Memo to the environment minister: a river does need all its water


Paul Humphries, Charles Sturt University and R. Keller Kopf, Charles Sturt University

Given her new role as federal environment minister, one of Sussan Ley’s comments in an interview with Nine Newspapers was eyebrow-raising, to put it mildly. She said:

Sometimes the environment doesn’t need all its water but farmers desperately do need water.

This is inaccurate and concerning, but not all that surprising, given the attitude to water and rivers of some in the community and federal government.

In this age of water sharing and trading, and storing water in dams, it is easy to lose sight of what water is to a river, and how every drop of water that enters (or should enter) a river defines the character and function of that river.

Ultimately, the community – not scientists or even river managers – decides how much water a river should get. But it’s essential to be honest about the effects these decisions have on rivers and the ecosystems they support. This is vital for long-term environmental sustainability, upon which all our industry, agriculture and indeed our society are based.

Crises and concerns

Recently the Murray-Darling river system has suffered several crises, including fish kills, hypoxic water, acid-sulfate soils, and algal blooms. These are all wake-up calls that the way we manage rivers are not working.




Read more:
Damning royal commission report leaves no doubt that we all lose if the Murray-Darling Basin Plan fails


But besides these disastrous incidents, there are many other ways in which river ecosystems are changing, that are not as obvious to the general public.

Contraction of native species’ ranges, local extinctions, success of invasive species and the “need” to stock non-native recreational fish species are just a few of the insidious symptoms of a general malaise.

Water to a river is like air to a balloon. Let out a little air and the balloon is still balloon-shaped, albeit less taut than before. But let out more air and there comes a point, which is hard to predict exactly, when the balloon suddenly collapses. By this analogy, the Murray-Darling Basin is very deflated indeed.

The point is that if we take water out of a river, or change the patterns of its flow, we inevitably change the nature of that river. Irrigators undoubtedly need water. But we shouldn’t kid ourselves that we’re not altering the river and its ecosystems by allowing them to take it.

Do we want healthy rivers?

Our job as river scientists is not to say what type of river the community wants. Our job is to inform people on what the actions of changing river management will do to a river and its life.

We already have seriously degraded river ecosystems. Restoring them is exceedingly unlikely under current demands and management. But if we take even more of a river’s water away, we need to acknowledge that the river will become yet a different river, and in some cases, one that we hardly recognise.

The public backlash following the fish kills earlier this year suggests that the community has decided that further degradation of our rivers is not acceptable.




Read more:
5 ways the government can clean up the Murray-Darling Basin Plan


The Conversation


Paul Humphries, Senior lecturer in Ecology, Charles Sturt University and R. Keller Kopf, Research fellow, Charles Sturt University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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We could reduce pest carp in Australian rivers using a disease that came from Israel


Susan Lawler, La Trobe University

Everyone wants to give Australian carp the herpes virus. That’s right, introduced carp are a serious pest species and research suggests that a viral control agent may be the most effective solution.

I love stories like this one, where groups that would normally disagree come together in an “unlikely coalition”. That is to say, fishers, conservationists, irrigators, scientists and farmers agree on the desirability of an environmental release of the carp-specific virus.

After all, it worked for rabbits. The release of the myxomatosis virus in the 1950s and the more recent release of calicivirus have permanently decreased rabbit numbers on our continent. Using viral pathogens to control vertebrate pests can be extremely effective because it does not require ongoing human intervention.

Like rabbits, carp were introduced to Australia deliberately. The first introductions in the 1800s did not cause problems, but a strain bred for European aquaculture escaped from farm dams near Mildura in the 1960s and spread throughout the Murray Darling Basin. The impact of carp on our rivers has been well documented, including increasing turbidity (making the water muddy), destroying aquatic vegetation, and contributing to the decline of native fish.

In other parts of the world, carp are an important food species, often raised in fish farms. When I worked on a kibbutz in Israel in 1980 we caught and sorted carp from geothermal pools near the Sea of Galilee. The fish were a desirable food item and water from the fish ponds was used to fertilise banana crops via drip irrigation. I admired the sustainable farming practice that was then ahead of its time.

Twenty years later while participating in a fish survey at Horseshoe Lagoon near Albury, I remember pulling dozens of giant carp out of our nets, lamenting the lack of native fish. Because we were not allowed to return the carp to the water due to its pest status, we had to kill each one, resulting in a large pile of stinky dead fish that nobody wanted to eat.

The only similarity between these two memories was the method of death: although it looks brutal and cruel, hitting carp on the back of the head with a heavy wooden stick dispatches them instantly and humanely. On those two occasions this peaceful vegetarian turned into a lethal killing machine.

Ironically, at about the time I was whacking pest carp in Australia, the carp industry in Israel was affected by a new disease. The koi herpesvirus, or Cyprinid herpesvirus 3 (CyHV-3) appeared in Israel in 1998 and was so contagious that it soon spread throughout Europe and Asia. The carp industry was devastated.

While this virus is bad news for carp farming, it could be good news for managing feral carp in Australia. With an expected mortality rate of 70-80%, CyHV-3 may be just what we need to curb the plague of carp in our rivers.

Of course, given our sometimes disastrous experience with biological control species, caution is warranted. That’s why scientists have spent the last eight years doing research to ensure that the herpes will not affect other species. Ken McColl is a leader of the team that has examined the host specificity of the virus in an Australian context.

The good news is that CyHV-3 has no impact on other native fish, yabbies and trout. It cannot infect mammals, amphibians or reptiles. In other words, it looks safe.

The bad news is that it will affect ornamental carp (koi) which are highly valued, so people who keep koi will need to monitor their water and food sources. I see this as something like vaccinating your pet rabbits against calicivirus, an inconvenient but reasonable impost given the benefit for the nation and our environment.

What happens now? There are a number of government organisations that are responsible for biosecurity. Getting approval to introduce a virus into our waterways will probably take a few years, so the research will continue as the Invasive Animals Cooperative Research Centre goes through the application process.

There is also research underway to identify locations suitable for early releases, and this is where members of the public can get involved. Hotspots for invasive fish species will be identified by gathering data from concerned citizens at a new website called Feral Fish Scan. Anyone interested in learning how to identify invasive fish and record observations of their local waterways can do so at this link.

Other conventional approaches to reducing carp are still underway, from the development of traps that target carp to better ways for Charlie Carp to turn those feral fish into fertiliser. But harvesting tons of carp and turning them into pellets will never reduce the impact of this noxious pest as effectively as a carp-specific disease.

This is why virtually everyone is excited about the possibility of giving herpes to Australian carp. And even though I think it sounds like a good idea, I am also grateful that we have robust regulations about biocontrol, because there was a time when cane toads seemed like a good idea, too.

We can wait a couple of years to ensure that we do not regret our decision, but then we may enjoy a great irony: a disease that caused huge financial losses overseas could save freshwater environments in Australia.

The Conversation

Susan Lawler, Senior Lecturer, Department of Ecology, Environment and Evolution, La Trobe University

This article was originally published on The Conversation. Read the original article.

How healthy is your river? Ask a waterbug


Angus Webb, University of Melbourne

Changing wildlife: this article is part of a series looking at how key species such as bees, insects and fish respond to environmental change, and what this means for the rest of the planet.

In 2003, something seemed to be going wrong with the streams around Melbourne. After seven years of below-average rainfall, the aquatic macroinvertebrates – waterbugs – were telling us that something was changing.

In a small number of streams that had been sampled every year, the community of waterbugs seemed to be moving towards dominance by species normally associated with severe environmental impacts.

That was when I became involved. Using an expanded data set and statistical analyses, I demonstrated a widespread decline in ecological condition of Melbourne streams as the Millennium drought really began to bite.

This is an example of using waterbugs for biomonitoring – assessing environmental condition, its changes, and the causes of those changes, by sampling organisms directly. And around the world, waterbugs are the most widely used bioindicator of environmental health and pollution of rivers, lakes and wetlands.

A small diving beetle from a common family Dytiscidae.
John Gooderham and Eddie Tsyrlin in The Waterbug Book

What makes waterbugs so popular?

First, they are very easy to sample. With a pair of waders, a dip net, a sorting tray and a magnifying glass, anybody can observe these weird, wonderful, and often beautiful creatures.

They are everywhere in aquatic systems. Every river, lake and wetland is teeming with waterbugs of all different kinds. Different species are typical of different types of environments and different levels of human impacts.

Most Mayflies, for instance, are found in rivers with clear waters and little pollution – they are indicative of good environmental health.

In contrast, Chironomids (a type of midge), are highly tolerant of pollution and other disturbances, and so come to dominate environments that have been heavily-affected by humans.

Chironomids are a type of midge that can indicate pollution.
John Gooderham and Eddie Tsyrlin in The Waterbug Book

Waterbugs are a direct indicator of environmental impact. If they change, then some difference in the environment has caused it. In contrast, a water quality sample is an indirect indicator of impact. It may detect pollutants in a river, but we do not know if the concentrations are environmentally important.

They also integrate the effects of environmental conditions over time. Waterbug lifespans are relatively short – usually only a few months before aquatic larvae metamorphose into adults and leave the river. They also don’t move too much. Therefore, changes in the bugs found at a site are indicative of impacts over recent times, and this gives a much more complete picture compared to spot samples of environmental conditions, such as water quality readings.

For these reasons, waterbugs have been successfully used to detect environmental impacts of many kinds.

As well as the example above, I have detected impacts of trout farms on waterbugs in the Goulburn Valley, Victoria, and have developed new ways of assessing whether the waterbugs at a site differ from those that would be expected in the absence of human impacts. Currently, we are using waterbugs to assess benefits of environmental water being delivered by the Commonwealth and Victorian environmental water holders as part of the Murray-Darling Basin Plan.

A mayfly nymph (Atalophlebia sp) from family Leptophlebiidae. This genus is probably the most tolerant of this sensitive family.
John Gooderham and Eddie Tsyrlin in The Waterbug Book

But there also are difficulties

While the diversity of waterbug species makes them very useful as indicators of environmental health, there are so many species that many have never even been properly described.

Only experts can identify waterbugs to species, but fewer and fewer people are interested in studying invertebrate taxonomy and so the pool of expertise is shrinking.

Waterbug abundance is also incredibly variable over very small spatial scales (less than a square metre). There can easily be as much variation within a site as there is between sites or even between rivers.

For these reasons, bugs often only are identified to coarse taxonomic levels (usually Family). Many assessment methods also ignore abundances altogether, instead concentrating on waterbug taxonomic diversity. This means that we’re missing out on a lot of potentially useful information contained within the samples.

Change is in the wind

The basic techniques used in waterbug-based research and monitoring have changed very little for decades.

However, the relatively new field of environmental genomics may change all this. Environmental genomics is the study of DNA and RNA in environmental samples to understand biological structure, function, and responses.

It uses genetic approaches to identify the species in a sample. The cost of the genetic techniques has decreased rapidly, just as their speed has increased. This means large numbers of samples can be processed rapidly.

A snail (Austropeplea tomentosa) typically found in slow flowing and still waters, grazing on algae from hard surfaces. It can indicate pollution.
John Gooderham and Eddie Tsyrlin in The Waterbug Book

The analyses identify all the different genetic types in a sample, effectively identifying everything to species. This eliminates the need for taxonomic expertise to identify species.

Genetic analyses are even challenging our traditional notion of what constitutes a species, with many physically identical animals now being identified as separate genetic lineages, effectively multiple species.

Like any new technique, there are issues to deal with before genomic techniques can be used in place of the well-established waterbug biomonitoring approaches.

For example, when we process a sample, we do not only get DNA from the waterbugs in it, but also from what they have eaten, and what is living on their surfaces. Are all of these separate “species” to be considered in biodiversity indices?

Nevertheless, environmental genomic techniques have the potential to greatly increase the amount of waterbug data that can be collected, providing much better coverage of aquatic systems.

Together with large-scale, remotely sensed environmental data that are now becoming the norm, this has the potential to move bioassessment into the era of big data.

And together, these things could fundamentally change the way we use waterbugs to monitor stream health and pollution.

The Conversation

Angus Webb is Senior Research Fellow and quantitative ecologist at University of Melbourne.

This article was originally published on The Conversation.
Read the original article.

Watch this dry riverbed fill up in seconds


Grist

Nature’s been watching Michael Bay movies again! A crowd near Israel’s dry, dusty Zin River recently got caught off guard by a flash flood and had to hightail it to avoid getting swept away:

The Negev desert is better known for its arid sun — and plans to build a giant solar power station — than abundant rainfall. The Zin River had been dried up for years, so you can’t really blame the onlookers (and eager dog). Heavy rain in nearby mountains was SUPPOSEDLY the culprit, although the Plain of Sodom is nearby, so God might’ve been trying to scare all those teens using the back door.

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