No …… the mussel was not pumping radioactive green water out of its shell. This was just part of our experiment studying invasive species of Vancouver marinas. Our study composed of many parts but I was very interested in the experiments exposing our organisms like this mussel to low salinity water for a short time and seeing their response.
Most marine animals require their water to have a specific level of salt for their body to function properly and many animals cannot survive in water with a lowered salinity. As part of our project, we exposed both native mussels (Mytilus trossulus) and invasive tunicates (Botryllus schlosseri) found in Jericho and Coal Harbour marinas to waters with only 1/3 of the salt content they were found in. We looked at the differences in their activity levels in the two types of waters to understand their survival in different environments.
But… how can you tell how active a mussel is?
Here’s where the neon green dye came in. Because mussels are filter feeders, they draw water into their body from one opening and pump the water out through another. By colouring the water, we are able to physically see water flow generated by the mussel to determine its activity level.
It was much easier to find the activity of the tunicates as we could see individuals pumping their body under a microscope. We simply compared the number of contractions an individual performed in the two water types as activity level.
For both animals, we saw their activity lowering after being in the low salinity water. This was especially important for the invasive tunicates since this could mean they cannot tolerate or invade environments with low salinity. We did see this in the field where the tunicates were only found in the Coal Harbour marina which had a stable high salinity water while the tunicates were absence in the Jericho marina which had a very low salinity in the summer times.
Although this may not seem to be ground breaking results, but we learned about the invasion process of these tunicates and possible areas they could and could not invade. It is very true that invasive species can have a huge impact on a local community. The comb jellyfish for example, originally from the Americas was accidentally released into the Black Sea and caused the collapse of the entire anchovy fisheries worth over billions of dollars. This is why many scientists are studying invasive species to better protect our environment and economy. To protect our own ecosystems, Fisheries and Oceans Canada works with provincial governments and organizations to develop action plans to manage and control aquatic invasive species within Canada. You can learn about invasive species and their effect on the Canadian ecosystems and their corresponding action plans on their website.