Seahorses return to Sydney swimming baths

Seahorses that were temporarily moved to accommodate sea bath renovations will soon make a comeback.
By Amanda James November 26, 2010 Reading Time: 2 Minutes

A SEAHORSE HAVEN IN Sydney Harbour will soon flourish again, after the colony was temporarily removed for renovations to historical swimming baths.

White’s seahorse (Hippocampus whitei) – which ranges in colour from creamy white to caramel, and can sport brown polka-dots – is native to Watsons Bay in Sydney’s east and has decorated the shark nets on the rim of the baths for decades. It is a protected species in NSW waters and can be found from Sydney Harbour to Port Stephens.

“It is believed that the seahorses have been living in Watsons Bay for close to 6000 years, when the sea level rose and stablised,” says marine biologist Will Jones from the Marine Discovery Centre at Bondi, Sydney.

According to Will, the seahorses have adapted over millions of years to live in shallow, rocky reefs. Shark nets can act as an artificial replacement for these reefs, so 6 m-high shark nets have been strung between two piers enclosing the swimming areas, offering an even larger habitat for the seahorses than before.

More seahorses will find a safe habitat along the nets now, and the population could grow. “[The nets] give the seahorses a vertical home as well as keeping them safe from predators in the sea grass,” says Dave Thomas.

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The local municipal council called in conservation group Eco Divers, founded by scuba diver Dave, to relocate the seahorses from the old shark net prior to renovations.

Before the renovation to increase the size of the swimming area began in April 2010, Dave and his team painstakingly collected the seahorses from nets. They moved them to an area just outside of the swimming baths, where they could live undisturbed until the work was completed.

In time, the new nets will become coated in algae, which will attract a succession of creatures to the man-made habitat, including seahorses. “The final thing that comes along is a diver who’s attracted to that kind of environment,” says Will.

It could take up to a year for the algae to become plentiful enough to provide a comfortable home, but they are leaving the seahorses to find their own way back, says Dave. “Since the seahorses prefer a net with an algal cover, it could be until next summer before [that happens].”

Artificial habitat

“This brings up the interesting question of whether or not adding an artificial habitat draws the seahorses away from their natural areas, or whether an additional habitat enhances their numbers,” says Tim Glasby, a marine ecologist at the Port Stephens Fisheries Institute. “It’s likely to be the latter.”

There are also plans to reintroduce captive-bred seahorses from the Sydney Aquarium to the area around Watsons Bay Baths, says Dave. Other conservation measures include the installation of floating pontoons which provide a convenient entry and exit point into deeper water away from the sea grass, reducing the need for bath users to walk over marine life.

The Watsons Bay Baths will reopen to the public on 10 December 2010.