Transcript Document

The increase of disease in
our ocean’s.
Case study; the Pilchard’s
Sardinops sagax of the
Southern Oceans of
Australia.
Andrew G Challingsworth Ph:[email protected]
www.aquanetplace.com.au, Deakin University.
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Abstract;
• A literature review was conducted of ‘Scientific journals’.
• To accurately assess the scientific information, on the
increase of disease in our oceans.
• We can now accurately generalize that disease
outbreaks in marine organism have increased in recent
years.
• Disease outbreaks correspond to a list of
environmental factors.
• Case study the Australian pilchard Sardinops sagax and
how changing environmental factors resulted in a
disease epidemic.
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Introduction;
• After reviewing the scientific literature.
• We can accurately assess, that disease is more
prominent in the ocean environment.
• Environmental factors are increasing disease episodes in
our oceans.
• Environmental change can interact with disease in our
oceans in many ways. (Lafferty, Porter & Ford 2004).
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• The aquatic environment needs to be thoroughly
understood.
• ‘Growth and reproduction of fishes is affected
when the environmental parameters of aquatic
environments diverge beyond acceptable limits’.
• ‘This may lead to acute or chronic disease
conditions’. (De Silva et al 2003,Topic one).
Australian Pilchard Sardinops sagax,
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Methods;
• An accurate study of our environmental factors
needs to be established.
• Environmental factors;
• Physical factors; i.e. Temperature, Light,
Dissolved Gases.
• Anthropomorphic influences/factors; i.e.
Pollution from factories, Sewage.
• Biological factors; i.e. Microorganisms,
Dinoflagelates, Blue – green algae.
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• A biopsy of the Biology of the Australian Pilchard
Sardinops sagax.
• A biopsy of the disease epidemic; (PHV) Pilchard
Herpes Virus.
Dead pilchards on a beach in Western Australia
during the mortality event in 1998.
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Results;
• Environmental factors;
• Physical factors;
• Temperature; thermal tolerance limits,
•
optimum required. (De Silva et al 2003,Topic one).
Affects resistance to disease.
Red coral, tolerance limits to temperature
change, Climate warming.
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•
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•
•
A
Light;
Increasing light levels.
Growth in unicellular algae.
Result of climate change.
B
A; Increase in harmful algal blooms 1970-1990;
‘Climate change’. (Lafferty, Porter & Ford 2004).
B; Dinoflagellate.
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• Temperature changes solubility of toxic
compounds i.e. crude oil, pesticides.
•Crude Oil: Toxicants increase susceptibility to disease
by impairing defenses i.e. mucus production. (Lafferty,
Porter & Ford 2004).
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• Heavy metals also become more toxic.
(De Silva et al 2003,Topic one).
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Physical factors affecting the
aquatic environment;
• Light
• Light and the effects of climate change with increasing
•
temperature and light levels can cause growth in
unicellular algae.
There has been a notable increase in harmful algal
blooms between the periods of 1970-1990 corresponding
to climate change. (Lafferty, Porter & Ford 2004).
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Physical factors;
• Dissolved Gases
• Excess Carbon dioxide dissolved
in water can depress fish
respiration. Global factors include
predicted rise in oceanic carbon
dioxide concentrations. (Lafferty,
Porter & Ford 2004).
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Environmental factors;
• Anthropomorphic influences
• Pollution from factories
• Heavy metals;
• In Australia Mercury and Cadmium are contaminants of
fish.
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Anthropomorphic influences
• Non-Metals;
• Biodegradation resistant organochlorine compounds are
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•
•
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toxic to fish.
Can become concentrated in the food chain DDT and
dieldrin as they are highly resistant to degradation.
Sewage
Discharge reduces water quality causes oxygen depletion
caused by microbial growth.
Nitrates and phosphates may stimulate excessive algal
blooms and leads to oxygen depletion.
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