Meeting Abstract

S10.7  Wednesday, Jan. 6  Non-native ecosystem engineer alters estuarine communities HEIMAN, Kimberly*; MICHELI, Fiorenza; Muhlenberg College; Stanford University kheiman@muhlenberg.edu

Many ecosystems are created by the presence of ecosystem engineers which play an important role in determining species composition. Additionally, a mosaic environment of engineered and non-engineered habitats has been shown to increase biodiversity. Non-native ecosystem engineers can be introduced into environments without similar species, resulting in dramatic impacts on native community composition. Yet, little is known about how non-native ecosystem engineers interact with non-natives already present in the environment and whether non-native engineers are associated with increased local diversity. Through a removal experiment, we explore the effects of a non-native reef-building tubeworm, Ficopomatus enigmaticus, on community composition in the central Californian estuary, Elkhorn Slough. We show that assemblages living in the reefs are significantly different from assemblages in nearby mudflats, with the reefs providing habitat for many non-native polychaetes and amphipods, including Monocorophium insidiosum and Melita nitida. Infaunal assemblages under F. enigmaticus reefs show very low species abundance. Once reefs are removed, the newly exposed mudflat is populated by opportunistic non-native species, such as the polychaete Streblospio benedicti and M. insidiosum, making reef removal a questionable control strategy. There is some indication that the addition of the non-native reefs to the mudflat environment may enhance local species richness. Habitat provision by the non-native ecosystem engineer may be a mechanism for invasional meltdown in Elkhorn Slough.