New England Aquarium: Blood Chemistry

 

The Giant Ocean Tank at the New England Aquarium. If you haven't had a chance to visit, I highly recommend it! Photo- Turner Construction Company.

Hey folks,

I just got back to Tallahassee after a short trip to Boston and the New England Aquarium (NEAq), where our collaborator, Dr. John Mandelman, has invested in a flame photometer. You might be interested in some of his lab's work- their research is primarily focused on bycatch issues and applied fisheries science. You can check out the lab here.

Anyways, after some delays from the equipment's distributor, we managed to set up the machine and began analyzing shark blood samples for sodium and potassium ion concentrations. This post will serve as a brief description of the technique and how these results might be informative when we develop a model that predicts post-release mortality in Cuban dogfish.

 

A Jenway flame photometer.

First of all, a flame photometer is a device commonly used in a medical setting to determine the concentration of various metal ions. The two that we are most interested in are sodium and potassium because they've both shown promise as predictors of mortality. Both are linked to acid-base blood chemistry dynamics as well as ion transport in the gills, which is extremely important in the maintenance of homeostasis for fishes living in saltwater. In elasmobranchs, various studies have found that elevated levels of potassium, for instance, can result in mortality in stressed individuals. Potassium has also been linked to muscle tetany in some stressed elasmobranchs, which could be interesting when we examine the blood samples taken from gulper sharks that show little movement after release other than infrequent bursts of swimming activity.

The machine works by drawing from a sample of plasma diluted with deionized water and spraying it into a flame that has been optimized for the ion of choice. As the sample hits the flame, metals are excited to a higher energy level than normal and atoms become unstable and disassociated due to the thermal energy from the burner. As they return to their ground state, energy is emitted in the form of light radiation, and the intensity of that light relates to the concentration of that element in the sample. The photometer is able to measure this light intensity and give you a measurement on the display panel.

Pretty simple in theory... but in reality it involves a lot of pipetting and precise lab work which isn't my strong suit! In any case, I managed to work through a number of samples and became comfortable with the machine before coming back to Florida. The rest will be completed by our collaborators at UMASS and the NEAq, without whom we would be in a tough spot!

Big thanks to the Cape Eleuthera Institute Educational Opportunity Grant for providing the funding for this valuable learning experience and to the Henderson family for putting me up for a few nights! Thanks guys!

 

I spent many hours staring at this instruction manual...

So this is probably the last post for a while. I'm in the process of writing up the work we've accomplished over the past couple years and everything is coming together nicely, but field work is pretty much a wrap. The Island School students that worked on this project are applying for colleges, I'm trying to graduate, and I'll be in need of a job very soon! If anyone has any leads, feel free to send me an email...

I'll be sure to post the manuscripts as soon as they're published, hopefully late this year or early 2016. We're also planning on making a video abstract for this project and submitting it to the Ocean180 Video Challenge, so we're not done yet :)

Thanks so much for sticking with us throughout the process. Have a great week.

Best,

Brendan