Occurrence of tumors among gastropods Plicopurpura pansa (Gastropoda: Neogastropoda) in the Port of Manzanillo, Mexico.

In order to evaluate the health of Plicopurpura pansa, a species considered vulnerable, a population of this gastropod living in proximity to the port of greatest cargo movement in Mexico was monitored seasonally during 1 year. Morphometric characteristics and sexual proportion were recorded. A macroscopic analysis was carried out to detect malformations and imposex; a histological analysis was performed to evaluate disseminated and gonadal neoplasias; the presence/absence in soft tissues of butyltin species (BTs) as possible contamination agents was also estimated. A total of 508 P. pansa specimens were collected. The largest specimens were obtained in winter. The coefficients of determination inside the port were low (R = 0.453). In general, there was a greater proportion of females than males throughout the year. Distinctive foot malformations (tumors) were recorded, but without signs of imposex. The histological examination confirmed the presence of disseminated neoplasias in the foot and gonads of P. pansa in the Port of Manzanillo. The comparative analysis of the morphological and histological features of the studied gastropod population allowed us to recognize impact patterns in relation to proximity to the port. There were high concentrations of monobutyltin (MBT) and greater abundance of tumors in heavier specimens; this was associated with port proximity zones. P. pansa could therefore serve as a sensitive bioindicator of environmental health in marine systems.