Nov 132015
 

After a couple of storm related postponements last Summer Brisbane City Council is giving it another go!

If you missed out last year BCC will open Forest Lake to fishing for one day on Saturday, November 21 so that we can remove some feral fish and spread the message about how much of a threat they are to our waterways and native fish species. There's been a surprising amount of interest on facebook so we'd certainly appreciate any members who wanted to come along and help out. It's a unique opportunity for the club to engage with a lot of people we normally wouldn't get to meet. If you'd like to help with putting some of the gear together give Steve Baines a call on 0448890798. Continue reading »

Oct 222015
 

Original story by Tim Stephens, University of California - Santa Cruz.

Scientists investigating ecological consequences of sexual dimorphism and sex ratio variation in mosquitofish populations found dramatic effects.
Mosquitofish have been introduced worldwide as a means of mosquito control. (Photo by Kevin Simon)

Mosquitofish have been introduced worldwide as a means of mosquito control. (Photo by Kevin Simon)

Female mosquitofish are not only bigger than the males, they have bigger impacts on freshwater ecosystems. In a controlled study conducted in experimental ponds, researchers found dramatic differences in pond ecosystems depending on the ratio of males to females in the mosquitofish populations. In ponds dominated by female fish, the researchers observed more pronounced ecological changes, including fewer zooplankton and a greater abundance of algae, than in male dominated ponds.

Mosquitofish, which are often used to control disease-spreading mosquitos, are probably the most widely introduced freshwater species in the world, according to Eric Palkovacs, assistant professor of ecology and evolutionary biology at UC Santa Cruz. They are also listed among the world's 100 worst invasive species by the International Union for Conservation of Nature.

Mosquitofish are known to have detrimental effects on native freshwater fauna, and in a lot of places there are efforts to control and extirpate them. It's been called the 'plague minnow' in Australia and New Zealand because its effects are so drastic," Palkovacs said.

Palkovacs and graduate student David Fryxell are senior author and first author, respectively, of a paper on the new findings published October 21 in Proceedings of the Royal Society B.

Trophic cascade

Female-biased populations (right) reduced water clarity compared to male-biased populations (left) due to the trophic cascade. (Photo by Eric Palkovacs)

Female-biased populations (right) reduced water clarity compared to male-biased populations (left) due to the trophic cascade. (Photo by Eric Palkovacs)

In addition to eating mosquito larvae, mosquitofish prey on other insect larvae, amphibian larvae, and zooplankton such as Daphnia, tiny crustaceans that graze on algae in freshwater ecosystems. Female mosquitofish prefer larger food items than males, have higher feeding rates, and spend more time foraging in the presence of other females. High levels of predation can ripple through the food web in what ecologists call a "trophic cascade." When mosquitofish consume a lot of Daphnia, the resulting trophic cascade leads to an increase in algae.

"Daphnia are the principle grazers in freshwater ponds, keeping algal populations in check," Palkovacs explained. "We found that female-dominated mosquitofish populations cause much more dramatic trophic cascades. When there are more males, the Daphnia population remains higher and algal abundance is lower."

Other effects seen in female-dominated ponds included increased temperature and pH.

Palkovacs noted that many studies have looked at the evolutionary biology of sexual dimorphism (differences between the sexes in traits such as body size or coloring) and variations in sex ratios (when populations deviate from a one-to-one ratio of males to females). But little attention has been paid to the ecological consequences of these phenomena.

"When males and females of a species differ in traits like body size, they might use different resources or interact with the ecological community in different ways. As a result, the species can shape the ecosystem differently depending on the sex ratio of the population," Palkovacs said.

Control strategies

Sex ratios in natural populations of mosquitofish vary considerably from place to place around the world. Furthermore, several of the methods used or proposed for use in controlling mosquitofish populations can lead to changes in the sex ratio. For example, trapping or netting selectively removes larger fish, so would principally target females. "In this case, removing more females than males is a good thing because females have the biggest effects on the ecosystem," Palkovacs said.

Female mosquitofish (top row) are larger than males and often display a distended abdomen due to pregnancy (mosquitofish are live-bearing fishes). Males are smaller, thinner, and characterized by an elongated gonopodium. (Photo by David Fryxell)

Female mosquitofish (top row) are larger than males and often display a distended abdomen due to pregnancy (mosquitofish are live-bearing fishes). Males are smaller, thinner, and characterized by an elongated gonopodium. (Photo by David Fryxell)

Another strategy has been proposed that would involve genetically manipulating the fish so that females only produce male offspring. "The idea was to reduce the reproductive output of the population. Our research shows that this strategy could be doubly beneficial, leading to smaller populations in the long run while also creating more male-biased populations in the short run with less severe ecological impacts," Palkovacs said.

Beyond its practical implications for mosquitofish management, the study highlights an important phenomenon that may be widespread in nature. "Sexual dimorphism is very common, as is sex ratio variation. It's not just a mosquitofish phenomenon," Palkovacs said.

To conduct the experiment, the researchers set up an array of large stock tanks on a level field at UCSC's Long Marine Laboratory. They added sediment and plankton collected from a nearby pond to establish a small freshwater ecosystem in each tank. Mosquitofish were obtained from a California mosquito vector control district, sorted by sex, and introduced into the tanks at five different sex ratios, plus a fish-free reference treatment.

Bird netting kept out birds and mammals that might prey on the fish, but allowed naturally occurring insects and amphibians to lay eggs in the tanks. In the experiment, amphibians laid eggs in all of the treatments, but larval amphibians (tadpoles) were only found in tanks without mosquitofish.

The detrimental effects of mosquitofish on native biodiversity have been widely studied. Sex ratios may play an important role in this, although additional studies in natural settings will be needed to see what the effects of sex ratio variation are in the wild, "in the midst of all the other natural variation," Palkovacs said.

In addition to Fryxell and Palkovacs, the coauthors of the paper include UCSC graduate student Travis Apgar and Heather Arnett and Michael Kinnison of the University of Maine. This work was funded by the National Science Foundation, UC Santa Cruz, and the Maine Agricultural and Forest Experiment Station.

Feb 102015
 

This meeting we'll have two guest speakers who have traveled the state in search of creatures that swim. Both presentations will be an excellent lead up to the Forest Lake Pest Fishing Day on February 21.

Glynn Aland will give us a talk about the feral fish that are invading our waterways. Glynn has worked in a variety of roles with Fisheries Queensland and Seqwater and has conducted fish surveys all around the state.

Glynn Aland at Weary Bay

Gavin Brown will present some turtles from around Australia and take us on a tour of all sorts of turtle habitat. Gavin is a member of Australian Freshwater Turtles (AFT - a non-profit organisation) and has a wealth of experience with keeping turtles and observing them in the wild.

Rare Fraser Island Broad-shelled Turtle, from one of Gavin's expeditions.

The drinks stand and the shop will be open for books and aquarium supplies, and there'll be an auction where members can sell fish, plants, and other aquarium related items. Guests are welcome to come and have a look, you can join up on the night if you're interested.

ANGFA Qld Meetings are held on the second Friday of every other month (even numbers) at the Bar Jai Community Hall, Clayfield, starting 7:30 pm.

Oct 092014
 
Rick Shine says the cane toad's evolution is different to

Rick Shine says the cane toad's evolution is different to "the sort of thing (Charles) Darwin talked about". Photo: James Purtill/ABC News

Original story by James Purtill, ABC News

Cane toads in the Northern Territory and Western Australia have evolved "very very rapidly" to hop in a straight line and cover up to six times more ground than distant cousins back in Queensland, scientists say.

Research published in the Proceedings of the Royal Society of London journal shows "a new kind of evolution" and a phenomenon dubbed "spatial sorting", according to the article's co-author and University of Sydney professor Rick Shine.

"The front has accelerated from about 10-15 kilometres per year to about 60 kilometres per year over the time toads have been in Australia," Professor Shine said.

"To move at that rate, toads have to behave in very strange ways - ways that no other frog has before. Continue reading »

Jul 082014
 

Original story by Selina Bryan, ABC News

Scientists at the Tamar Island Wetlands near Launceston are about to wage genetic warfare on a small pest that is causing a lot of trouble.

The mosquito fish, or gambusia, was introduced to Australia more than 100 years ago to fight malaria and was released in the Tamar in the 1990s.

Because the gambusia thrive in calm shallow water and feed off insect larvae, they seemed to be the ideal mosquito control agent.

But being fast breeders and voracious eaters, the mosquito fish, like the cane toads of the mainland, have become the problem.

Now the University of Tasmania is leading a national campaign to eradicate the fish with the support of a $476,000 grant. Continue reading »

Jul 062014
 

Original story at ABC Tropical North

A north Queensland community is trialing the use of barramundi to eradicate a pest fish from public waterways.
Volunteers release barramundi into the Gooseponds in Mackay to help reduce the number of tilapia, a South African fish that is harmful to native species. Photo: Kim Kleidon, ABC Local

Volunteers release barramundi into the Gooseponds in Mackay to help reduce the number of tilapia, a South African fish that is harmful to native species. Photo: Kim Kleidon, ABC Local

The South African tilapia has been introduced into the Mackay Gooseponds and experts fear they could take over and threaten native species.

Reef Catchments aquatic habitats coordinator Tim Marsden says the species was first identified in far north Queensland in the 1970s.

"There's no natural predators to tilapia here in Australia, they can survive in hot water, cold water, low dissolved oxygen, really poor water... and so that means whenever we've got any conditions, for example an urban waterway where you might have less than ideal conditions, tilapia will end up dominating that waterway," he said.

He says while tilapia are very difficult to eradicate, he hopes the use of 1,000 barramundi will help reduce the number of fish in the pond.

"We're putting up a biological control option as a trial to see if we can do something," said Mr Marsden. Continue reading »

Jul 052014
 

Original story at Bush Telegraph

One of the oldest fish species in Australia that predates the breaking up of Gondwanaland, is under threat.
The ancient Salamander Fish, the Lepidogalaxias salamandroides, is facing threat from a lack of rainfall and a predator. Photo: Brad Pusey

The ancient Salamander Fish, the Lepidogalaxias salamandroides, is facing threat from a lack of rainfall and a predator. Photo: Brad Pusey

The salamander type fish is found in an isolated pocket of Western Australia in an area known as the Southern Acid Peat Flats, west of Albany. Continue reading »

Jun 042014
 

News release from the American Society for Microbiology

A bacterium causing an epidemic among catfish farms in the southeastern United States is closely related to organisms found in diseased grass carp in China, according to researchers at Auburn University in Alabama and three other institutions. The study, published this week inmBio®, the online open-access journal of the American Society for Microbiology, suggests that the virulent U.S. fish epidemic emerged from an Asian source.

Loading U.S. Farm-Raised Catfish. Photo: Jim Steeby

Loading U.S. Farm-Raised Catfish. Photo: Jim Steeby

Since 2009, catfish farming in Alabama, Mississippi and Arkansas has been seriously impacted by an emerging strain of Aeromonas hydrophila, which causes Aeromonas septicemia in catfish. A serious infection that can cause death in as little as 12 hours, Aeromonas septicemia’s clinical signs include skin lesions and blood loss. Continue reading »

Jun 042014
 

News release from Biosecurity Queensland

Biosecurity Queensland and Toowoomba Regional Council have commenced a hunt for exotic pest turtles to protect local fauna, following Australia’s first discovery of a Chinese stripe-necked turtle (Ocadia sinensis).
Chinese stripe-necked turtle (Ocadia sinensis), San Diego Zoo. Photo: Howard Cheng/Wikimedia Commons

Chinese stripe-necked turtle (Ocadia sinensis), San Diego Zoo. Photo: Howard Cheng/Wikimedia Commons

The turtle was suspected of being dumped in Toowoomba’s Bicentennial Waterbird Habitat. 

Agriculture, Fisheries and Forestry Minister John McVeigh said a Chinese stripe-necked turtle plus nine non-native turtles were recently found during a recent fauna assessment. Continue reading »