Polychaete infestation in cultured abalone (Haliotis rufescens Swainson) in Southern Chile.
This study employed univariate and multivariate methods to explore the abundance and composition of polychaetes infesting the shell of abalones from 2 representative areas of Southern Chile. 18 and 39 abalones were collected from aquaculture facilities located in Puerto Montt and Castro-Chiloé, respectively. A total of 1867 polychaetes from 7 species were collected. Dipolydora huelma and Polydora rickettsi were the most abundant polychaetes in Puerto Montt and Chiloé, respectively. They accounted for about 97% of the total number of polychaetes collected. Less abundant were species from the genera Serpula (2.14%), Cirratulus, Nicolea, Phyllodoce, Nereis and Potamilla (each <1%). The occurrences of infesting polychaetes were 100 and 72% in Puerto Montt and Chiloé, respectively. The total number of polychaetes increased with the length of the abalone shell. The polychaete species richness and density of P. rickettsi also increased with the shell length, but this increase was significant only in Chiloé. Total density and species richness, as well as D. huelma density were all significantly higher in Puerto Montt. As shown by the multidimensional scaling (MDS) plot, between site- and size-related differences were unrestricted to total density and species richness but included species composition and relative abundance as well. Although the distinction of assemblages associated with immature and mature abalones was less obvious in the MDS, the differences between them were also significant.