Studying Mosquitofish from the South of France is Not as Glamorous as It Sounds, Part 3

The fish have been collected, the experimental plans organised, and now ... it's time to watch and swim and measure fish.

 

Robbie and Frank split up the work associated with their experiment - Robbie observed the females' behaviour and Frank measured metabolic rates.  

Here's the behavioural set-up:

And the metabolic set-up:

 

Frank swam fish in a little glass jar to ramp up their metabolic rates, so he and Robbie could calculate the metabolic scope.

That's all we can say for now, as the data haven't been analysed and the paper has yet to be written. But we wanted to give you some insight into what an eco-physiological experiment entails. It may not be as glamorous as it sounds, but the excitement of discovery and exploring new ideas is what keeps scientists going. The development of an experiment like this one was a lot of fun!

Studying Mosquitofish from the South of France is Not as Glamourous As It Sounds, Part 2

We now return to our story of mosquitofish from murky waters in southern France ... gallantly collected and brought back to the lab, where they were used to address a very important question:

How expensive is pregnancy?

Now, having been pregnant once before, I was willing to share my own experiences with expense in pregnancy: the financial costs associated with becoming addicted to eBay; the social costs of inexplicable moodiness; the energetic costs of lumbering to and from the bathroom; the mental costs manifested in an inability to concentrate/find keys/remember things.

But, apparently fish are different.

Mosquitofish, in fact, are live-bearers that can produce 20 to 70 young in a pregnancy - young that altogether can weigh up to 30-40% of the female's own body weight.

This extra mass and the energy required to produce all these baby fish can substantially increase a female's metabolism - even when she's resting. A higher resting (or basal) metabolism would be expected to limit a female's metabolic scope.

What's metabolic scope? It's the difference between resting and maximum metabolic rates - or the amount by which the body can increase metabolism to deal with high levels of physical activity or stresses. Because maximum metabolic rates are limited by the body's capacity to uptake oxygen and eliminate cell waste, they don't change much. So we expect the metabolic scope of a pregnant mosquitofish to diminish as her resting metabolic rate increases.

But.

That's not all.

Temperature also increases the resting metabolic rate of fish: higher temperatures mean higher resting metabolic rates.

So that's what Robbie and Frank and their French collaborators were keen to look at - how temperature affects the metabolic scope of pregnant mosquitofish.

(to be continued ...)

Studying Mosquitofish from the South of France is Not as Glamourous As It Sounds, Part 1

Recently, Robbie was invited to collaborate with scientists at France's prolific CNRS (Centre National de la Resherche Scientifique). These researchers included Head of the CNRS's Ariege unit, Prof Jean Clobert; and Marie Curie Fellow, Dr Camille Bonneaud. Robbie joined his long-time Australian collaborator and friend - A/Prof Frank Seebacher - in the idyllic location of Moulis* to study the behaviour, physiology, and performance of the invasive mosquitofish (Gambusia holbrooki) relative to their state of pregnancy.

*Let me assure you, that for all the un-glamourousness of the fish- and data-collection, the research station was spectacularly situated.

Imagine working in a well-funded research program in a quaint French village, in a building that adjoins a rushing brook amidst the green-capped mountains of the Pyrenees.
Mag. nif. ique.

But, alas, mosquitofish don't like pristine, bubbling streams. They prefer dank, stagnant places. So when Robbie and Frank took a drive toward the Mediterranean coast, it was looking for swamps. And though there are no pictures to document the collection of the fish, it allegedly involved:

1) wading through reeking swamp mud
2) numerous biting insects
3) a decomposing, floating, probable-mammal the size of a beaver
4) a swift change of clothes before returning to the hire car

And a pink net.

Some hearty beef stew and a few beers upon returning home didn't hurt, either.

Then it was off to the lab to set up the experiments ... (to be continued) ...