Friday, October 14, 2011

Brain surgery......on fish?

What do you do when a) you need to do brain surgery b) your subject is about 6 cm long, and c) you are not known for your dexterity i.e shaky hands? I don't know but these are the problems I am facing as I proceed to dissect the brains from my fish. The added pressure is that we have been given only a few of these specimens from a musuem, and they are endangered, so there really is no room for any mistakes.

This video dissecting zebrafish (start at 7:55) highlights how this is done. Through some very good luck I have an undergrad student who has volunteered to help with this project and seems to be a little more of a delicate 'brain surgeon' type. So I am hoping she will come through. We have some test fish and plan to do some dissections today. Fingers crossed!!!!!

Friday, October 7, 2011

Give Me Brains

Its been far too long despite my good intentions of having a busy research blog. The constant back and forth between Canada and New Zealand can certainly be disruptive. As much as it is an ideal situation, it also has it's downsides. Mainly, that you never really feel settled in one particular location. But I have seen enough people with blogs where strange connections have been made not to try this again. In addition, blogging is like watering your garden of motivation. It is also a great place to put my thoughts and ideas. 

This year has been pretty successful so far. I have managed to get the remaining publications out for my PhD.....two in the Journal of Fish Biology(1,2) and another in the Journal for Experimental Marine Biology and Ecology. Another that I am collaborating on with Professor Jacqueline Webb at the University of Rhode Island has been submitted to the Journal of Experimental Biology. 

I am in Canada right now and am about to begin dissecting fish brains. We have specimens of several exotic and native species from Ontario. We are wanting to look at whether exotic species exhibit differences in their brain morphology compared to native species. More specifically do exotic species have enlarged regions of their brain dedicated to non-visual senses. Having the capability to 'see' without using vision would provide strong advantages when an introduced fish is trying to establish within a degraded turbid ecosystem where the use of vision is limited. Visual native species may be at a disadvantage in such a system, and may die out due to competition with better adapted exotic species (biotic factors), or simply be unable to find food due to an increase in turbidity (abiotic factors). This is a key question that needs further exploration - is it biotic or abiotic factors that matter? But first we must identify that the pattern exists. We can certainly see from our fieldwork in New Zealand that exotic species are more successful in turbid environments and other papers back this work up. 

Tuesday, February 22, 2011

The Eyes Don't Have It

Its a long tale on how this grant and research came to be. But as usual its best to start at the beginning. In 2007 I completed my PhD, which investigated nocturnal fish and asked the broader question 'how do fish survive and function in darkness where the use of vision is limited'? This question has always interested me as I have always had a fascination with the deep-sea and those fish that live in extreme environments.

After my PhD I moved to Rhode Island and began a one year postdoc where I looked at the nocturnal feeding behaviour of a Lake Malawi Cichlid. During this time I became aware of the many alien fish species in the United States, and the large impact they are having on the local freshwater ecosystems. The most notable examples are Carp, the Ruffe and the Round Goby. Because my background was in sensory ecology I noticed that all these species were non-visual sensory specialists. Or to put it more simply - they can feed and function without using vision. Thus, habitats that were extremely murky would be no problem to survive in for these fish. Which leads me to the next link in the chain. I also became aware that most invasions by alien fish occurred within these very murky habitats, and it was here that the idea was born. Do turbid or murky ecosystems provide an invasion pathway for exotic non-visual fish? 

In 2010 I was lucky enough to be awarded a grant by the Foundation for Research in Science and Technology (NZ) to investigate this very question. At this time I was already working in Canada at the Memorial University of Newfoundland under the guidance of Professor Mark Abrahams. However, at this stage I was investigating predator-prey interactions between two marine fish. But with a quick change of focus I found myself returning home to New Zealand to begin the first phase of my research. My goal for the summer was to look at biodiversity in turbid and clear freshwater rivers and see if in fact non-visual species increased in the murky sites. 

Setting up any fieldwork is not without it's problems and my research was not going to be exempt from this rule. Our initial problem was site selection and getting sites that were close enough that other factors couldn't account for any differences in fish biodiversity. For example propagule pressure presented a problem because we needed to make sure that one site didn't have more exotic fish simply because they were been released there more often. After looking through historical data, and talking to many people in the know, we found three sites that seemed appropriate for what we wanted to do. The sites included a highly turbid river emptying into the relatively clear Waikato River. The Waikato River is New Zealand's largest river and the hub of exotic fish invasions. The demarcation line between the two rivers is very strong with one side been turbid, the other clear. We would simply need to sample on either side of the demarcation line with fyke nets and minnow traps and look for differences in fish populations.


To Be Continued.........