Pathology, Effects, and Transmission of Black Gill in Commercial Penaeid Shrimp from the South Atlantic Bight

ABSTRACT Severe outbreaks of black gill (BG), heavily melanized gills of crustaceans, have been reported in white (Litopenaeus setiferus) and brown shrimp (Farfantepenaeus aztecus) from coastal Georgia and South Carolina during late summer and fall since the mid-1990s. The cause of this condition is an apostome ciliate that elicits the innate immune response of the shrimp, resulting in the formation of melanized nodules in shrimp gill tissue. In the absence of a definitive identification, the causative ciliate is referred to as the shrimp black gill (sBG) ciliate. During outbreaks, necrosis of gill tissue was often seen in microscopic sections; in some cases, there appeared to be penetration of the ciliate into gill tissue. Shrimp with BG exhibited reduced physical endurance and escape responses compared with shrimp without symptomatic BG. Physical impairment due to BG may contribute to higher predation rates and increased vulnerability to environmental conditions. The infection transmission rate of the s...