LAPEROUSE

Yesterday’s choppy conditions produced an extensive amount of foam in Botany Bay with Algal Bloom like patches being observed around Congwong Bay, Bare Island and into Frenchman’s Bay. The patches of brown material seen in the photo above are concentrations of organic matter (likely broken up macroalgae) mixed with the foam and forming the scum lines.

Samples were collected by local resident Charles Abela and given to Tim Ingleton, Marine Biologist and phytoplankton expert with  the Department of Environment, Climate Change and Water, for analysis.  The Department confirmed that in this instance it was only foam not an algal bloom.  But Algal Blooms have occurred on other occasions. The Department gets about 10 to 15 calls a year to examine potential Algal Blooms.  Botany Bay has had its share of these species like Noctiluca scintillans and the particularly toxic Alexandrium catenella.

When there is a bloom of Noctiluca swimming should be avoided because it may cause skin irritations.  Noctiluca use ammonia for buoyancy which they accumulate more and more of as they get older, rising to the surface and then getting effected by winds and surface currents and thus are brought into beaches and embayments where the public swim or fish and become ‘visible’ accumulations or blooms.  In November 2004 Alexandrium was observed, resulting in the closure of some of the beaches in Botany Bay.  The Bay is particularly vulnerable to the introduction of new toxic species because of international shipping - see Invasives Species Council information on Ballast.

Historically, blooms of potentially harmful algal species (HABs) have been infrequent in NSW marine waters.  The greater threat has been the blue-green algae in freshwater systems.  Safe Foods NSW  conducts regular testing in conjunction with shellfish farmers to monitor for HAB for public health consumption. Otherwise there is no regular monitoring of phytoplankton and HABs for NSW estuaries and coasts.

For recorded information on algal alerts telephone the Algal Information Line on 1800 999 457To report suspected algal blooms during business hours, please phone the respective Regional Algal Coordinating Committee (RACC) Technical Co-ordinator in your area of the state. (The RACC is administered by The Department of Water )  If they are not available please contact the secretariat, media officer, the Statewide Algal Technical Advisor and then the Statewide Algal Advisory Group Secretariat, in that order. Metropolitan and South Coast Regional Algal Coordinating Committee - Technical Co-ordinator (Teresa Rose): ph (02) 6452 1455 or 0407 924 354;Alternative: Lee Bowling ph (02) 9895 7466 or 0448 091 982

To report suspected algal blooms at all other times (state wide), please phone the Environment Hotline: 131 555

Marine algal blooms are a common natural phenomena along the NSW east coast and can result from upwelling of colder nutrient rich water. Studies from a long term coastal station off Sydney found that marine phytoplankton blooms appeared to correspond with upwelling/uplifting or slope water intrusions lasting 2 to 22 days and occurring from September to February.

Nutrient fluctuations as a result of anthropogenic changes can also influence the presence of algal blooms and species succession and may even influence when toxins are generated. Marine blooms may threaten fish resources, human health, ecosystem function and recreational amenity of beaches and bays. Marine algal blooms fall into the classes of:

• BACILLARIOPHYCEAE (diatoms)
• DINOPHYCEAE (dinoflagellates)
• PRYMNESIOPHYCEAE (golden–brown flagellates)
• CHRYSOPHYCEAE (golden–brown algae)
• RAPHIDOPHYCEAE (chloromonads)
• DICTOCHOPYCEAE (silicoflagellates)
• CYANOPHYCEAE (marine blue–green algae) (Hallegraef,1991).

Marine algal blooms can appear as red water discolourations commonly referred to as ‘red tides’ or a range of other discoloured water, from green, yellow and brownish to an oily or milky appearance. These algal blooms are commonly mistaken by the public for sewage or some other form of pollution. Other blooms can show no discolouration but be highly toxic at low levels. It is important that samples of marine algae are analysed, as relatively harmless algae and potentially toxic algae cannot be differentiated by the naked eye. However, some nuisance red tide blooms can be differentiated in the field by the trained eye or easily identified by microscopy. This includes Noctiluca scintillans, a dinoflagellate, that is easily identified under a crude microscope due to its size and distinct balloon–like shape.

Similar to freshwater blue–green algae, some estuarine and marine algal species produce irritants that can cause respiratory irritation and severe contact dermatitis. The major route for human exposure is through consumption of seafood and shellfish as some species produce potent toxins that can be accumulated in fish and shellfish. Even low densities of toxic algae may be sufficient to cause illness or death in humans, while some species can selectively kill fish by inhibiting their respiration. Not all potentially toxic algal species are toxic in every situation.

Although the distribution of marine and estuarine algae is uncertain in Australia , the number and intensity of marine algal blooms is believed to be increasing world–wide due to:

• Expansion of aquaculture in coastal areas
• Coastal eutrophication and unusual climatic conditions
• Movement of shellfish stocks and transport of resting cysts in ballast water.

Unlike freshwater algal species that may be present for extended periods and normally occur where water movement is minimal, marine algal occurrence responds to nutrient enrichment, water circulation such as tides and currents, and wind patterns. As such, their occurrence is often short–lived in a particular area and difficult to predict.

Excessive input of nutrients from land and fresh water is one of the strongest factors promoting bloom development. Implementation and enforcement of comprehensive and integrated coastal management plans to control nutrient discharges at point sources (rivers, pipes and drains) and from diffuse sources will reduce the potential for algal growth andf ormation of blooms.  It is now well recognised that it is important to control and manage the transport of exotic toxic phytoplankton species via ship ballast water.  For details on Health Risks:  Guidelines for Managing Risk in Recreational Waters

Algal blooms can cause significant operational issues for Desalination plants resulting in increased chemical consumption, increased membrane fouling rates, and in extreme cases, a plant to be taken off-line. Early algal bloom detection by desalination facilities is essential so that operational adjustments can be made to ensure that production capacity remains unaffected.  (see studies such as “Harmful algae and their potential impacts on desalination operations off Southern California’, D.A. Caron et al)  Reference in the Sydney Water Desalination Environmental Assessment

For more information on modelling risks from the DECCW website: Coastal eutrophication risk assessment tool

Seabed habitat mapping

This entry was posted on Thursday, January 21st, 2010 at 12:12 pm and is filed under Environmental Action, Research. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.