ARS | Publication request: PATHOGENICITY OF AN EXOTIC HETEROPHYID TREMATODE INFECTING THE GILLLS OF THE ENDANGERED SPECIES ETHEOSTOMA FONTICOLA (FOUNTAIN DARTER).

Submitted to: International Aquatic Animal Health Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 30, 1998
Publication Date: N/A

Technical Abstract: A heterophyid trematode associated with an exotic aquatic snail (Melanoides tuberculata) caused massive gill infections in the endangered fountain darter (Etheostoma fonticola) living in the Comal River near San Marcos, Texas. Every darter (n=150) examined was infected. A host response encased and killed the trematodes leaving hardened cysts (70-100æ X 150-200æ) that numbered in excess of 200 per gill arch in some fish (25 to 35 mm - total fish length). Wet mount microscopy demonstrated extensive proliferation of gill epithelium and cartilage displacement and deformity. Histological examination revealed parasites adjacent to the cartilage in the central sinus of gill filaments. The parasites were encased in masses of cartilage that swelled affected filaments to several times their normal diameter and completely disrupted the normal gill structure. Affected filaments were short, thick, distorted and had few if any lamellae.