| Fundulus heteroclitus, the killifish or the mummichog, is commonly found in estuarine waters. Fundulus spp. have played important roles in advancing our understanding of different aspects in biology such as physiology, behavior, and genetics due to their hardiness and distribution and abundance.; Because parasites are so ubiquitous and can affect host physiology, behavior, and ultimately ecology, it is important to know how parasites are distributed among host populations and which populations are more susceptible to infection. A baseline survey was conducted over two-years, examining the parasite communities of 280 F. heteroclitus (138 males, 142 females) from seven sites throughout New Jersey and New York in early and late season collections. The gills, digestive tract, liver, body cavity and swim bladder were examined and all macroparasites were recorded. Parasite communities varied spatially over site and habitat, and temporally by year and season. Host sex did not play a significant role. Salinity appeared to play a large part in structuring communities as did site disturbance (e.g., restoration).; Heavy gill infections (>2,000 parasites) were found in fish from a restored site during the baseline survey so a more focused investigation of F. heteroclitus gills ensued. Using fish from three restored and three unrestored sites from the Hackensack Meadowlands, behavior, physiology, anatomy and gill parasite abundance were examined. Fish from restored sites had the greatest number of digenean trematode metacercariae gill infections (Ascocotyle phagicola diminuta and Echinochasmus schwartzi) compared to fish from unrestored sites. Heavily parasitized individuals spent more time at the water's surface and exhibited more conspicuous behaviors, which could enhance trophic transmission. Heavily parasitized fish also had greater stamina, lower respiration rates, larger red blood cells and greater blood volume. They also induced gill tissue growth, forming additional branches as a response to the metacercariae, probably as a way to compensate for reduced oxygen extraction.; This study has shown that parasite-host relationships are highly dynamic interactions and that heavy gill infections with digenean trematode metacercariae can significantly shape host's physiology, behavior and anatomy. |
