Environmental and economic impacts
in the event of an oil spill
This chapter examines the potential economic and environmental impacts
on the Great Australian Bight in the event of an oil spill.
The capacity to mitigate the effect of an oil spill is discussed in
Oil spill modelling
Oil spill modelling is crucial to understanding the potential impact of
an oil spill on the surrounding natural environment, local industries which
rely on the marine and coastal environment, and nearby communities. This
section provides an outline of the results of oil spill modelling conducted for
BP's proposed drilling in the Great Australian Bight.
Modelling commissioned by The
BP submitted its Environment Plan to NOPSEMA for approval on 1 October
2015. At that time, the company had not publicly released any oil spill
modelling which would demonstrate the impact of a potential spill in the Great
Australian Bight. As a result, The Wilderness Society commissioned Mr Laurent
Lebreton, an independent consultant, to conduct a stochastic analysis
of deep sea oil spill trajectories in the Great Australian Bight.
Mr Lebreton's analysis considered a range of potential incidents
including an 'optimistic' scenario of 5,000 barrels of oil per day being
released, and a 'pessimistic' scenario of 50,000 barrels of oil per day being
released. The model also utilised a 'conservative worst case' spill duration of
87 days based on the time it took to cap the Deepwater Horizon spill and an
optimistic scenario of 35 days based on BP's publicly stated ability to cap
wells within 35 days.
The numerical model predicted that 'regardless of the oil spill
scenario' it is 'predicted that at a minimum, there is a 70 per cent to 80 per
cent likelihood of oil droplets reaching the Australian coastline'.
It also predicted that if an oil spill occurred in summer then oil would very
likely impact the shores of Western Australia, reaching as far as Albany and
Denmark. If an oil spill were to occur in winter, then the model showed that
oil would very likely impact the Eyre Peninsula, Kangaroo Island, and Spencer
Gulf in South Australia. Further, it was predicted that it could also reach
much of the Tasmanian and Victorian coastline, through the Bass Strait towards
Mr Lebreton's modelling was referred to by a number of submitters
who raised concerns with the potential impact of an oil spill in the Great
Australian Bight. However, it was also criticised by other organisations.
Release of BP's 'worst credible
case' oil spill modelling
In September 2016, BP publicly released 'worst credible case' oil spill
modelling it had conducted for the proposed Stromlo-1 and Whinham-1 wells.
This modelling utilised a 149 day oil release scenario based on BP's assessment
that it would take this long to drill a relief well to permanently stop a
blowout. The scope of the modelling examined the potential risk of exposure to
the surrounding waters, and contact with coastlines during three distinct
seasons. Namely, summer (October to March), transitional periods (April and
May), and winter (June to September).
Table 5.1 below contains a summary of BP's modelling. It shows the
probability of moderate shoreline contact in each of the modelled seasons, and
at a number of key locations. It shows that if there is an oil spill it may
reach as far as the New South Wales South Coast, Tasmania, and the coast of
Table 5.1—Modelling showing probability of
moderate shoreline contact
|| Probability of moderate shoreline contact (%)
| Port Lincoln
| Kangaroo Island
| Great Australian Bight Marine National Park
| Esperance (WA)
| Apollo Bay and Wilsons Promontory (Vic)
| New South Wales South Coast
BP, Fate and effects oil spill modelling assumptions, parameters and results,
14 September 2016, pp. 14–15.
Economic impact in the event of an oil spill
Oil spill modelling demonstrated that coastal communities and industries
which rely on the marine environment would be affected in the event of an oil
spill resulting from activities in the Great Australian Bight. Some submitters
argued that any potential economic benefit of offshore oil or gas production in
the Great Australian Bight must be weighed against the risk to other industries
such as tourism, aquaculture and fisheries, in the event of an oil spill. The
City of Victor Harbor stated that 'an oil spill within the Bight may represent
a low occurrence risk, however such an event would represent a potentially
catastrophic consequence risk'.
In considering the effects of an oil spill in the Great Australian Bight,
the South Australian Oyster Growers Association (SAOGA) questioned who would be
'responsible and what is the capacity to support industries impacted by oil
spill event(s)' especially if impacts extend for long periods of time. It submitted
that in the event of an oil spill:
Compensation for impacted businesses must be immediately
available (not after lengthy legal proceedings) and must include consumer
perceptions in the situation through and following a spill (the experience of
seafood producers and harvesters in the Gulf of Mexico was that consumer
perceptions were still prevalent years after the product was officially cleared
Ms Trudy McGowan, Executive Officer of SAOGA, told the committee that in
the event of a catastrophic oil spill, the industry's brand would not be able
to be recreated. Ms McGowan stated:
I personally do not believe you can recreate the brand. If we
had a catastrophic oil spill that wiped out the coast of South Australia,
firstly, the industry would go. The majority of them are not going to be able
to wait for six years; they are family businesses. They are going to have to do
A number of submitters also raised concern that as a premier eco-tourism
destination, the tourism industry would be damaged in the event of an oil spill
in the Great Australian Bight. For example, Dr David Ellis submitted that:
Ecotourism business such as scuba diving, dolphin and whale
watching tours, fishing charters and guided tours such as the many operating on
Kangaroo Island would be unable to operate and boast the Southern Ocean's
reputation as a clean, wild and healthy ecosystem to their clients, many who
visit from overseas. The South Australian government's very own ecotourism 'business'
Seal Bay would have to close and many international visitors would no longer
come to South Australia.
The City of Victor Harbor, in noting that the Great Australian Bight
provides a critical sanctuary for many threatened species, and supports a
significant tourism industry stated that:
If an oil spill interfered or discouraged the annual
migratory habits of Southern Right Whales or other migratory species, there
will be economic and social consequences for our community and our visitors. One
only needs to reflect on the 2010 BP Deepwater drilling rig blow out in the
Gulf of Mexico to understand how extensive the consequences could be.
Similarly, the AMCS described the tourism industry in the Gulf of Mexico
as 'wrecked' by the Deepwater Horizon disaster. 
Mr Ben Byass, a tourism operator on Kangaroo Island expressed concern
that in the event of an oil spill, 'tourism and aquaculture industries would be
decimated'. Mr Byass also drew comparisons to the Gulf of Mexico and concluded
that oil and gas activity in the region 'is a serious threat to our way of life
The Kangaroo Island Council submitted that it:
...did not consider the multibillion-dollar tourism, fisheries
and aquaculture industries in SA, Victoria and Tasmania should be put at risk
for the meagre potential economic gains from an industry that is fast becoming
a dinosaur for future energy resources to supplement world consumption.
The Aboriginal Lands Trust, which operates the Head of the Bight
Visitor/Interactive Centre stated that it 'is committed to the economic
prosperity of the Region through engaging with local and other Aboriginal
stakeholders through its procurement arrangements'. This includes a range of
activities including 'the purchase of Aboriginal specific merchandise to
contracting services for maintenance'.
The Aboriginal Lands Trust went on to state that:
Through its interest in the protection of cultural and
conservation values, the Trust has been able to provide economic benefit to
Aboriginal people in the region. It is
concerned that these benefits could be undermined by a potential oil spill.
Impact on Indigenous communities
Aboriginal groups along the coast of the Great Australian Bight uphold
strong spiritual and physical connections the area. The committee received
evidence that an oil spill could potentially harm these connections. The
Aboriginal Lands Trust submitted that:
The HOB [Head of the Bight] and its cultural relevance
continues to be significant to the local, regional and wider Aboriginal
stakeholders with the various groups continuing to maintain their interest in
the traditional knowledge systems and structures that emerge from this area.
Ms Colbung, Chief Executive of the Aboriginal Lands Trust, told the
committee that the area is 'very rich in cultural heritage' and that:
...there are important storylines that run right down to the
Head of the Bight and also that there could be potential damage to some of
those storylines, as far as the local groups like the Mirning are concerned,
because the southern right whales, as I understand it, represent those totemic
species that are integral to the maintenance of Aboriginal culture...
Mr Bunna Lawrie, an Elder and songman of the Mirning people, explained
that the Nullabor and the Great Australian Bight are central to the Mirning
people's spiritual beliefs and customs. Mr Lawrie told the committee that the Mirning
people believe that during the Dreamtime, the great white whale Jiddara came to
the Great Australian Bight to give life and to give breath into the land and
the ocean. The Mirning people also believe that during the Dreamtime, whales
used to come into the caves of the Nullabor cliffs and the Mining people 'used
to look after the whales and treat them when they were not singing'. Mr Lawrie
explained that the Mirning medicine men and whale songmen protected the land
and 'that is why that beautiful country and that beautiful land is still
standing and looking good today and clean and untouched'.
Mr Lawrie emphasised the spiritual importance of the area, telling the
committee that it was where his initiation took place and that the area:
...is full of energy, it is full of life and healing; it is a
medicine to the whales and it is a medicine to my people, the Mirning people.
And it is a very spiritual place too, so it is a place where us Mirning
people—we honour that tradition, that custom. We honour that Dreaming.
Mr Lawrie also highlighted the importance of the area as a place of
learning for the Mirning people and described it as a museum and a university.
He also stated that:
This ocean is sacred. It is very sacred to mankind. It is
sacred to all the marine life. It is sacred to all the mammals in the ocean. It
is a sacred place, and also it is an energy, so it is a living being. It is
part of the earth. It gives life, and the main thing: it keeps our planet earth
alive. It sustains all we need. 
Mr Lawrie told the committee that his duty and responsibility as an
Elder and a whale songman is to 'protect and preserve our country' and as such
'we are at great risk and danger if oil spills happen in the Great Australian
He concluded that:
We do not want BP or any other oil companies in our Great
Australian Bight. We want you out of here, because you have already done damage
around other parts of the world, and we do not want you to come here and
destroy our beautiful oceans and the Great Australian Bight.
Similarly, the committee received evidence from Ms Sue Coleman Haseldine,
a Kokatha Mula custodian from Ceduna who stated that she is dependent on the
ocean for food, and that an oil spill would result in the loss of her
livelihood and traditional lifestyle. Ms Coleman Haseldine told the committee
If we get any kind of interference with our ocean, all our
traditional ways are going to be gone. We will not be able to go for raids to
fish scallops, oysters, cockles, crabs—anything that we can get when the tide
is out or even from a boat. Everything we have treasured will be gone.
Ms Colbung also told the committee that the local Aboriginal people rely
on the area as a source of food. Ms Colbung stated:
...the local Aboriginal people rely on [the marine life] as a
food source right through from the Head of the Bight to the vicinity of Dog
Fence Beach. People rely on that part of the coast to fish and camp, and the
marine life—mulloway, salmon et cetera—is a fantastic supplemental source of
food for the local Aboriginal people.
Impact on the marine environment in the event of an oil spill
The waters of the Great Australian Bight are recognised as being some of
the most biologically diverse in the world. They provide habitat for between
12,000 and 14,000 invertebrate species, 1,500 algal species, 612 fish species
(occurring above 50m depth), 16 breeding seabird species, 33 mammal species,
and 12 seagrass species. A number of the species of fauna such as southern
right whales and Australian sea lions are recognised as internationally and
nationally significant. Further, 95 per cent of seagrasses, 85 per cent of fish
species and 75 per cent of red algae in the Great Australian Bight are found
nowhere else in the world.
The City of Victor Harbor stated that:
The Great Australian Bight is a relatively pristine ocean
environment and a critical sanctuary for many threatened species. There are
species found in the Bight that are found nowhere else in the world. And it is
an important migratory path for several marine species. It is these unique
qualities that our South Australian Marine Parks network was established to
protect for future generations.
Mr Collis, International Fund for Animal Welfare (IFAW) similarly explained
that the Great Australian Bight is:
...home to nearly half of all the world's species of whales and
dolphins, and all three species of seals and sea lions found regularly in
mainland Australian waters. The Australian government has mapped biologically
important areas in the bight for blue whales, southern right whales, sperm
whales and the Australian sea lion, some of which overlap directly with, or are
in close proximity to, BP's proposed drilling area. The bight is also
recognised as globally important for elusive and rarely seen beaked whales.
As such, the key concern raised in evidence was the potentially
catastrophic impact of an oil spill on: marine wildlife such as cetaceans and
seabirds; fisheries; seabed flora and fauna; habitats; and food species. Oil
spills have the potential to have negative effects both at the individual, and
at the population level. The Wilderness Society submitted that:
Individual impacts include death, disease, impaired
reproduction, genetic alterations, changes to endocrine or immune functions,
hypothermia and a range of other biological disorders. Group-level impacts
include changes to local population sizes, community structures and overall
biomass. The most obvious toxic impact of spilled oil is direct contact with
wildlife and habitat.
Mr Matthew Collis, IFAW, told the committee that:
...it is important to remember that much of the damage to
wildlife would be out in the ocean, far from the coast, where animals rely on
this habitat for feeding and migration. Potential effects of a spill on marine
mammals include hypothermia and metabolic shock, organ dysfunction due to
ingestion of oil and exposure to toxic metals, lung disease and damage,
gastrointestinal ulceration and haemorrhaging, eye and skin lesions, decreased
body mass due to restricted diet, and stress due to oil exposure and
Any ability to predict the potential impact of an oil spill in the Great
Australian Bight is influenced by the size of the potential spill, the
mitigation strategies which would be employed, and the time of year it occurs.
As such, many submitters provided general evidence of the potential effects of oil
pollution in the marine environment, and evidence of the effects of incidents such
as the Deepwater Horizon and Exxon Valdez spills. It isn't known which of these
effects would be seen in the Great Australian Bight in the event of an oil
spill, but it is possible that they may occur.
Oil is comprised of thousands of chemical compounds, each with varying
levels of toxicity to humans, wildlife and the environment. The most acutely
toxic components of oil are water-soluble fractions (WSFs) and volatile organic
compounds (VOCs) which evaporate into the air or mix with marine waters. These
components include benzene, naphthalene, xylene and toluene. Once released into
the environment and after being subjected to weathering, the WSFs and VOCs are
generally lost. The remaining oil generally contains proportionately higher levels
of polycyclic aromatic hydrocarbons (PAHs). These are also toxic to both
wildlife and humans, and potentially linger in the environment for many years.
NOPSEMA submitted that the skin, fur and plumage of marine wildlife are
often the first part of the animal to be exposed to direct contact with oil and
oil-dispersant mixtures. For cetaceans and dugongs, skin contact with oil can
lead to skin irritation, inflammation, burns and necrosis. It can also increase
the risk of secondary health problems such as infection from open sores and
When birds are exposed to oil, their plumage is affected in such a way
that the feathers are no longer able to provide insulation or repel water. This
can affect the ability of birds to swim, fly or forage, and rescued birds have
shown signs of hypothermia. Similarly, the haircoat of pinnipeds provides
insulation, regulates body temperature, and provides buoyancy. When oil covers
the haircoat, it allows water to come into direct contact with the animal's
skin resulting in rapid onset hypothermia.
The Wilderness Society stated that 'a large spill can cause a massive
acute die-off of oiled birds. These mass seabird deaths can also create trophic
cascade effects that impact their prey species and fisheries'.
The Wilderness Society submitted that in the six months following the
...wildlife responders had collected "8,183 birds, 1,444
sea turtles, and 109 marine mammals affected by the spill—alive or dead,
visibly oiled or not". The US Department of the Interior for Fish,
Wildlife and Parks stated that the three most affected bird species appeared to
be brown pelicans, northern gannets, and laughing gulls. It has been estimated that approximately one million seabirds
and between 600,000 and 800,000 coastal birds were killed as a result of
the oil spill. More than 1,000 sea
turtles were found dead following the spill and
between January and March 2011, 200 dead dolphins were found in the Gulf of
Greenpeace Australia Pacific also highlighted that mass mortalities were
recorded in the Gulf of Alaska following the Exxon Valdez spill with 250,000
seabird deaths recorded in the immediate days after the incident. It also noted
that a number of marine bird populations continue to show signs of exposure, and
a decline in population in studies conducted 9 years after the incident.
Oil making direct contact with the eyes of wildlife has also been found
to cause significant injuries. NOPSEMA noted that necropsies of harbour seals
exposed to the Exxon Valdez oil spill showed signs of suffering conjunctivitis.
It also noted that though research on other species is rare, it should be
anticipated that such effects would be found in other species that swim through,
or break the surface of oil-affected water.
Marine wildlife is also likely to suffer from the negative effects of
ingesting oil when foraging, feeding, and grooming. In particular, cetaceans,
pinnipeds, dugongs and birds are at considerable risk of ingesting oil while
foraging in oil-affected areas, and in consuming oil-affected food resources. NOPSEMA
highlighted that baleen whales are particularly susceptible to oil ingestion
due to their mouth anatomy and feeding behaviour. In particular, filtering
large volumes of oil-affected water while feeding has the potential to lead to
the fouling of the baleen which in turn can adversely affect the animal's
IFAW submitted that:
Although not specified in the public summary that was
released of BP's recent environment plan submission, the original oil spill
modelling referenced in BP's EPBC Act referral back in 2013 estimated the
probability of hydrocarbon contact with whale foraging areas in the water
column in the GAB was 50-60% with no intervention (BP, 2013). This would likely
have a significant impact on blue, sperm and beaked whales feeding in the water
column in these areas both in terms of ingesting oil (and potentially toxic
dispersants) and on prey availability in these areas.
Similarly, Mr Collis, IFAW told the committee that:
The issue for marine life is that, particularly for
deep-diving species like sperm whales and beaked whales and also blue whales
that feed in the Great Australian Bight, is that they often feed at depth under
water. Blue whales are what we call filter feeders—they gulp in large amounts
of water and extract krill from that. So they will be taking in large amounts
of water which will include whatever level of oil has spilled in the water
column, not just at the surface. However, they would also be affected at the
surface when they come to breath. So there are those dual aspects of how marine
mammals would be affected by oil both in the water column and at the surface.
Dugongs may also have their ability to feed affected by oil collecting
on the sensory hairs around their mouth. These hairs are believed to have a
role in dugong foraging behaviour. As well as feeding in oil-affected waters,
birds spend considerable amounts of time preening their feathers and there is a
high likelihood that an oiled bird will ingest oil as a result. 
Ingested oil can cause a range of injuries and physiological effects on
wildlife. It can damage the gastrointestinal tract which can in turn effect
digestion and the uptake of nutrients. It can also damage the kidneys and liver
both of which play important roles in the metabolism of waste and toxins.
Studies have also found ulcers, diarrhoea, a decreased ability to absorb
nutrients from food, and a negative effect on egg condition in marine life
which has ingested oil.
IFAW submitted that researchers found a high prevalence of
hypoadrenocorticism (low functioning of the adrenal gland which alters stress
response) in live bottlenose dolphins in Barataria Bay, Louisiana, after the
Deepwater Horizon spill. In addition, skin tissue of sperm whales collected
from the Gulf of Mexico found elevated concentrations of toxic chemicals such
as chromium and nickel. According to IFAW, researchers suggested that exposure
to toxic metals is an understudied area of concern for whale populations swimming
in oil contaminated waters.
IFAW also highlighted that a study found that dispersants used during oil spill
recovery efforts can both kill cells and damage cell DNA in sperm whale skin,
at relatively low levels of exposure. This exposure can lead to sub-lethal but
potentially long-term harmful effects in whales.
The inhalation of oil droplets and volatile hydrocarbons
also has the potential to damage the mucous membranes and respiratory tissues
of wildlife. Following the Exxon Valdez oil spill, harbour seals were found
with symptoms of pneumonia and interstitial emphysema, and NOPSEMA submitted
that such similar effects might be anticipated in other mammals. Inhalation of
hydrocarbon vapours is also known to cause nerve damage and behavioural
problems in humans, and it may also be reasonable to assume such an impact will
be seen in marine mammals.
The Wilderness Society submitted that following the Exxon Valdez spill, an
estimated 302 harbour seals most likely died from the inhalation of toxic
Similarly, IFAW highlighted a study that found a high prevalence of lung
disease in bottlenose dolphins in Barataria Bay, Louisiana, United States of
America, following the Deepwater Horizon spill.
5.46 Exposure to oil pollution has also been linked to an increase in cetacean
strandings, and foetal loss in pregnant cetaceans. The US National Oceanic and
Atmospheric Administration (NOAA) declared an Unusual Mortality Event in (UME)
for cetaceans in the Northern Gulf of Mexico from 2010–2014 which determined
that the Deepwater Horizon oil spill is the most likely explanation of the
persistent, elevated stranding numbers of cetaceans in the Gulf of Mexico. It
also found that evidence supports that exposure to Deepwater Horizon pollution
was the most likely explanation for adrenal and lung disease in dolphins, and
increased foetal loss. In research published in April 2016, scientists stated
that 'exposure to petroleum compounds following the Deepwater Horizon oil spill
severely harmed the reproductive health of dolphins living in the oil spill
footprint in the northern Gulf of Mexico'. In addition, 'Gulf of Mexico
bottlenose dolphins were particularly susceptible to late term pregnancy
failures, signs of foetal distress and development of in utero infections
Mr Collis, IFAW, stated that:
The true extent of impact on marine mammals from the
Deepwater Horizon spill in the Gulf of Mexico is only just coming to light.
Over 1,500 whales and dolphins are stranded since the Gulf of Mexico spill. To
put that in context, the historical average in the affected region is six
strandings per year. The huge death toll represents a minimum number of animals
that have died as a result of that spill, since not all animals that have died
will wash ashore or be found. Scientists studying historical stranding rates in
the Gulf of Mexico have estimated that carcasses recovered after the disaster
represented only two per cent of spill related deaths. Therefore the actual
death toll could be up to 50 times higher. Any large spill in the bight will
likely see similar impacts on whales and dolphins in terms of lethal and
sublethal injuries and extended periods of disease and mortality, and whales
being forced to relocate away from biologically important habitat.
Ms Kathryn Warhurst, Conservation Council of South Australia, told the
committee that if the main nursery areas for the southern right whales along
the coastline of South and Western Australia are polluted during an oil spill 'then
you are going to have a whole bunch of southern right whales that are likely to
have significant issues in reproduction and ongoing health issues'.
Sea Shepherd Australia stated that:
A spill in the GAB would be catastrophic to the southern
right whale population. It would destroy the whale nursery where the mothers
give birth and nurture their young. Southern right whales either skim along the
ocean filtering the water for food or at times, are bottom feeders. Either way,
a spill would annihilate the population of southern right whales still
recovering from the commercial whaling era.
The Wilderness Society noted that following the Exxon Valdez spill, some
whale species such as bowhead whales were observed avoiding oil contaminated
areas, however other species such as killer whales were seen swimming through
oil slicks. Following the spill, 22 killer whales died—a single pod lost seven
members in the first week, and seven or eight over the next two years.
Intertidal and seabed flora and
Intertidal flora and fauna are particularly at risk if an oil spill
reaches the shoreline. This includes: mangroves; saltmarshes; coral reefs;
seagrass beds; macroalgal stands and their inhabitants; filter feeding
organisms such as sponges, and soft corals and their inhabitants; inhabitants
of rocky and sedimentary shores; microalgal assemblages such as stromatolites
and rhodoliths; and any other living organisms and assemblages that occur on
the seabed or seashore.
Oil can cause mortality in flora through smothering caused by oil
covering photoreceptors and pores for oxygen exchange. Mangroves, which are
dependent on oxygen supplied through pores in aerial roots, are particularly
susceptible to smothering. In mangroves, it has been found that toxic compounds
present in oil can also damage cell surfaces in subsurface roots, impair the
plant's salt exclusion process and interfere with the plant's ability to
maintain a salt balance. Seagrasses have also been found to blacken when in
contact with oil, and have lowered rates of growth.
Intertidal habitats such as mangroves, coral reefs and rocky shores also
encompass microhabitats such as rockpools, overhangs, cracks and crevices which
are populated by soft bodied sessile animals such as sea anemones, sponges,
echinoderms, and sea squirts. They also provide refuges for molluscs,
crustaceans and fish. Though oil on the surfaces of these shores is often
quickly washed away, it can concentrate in these habitats and cause
considerable damage to both flora and fauna.
Seabed flora and fauna inhabiting sedimentary shores or in seabed
sediments in both intertidal and subtidal zones are also susceptible to being
smothered by oil, particularly at low tide. Oil can penetrate sediments killing
resident fauna such as crabs and worms, and can coat molluscs, barnacles, and
bivalves on the sediment surface. Oil can persist and remain toxic in sediments
for many years and can inhibit seed establishment and asexual vegetative
seasonal growth in a number of flora species. NOPSEMA noted that the long term
effect of residual oil has been well documented in the northern hemisphere. For
example, the survival and growth rates of intertidal clams and fish were still
affected more than five years after the Exxon Valdez spill.
NOPSEMA also noted that following the Deepwater Horizon oil spill, there
has been a documented decline in the health of corals present in the area. It
stated that studies have found that dinoflagellate
function has been affected by both exposure to oil and dispersants. Studies have
also found that coral larval fertilisation, metamorphosis and survival have
been affected by exposure to oil and dispersants. NOPSEMA also noted that
greater investigation of the impact of exposure to oil on corals and other
seabed flora and fauna in deep water habitats is warranted.
Sea Shepherd Australia noted the rich biodiversity of the Great
Australian Bight and stated that high density zooplankton communities support
the highest densities of small fishes in Australian waters.
It noted that following the Deepwater Horizon disaster, there was a 'massive
die-off' of foraminifera—microscopic organisms at the base of the food chain.
It also noted that other studies have shown that plankton have been killed by
oil and dispersants, or have absorbed PAHs before being consumed by other
Fish and fisheries
Oil spills have a wide range of negative effects on fish and fisheries
including on the development and survival of eggs, embryos and larvae. NOPSEMA
noted that though mass mortalities are rarely observed in mobile species of
fish, seabed fish and fisheries species, and strongly habitat associated
demersal fishes are more likely to be affected.
NOPSEMA noted that the direct impacts of an oil spill on fish are likely
to be greatest for eggs, embryos, and larvae as they are particularly sensitive
to pollution events. For example, toxic compounds such as polycyclic aromatic
hydrocarbons can affect the growth, development and survival of embryos and
larvae. Oil in sediment on the seabed is likely to affect seabed egg-layers
such as damselfishes, squid and trigger fishes while contaminated surface
waters are likely to affect pelagic fish species.
are inherently vulnerable to the effects of an oil spill as fish are unable to
actively avoid pollution. Intertidal mollusc mariculture operations are
considered particularly vulnerable to the effects of an oil spill, with long
term effects likely where oil is retained in sediment.
Greenpeace Australia Pacific noted that following the Exxon Valdez spill, the
area's salmon populations were found to have stunted growth and lower survival
rates, and highlighted the implications for the Great Australian Bight's fisheries.
Mariculture operations are also vulnerable to tainting, which renders
fish and molluscs unfit for consumption. Tainting refers to the uptake of oil
derived substances in the tissues of the fish or molluscs, and which creates an
odour and flavour which is foreign to the food product. It can occur through
either direct absorption from contaminated water and sediments, or indirectly
through the consumption of contaminated prey species. Bivalve molluscs, such as
oysters, and fish with high fat content such as tuna are particularly prone to
tainting, and have a high bioaccumulation potential. Tainting also has the
potential to considerably damage the fisheries and aquaculture industries, as
consumers may avoid purchasing seafood for long periods of time—even after
levels of hydrocarbons in fish tissue have been found to return to normal.
Ecosystems and habitats
Oil spills have the potential to significantly affect the functions of
an ecosystem through changes in habitat, and changes in predator-prey relationships.
Populations which rely on specific habitat features for feeding, breeding and
nursing young are likely to be significantly affected. For example, a reduction
in the availability of prey species is likely to affect the health and survival
of higher order consumer species.
The Wilderness Society submitted that
Apex predators, particularly those that are long lived, can
also be especially impacted by toxic oil spill pollution. Some animals that are
high on the food chain already experience the effects of bioaccumulation of
persistent organic pollutants through bio-magnification. This continues in each
predator-prey interaction, and animals at the top of the food chain, such as
southern bluefin tuna, great white sharks and toothed whales, as well as
humans, can accumulate high levels of these toxins.
A number of submitters highlighted the importance of natal site fidelity
in species common in Great Australian Bight, and the impact that an oil spill
would have on that behaviour. IFAW stated that there would be 'longer-term
repercussions if specific breeding or calving sites were impacted'.
Similarly, the Humane Society International noted that:
As an endemic species found only in South and Western
Australia, the Australian Sea Lion stands to be significantly impacted by an
oil spill, as females have high site fidelity to breeding locations and feeding
locations, making them unable to avoid the impacts of such a spill should one
Ms Kathryn Warhurst from the Conservation Council of South Australia similarly
told the committee that:
South Australia has 85 per cent of the Australian sea lion
population in the world. The other 15 per cent is in Western Australian waters.
A large part of that area would be catastrophically impacted if there were a
spill...if there were any kind of significant event, I think it would be game
over for that species, or it would be very likely to be game over. The way this
species operates, too, is that it has a lot of genetically unique
subpopulations. If these subpopulations are knocked out, if there is a major
mortality event, they do not go back to those areas, because the females only
go back to breed where they were born. So there will be no re-immigration from
other sea lion populations. That area will effectively be dead to sea lions, so
that just will not be an option in terms of recovery in the future.
Mr Lyndon Schneiders, The Wilderness Society, told the committee that
the Great Australian Bight is a unique oceanic system with 'huge subsea
canyons' on the edge of the continental shelf. Mr Schneiders explained that:
Those subsea canyons drive what is called deepwater
upwellings. What happens is that huge amounts of phytoplankton is driven from
deep below the surface up to the shallows. That is what drives the southern
Australian marine environment. That is why there are so many big whales that
move through there. That is why, for instance, the big pelagic species like the
southern bluefin tuna and others move through, because they of course feed on
the pilchards that feed on the zooplankton. Zooplankton is the base of the food
chain. Zooplankton is also very sensitive to oil.
NOPSEMA noted that outside of predator-prey relationships, oil spills
are likely to have other flow-on effects on marine ecosystems. For example,
seagrasses and mangroves provide important habitat to a number of fauna
species. These flora assemblages also provide crucial services such as fish
nursery habitats, and damage from oil spills is likely to affect ecosystems
beyond the immediate habitat.
NOPSEMA also noted that a number of species are involved in maintaining
water quality through the removal of detritus from the water. If species such
as amphipods and fiddler crabs are removed from an area, decomposition may
significantly slow and water quality is likely to be affected. Similarly, the
removal of species such as crabs and starfish which predate on snails and
mussels may alter an ecosystem's grazing balance and create competition for
Long-term changes in the abundance and diversity of both flora and fauna
species have been seen following oil spills. For example, following the
Prestige oil spill in Spain there were found to be decreases in the biomass,
size and species abundance of algae in rocky shore assemblages six months after
the spill. However, in the longer term there was an increase in richness and
diversity as a result of changes in the abundance of dominant species. Species
replacement has also been observed in experimental oil spill research on
saltmarsh plants conducted in Wales, which saw the elimination of species such
as the sea rush Juncus, and the flourishing of the oil tolerant fast-growing
creeping grass Agrostis. NOPSEMA stated that 'the flow-on effects of an oil
spill on biological assemblages should not be underestimated'.
The Humane Society International submitted that:
However for many of the threatened species found in the Great
Australian Bight, there is still little scientific research to be able to
identify critical habitat. As a result the impacts of oil or gas development in
the area are likely to be more severe than current scientific knowledge
suggests, with significant implications when considering exploration or
drilling activities or should an oil spill occur.
Concerns were raised in relation to the potential for human health to be
negatively affected through the consumption of contaminated seafood. The Clean
Bight Alliance Australia also raised concern that dispersants used during
cleanup activities can have a toxic effect on both the residents of
contaminated areas, and those engaged in clean-up activities.
In BP's Environment Plan summary, it acknowledged that concerns
regarding the toxicity of dispersants had been raised during public consultations.
In particular, references were made to the impact of dispersants used during
the Deepwater Horizon incident. BP stated that it provided information on the
kinds of dispersant that may be used in the Great Australian Bight in the event
of a spill. It also noted that the Australian Oil Spill Control Agents (AOSCA)
Register sets requirements for the toxicity and efficacy testing of dispersants
prior to approval for use in Australia.
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