Interannual and spatial variation in the parasite communities of Pacific sierra Scomberomorus sierra (Jordan et Starks) on Mexico's Pacific coast

Over evolutionary time host species at higher trophic levels (i.e. carnivorous and piscivorous fish) would therefore be exposed through diet to greater numbers of infective endohelminth larvae from a broader range of parasite taxa than would those at lower levels (Luque and Poulin 2008, Timi et al. 2011). Infection levels for each parasite species were described using prevalence (percent of fish infected with a particular parasite species); mean abundance (mean number of individual parasites of a particular species per examined fish), expressed as the mean ± standard deviation (SD); and intensity (number of a particular parasite species per infected fish), expressed as range (minimum-maximum) (Bush et al. 1997). The total prevalence (i.e. the percentage of infected fish with at least one of the parasite species) and the total mean intensity (mean total number of parasites in each sample) were used to determine possible relationships between the fish total length and these infection parameters within and between locations or sampling years. Component community parameters included total species richness; total number of individuals of each parasite species; the Shannon-Wiener Index (H) as a measure of diversity; species evenness (equitability); and the Berger-Parker Index (BPI) as a measure of numerical dominance.