The Shark-o-meter

Black-tip reef shark

Black-tip reef shark. Picture by Tsumaguro.

Counting sharks isn’t quite like counting sheep – you can’t just sit underwater going ‘One, two, three …’ and hope for an accurate result. But it’s something that has to be done. It’s important for measuring the condition of the marine ecosystem and it informs policies about conservation or harvesting of sharks.

The counting sheep method can be unreliable because sharks respond to the presence of divers. Until now, though, simple counting has been one of the main methods used to work out coastal shark numbers.

Another counting method is video cameras with mounted baits. It also has its drawbacks. Bait tends to attract sharks – after all, that’s its job – so the count can be skewed depending on how far the smell has dispersed, and confused by other species entering the area.

One other good option is remote underwater video cameras without bait, but even these don’t provide a complete picture. They aren’t very good at estimating the density of sharks in an area.

So we put our thinking caps on, took our calculators out, and got to work on the problem. We built a model that can fill in the blanks.

It’s what’s called an agent-based model. This is a kind of computational model that works on the principle that simple actions generate complex behaviour. The model simulates what the sharks are doing when they interact with their environment – the reef crest, the coastline, other sharks – as a way to assess their effects on the system as a whole. You could think of it as rather like a video game, where you’re watching sharks swim around and sometimes passing the camera. Then we used this model to work out how often the video cameras would detect a shark, and compared what the model said to what the cameras found.

We surveyed 16 sites in Ningaloo Marine Park – eight of them in the marine sanctuary, the others in the recreation zone that adjoins it. Twice a day, at noon and dusk, we made observations. We later checked out the results against an earlier acoustic tagging survey to see if the model held up, and it did. That’s good news.

The even better news for conservation in this World Heritage Area is that the density estimates for this species are among the highest recorded.

Want to see some?


Going with the throughflow

Hose spraying water

The backyard experiment any hose-owner can try. Image: Flickr / Scott Akerman

By Simon Torok

Here’s a simple backyard science experiment for you to try, which has global implications.

Grab a garden hose, turn it on, and then put your thumb over the end of it. The flow of water thins, while its power intensifies.

Okay, now multiply that by a few million and you have some idea of the impact of recent La Niña conditions on a major ocean current north of Australia.

The Indonesian Throughflow is a series of ocean currents linking the Pacific and Indian Oceans. It carries water from the Pacific to the Indian Ocean through the passages and straits of the Indonesian Archipelago.

Schematic of the ITF. Values of the flow and the major passages are indicated by red. Water enters the ITF from the western Pacific and exits into the Indian Ocean.

Schematic of the ITF. Values of the flow and the major passages are indicated by red. Water enters the ITF from the western Pacific and exits into the Indian Ocean. Image: Wikipedia.

Researchers – led by Janet Sprintall at Scripps Institution of Oceanography in the United States, and including Susan Wijffels from CSIRO in Hobart – have found that the flow of water in the Indonesian Throughflow has become more shallow and intense since the late 2000s due to La Niña conditions, just as the water flow thinned and intensified while you played with that garden hose.

The paper, The Indonesian seas and their role in the coupled ocean-climate system appears in today’s online publication of the journal Nature Geoscience.

The Indonesian Throughflow is the only place in the world where warm equatorial waters flow from one ocean to another; consequently, the throughflow is an important chokepoint in the flow of heat in the climate system.

The paper suggests that human-caused climate change could make this shallowing and intensification a more dominant feature of the Indonesian Throughflow, even under El Niño conditions.

Changes in how much warm water is carried by the Indonesian Throughflow will affect the sea surface temperature, and in turn the patterns of rainfall in our region.

So you may need to think a bit more about how you use that garden hose.


Mega-pest worms its way into Brazil

Helicoverpa armigera_5

By Wee Tek Tay, Research Scientist, CSIRO Biosecurity Flagship

We often speak of the risks of new invasions in our increasingly interconnected world, and stress the need for a strong and reliable biosecurity system to safeguard our borders.

As global trading and markets increase, it’s essential to develop our ability to detect incursions using new and innovative surveillance techniques combined with rapid identification capabilities.  This is important because Incursions by exotic pests and diseases have the potential to seriously impact Australia’s people, agricultural industries and unique environment.

And right now, a team of Australian and international scientists are working closely with colleagues in Brazil as one of the most destructive pests known to agriculture – the cotton bollworm (Helicoverpa armigera) – worms its way into Brazilian agricultural fields.

Helicoverpa armigera has long been recognised as a serious biosecurity threat to the Americas, where it has the potential to establish across the South and North American continent with far greater anticipated potential economic loss to corn and cotton than the closely related Helicoverpa zea which is endemic to the Americas.

Incredibly, despite being intercepted at US Ports of Entry a staggering 4431 times since 1985, this mega-pest had not been previously reported to take hold on the American continents.

In Australia, Asia, Africa and Europe, where cotton bollworm is considered native, the damage it causes is estimated to cost $US 2 billion each year. In the last two growing seasons, high infestations of Helicoverpa species larvae were found in different regions of Brazil, resulting in substantial economic losses of up to 10 billion Brazilian Reals ($US 4.4 billion).

A cotton bollworm larvae decimating a cob of corn

A cotton bollworm larvae decimating a cob of corn

At first it was assumed that the damage was being caused by Helicoverpa zea, because the cotton bollworm had never previously been detected within the country. However, as the scale of spread and destruction was monitored, the Brazilian scientists knew that something was different and suspected that maybe the dreaded incursion of Helicoverpa armigera had indeed begun. At this point, Brazilian scientists from the Mato Grosso Cotton Institute approached CSIRO researchers to assist in the careful identification of the species attacking their crops.

Our scientists, together with French and Indian colleagues from CIRAD and IRD in France and the Indian Council of Agricultural Research used evolutionary and population genetics to confirm that the cotton bollworm has now successfully invaded Brazil.

Along with the confirmation that the Brazilians are indeed dealing with a new incursion of a serious exotic pest, the international team led by scientists from the CSIRO Biosecurity Flagship and Matto Grosso Cotton Institute is providing further vital data that will assist Brazil to manage this new menace.

The next steps for the research team are to investigate where the moth originated, where they are currently distributed, its spread across the South American continent, and the incidence of resistance to key pesticides. This information, coupled with CSIRO’s extensive expertise in insecticide resistance management will assist Brazil to develop effective strategies to manage this mega-pest.

You can read the full research paper at PLOS ONE.


For media enquiries contact Emma Pyers: +61 3 5227 5123, emma.pyers@csiro.au


Putting a stop to the rot

Queensland Fruit Fly

The Queensland Fruit Fly

Flies aren’t only a nuisance for beach goers, some species can cause havoc for Australia’s agricultural industries and threaten the production and export opportunities of our fresh fruit and vegetable produce.

Queensland Fruit Fly (Q-fly) is one of these species. It’s the highest priority pest for a broad range of horticultural industries and can inflict significant costs on producers through management costs, lost production and reduced export opportunities, and on government and industries through eradication campaigns in areas where fruit fly does not regularly occur. These costs all eventually flow through to consumers and taxpayers.

An outbreak of Q-fly in a major fruit or vegetable production area, such as the Riverland in South Australia, has the potential to impact Australia’s export and domestic horticulture markets.

CSIRO’s Biosecurity Flagship together with Horticulture Australia Ltd, Plant & Food Research Australia and the Department of Primary Industries and Regions South Australia are joining forces to find a solution to this Q-fly problem.

Today marks the beginning of this partnership with the South Australian Premier Jay Weatherill announcing the establishment of a $3 million facility to breed male-only sterile Q-flies for use in Sterile Insect Technology (SIT) programs.

SIT is a scientifically proven method for suppressing or eradicating fruit fly populations and managing their potential impacts in horticulture production areas.

The $3 million State investment is in addition to a collaborative $15 million research and development consortium which will focus on new technologies to produce the male-only sterile Q-flies, and then the most effective release strategies and monitoring technologies needed to underpin effective area-wide control of Q-fly.

Boy biting into peach with blue sky in the background

Image: iStock

SIT approaches have already been used with great success around the world and in South Australia to combat Mediterranean fruit fly. However, the development of male-only sterile Q-fly will be a world first and will significantly enhance the cost effectiveness of SIT.

SIT is environmentally friendly and can be used in orchards, urban and environmentally sensitive areas, where application of conventional chemical treatments isn’t possible or is intrusive.


For media enquiries contact Emma Pyers: +61 3 5227 5123, emma.pyers@csiro.au


The turbulent times ahead for airborne pests

Boy on beach playing with sand

Image: Shutterstock

By Emma Pyers

Picture this – it’s a windy day in Northern Australia; in fact it’s a northerly wind. What are your initial thoughts?  Maybe heading to the beach with the family, hosting a BBQ or spending time outside with your canine friend?  But did you think about the risks these winds pose to our country’s biosecurity status?

If not, that’s OK because that’s what our scientists are here for – to help find solutions to protecting our environment and people from nasty pest and disease threats.

Currently the biggest biosecurity threat to Australia comes from the import of animals, plants, seeds and food that carry pests or pathogens.

So it makes sense that most of our surveillance effort goes into detecting these potential biosecurity threats at air and marine ports, and using our quarantine system for imported animals, although this still leaves open another ‘pathway’ for these nasties to use.

It’s on the wind.

It’s not as common as the direct import pathway, but it’s more concerning as it’s out of our immediate control.

So, we’re turning to mathematics and computer modelling to develop surveillance systems that can predict when and where pests and pathogens might be blown into, and from, Australia.

Yellow hot air balloon in the sky

Been hot air ballooning? Then you’ve experienced travelling with air layers and currents. Image: Zurijeta/Shutterstock

Traditionally wind trajectories have been used to show wind direction, but transport on the wind is more complex, as the pests and pathogens are also taken vertically.  The higher they are taken, the further they can travel.

Fortunately this is an area of great significance to atmospheric physicists, as they are interested in predicting things like how pollutants are dispersed in the air by chimneys, and how radiation might disperse following a nuclear accident.

This has led them to use a combination of mathematics and computer simulation to represent transport of particles in the atmosphere. There are now a number of computer applications that can do the hard work of combining the climate and weather data with the maths and physics of wind dispersion.

Infographic including maps detailing the dispersal of culicoides midges blowing into northern Australia

However, pest or pathogen dispersion is different to dust or pollutant dispersions, as living organisms respond differently within the atmosphere.  They might die if it’s too hot or cold, if the wind is too turbulent, or even if they’re susceptible to ultra-violet light.  All these organism-specific parameters need to be taken into account on top of standard dispersion modelling approaches to establish if there is a biosecurity risk or not.

It’s a challenge to bring these important elements together and make optimal decisions about when and where to do surveillance for wind-borne threats, even allowing for a high performance computer to analyse the data.

We’re working to solve this problem for all the relevant biosecurity domains interested in wind-borne spread, for example plant, animal and human health.

We are in the process of building a web-based tool that will link to the Bureau of Meteorology’s high-performance computing.  This new application is called the Tool for Assessing Pest or Pathogen Airborne Spread, also known as TAPPAS (sorry, it’s not Spanish cuisine). 

We expect TAPPAS to be ready for government, industry and research agencies interested in predicting and responding to airborne biosecurity threats for a ‘user acceptance testing” workshop in around 12-18 months time.

Our very own Peter Durr is presenting a talk on TAPPAS at the Biosecurity and Bioinvasion workshop tomorrow at CSIRO Discovery in Canberra.  CSIRO is co-hosting this event, which is part of the International Year of the Mathematics of Planet Earth, with AMSI, ANU and DAFF.


Requiescat in pace – FFT

Nearly three years after Friday Fish Time was spawned, the time has come to kill it off. FFT served us well, but now the blog has caught on (and everyone wants to get on board) there is little room left for little fish tales. Time to cast them off, throw them back, reject the best, and recast. So, goodbye my scaly friends.

Nearly three years after Friday Fish Time was spawned, the time has come to kill it off.
FFT served us well, but now the blog has caught on (and everyone wants to get on board) there is little room left for little fish tales. Time to cast them off, throw them back, reject the best, and recast.
So, goodbye my scaly friends.


Preventing a pathway for pathogens

Part of the Biosecurity Series

By guest blogger Professor Peter Doherty

Photo of the tail of three planes

Image: caribb/Flickr

It’s no big secret that we’re citizens of an increasingly globalized planet where ideas, information, goods and services get around very fast. One of the downsides of this brave new world is that the same is true for pests and pathogens.

The security services, customs officers and quarantine regulations/officials protect Australia from such invasions as much as possible, although given the volume of trade and human movement, stopping bad things at the borders can only be part of any effective strategy.

There’s also a need for continual environmental monitoring to make sure that nothing dangerous slips through which could compromise Australia’s agricultural industries, wildlife and natural environments.

When it comes to biodefence against invading viruses, bacteria, insects, plants, marine parasites (on the hulls of ships) and so forth, we have layers of operation that function both at the Federal and State level.

This is, of course, where the wonderful high security CSIRO Australian Animal Health Laboratory (AAHL) comes into its own, providing the essential diagnostic tools and facilities for safe studies of deadly viruses in animals that are unique to the South-east Asian region.

Photo of the exterior of the Australian Animal Health Laboratory

The Australian Animal Health Laboratory in Geelong, Victoria

Apart from its service to the veterinary world, AAHL has also pioneered studies of bat-borne viruses like Hendra and Nipah (active to the North-West of Australia) that can transmit to people from infected horses and pigs respectively. These are classic cases of the “One Health” view CSIRO takes that stresses the intimate interplay between animal disease and human disease. Apart from the Henipaviruses, AAHL also has the facilities that allow CSIRO researchers to study the avian influenza A viruses, that are a looming threat to both domestic poultry and people.

An artificially coloured electron micrograph of the new-SARS like virus – now known as the Middle East Respiratory Syndrome (MERS) – which has caused an ongoing outbreak of respiratory disease and has spread from the Middle East to the United Kingdom, Germany, France, Italy and Tunisia.

An artificially coloured electron micrograph of the new-SARS like virus – now known as the Middle East Respiratory Syndrome (MERS) – which has caused an ongoing outbreak of respiratory disease and has spread from the Middle East to the United Kingdom, Germany, France, Italy and Tunisia. (click for full size image)

The new CSIRO Biosecurity Flagship pulls together research capability from across CSIRO together with a broad range of collaborating centres and groups. Sharing information is vital for such activities.  Clearly, Australia cannot afford to have “silos” and artificial barriers that in any sense compromise our biological security. Of ongoing concern are the hi-path variants of the avian influenza H5N1 viruses that continue to circulate in wild and domestic birds (and occasionally infect and kill people) in the countries to the north-west of Australia. While we’ve avoided that particular threat so far, the situation requires constant monitoring.

Another threat is the recently emerged H7N9 avian influenza virus and MERS, a novel coronavirus in the Middle East.

I’ve said nothing about plant, insect and fish pathogens, but there are many diseases of key species, such as bees, trout and salmon that we have so far managed to keep at bay.

The new CSIRO Biosecurity Flagship is a great step in the right direction, and we need to continue doing all that we possibly can to ensure the long-term health and wellbeing of all the life forms that inhabit our extraordinary and unique country.

Join the Conversation: #bflaunch


About the Author

Photo of Peter Doherty

Peter Doherty trained initially as a veterinarian and shared the 1996 Nobel Prize for Physiology or Medicine for discoveries concerning our immune defence against viruses. He published the non-fiction book “Sentinel Chickens: What Birds Tell Us About our Health and our World” in 2012, and his new book “Pandemics: What Everyone Needs to Know” will be available in Australia from October.

Follow Peter on twitter: @ProfPCDoherty


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