Grace’s Notebook: Juneau, November 27, 2017

*I will double check some specifics of information (denoted by * or __) with Pam and edit post accordingly.

Effects of temperature change and Hematodinium sp. infection (Bitter Crab Disease) on Tanner crab (Chionoecetes bairdi)

Final sampling day of Tanner Crab (Chionoecetes bairdi) blood 

Pam Jensen and I arrived at the Ted Steven’s Marine Research Institute in Juneau at ~7:45am. We worked in the Annex (right image).

Experimental Set-up

There were three header tanks at different temperatures (4˚C – cold; 10˚C – warm; ~6˚C – ambient). The cold and ambient had coolers, and the warm had heaters. The water flows (2L/min) into the tanks.

There was a mass mortality in the warm tanks due to the temperature getting too high over a weekend. As a result, by today’s sampling day, there was only one crab in each of the three warm tanks.


Set-up of the lab

The header tanks with the coolers had brass floats. If the water went to high, it would close the valve with the water source (much like a toilet) to prevent the water from overflowing as well as the temperature becoming too cold. Additionally, both cooling tanks had pumps to circulate the water to homogenize the temperature.

The temperature was logged every 15minutes using HOBO Tidbits. One TidBit in each tank (9 total).


Tanner Crab phlebotomy 

The crabs were corralled into one end of the tank, and a screen was placed to hold them back. Additionally, bricks were laid at the bottom because the crabs could crawl under the gaps in the screen. In between samples, we kept foam over the top of the tank, to keep the temperature from fluctuating too drastically, since the room was likely quite a bit warmer (even though we did not have the heat on) than the water in the tanks.


Crabs to be sampled.

Each crab has two tags of different numbers. There are two because sometimes the tags will come off, or their entire leg with the tag, will come off. All the crabs are male and young in order to keep from having too many variables.


After the tag numbers were recorded with a tube number, a Q-tip with rubbing alcohol was rubbed in order to clean the area of other dinoflagellates. Then, a syringe is used to sample the blood at the base of the front claw.

A drop of blood is placed on a labeled slide to create a blood smear, and then 0.2 ml is placed in three tubes containing RNAlater (6 for the warm water crabs, because we only had three total).

The blood smears will be stained by _____ at _____. She will use the slides to determine the life stage of the Hematodinium.

Clean up

The blood smear slides were let to dry and then placed in a slide box. The HOBO Tidbit temperature data were downloaded.

Pam and I began the process of taking down the lab. We had to sacrifice all the crabs even though they were collected from Stevens Passage in Juneau. Pam removed the tags and placed them in the dumpster.

We took apart all the plumbing and pumps. Rinsed everything with freshwater, drained the tanks.

Tomorrow we’ll clean, pack everything up, and ship things to the Kodiak Lab.

Other Info:

Pam said that while other types of infection can cause this mottled appearance in their legs, it is likely the result of Hematodinium infection because ~50% of Tanner Crabs are infected in the fall in  the Juneau area.