeds may not survive.

Soft corals, as their name suggests, are soft and flexible. Unlike hard corals, they do not have a stony skeleton and this allows them to sway beautifully with the current. When exposed to air, they flop over and often look deceptively like a pile of jelly. In fact, soft corals are relatives of jellyfishes, belonging to the phylum Cnidaria.

The most common soft corals found in our marinas belong to the family Nephtheidae. These flowery soft corals come in bright colours such as cream, yellow, orange, brown and pink. One such example is the bushy looking soft coral, a species of Dendronephthya. Its vivid pink colour makes it hard to miss as it stands out against the background. What is easier to miss are the small brittle stars or crustaceans that are often found hiding and seeking shelter among its branches!

A wide variety of sponges can be found in our marinas, adding vibrant colours and textures to the otherwise dull-looking pontoons and seawalls. Sponges feed by filtering plankton from the water and, in doing so, improve the water’s clarity.

One of these, Lendenfeldia chondrodes, is a sponge that forms a layer over coral rubble and is often seen on our southern shores. Like icing on a cake, this sponge has a glossy, smooth but rubbery texture. Sometimes it can also exist as irregularly shaped knobs, folds or lobes.

Sticky Stingers

Frilly Sea Anemone     

Dancing Ribbons

Pseudoceros sp.