Ecological Archives E095-025-A4

James E. Palardy, Jon D. Witman. 2014. Flow, recruitment limitation, and the maintenance of diversity in marine benthic communities. Ecology 95:286–297.

Appendix D. Detailed effects of flow on species richness.


Fig. D1. Species richness increases with flow in the 2006 Seldovia deployment. Although local richness displayed seasonal variability in the 2006 deployment at Seldovia, species richness (Chao2 ± SE) was higher on settlement plates exposed to enhanced (open circles) flow than on plates exposed to control (filled circles) flow treatments at all sampling dates. Effects of flow treatment is significant (Table D1). For time < 20 weeks, n = 24; for time between 20 and 45 weeks, n = 18; for time > 45 weeks, n = 12.



Fig. D2. Species richness increases with flow at all sites in the 2007 deployment. Local species richness (Chao2 ± SE) on settlement plates exposed to enhanced flow (open circles) was higher than on settlement plates exposed to control flow (filled circles) at sites in Maine (York, Kittery) and Alaska (Seldovia, Jakolof) for flow enhancers deployed in 2007. Error bars represent standard errors of the mean number of species added, and overlap on only two occasions: 5 weeks at York, and 5 weeks at Seldovia. Among times, flow significantly enhanced richness (Table D1). All n = 24. Interestingly, while local richness displayed seasonal variability in Seldovia in the 2006 deployment (Fig. D1), and at York and Kittery in the 2007 deployment, richness continued to increase in Alaska throughout the 90 week duration of the 2007 deployment with no apparent seasonal pattern. Across sites, species richness in control flows varied from 14.0±0.2 species in Kittery to 20.8±0.8 species in Jakolof. In enhanced flow regimes, species richness varied from 23.0±0.4 species in Kittery to 31.7±0.8 species at Jakolof.


Table D1. Analysis of species richness. Paired t tests assessing the effects of water flow treatment on the species richness of communities across all sampling periods.





Seldovia - 2006




Jakolof - 2007




Kittery - 2007




Seldovia - 2007




York - 2007




The abbreviation "df" is the number of degrees of freedom in the t distribution, t is the value of the t statistic, and p is the probability of an identical or more extreme t result if the null hypothesis of no difference between flow treatments was true.

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