During the Late Ordovician (Katian) in the Cincinnati Series of North America, shallow marine ecosystems flourished and remained stable for several million years. Previously isolated ocean basins in the surrounding regions connected due to a sea level rise, leading to an influx of non-native species termed the Richmondian Invasion (RI). The Cincinnati Series thus preserves an ideal sequence of events to test hypotheses determining the effects of biotic immigrations on ecosystem structure and functioning. The RI resulted in several changes in ecosystem dynamics. Loss of species may have led to loss in functional groups and invaders occupied all of the preinvasion functional guilds as invaders replaced incumbents, filling pre-existing niche space and outcompeting natives. The Ordovician serves as an analogy for the Antarctic, as both rely on detritus as significant sources of energy, and both lack durophagous predators. As ocean temperatures continue to rise, polar communities are expected to undergo widespread invasions rapidly. Thus, we plan to compare modern Antarctic and Ordovician ecosystems to analyze community stability, resistance, and to identify potential impacts of impending biotic invasions. Changes in Ordovician food web structure and functioning suggest that conservation efforts may need to focus on preserving functional diversity in Antarctic ecosystems if more diverse ecosystems are not inherently more stable. The modern Antarctic food web is being constructed using the largest modern Antarctic food web dataset published to date (Raymond et al., 2011). Using this dataset, food web models will be built using the consumer-resource links assigned by Raymond et al (2011). Through comparisons between Antarctic and Ordovician food webs, we hope to identify specific aspects of Antarctic food webs that may make them vulnerable to invasion. The response of Late Ordovician paleocommunities to the RI will also be used to make predictions for future immigrations and invasions in Antarctic communities.
Authors: Evan Hill and Carrie L. Tyler
Faculty Advisor: Carrie L. Tyler, Geology and Environmental Earth Science
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