Paràsits i patologies de la gamba blanca (Parapanaeus longirostris) i el seu potencial ús com a sentinelles de l’impacte ambiental

Abstract

The white shrimp (Parapenaeus longirostris) is a key fishery resource in some regions of the Mediterranean, being one of the commercial species with the highest revenues, but despite its economic importance, it is very little studied compared to other commercial species. For this reason, this study aims to improve the understanding of the threats and diseases that can impact the natural populations of white shrimp, susceptible to various infections that can cause severe symptoms and mortality. During the month of February, white shrimp samples were collected in two areas of the Catalan coast, Barcelona and La Rápita, characterized by presenting different degrees of pollution. Through the dissection of the specimens, macroscopic examination, histological analysis and quantitative analysis of various biological parameters, the presence and diversity of parasites has been studied, possible diseases and alterations have been detected, and the health status of the populations of this species in both locations has been compared based on the condition index. The most notable macroscopic alterations have been melanosis and calcification of the exoskeleton. However, these conditions are considered normal post-mortem processes originating during the handling and storage of the samples, and do not pose a direct risk to the health of the shrimp. A remarkable aspect has been the detection of ciliated protozoa in the shrimp from Barcelona, while these microorganisms have been observed in smaller quantities in the samples from La Rápita. The presence of these parasites could be indicative of water pollution or poor quality in certain areas of the Barcelona coast. However, it will be necessary to deepen the identification and study of these parasites to determine their pathogenic capacity and their potential as a bioindicator. Finally, it has been seen that although the shrimp from Barcelona have a slightly smaller body size than those from La Rápita, the lowest condition index has been recorded in the samples from the latter location, which suggests that the physiological state of the individuals from La Rápita is worse. In fact, in this area all the recorded histopathologies (encapsulations, cysts and hemocyte infiltrations) have also been detected, which could be related to both environmental factors and possible pathogenic organisms to which the shrimp are exposed. In general, the study has revealed the presence of some pathogens and alterations in the analyzed samples, but the evidence of pathogens associated with the white shrimp found so far is scarce. In addition, no serious lesions or pathologies have been detected in the examined specimens, which could be indicative that the white shrimp populations are not affected by diseases that can compromise their survival. However, further research is needed, expanding the number of samples and conducting seasonal monitoring, to obtain a more complete and representative view of the health status of this fishery resource on the Catalan coast