If we consider the "general defence mechanism" of crustaceans, it primarily involves beta-glucan-binding protein, lipopolysaccharide- and glucan-binding protein (LGBP) and lectins produced by various haemocytes. These pattern recognition proteins activate prophenoloxidase (proPO) system to initiate immune response. LGBP is the main molecule in response to infection with fungi and oomycetes.

As to your observation, it can be a tricky business because it is not clear whether the chitinases and LPMOs are from the crayfish or oomycete. This is because these chitin-binding molecules are actually the primary products of the pathogens. And particularly, LPMOs can be the pathogenic factors against the haemocytes of crayfish.