Histology of Alarm Substance Cells in Relation to Parasite Load and Fish Size for Creek Chub (Semotilus atromaculatus)

Abstract

It is generally thought that alarm substance cells (ASC) in fish epidermis evolved as a means of reducing predation risks via the release of a chemical substance these cells hold. It has been recently hypothesized, however, that the evolution and presence of ASC in fish may have more of a relationship with parasitism than predation. The goal of our study was to determine if an increase infestation of the black spot parasite (Neascus pyriformis) in creek chub (Semotilus atromaculatus) also correlates with an increase in the density of ASC. Additionally, we wanted to determine whether there was a correlation between epidermal surface area and ASC density. To our knowledge, this is the first study to field test this recently developed parasitism hypothesis concerning the evolutionary origins of ASC in freshwater fish.