06 October 2008

Preventing 'Red Tides' at Shelly Beach, Manly

Shelly Beach is a small sheltered beach, facing Manly Beach. A coastal walkway, leads along the Cabbage Tree Bay Tree Aquatic Reserve to Shelly, which has one of the few small unbuilt headlands with native vegetation on it. Some of original cabbage tree palms were replanted as they once fringed the watercourses leading to the beach. The headland leading back to Manly beach has been undergoing intense development for years. The beach facilities are also under intense demand.

Dead Fish, how come?
Last week (02 & 03.1008) many dead puffer fish and a moray eel were washed up on Manly beach. We assume, these 'cave dwellers' were from the 'Aquatic Reserve'. On the 051008 the first blooms of an apparent red tide was visible at Shelly Beach. On the 021008 "a mysterious red sludge", believed to be red algae bloom was found on a beach in the Manly area, at Clontarf.(Image)

Nice Beach as a drain, growing harmful bacteria?
The walkway from Manly beach to Shelly beach along the aquatic reserve is studded with old, often decayed pipes of all sizes, draining the dense sub-urban development on top of the headland, down into the little bay/'reserve'. The mossy green rocks are the sure-sign for 'rich run-off'. The little creek behind the restaurant, has spaghetti-like pipes all leading into it and straight into the beach. Most of the properties, strain to grow water and nutrient intensive foreign vegetation. A large paved car park on top of Shelly, is increasingly denuded, leading to even more run off. Numerous dogs on the beach and unleashed along the walkway help to contribute their untreated feces into the adjacent cabbage bay aquatic reserve. Sydney on the whole “dumps a billion liters of sewage into the ocean every day...” (Maude Barlow, Blue Covenant, 08 p28.) Habitat degradation, generous run off and extreme warming of the atmosphere and the ocean is a guaranteed recipe for 'red tides', then harmful algea (HABs), then hypoxic or 'dead zones'. The beaches become at first unusable, smelly and might irritate the skin and eyes. Later, even just breathing the 'mist' can cause health problems and fish suffocate in the oxygen-deprived sludge, “fish-kill” (video). Marine species have their central nervous systems attacked by the poisons generated by the bacteria and also seek to 'leave the ocean' gasping for oxygen. Marine mammals, such as humpbacks are also poisoned and 'beached'. 'Food-species' can become deadly to fish, shellfish and people. Sea and shorebirds fall out of the sky(pdf). The stench would repel any visitor, closing beaches becomes very costly for the human economy. Rehabilitating the ecology of a 'dead zone' is usually left for the next generations.

Beyond denial - Doing something against the red tide
Elsewhere environmental groups are enforcing measurable standards to prevent the fouling of their beaches."..To set numeric limits on the excess nutrients which trigger harmful blooms of blue-green algae...Blue-green algae - also known as cyanobacteria - produce "dermatoxins" that can create severe dermatitis and are known tumor promoters; "neurotoxins" which interfere with nerve cell function; and "hepatotoxins" which attack the liver. Exposure to blue-green algae toxins through ingestion, skin contact or inhalation can cause rashes, skin and eye irritation, allergic reactions, gastrointestinal upset, serious illness, and even death..."
Their drinking water" is now subject to almost year-round blue-green algae blooms as a result of nutrient pollution"

It is too dear to not act
The red tide algae, Karenia brevis, "costs approximately $20 million per bloom in economic damage off the coast of Florida alone." The beauty of a beach is lost forever.

Ocean Care includes the acknowledgement of eutrophication, it seeks to alter the behaviour of individuals and the authorities bestowed with the stewardship of an biome and urban planning.

1. Shelly Beach, Google Maps, 2008
2. The walkway from Manly Beach to Shelly beach along the Cabbage Tree Bay Tree Aquatic Reserve on the one hand and the suburb on the other, Google Maps, 2008
3. Shelly Beach looking back onto the walkway with thick s
treakes of 'red slime' 051008
4. Shelly Beach with 'red slime'', with view to Manly Beach opposite

Red Tide 11.2010: North Head images, 1 & 2,

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