Testing deceased wildlife

A 3-year-old female Australian sea lion was found displaying signs of neurological disease and died overnight. Laboratory examination found a severe bacterial infection (Streptococcus phocae) in the brain, which would have contributed to the clinical signs and possibly the death of this animal.

Rocks were found in the stomach and are likely to be a normal finding; their role is unknown, but it is thought that they help with digestion.

Other findings were likely to have occurred at the time of death (lung congestion and bleeding) or were considered incidental (not contributing to illness), including inflammation of multiple tissues and worms in the gut.

Testing for avian influenza, tuberculosis (Mycobacterium tuberculosis complex organisms) and Cetacean morbillivirus was negative. Brevetoxins and other algal biotoxins were also not detected.

A little penguin was found dead on Carrickalinga Beach, in the same area as another dead little penguin and dead leatherjackets. Laboratory examination revealed a mild hepatitis (inflammation of the liver), possibly due to a bacteraemia (bacteria in the bloodstream}. Culture was not recommended as post-mortem bacterial growth would make interpretation of results unreliable. There were no findings to explain the cause of chronic weight loss in this bird.

Testing for avian influenza and Newcastle disease was negative. Brevetoxins and other algal biotoxins were also not detected.

A female juvenile Australian fur seal was found dead. Laboratory examination could not determine the cause of death. The animal had an infection of the lungs caused by bacteria and parasites which likely contributed to illness, and possibly chronic weight loss and death.

Inflammation and cell death found in the liver and heart were likely a result of the infection spreading via the bloodstream (bacteraemia).

The worms found in the stomach (roundworms), intestines (roundworms and tapeworm), and subcutaneous tissue (tapeworm), along with the bradyzoites within the skeletal muscle (likely Sarcocystis spp.) are all common findings in wild seals.

Testing for avian influenza, brucellosis (Brucella spp.) and tuberculosis (Mycobacterium tuberculosis complex organisms) was negative. Brevetoxins and other algal biotoxins were also not detected.

Two sick and two dead pied cormorants (Phalacrocorax varius) were found. The sick birds were showing neurological signs (circling, wobbliness, unable to fly). The two dead birds were submitted for laboratory examination, which found that both birds were underweight, which would have contributed to morbidity (illness), but the cause of weight loss couldn't be determined. Decreased feed abundance could be a contributing factor. Parasites (roundworms) were found in the gut of both birds, which is a common finding in marine birds.

Testing for avian influenza and Newcastle disease was negative in both birds. Brevetoxin was found in the liver, kidney, heart and brain of one bird (the other bird was not tested for toxins). Pulmonary oedema (fluid in the lungs) contributed to morbidity (illness) for this bird. Brevetoxins have been recorded to cause vascular damage including pulmonary oedema. They are also known to cause neurological signs in avian species, consistent with the signs seen in the two sick birds.

A juvenile female bottlenose dolphin (Tursiops aduncus), believed to be “Rocket” of the Port River Dolphin Sanctuary, was found dead. Laboratory examination revealed that trauma (injury), likely from a boat strike, was the cause of death. There was no other evidence of disease found. Changes seen in the lung on necropsy were likely agonal vascular changes (occurring at the time of death), as no abnormalities were found on histopathology.

Testing for brucellosis (Brucella species bacteria) was negative. Brevetoxin 2 was found in the stomach contents and domoic acid (another algal biotoxin) was found in the liver. As these are neurotoxins (nerve toxins), it is possible that they contributed to abnormal behaviour in this animal, leading to the injury (suspected boat strike) that caused death. However, given the animal was not observed prior to death, this is purely speculative.

An adult male Australian sea lion was found dead at Seal Bay on Kangaroo Island. The animal was observed by rangers the day before being found dead and appeared outwardly normal.

Domoic acid (an amnesic shellfish toxin) was detected in the brain and gonyautoxin (dcGTX1), a type of saxitoxin (a paralytic shellfish toxin), was detected in the heart, kidney, and lung.

Domoic acid and saxitoxins are potent neurotoxins (toxins affecting nervous tissue) produced by some marine organisms (including algal species) that can accumulate in shellfish and other aquatic animals. Domoic acid can cause amnesic shellfish poisoning (ASP) and saxitoxins can cause paralytic shellfish poisoning (PSP) in humans and can also pose a risk to animals when ingested.

The presence of these toxins in the sea lion's tissues may have contributed to its illness and death. However, interpretation of these findings is limited by the absence of clinical signs prior to death and by histological findings in the brain that were not consistent with domoic acid-associated neuronal degeneration, noting the brain was significantly decomposed, which limited laboratory examination. Given these limitations, any association between domoic acid and gonyautoxin exposure and this animal's illness and death should be interpreted with caution and remains speculative.

The likely cause of death in this animal was meningoencephalitis (inflammation of the brain and protective membranes), based on the changes seen in the brain which were consistent with a bacterial, fungal, protozoal or (less likely) viral infection, and were not consistent with neuronal degeneration (death of nerve cells) typically seen with domoic acid toxicity.

An adult male long-nosed fur seal (Arctocephalus forsteri) was found dead. Laboratory examination found a bacterial infection (Edwardsiella tarda) causing peritonitis (infection in the abdominal cavity) and brochopneumonia (infection in the lungs and large airways), which would have contributed to the animal's death.

The seal also had multiple small abscesses under the skin that may have been caused by bite wounds or the bacterial infection spreading via the bloodstream. Tapeworms were found in the colon. Both the abscesses and the tapeworms are likely to be incidental findings (not contributing to disease).

Testing for avian influenza, tuberculosis (Mycobacterium tuberculosis complex organisms) and brevetoxins was negative. Neosaxitoxin (a type of paralytic shellfish toxin) was found in the stomach contents. This is a potent neurotoxin (nerve toxin) and may have contributed to illness and death of this animal. Given the animal was not observed prior to death this is purely speculative.

An adult male Australian sea lion (Neophoca cinerea) was found on the roadside near a beach. It was underweight and appeared unwell or injured and was euthanised. Laboratory examination revealed severe trauma and infection to the left eye, and a chronic (long-term) lung infection, which had spread to the kidneys. The cause of infection was not confirmed but was most likely to have been Streptococcus spp. bacteria; testing ruled out tuberculosis as the cause. These conditions would have contributed to weakness and limited the animal’s ability to hunt and forage for food, resulting in the weight loss seen.

Nasal mites (parasites) were also found in this animal, which would have contributed to the nasal discharge seen. These mites are reported in sea lions; high burdens can cause breathing difficulties. Testing for avian influenza was negative. Brevetoxins and other algal biotoxins were also not detected.

One adult female bottlenose dolphin found dead. Laboratory examination found a severe bacterial infection (Streptococcus iniae) in the lungs, airways and chest, which likely contributed to the death of this dolphin. Streptococcus iniae is a known pathogen of marine mammals and fish, however predisposing factors for infection and disease due to S. iniae in wild dolphins is unknown.

Inflammation and cell death was found in many other organs, likely as a result of the infection spreading via the bloodstream (bacteraemia) and associated endotoxaemia (bacterial toxins within the bloodstream). The cause for the chronic pancreatitis was not evident, and did not appear to affect the animal as it was in moderate body condition.

The gastric cestode (stomach worm) is an incidental finding. The species of the worm could not be identified, however Tetraphillydea cestodes are reported in healthy dolphins.

Testing for avian influenza, tuberculosis (Mycobacterium tuberculosis complex organisms) and Cetacean morbillivirus was negative. Brevetoxins and other algal biotoxins were also not detected.

Three pied cormorants were found dead at Browns Beach, Kangaroo Island. One bird was sent for testing.

Prior to death, the birds were reported to have been displaying neurological symptoms (weakness of limbs, wobbly).

Laboratory examination (necropsy and histopathology) found gastrointestinal parasites and bacterial infection affecting the heart, lung, liver, spleen and brain that may have contributed to chronic weight loss, illness and neurological symptoms.

Testing for avian influenza and Newcastle disease was negative.

Brevetoxins were detected in the bird’s liver. The levels detected are consistent with those found in marine birds overseas that were reported to have been exposed to harmful algal blooms.

It cannot be determined whether the brevetoxin presence in the cormorant was a direct contributor to its death or a non-lethal co-morbidity given the poor condition of the bird at death. Pied cormorants primarily feed on fish. It is considered that the most significant exposure of the cormorant to brevetoxins is likely to have been via its consumption of fish organs containing brevetoxins.

Seven pied cormorants were found dead along Nepean Bay, Brown Beach and Ironstone Creek, Kangaroo Island. Of these, one bird was sent for testing. An additional four live and healthy cormorants were observed in the same area.

Laboratory examination (necropsy and histopathology) found gastrointestinal parasites and bacterial hepatitis (liver infection) may have contributed to chronic weight loss and illness.

Testing for avian influenza and Newcastle disease was negative.

Brevetoxins were detected in the bird’s liver. The levels detected are consistent with those found in marine birds overseas that were reported to have been exposed to harmful algal blooms.

It cannot be determined whether the brevetoxin presence in the cormorant was a direct contributor to its death or a non-lethal co-morbidity given the poor condition of the bird at death. Pied cormorants primarily feed on fish. It is considered that the most significant exposure of the cormorant to brevetoxins is likely to have been via its consumption of fish organs containing brevetoxins.

No cause of death was identified. Examination (necropsy) found that the shark’s overall body condition was lean and heavily decomposed. The stomach was empty with no evidence of recent feeding. The liver to bodyweight ratio was normal, suggesting it was not malnourished.

Brevetoxins were not detected in either liver or gill tissues above reporting limits.

Eight pied cormorants were found dead or in poor condition at Bay of Shoals, Kangaroo Island.

Of these, three live birds were observed with neurological symptoms (weakness of limbs, wobbly). The remaining five birds were already dead.

Laboratory examination (necropsy and histopathology) on all birds could not determine the cause of chronic weight loss, neurological signs and death. Hepatitis (liver inflammation) may have contributed to one of the birds being unwell.

Three birds were sent for additional testing.

Testing for avian influenza and Newcastle disease was negative.

Brevetoxins were detected in the tissues of all birds tested. The levels detected are consistent with those found in marine birds overseas that were reported to have been exposed to harmful algal blooms.

It cannot be determined whether the brevetoxin presence in the cormorants was a direct contributor to their death or a non-lethal co-morbidity given the poor condition of the birds at death. Pied cormorants primarily feed on fish. It is considered that the most significant exposure of the cormorants to brevetoxins is likely to have been via their consumption of fish organs containing brevetoxins.

Two adult penguins were found dead on beaches of the Fleurieu Peninsula. Both birds were in good body condition. Laboratory examination could not identify the cause of death of either penguin, however multiple processes likely contributed to their illness and possibly death.

Penguin 1 had signs consistent with a chronic (long-term) infection in the air sacs caused by fungi, with secondary (subsequent) bacterial infection. The fungal infection is a common lesion in birds, especially those that are immunosuppressed. The bird also had signs of inflammation in many organs and some gut parasites.

Penguin 2 had a chronic (long-term) infection in the liver, which could have been caused by fungi or bacteria. The bird also had parasites in the kidneys.

Testing for avian influenza and Newcastle disease was negative in both birds. Brevetoxins and other algal biotoxins were also not detected.

Physical symptoms (including inflamed gills) were consistent with a cause of death related to exposure to high levels of Karenia spp.

No alternative cause of death was identified. Laboratory examination (necropsy) found that the shark’s overall body condition was good and the stomach was empty, with no evidence of recent feeding or stomach eversion. The liver to bodyweight ratio was normal, suggesting it was not malnourished.

Negligible concentrations of brevetoxins were detected in the gill tissues; however these levels are considered too low to have had any significant impact on the shark’s health.

No cause of death was identified. This shark was not able to be retrieved from its stranding location and was dissected in water. The shark was too decomposed to allow for soft tissue diagnosis, such as examining the gills.

Negligible concentrations of brevetoxins were detected in the liver tissues; however these levels are considered too low to have had any significant impact on the shark’s health.

Approximately 50 cormorants were found dead or close to death at Outer Harbour. Five birds were submitted tor testing. Laboratory examination of two birds found they died from vertebral (neck) fracture. It is not known whether these two birds were found dead or euthanised. The factures therefore may have been due to the method of euthanasia or trauma. Neck fractures were not found in the other three birds.

Both birds necropsied also had multiple signs of illness, including inflammation of the lungs, liver and gut, likely caused by a bacterial or viral infection. The ascarids (worms) found within the gut are a common finding in marine birds. Testing tor avian influenza and Newcastle disease was negative in all five birds.

No cause of death was identified. Examination (necropsy) found that the shark’s overall body condition was lean and the stomach was empty, with no evidence of recent feeding or stomach eversion. The liver to bodyweight ratio was low to normal, suggesting it was not malnourished.

Due to the initiation of early decomposition, it was not possible to conduct a viable analysis of the gill tissues.

Negligible concentrations of brevetoxins were detected in the gill tissues; however these levels are considered too low to have had any significant impact on the shark’s health.

No cause of death was identified. Laboratory examination (necropsy) found that the shark’s overall body condition was good and the stomach was empty, with no evidence of recent feeding or stomach eversion. The liver to bodyweight ratio was normal, suggesting it was not malnourished.

Due to the initiation of early decomposition, it was not possible to conduct a viable analysis of the gill tissues.

Negligible concentrations of brevetoxins were detected in the gill tissues; however these levels are considered too low to have had any significant impact on the shark’s health.

Physical symptoms including gill damage, were consistent with a cause of death related to exposure to high levels of Karenia spp.

No additional cause of death was identified. Laboratory examination (necropsy) found that the shark’s overall body condition was good and the stomach contents were minor and unidentifiable, without evidence of recently consumed prey. The liver was large and healthy, suggesting it was not malnourished.

Negligible concentrations of brevetoxins were detected in the gill tissues; however, these levels are considered too low to have had any significant impact on the shark’s health.

No cause of death was identified. Laboratory examination (necropsy) found that the shark’s overall body condition was lean, with the stomach everted. The liver was in the normal body to weight ratio range, suggesting it was not malnourished.

Advanced decomposition prevented viable analysis of the gill tissues.

Negligible concentrations of brevetoxins were detected in the liver tissues; however, these levels are considered too low to have had any significant impact on the shark’s health.

No cause of death was identified. Laboratory examination (necropsy) found that the shark’s overall body condition was good, with a healthy liver, suggesting it was not malnourished.

Thawed gill tissues were unable to be analysed.

Negligible concentrations of brevetoxins were detected in the gill tissues; however these levels are considered too low to have had any significant impact on the shark’s health.

Physical symptoms, including gill damage, were consistent with a cause of death related to exposure to high levels of Karenia spp.

The shark could not be retrieved from its stranding location and was dissected on the beach. As a result, a comprehensive necropsy was not conducted. The shark’s overall body condition was good, with a large liver and full stomach, suggesting it was not malnourished.

Negligible concentrations of brevetoxins were detected in the liver and gill tissues; however these levels are considered too low to have had any significant impact on the shark’s health.

Large numbers (approximately 70 out of 200) of western grey kangaroos were found with difficulty standing at Tunkalilla Beach. The sick kangaroos were all found close to the beach, which was affected by the algal bloom at the time. This was confirmed by detections of Karenia spp. in the ocean and adjacent creek.

Several kangaroos were euthanised on welfare grounds, and 7 underwent further examination (necropsy and histopathology). Findings in 5 of the kangaroos were inconclusive, and findings in the other 2 kangaroos were consistent with Phalaris toxicity, which is considered to be the most likely cause of the symptoms. Phalaris toxicity is a well-known disease that affects livestock and wild animals (including kangaroos) and is caused by eating a type of pasture grass (Phalaris aquatica) that contains neurotoxins. The risk of Phalaris toxicity is highest with new grass growth, but it can occur at any time of year. Phalaris grass grows throughout South Australia.

Brevetoxin was detected in both kangaroos tested and another algal biotoxin (PST) was also detected in one of the kangaroos. The low levels of brevetoxin and PST detected in this case are considered unlikely to have materially impacted on the health of the kangaroos.