Ecology of the Brain Trematode Euhaplorchis californiensis and Its Host, the California Killifish (Fundulus parvipinnis)

• Published in: The Journal of parasitology 2010-06, Vol.96 (3), p.482-490
• Main Authors: Shaw, J. C, Hechinger, R. F, Lafferty, K. D, Kuris, A. M
• Format: Article
• Language: English
• Subjects: Aggregation; Agnatha. Pisces; Animals; Aquatic habitats; Biological and medical sciences; Biomass; Brain - parasitology; Brain Diseases - parasitology; Brain Diseases - veterinary; California - epidemiology; ECOLOGY-EPIDEMIOLOGY-BEHAVIOR; Ecosystem; Estuaries; Euhaplorchis californiensis; Female; Fish; Fish Diseases - epidemiology; Fish Diseases - parasitology; Freshwater; Fundamental and applied biological sciences. Psychology; Fundulidae - parasitology; Fundulus parvipinnis; General aspects; General aspects and techniques. Study of several systematic groups. Models; Habitats; Invertebrates; Linear Models; Logistic Models; Male; Marine; Metacercariae; Mexico - epidemiology; Mollusks; Nemathelminthia. Plathelmintha; Parasite hosts; Parasites; Parasitism; Prevalence; Snails; Trematoda - growth & development; Trematoda - physiology; Trematode Infections - epidemiology; Trematode Infections - parasitology; Trematode Infections - veterinary; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Wetland ecology
• ISSN: 0022-3395; 1937-2345
• DOI: 10.1645/GE-2188.1

We describe the distribution and abundance of the brain-encysting trematode Euhaplorchis californiensis and its second intermediate host, the California killifish (Fundulus parvipinnis), in 3 estuaries in southern California and Baja California. We quantified the density of fish and metacercariae at 13–14 sites per estuary and dissected 375 killifish. Density (numbers and biomass) was examined at 3 spatial scales, i.e., small replicate sites, habitats, and entire estuaries. At those same scales, factors that might influence metacercaria prevalence, abundance, and aggregation in host individuals and populations were also examined. Metacercaria prevalence was 94–100% among the estuaries. Most fish were infected with 100s to 1,000s of E. californiensis metacercariae, with mean abundance generally increasing with host size. Although body condition of fish did not vary among sites or estuaries, the abundance of metacercariae varied significantly among sites, habitats, estuaries, and substantially with host size and gender. Metacercariae were modestly aggregated in killifish (k > 1), with aggregation decreasing in larger hosts. Across the 3 estuaries, the total populations of killifish ranged from 9,000–12,000 individuals/ha and from 7–43 kg/ha. The component populations of E. californiensis metacercariae ranged from 78–200 million individuals/ha and from 0.1–0.3 kg/ha. Biomass of E. californiensis metacercariae constituted 0.5–1.7% of the killifish biomass in the estuaries. Our findings, in conjunction with previously documented effects of E. californiensis, suggest a strong influence of this parasite on the size, distribution, biomass, and abundance of its killifish host.