Abstract. Predictions of ecological patterns can be strengthened through replication of foundational studies under different environmental conditions to evaluate the consistency in their underlying processes. In this study, we replicated Sutherland and Karlson's classic ecology study that tested terrestrial paradigms of community development in a marine fouling community. The abundance patterns of marine fouling species were quantified on sequentially submerged settlement plates to investigate the effects of disturbance date on short-and long-term patterns of community development, and the original study's data sets were reanalyzed for comparison. In both studies, community structure was initially shaped by disturbance date due to monthly and annual variation in larval recruitment; however, the influence of disturbance date diminished over time. Despite these similarities, the underlying drivers of long-term patterns of community development have shifted substantially since the 1970s. During the present study, an exotic tunicate, Clavelina oblonga, dominated plates over time and its dominance was associated with significant declines in species diversity. In contrast, the 1970s long-term community was characterized by a heterogeneous mixture of species that varied inter-annually, yielding increased species diversity over time. Continued observations of our settlement plates (2 yr total) indicated that C. oblonga remains the dominant species in this community, suggesting that these findings are not the result of a single, novel recruitment event. These results highlight how an exotic species can alter patterns of community development and biodiversity. Moreover, this study demonstrates the need to replicate foundational ecological studies to evaluate community dynamics and underlying processes in light of ongoing ecosystem change.

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Invasive species can positively, neutrally, or negatively affect the provision of ecosystem services. The direction and magnitude of this effect can be a function of the invaders’ density and the service(s) of interest. We assessed the density-dependent effect of an invasive marsh grass, Phragmites australis, on three ecosystem services (plant diversity and community structure, shoreline stabilization, and carbon storage) in two oligohaline marshes within the North Carolina Coastal Reserve and National Estuarine Research Reserve System (NCNERR), USA. Plant species richness was equivalent among low, medium and high Phragmites density plots, and overall plant community composition did not vary significantly by Phragmites density. Shoreline change was most negative (landward retreat) where Phragmites density was highest (-0.40 ± 0.19 m yr-1 vs. -0.31 ± 0.10 for low density Phragmites) in the high energy marsh of Kitty Hawk Woods Reserve and most positive (soundward advance) where Phragmites density was highest (0.19 ± 0.05 m yr-1 vs. 0.12 ± 0.07 for low density Phragmites) in the lower energy marsh of Currituck Banks Reserve, although there was no significant effect of Phragmites density on shoreline change. In Currituck Banks, mean soil carbon content was approximately equivalent in cores extracted from low and high Phragmites density plots (23.23 ± 2.0 kg C m-3 vs. 22.81 ± 3.8). In Kitty Hawk Woods, mean soil carbon content was greater in low Phragmites density plots (36.63 ± 10.22 kg C m-3) than those with medium (13.99 ± 1.23 kg C m-3) or high density (21.61 ± 4.53 kg C m-3), but differences were not significant. These findings suggest an overall neutral density-dependent effect of Phragmites on three ecosystem services within two oligohaline marshes in different environmental settings within a protected reserve system. Moreover, the conceptual framework of this study can broadly inform an ecosystem services-based approach to invasive species management.