Ecological Archives E096-123-A13
Chelsea L. Wood, Julia K. Baum, Sheila M. W. Reddy, Rowan Trebilco, Stuart A. Sandin, Brian J. Zgliczynski, Amy A. Briggs, and Fiorenza Micheli. 2015. Productivity and fishing pressure drive variability in fish parasite assemblages of the Line Islands, equatorial Pacific. Ecology 96:1383–1398. http://dx.doi.org/10.1890/13-2154.1
Appendix M. Possible correlates of productivity in the across-islands data set.
In our across-islands data set, other factors might co-vary with productivity. Like productivity, temperature exhibits a latitudinal gradient across the Line Islands, with colder temperatures in the south and warmer temperatures in the north (Appendix B). While this correlation is consistent with temperature as the driver of the productivity–parasite abundance relationship, we think this is unlikely. Previous studies have documented increases in parasite abundance with increasing sea surface temperature, particularly for directly transmitted monogenean parasites, probably due to the rapid development rates and reduced generation times experienced by parasites at higher temperatures (Poulin and Rohde 1997; Rohde and Heap 1998; Rohde 2002). In contrast, we observed decreasing parasite abundance overall with increasing temperature (i.e., at more northerly, lower-productivity islands), suggesting that temperature is not responsible for the productivity–parasite abundance relationships documented here. Other physical variables might correlate with productivity across this latitudinal gradient, and caution is warranted in interpreting these results. However, our analysis suggests that productivity is a likely cause of increased parasite abundance at our southerly islands.
Literature cited
Poulin, R., and K. Rohde. 1997. Comparing the richness of metazoan ectoparasite communities of marine fishes: Controlling for host phylogeny. Oikos 110:278–283.
Rohde, K. 2002. Ecology and biogeography of marine parasites. London, UK: Academic Press Ltd.
Rohde, K., and M. Heap. 1998. Latitudinal differences in species and community richness and in community structure of metazoan endo- and ectoparasites of marine teleost fish. International Journal for Parasitology 28: 461–474.