Magnetic Island

The Arcadian village bays, Alma and Geoffrey, face east and south respectively into Cleveland Bay and are home to a community of around 250 residents. Arcadia is one of only 4 communities on Magnetic Island with a combined population totalling approximately 2,300. However, the population of Arcadia swells substantially during holiday periods, particularly during the dry season from around Easter through to the September school holidays. Tourism and environmentally-based recreational activities are the major drawcards to the island. Walking trails from Arcadia lead both to Nelly Bay and Horseshoe Bay via the Forts walk. The dry season is also the most comfortable of the two seasons – wet and dry. Magnetic Island and its surrounding waters are all part of the Great Barrier Reef World Heritage Area. Most of Magnetic Island is designated as National Park.

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View overlooking Arcadia village. Alma and Geoffrey Bays face into Cleveland Bay, with Cape Cleveland in the background.

Alma Bay undoubtably provides the best and safest swimming of all the more easily accessible beaches on Maggie. Swimming and snorkelling amongst the corals, abundant fish and occasional turtle along the rocky edges of the bay can be an absolute pleasure when the water is calm and clear, and the tide is low. While marine stingers are present around Maggie during the wet season, from around November to March, Alma Bay seems to miss out on most of them and the risk of being stung here is relatively low. The main currents that transport the jellyfish largely bypass this small bay. Nevertheless, it is wise to use a stinger suit or other form of protection when entering the water during this season. Stings can be very painful and life-threatening, depending upon the species.

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Alma Bay at low tide.

Geoffrey Bay, in contrast to Alma, is a long open bay with an extensive reef protecting the beach. The reef edge has some of the best snorkelling around the island and the reef flat has a diverse assemblage of marine organisms. Swimming over the reef flat is really only possible on the high tide. I find using a kayak as a base or platform is a good way to explore and snorkel along the reef front where the best coral can be found. The wreck of the Moltke, a three-masted barque built in Hamburg, Germany in 1870, lies submerged at the eastern end of Geoffrey Bay and is now a popular dive and snorkelling site. It is one of twenty known shipwrecks around Magnetic Island.

For over 30 years I’ve been keeping a professional eye on this reef. In the early 1980s, as a student of marine biology, I spent many hours running transects over the reef flat at Geoffrey Bay. I recall an abundance live coral and other invertebrates, such as molluscs, starfish and crustaceans. Along the reef edge there were large stands of branching staghorn coral, Acropora formosa. The condition of the reef has clearly deteriorated since then, live coral cover over the reef flat is greatly reduced, although it is still a vibrant wonderland. The most significant impact over this period was from the 1998 El Niño event and associated mass coral bleaching. This bleaching event, caused by global warming and elevated water temperatures, killed the more vulnerable species of hard coral. Virtually all Acropora species of hard coral were killed off, but as of 2016 this group of corals had recovered nicely and they are once again abundant over the reef, except for the large stands of Acropora formosa. Video footage of reef status and coral recovery taken in 2014, fifteen years on, can be seen by clicking here. Reef recovery after the 1998 bleaching event has undoubtably been slowed by poor water quality from coastal river runoff and suspended sediment from the constant maintenance dredging for the Townsville port. Plumes of sediment, suspended by dredging, are transported over the reef when currents are favourable. Dredged sediment is also dumped in Cleveland Bay and resuspended during strong winds and storms. Coral distribution and abundance over the reef flats of inshore reefs is known to be controlled by factors such as sedimentation and water movement, and therefore it should not come as a surprise that increased sediment loads are affecting the health of reefs such as Geoffrey Bay. Further bleaching events as a result of climate change and additional dredging for a proposed port expansion in Townsville pose major threats to the future health of Geoffrey Bay reefs.

The wet season, while less comfortable because of the heat and high humidity, provides its own delights. Storms can cause major disturbances and shoreline change during the wet season, eroding the beaches and flushing sediments out of the creeks. Water clarity is greatly reduced during this season. But on land, the the normally dry creek beds flow swiftly during most years, providing swimming holes and a reprieve from the heat. The island vegetation comes to life again with the onset of the rains.

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