Relação do tempo de coagulação com a quantidade de Vibrio na hemolinfa de camarões Litopenaeus vannamei oriundos de três fazendas de cultivo do Estado do Ceará

Abstract

Most of the time, shrimp infection by bacteria is mainly caused by Vibrio. These kinds of infections can bring about high level of mortality with significant economic damages in shrimp-producing countries. When bacteria are located in haemolymph, it indicates a general bacterial infection The purpose of the present study is to relate coagulation time with Vibrio presence in the haemolymph of shrimps reared in three farms located in Ceará State, from October, 2005 (dry period) to October, 2006 (rainy period). In all, 18 samples were withdrawn, in each of which 10 shrimps were analyzed. The cultivation time of the experiment varied from 60 to 120 days. The intervening time of haemolymph coagulation in the farms and in both periods varied in the range of 5 - 55 seconds, in the 51 shrimps infected with Vibrio and, for the remaining ones (129) not infected, the intermission time ranged from 4 to 57 seconds. The Plate Standard Counting (PSC) of Vibrio in haemolymph referring to 51 individuals varied from 10 to 28.000 Colony-Forming Units (CUF/mL). For the farms A, B and C the intervening times of Vibrio PSC in haemolymph in the dry period were, respectively, 1,000, from 10 to 140, and from 1.000 to 28.000; for the rainy period, they varied from 10 to 2,000, from 110 to 1,000 and from 10 to 1,605 CFU/mL. Out of 132 isolated strains of the shrimp haemolymph which contained Vibrio, 13 species were identified. The highest diversity of Vibrio was observed in the following decreasing order of the farms, namely B, C and A, and also that haemolymph contamination was mostly favoured by rainfall. No relationship was found to exist between bacterian presence in the haemolymph and coagulation time.