Preliminary Parasites Data, Alright!

Christian has given me her Excel dataset from examining scarlet and striped shiners for Dactylogyrus gill parasite infestations in Swan and Limestone Creeks in north 'bama. This is a case where negative results are interesting; we found no statistically significant different in gill parasites per fish either between species, or between creeks. In principle there should be some difference, since the creeks are in different basins and the parasites are different species that infect specific species of fish. The one trend, albeit a weak one, is that fish have more parasites as they get bigger and older. This could mean that they're bigger targets for parasites to settle out of the water on the gills, or just that with time a given fish picks up more parasites by chance. Probably about 10% of the examined fish had no parasites (I should mention that we only examined the right gill structures as a proxy for all of the gills....)

Below are the data for all scarlet shiners (Lythrurus fasciolaris) examined from both creeks. A trend line shows the weak tendency for larger fish to have more parasites, with a correlation coefficient of 0.02 (that's what I mean by weak):

Below are the data from Swan Creek combined for both species. Again, there's a weak trend represented by the line, and a low correlation coefficient of 0.04:

So what does it all mean? I'm not completely sure yet, and that's what I'll be cogitating about as we further kick around the data.

And I still haven't talked more about Root Boy Slim and the Sex Change Band in my Vertebrate Reproduction class, I'll to get it together on that too.