The crystal clear waters of beautiful Jervis Bay. Photo: Franklin Dattein.

Many of us have heard of Jervis Bay. It’s a beautiful, quiet beachy area with crystal clear water 3 hrs (180km) south of Sydney and 20km southeast of Nowra. It’s home to the Jervis Bay Marine Park which spans over 100km of coastline and adjacent ocean extending from Kinghorn Point in the north to Sussex Inlet in the south. This marine park was established in 1998.

Jervis Bay Marine Park houses a range of habitats because of the unique current conditions that affect the area. Warm waters travel south in the East Australian Current into the park and cooler waters flow north from the Bass Straight into the park. These waters enter Jervis Bay near Bowen Island and flow in a clockwise direction around the bay. On average it takes 24 days for the waters to travel out of the bay near Point Perpendicular, but sometimes it can happen in as fast as 7 days.

Hundreds of Species of Plants and Animals

There is a unique mix of tropical and temperate species, including the weedy sea-dragon, the big bellied sea horse, the eastern blue devil fish and crowd favourites like whales, bottlenose dolphins, little penguins and fur seals.

Tourists flock to the otherwise serene area to watch whales, dolphins and other wildlife. Humpback and southern right whales pass by on their seasonal migrations, and sometimes enter the bay to rest. About 60 bottlenose dolphins also frequent the area, swimming and feeding around the perimeter of the bay. Common dolphins can often be seen in the deeper ocean waters beyond the bay. There are also a number of endangered grey nurse sharks.

A zoning plan protects the valuable plant and animal populations while still allowing people to have a lot of fun too. Locals, tourists and holidaymakers alike love the area for boating, fishing, kayaking, scuba diving, snorkelling, swimming, surfing, and beach walking.

This beautiful marine park is home to more than 230 species of marine plants and hundreds of species of invertebrates. Over 216 species of reef fish, sharks and rays also can be found around the shallow reefs. Harmless Port Jackson sharks, one of the oldest known sharks still living, breed among the shallow reefs and seagrass beds. Hundreds of their empty egg cases can be found washed up on the bay’s shores at the right time of year.

The Secret of the Crystal Clear Water

So what’s the secret of Jervis Bay’s crystal clear blue water? The answer is seagrass beds. Not only do they provide food and shelter for many fish species, but the seagrass also helps to stabilise the sediment so that the water rarely looks muddy.

Runoff from the land containing fertilisers can cause ‘blooms’ of algae to grow in water. Algae, pesticides, pollution and chemicals can settle over seagrass beds and slowly smother them. This results in fewer areas for fish to feed, shelter and breed, and has a flow on effect to the rest of the ecosystem. Always be careful to dispose of chemicals and fertilisers thoughtfully as they could eventually end up in the ocean and damage marine ecosystems.

The seagrass meadows and mangrove forests of the Jervis Bay Marine Park are protected so that the numerous plants and animals that live there remain safe. It is also important that boats within the park avoid travelling over shallow seagrass beds and travel slowly so as not to erode the banks. Visitors to the park should take their rubbish away with them when they leave, and pick up rubbish they see. Rubbish isn’t just ugly – it’s dangerous to animals. A single plastic bag can last for up to 1000 years if it enters the ocean, and could claim many animal victims before it finally breaks down.

All plants and animals depend on the health of the total ecosystem to survive. By taking care of the marine environment you can make sure they will be there for future generations to enjoy too.

Foundation Projects

2010 Marine Science Grant Recipient - Studying Jervis Bay Marine Park

Congratulations go to Gwenael Cadiou, a PhD student of the University of Technology Sydney (UTS), who was awarded the Foundation's 2010 Marine Science grant, valued at $7000. Gweneal will be working in the beautiful Jervis Bay Marine Park, examining fish movements in order to understand the connectivity between habitats in and out of sanctuary zones.

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