UCLA

Parasitism is one the most common lifestyles on earth. Parasites are important components of virtually all ecological communities and parasite research can help to elucidate many aspects of the ecology of their hosts. This dissertation focused on studying the metazoan parasites of the California grunion, Leuresthes tenuis and other fish hosts in the family Atherinopsidae. In Chapter 1, the metazoan parasites of L. tenuis were investigated at five localities in southern California. A total of 2,902 parasites belonging to 26 taxa were recovered from 900 specimens of L. tenuis collected between 2016 and 2018. Comparisons of parasite communities showed that the parasite fauna of L. tenuis varied among localities. This variation suggests that L. tenuis may stay relatively close to their spawning grounds throughout their lives. In Chapter 2, a redescription is provided of the parasitic copepod Caligus olsoni, associated with L. tenuis and other fishes in the northeast Pacific. Caligus olsoni was morphologically compared to another species, Caligus serratus. In light of the morphological similarities observed between these two species, we propose to treat C. serratus as a junior subjective synonym of C. olsoni. Based on previous reports, C. olsoni appeared to be highly host-specific. However, with the proposed synonymy of C. olsoni and C. serratus, C. olsoni has, in fact, low host specificity, with 16 fish host species currently reported from 12 families. In Chapter 3, the parasite communities of L. tenuis and three other host species in the family Atherinopsidae were compared. A total of 5,677 parasites from 25 taxa were recovered from the four host species. The results showed significant differences in parasite communities in relation to host species. The three most abundant parasite taxa found in this study, which combined accounted for more than 78% of the total number of parasites recovered, were associated with two of the host species. Differences in parasite communities may be explained by variations in diet and feeding strategies among the hosts species investigated.