Tag Archives: freshwater

Monitoring Freshwater Populations in the Chernobyl Exclusion Zone

Radiation can have extremely negative effects on an individual. But is it as easy to measure its effects on an entire population? (Image Credit: Hnapel, CC BY-SA 4.0, Image Cropped)

Variation in chronic radiation exposure does not drive life history divergence among Daphnia populations across the Chernobyl Exclusion Zone (2019) Goodman et al., Ecology and Evolution, DOI: 10.1002/ece3.4931

The Crux

As anyone who has recently watched HBO’s Chernobyl can tell you, large doses of radiation are capable of doing some pretty serious damage to an organism. But whilst examining the effect of radiation on an individual might be simple, monitoring those effects on a population can be difficult. Whilst radiation negatively effects fitness, it can also help individuals with higher radiation tolerance to reproduce and dominate within the population of a single species, making it difficult to monitor the exact effects of radiation on that population. If a population is filled with only those who were strong enough to survive, you don’t get an idea of the variation in the radiation’s effects.

This week’s researchers tried to break through that problem by looking at different populations of a water flea in Chernobyl’s Exclusion Zone (CEZ) – the area still barred from entry in eastern Europe.

What They Did

The researchers sampled populations of the water flea Daphnia pulex (see below) from 8 lakes within the CEZ, all of which had experienced different doses of radiation since the Chernobyl disaster. Information on how much radiation those lakes were subject to was taken from Ukraine’s radiation databases and water samples collected at the site. The 38 types of Daphnia from the 8 lakes were then transported back to a laboratory and bred for three generations. The survival and reproductive success of this third generation was then modelled against radiation dose.

Did You Know: Daphnia as Study Organisms

Some species are frequently used across different ecological disciplines as model organisms. One example is the genus Daphnia, a genus of water fleas. They have a short life cycle, and can reproduce asexually. This means that scientists have the opportunity to disentangle environmental effects on populations of genetically similar individuals, as well as between populations of different genetic backgrounds.

What They Found

Whilst reproductive success and survival varied between the populations of Daphnia at different lakes, this did not seem to occur as a result of radiation dose. Radiation did not have a pronounced effect on any fitness variable.

Problems?

Daphnia_pulex

The water flea Daphnia, here used to test the effects of radiation on populations (Image Credit: Paul Hebert, CC BY 2.5)

Sample size is of course an issue here. Only having 8 lakes to compare the effects of radiation on populations was always going to make an effect of radiation dose hard to find. It was made more difficult by the fact that the effects of one lake were significantly different to the others, skewing results considerably. This is of course no fault of the authors, and hopefully technology in the future will allow us to expand the data used in these projects.

So What?

It’s important to note here that these results do not necessarily mean that radiation has no effect on Daphnia populations. Radiation is known to have negative effects on individual fitness, so what this study could tell us is that we need to view radiation as an environmental process which acts in concert with a variety of other biotic factors. Perhaps a study which takes into account further environmental variables and more lake populations would be able to further advance the work done in this paper.

Keep Your Eyes Open

Natural selection favors a larger eye in response to increased competition in natural populations of a vertebrate (2019) Beston & Walsh, Functional Ecology, doi: 10.1111/1365-2435.13334

The Crux

Studying the evolution of traits in response to selection pressure often helps us understand why species look and act the way they do. Selection pressure can include the need to find food before other members of your species, or the need to escape predation.

But what happens when improving your ability to obtain resources also means you’re more vulnerable to predation? Which will win out? This paper looks at a small species of freshwater fish, Rivulus hartii, and determines which of the two pressures contributes most to the evolution of the size of their eye.

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Fishers and Fish Science: The Australian Fish Scientist Perspective

Fishing is an important part of Australian society. So is communication between fish scientists and fishers strong enough?

Fishing is an important part of Australian society. So is communication between fish scientists and fishers strong enough? (Image Credit: State Library of Queensland, CC0)

Last Thursday, I posted an article on the need for more contact communication the fish scientist community and the fishing community, which you can find here. It gives a breakdown of why better communication between the two groups is mutually beneficial, and how it could be improved. The piece was written after talks with a number of prominent Australian fish biologists, whose thoughts I’ve shared in more detail below.

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If You Can’t Stand the Heat, Get Out of the Pond

Dragonflies like this Western Pondhawk female are particularly vulnerable to warming due to climate change. (Image Credit: Eugene Zelenko, CC BY-SA 4.0)
Simulated climate change increases larval mortality, alters phenology, and affects flight morphology of a dragonfly (2018) McCauley et al., Ecosphere, doi:10.1002/ecs2.2151

The Crux

Climate change is something that we hear about on a daily basis. The dire warnings tend to concern sea levels rising and temperatures varying so much that we have more intense and deadly storms than before, but these are all direct effects of the climate. Another thing that climate change can do is have indirect effects on organisms.

Organisms with complex life cycles spend the juvenile part of their lives in one environment before moving on to the adult stage in another environment. The researchers in this study wanted to know how simulated climate change during the juvenile stage of the organisms lifetime could affect the adult stage.

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Peter Unmack & Karl Moy: Saving an Endangered Fish from Extinction

A release of the formerly endangered Running River Rainbowfish. So how were they brought back from near-extinction?

A release of the formerly endangered Running River Rainbowfish. So how were they brought back from near-extinction? (Image Credit: Karl Moy, University of Canberra, CC BY-SA 4.0)

We talk a lot about getting the public interested in conservation and ecosystems on Ecology for the Masses, but we’ve rarely talked about how conserving a species is actually accomplished. Where does funding come from? How do you decide which individuals to save? And how do you allow a population room to grow?

In 2015, Peter Unmack was sampling in the Burdekin river system in northern Queensland, Australia, when he noticed an alien population of Eastern Rainbowfish had established in Running River. Specifically a 13km stretch bounded by two gorges, which housed the Running River Rainbowfish, a species distinct to this one stretch. Knowing that the presence of the Eastern Rainbowfish could spell the extinction of the local species, he started a crowdfunding initiative, and essentially saved the Running River Rainbowfish. I spoke to Peter and postgraduate student Karl Moy about the conservation effort.

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Victory May Not Guarantee Survival in Species Conflicts

Spreading of the Australian yabby has led to decreases in other local species. But what happens when these species meet?
Spreading of the Australian yabby has led to decreases in other local species. But what happens when these species meet? (Image Credit: Daiju Azuma, CC BY-SA 2.5)
Insight into invasion: Interactions between a critically endangered and invasive cray fish (2018) Lopez et al., Austral Ecology, doi:10.1111/aec.12654

The Crux

When we talk about invasive species, often the first thing that pops into our minds are things like feral cats, wild pigs, vicious newcomers that wipe out species or transform vast areas. But often what we focus on less are species which arrive and simply outcompete the locals.

The yabby (Cherax destructor) is one such invader. An Australian species, it has been introduced to new waterways through the country and is now threatening other species, including the Falls Spiny Crayfish (Euastacus dharawalus) in eastern New South Wales, Australia. The introduction of the yabby has resulted in a decreasing habitat range for the crayfish, but what sort of mechanisms are causing this? This experiment aimed to document interactions between the two species.

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The Problem With ‘Carpageddon’

The Australian government has been throwing around the term Carpageddon for a while now. So why is it a problem?

The Australian government has been throwing around the term Carpageddon for a while now. So why is it a problem? (Image Credit: Ed Dunens, CC BY 2.0)

I think it’s fair to say that Australian politics can be guilty of a flair for the dramatic from time to time. From the recent spill crisis, to the name-calling that abounds in parliamentary displays, to Bob Katter announcing that he wasn’t wasting time on the marriage equality debate because “every three months a person is torn to pieces by a crocodile in Northern Queensland”, Auspol enjoys the sensational. So when they heard about plans to release a virus into Australian waterways to deal with Australia’s persistent carp problem, of course they named it ‘Carpageddon’. But is this in any way an appropriate title? And why is it such a problem that we use this sort of language to sell scientific endeavours?

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