The myxozoan Kudoa inornata is a common parasite of the skeletal muscles of spotted seatrout, Cynoscion nebulosus. This study was conducted to determine the distribution of plasmodia of K. inornata within individual C. nebulosus in order to identify muscle areas of least variation where future sampling would result in easily obtainable, repeatable, and dependable measurement of infection status. Fish were captured in the wild during June 2011. Muscle samples from 9 body areas were collected, in replicate, from each of 15 specimens of C. nebulosus of various ages and lengths infected by K. inornata. Body areas sampled included 6 locations from the fish epaxial and hypaxial muscles and 1 from each of the adductor mandibulae (cheek muscle), the cranial epaxial muscle, and the muscle of the caudal peduncle. Replicate samples were weighed and the number of plasmodia in each was recorded to determine the average density of plasmodia per gram of muscle in each area. The average density of plasmodia among fish was highly variable and was not correlated with fish size, age, or the homogeneity of distribution. Although the anterior hypaxial muscle (belly flap) was significantly more infected and the caudal peduncle less infected, when compared to all other areas examined in all fish combined, 10 out of 15 fish displayed an otherwise homogeneous distribution when data were analyzed fish by fish. Among the 5 fish with a nonuniform plasmodia distribution, 3 had a significantly higher burden in the belly flap, 1 in the area just posterior to the belly flap, and 1 in the cheek muscle. Based on these results, it was determined that hypaxial, caudal peduncle, and cheek muscles contributed greatly to the overall variation in plasmodia distribution observed whereas any portion of the epaxial muscle, as well as the cranial muscle, would be the least-variable areas to sample to determine the status of infection in any given fish.
Vol. 81 • No. 1
Vol. 81 • No. 1