Eelgrass experiments, field and lab

~I seem to have neglected to post this on Saturday, so today is will be a twofer from me. I’ve added some more information to the bottom to reflect what I did this afternoon~

The other day I posted a few graphs of the infection prevalence in eelgrass from Indian Cove and False Bay. The differences between the control and culled plots were hard to eyeball, so I decided to dig a little deeper into our data. At Indian cove, 36% of the blades in the control plots had one or more lesions, while just 27% of blades in the culled plot had lesions. We got similar results in False Bay where again, 36% of blades in the control plot had lesions and 29% of the blades in the culled plots had one or more lesions.
(Fisher’s exact test, p>0.05 for both sites. However, the pvalue for Indian Cove was p=0.055).

At Indian Cove, there was a significant difference in blade area between blades with and without lesions at Indian Cove (p0.05), but there was a significant difference (p<0.05) in the culled plot. Again, the lesioned blades were larger than those without lesions.

In the Groner et al (2014) paper they discuss a much more sophisticated model for exploring this kind of data, so I'm hoping to get a chance to sit down with Maya sometime this week and see what else we can learn about this experiment.

***
For our laby experiment in the lab we have been taking pictures everyday of each of the young eelgrass in each beaker in order to track the development of lesions over time.

Lesion photo day 1

Today was my fourth day photographing the blades, and the first day that I have tried to quantify the changes in number and shape of the lesions. I’m using a software package called ImageJ to circle the lesions on each blade and measure their dimensions. The image analysis has been a bit harder than I expected because the leaves have darkened significantly in the last four days so seeing the lesions on the blades is a challenge. Also, some of the leaves are coming off of their rhizome so the plants look different than they did on the first day, making it difficult in some cases to figure out which blade goes with which plant. I’ll have more to say about this tomorrow as I move through the rest of the photos.

Leave a Reply